Inventor Tales

The Rivnut - Just Another Blind Fastener Among Many

2025-05-09T19:03:00.000-07:00

Recently, I found myself in a situation where I needed a fastener in thin sheet metal, where I didn't have access to the other side of the material.

That rules out the typical nut. I was going to need a blind nut that could be installed from the outside of the part.

Enter the "Rivet Nut", more commonly called a "Rivnut".

An Autodesk Fusion model of two rivnuts in a piece of sheet metal.

Available in a variety of materials, they can be installed using a variety of tools that all work on the same principle.

The rivnut is installed into its hole, and a threaded mandrel is drawing by a tool to compress the nut tight against the parent material.

One type of Rivnut tool. There are more than one option, though

An uncompressed Rivnut threaded onto the mandrel, ready for installation.

It's similar to a "pop" rivet for those familiar with with those.

It's a pretty quick and easy way to create threads in a part.

An orthographic view of an uncompressed (left) and
compressed (right) rivnut,

An isometric view of the same view above.

I've only used aluminum rivnuts, so my experience is limited to those, but here are the drawbacks I've encountered

1) They're easy to cross thread if you're not careful. I've learned to start the screw with my fingers to ensure the threads are running true. Starting the screw with a socket or any kind of power screwdriver is a recipe for trouble (ask me how I know).

2) "Permanent" is a relative term. While reusable, rivnuts always seem to loosen over time. Eventually you end up with the dreaded "spinner". That rivnut that spins inside it's hole and must be carefully drilled out.

Fasteners out of other materials may be a little less prone to the above problems, but not having used them, I'll avoid speaking "out of class".

In conclusion, the rivnut is a fastener that has it's niche. If you made it this far, you may be thinking "That could be really handy!" or "That thing is useless and the universe will be cold and dead before I touch one".

Either way, that's fine! It's just another tool in the tool box!

As a wise 1980s cartoon once stated, "And now you know."

Acknowledgements:

Rivnut models downloaded from McMaster Carr and modified in Autodesk Fusion to create compressed version.

Fast vs. Effective. There is a Difference!

2025-04-21T21:16:00.000-07:00

This post originally appeared on my LinkedIn profile, it proved to be a far more popular post than I could have guessed, so I decided to share it here as a post.

Lessons of "Fast vs. Efficient". A lesson learned from a new tool, and an old tool

Old school versus new. The speed handle (left),
and the electric screwdriver

While removing and installing inspection panels on an aircraft, I found I love the electric screwdriver for running out the screws.

An example of inspection panels on the wing of a
North American B-25 Mitchel. The quantity required is "P" for plenty.

But I've found for stubborn screws, held in by"Nature's Threadlock" (aka corrosion), or with a boogered up screw-head throws a wrench in the works, you can't beat an old school speed handle.

Why? it has its own advantages.

I have placed the tail end of the speed handle and leaned into a stubborn fastener like a mob enforcer "balancing the books".

I've also have found I prefer the speed handle to install screws.

Why? I can better feel when the screws is run down, and I don't strip out the fasteners

Is the speed handle, with its 100 year old, muscle powered tech as fast as the lithium-ion powered, electric counterpart?

In a word? No.

Do i find that the old speed handle, with its better feel, resulting in fewer stripped screw heads and making quicker work for the next guy?

Arguably. Yes.

The thought it leaves me considering... That job might have been completed fast, to the joy of many who "made the number" this quarter.

But if a year down the road, hours are wasted undoing the minutes saved "getting it done quick".

Was it efficient?

When building a CAD model, there is quick. That means slapping the shape together, and can include:

Under-constraining sketches

Building features on top of features instead of editing the feature (think filling a hole with an extrusion instead of deleting the hole feature)

Creating uber complicated sketches that are difficult to edit.

Over-complicated sketch. I don't like 'em!

Many times, this can allow us to "spank a shape" quickly. But when that shape needs to change? Oh. The horror.

What can help make a model easy to edit? Here are some of my thoughts:

Fully constrain features. It makes model updates much more predictable.

Don't create unnecessary features. By that, I mean if a hole is going away, delete the hole. Don't "plug" it with an extrusion. Don't create a new extrusion on top of another if you can edit the feature and make it longer.

Keep sketches simple. I'll take more simple sketches over one that requires 283 constraints.

And finally, try (as much as possible), to build parts and assemblies in ways that mimic how they'll be made. One place I worked at strived (again as much as possible) to dimension their sketches in the same way as the part would be dimensioned on the drawing.

Are we always able to do this? No. Sometimes, the realities of deadlines force us into a corner. Can we get away with it if it's a "one and done" model that won't change in the future?

Trying to build models efficiently, may not be fast out of the gate, but as the edits, revisions and updates can become much easier.

Future you might be grateful.

Observations of a clever 1940s Design - The Trunnion Nut Socket

2025-01-26T10:23:00.000-08:00

One thing I find fascinating, is looking at old designs and seeing how the designers of the past tackled a problem.

I love vintage aircraft and as part of that passion I like to look at vintage prints for these aircraft.

A drawing that caught my attention was for a "Main Landing Gear Trunnion Nut" for a P-51 Mustang.

A P-51 Mustang at Chino Airport in Southern Californai

In short, it's a big socket that tightens a big nut that holds the landing gear on the airplaane But what I found most interesting was how it was made.

The socket was made in two halves and welded together. The side intended to accept the ratchet is one piece, and the side intended to drive the nut is another piece.

An image of the two separate socket halves

The square drive and 12-point drive geometry are made by broaching. And by making each half separately, it allows the tool clearance to create the geometry. (Not familiar with broaching? Here's a video that shows an example!)

The Welded Socket

Given what I know of 1940s manufacturing, it was a clever way to tackle the problem and design for manufacturing.

Today, the part could be made by using EDM (Electro Discharge Machining), but I can see how the same process could be used to make the part.

3D Printed Parts for an Aircraft Restoration - An Update

2024-10-18T07:35:00.000-07:00

I think it's about time to update on my project 3d printing "faux gun barrels" for the restoration on a Bell P39 Airacobra non-flying display.

A restored P-39 Airacobra

The P-39 Airacobra I'm helping restore.

There's been some progress since my previous post!

The black PETG I was waiting for arrived, and I printed the new barrels using black instead of the gray I used for a test fit.

One of the finished barrels

I found the PEtG I used worked well, but it was a little "stringy", and the finish wasn't quite as good as PLA or ABS. But it's nothing that a little sanding can't fix. It also helps that the barrels will be buried inside the flash suppressors, so a lot of them won't be seen.

One of the guns temporarily placed in its the suppressor

What's left now is a final sanding to knock of the layer lines and a weathering to make the barrels look a little more weathered.

Overall, it's been a pretty good first attempt!

3D Printed Parts for an Aircraft Restoration

2024-09-30T21:10:00.000-07:00

Recently, I had an opportunity to mix some modern technology with the restoration of an 80 year old airplane.

The project is a Bell P-39 Airacobra, which is being restored to be a non-flying display at Planes of Fame Air Museum. One of the tasks I was given was to come up with four faux .030 caliber machine gun barrels for the wing mounts.

An example of a restored P-39 Airacobra
By San Diego Air and Space Museum ArchivesUploaded by Bzuk at en.wikipedia - Source, Public Domain, https://commons.wikimedia.org/w/index.php?curid=24375991

The P-39 I'm helping with has a little ways to go before its finished!

All that was needed was a short length four to six inches so it looked like there was a barrel inside the flash suppressor.

Given the tools I had available to me, I opted to 3D print the barrels.

The first step was to get some measurements. Fortunately, Planes of Fame has an SNJ Texan that has a fake 30 caliber machine gun barrel I could use for measurements.

The SNJ and the barrel I could use for measurements.

With measurements sketched on a piece of paper,, I headed home andI created the model I needed in Autodesk Fusion. It wasn't a difficult model. I had it in about an hour or so.

The 3D Model in Autodesk Fusion

The next step was to print it out. My plan was to print in black PETG, but it didn't arrive before the weekend, so I printed in gray PLA so I would have something to test fit.

The PLA Print in Progress

Once Saturday rolled around, I had a chance to see how the test barrel fit.

I was pleasantly surprised to see it fit well! It fit perfectly in one flash suppressor, and should go into the other three with a little light sanding.

The 3D printed test part next to its "sample

The 3D printed part placed in its tube.
Its not fully seated here.

The 3D printed barrel recessed in the tube.
This will be its final position.

The next step? Print in the PETG I intended to, perform another test fit, and make preparations for permanent attachment.

In conclusion, it was a unique experience to be able to be able to use Fusion to create a model that could be 3D printed for the restoration. I'm grateful for the opportunity.

But my part was indeed small, and I'm not the only one creating models that are turning into parts for this restoration.

To see some amazing Inventor work that has turned into real parts for this restoration, check out Aviation CAD Technotes here!

One last bit of "Legal Talk".

Any opinions expressed here are my own, and not necessarily those of Planes of Fame Air Museum.

Barstool Philosophy - My Lessons From a Dog-Eared Notebook.

2024-08-16T08:50:00.000-07:00

A few years ago, I developed what some might consider an odd habit as I started to learn aircraft mechanics.

Every weekend, I'd sit at the local watering hole, enjoy an "adult beverage" (responsibly of course), and do something not many people see in a pub.

I'd pull out a composition notebook, and write down a few things I learned.

You read that right, a notebook, writing with a pen and paper.

Sometimes it took me five minutes. Sometimes it took me thirty minutes, but I always tried to get those notes record that lesson learned..

It might be something I learned not to do, or some pearl of wisdom from a silver haired mechanic who had been working on airplanes since Kennedy was President of the United States.

I don't recall what prompted me to do it. But I found the act of putting my thoughts on that paper with ink helped me slow down and rethink the lesson. It gave me the ability to relive the lesson, and hopefully commit it to a deeper memory.

Eventually, after a few years of collecting notes, I've got a very well used, and nearly full notebook full of lessons.

Looking at that somewhat beat up notebook, I realized it's a collection of knowledge and experience, something I can look back, and reflect on.

At some point I plan on transferring those lessons electronically, I may even do that on on this blog. While this lessons aren't CAD related, they at the very least may teach transferable lessons to the CAD world.

For now, I'll leave you all with this thought. consider coming up with your own version of the dog-eared notebook. We all learn something every day.

Maybe we just need to take a few minutes to slow down, and remember the lessons.

They can pay off one day, either for yourself, or perhaps for the next person that comes along.

About the Author:

Jonathan Landeros is a degreed Mechanical Engineer and certified Aircraft Maintenance Techncian. He designs in Autodesk Inventor at work, and Autodesk Fusion 360 for home projects.

For fun he cycles, snowboards, and turns wrenches on aircraft.

Barstool Philosophy - When Did I Become the Expert!

2024-05-30T21:57:00.000-07:00

Every once in a while, I responsibly enjoy an "adult beverage" and ponder life.

I call it "barstool philosophy".

The beverage over which much
wistom is shared

Recently, I celebrated my 51st time riding a giant rock around a "gianter" ball of fire floating in the vast expanse of space.

Only a few days after that, I found myself helping seal the fabric envelope on a 1940s vintage Taylorcraft.

The Taylorcraft with fabric
over its steel tube frame

But this time "helping" meant handing the brush to someone half my age and saying, "you're up, kid".

Somehow, when someone said, "he's the expert", and we looked around for that guy, I realized the eyes were looking at me.

It didn't seem right. There's so much I don't know, so much I haven't done yet.

I learned, or rather re-learned, teaching is a different mindset.

It's watching, guiding, stepping in, but not too much. It's saying, "if you do that, this bad thing will happen. Ask me how I know."

But we reached the finish-line in that milestone. The end product was pretty good

The kids looked at me and said , "I hope we did good. "

Little do they know, the thought going through my mind was...

"I hope I did good."

So what lessons did I learn from this anecdote? \ "old guy with experience". I'm not sure when that happened.

But happened it did. And I realized I had something to offer. While I don't know it all, the years had taught me more than I realized. Things that had become second nature by me were new, valuable lessons to those just starting out.

Somewhere, without my realizing it happened, I became a mentor.

I learned patience. I learned to look at a student and say, "You made this mistake. This is what you did wrong." And with a wry smile I'd say, with accurate self-deprecation, "Ask me how I know. I did it too.'

And finally..

This post is pretty far removed from the Computer Aided Design Posts I've done in the past. My life and career has evolved. I'm not as deep in 3D modeling tools as I once was. The versions I use are old, and I don't use them at the level I did a few years go.

But the lesson shares common ground.

For those of use who have a little more gray in our hair, and find ourselves squinting a little harder at our screens because "someone made the fonts smaller".

Look to the fresh faced kids who were born after we graduated high school.

You might have something to teach them.

Why Combine Two Different Radii Fillets in One Feature? - Food for Thought for Autodesk Inventor and Fusion 360

2023-06-30T10:12:00.003-07:00

Once upon a time, I was asked, in reference to Autodesk Inventor and Autodesk Fusion 360, "Why would someone want to have a fillet feature with more than one radius in it?"

An example of two different fillet radii in Fusion 360

It's a fair question. It's likely we can pick a feature in just about any CAD tool and ask, "Why is that there?"


But to that end, I did have a reason one might want to combine two different fillet radii in one feature. 

It's a matter of organization. In my design work, I often find myself modeling O-ring grooves, which nearly always have a different radius at the top and the bottom of the gland. Having the ability to combine the different radii in the same feature allows me to combine the fillets into a "O-ring Radius Feature", and maybe shave down the feature tree a little bit.



An O-ring groove using two different radii fillets in the gland.




O-rings installed in the glands.
Just to give some context to the first image.

Another case I've used was way back when I was designing sheet metal tooling. I used it when "keying" a rectangular insert. In that example, the opening has 3 radii of one size, and the fourth is a different radius. The insert has chamfers of a similar size. This prevents the insert from being inserted in the wrong direction. Why fillets on the opening and chamfers on the insert? It was easier to machine with the tooling of the time!


An example of a sheet metal stamping insert


The"keying" feature up close. 


Admittedly, these two example are very specific to my own design experience. But perhaps it might give someone food for thought.


While you might not run into one of these particular examples I've described, maybe there will be something similar that you can use.  

Is it life changing? Not very likely. But maybe it's a little food for thought as you make your way through the 3D CAD world.

Drilling for Truth - Implied Drill Tolerance

2023-05-29T08:08:00.000-07:00

First, I have to start with my big disclaimer.

While I've had experience with drawing standards, I don't consider myself a full blown expert. There is so much detail in standards, I can't say I'm an authority on all of them.

Also, living in the United States, I work in the ANSI/ASME standards.

My apologies to those who are living the ISO life (which is basically everyone who isn't the United States), I'm only acquainted with that standard.

So this post will be based on "freedom units", that is feet, inches, and bald eagles.

Joking aside, I hope this post is entertaining at least. Onward to the post.

My current place of employment has a lot of legacy drawings. It's not uncommon to find a scanned drawing from the 1970s in our data management system.

It's like digital archeology!

One of the things I find can be a big challenge, and very interesting, is interpreting dimensions, notes, and callouts that have fallen out of favor over the years.

Recently I was part of a discussion regarding a hole callout on one of these old drawings.

The callout stated "Drill" and called out a specific drill size. In the case of the screen capture shown below, the drill size called out is a #30 drill, which is .1285 inches in diameter. But even the diameter is called out as a reference dimension.

The really interesting thing about this callout is that it implies it's own tolerance, in accordance with AND10387.

The tolerances are based on the size of the drill, and a screen capture is shown here from Engineers Edge. You can even see that it has a link to AND10387

But now comes a plot twist.
According to Everyspec, AND10387 was cancelled for new design and is only used for "replacement purposes". No new standard is shown to supersede this one.

So what does that mean?

I wasn't able to find a specific standard that states specifically how to handle drilled holes now. But my experience has taught me that, if required, a tolerance will be implicitly stated next to the dimension. If no tolerance is stated with the dimension, then the block tolerance will be used.

A hole with the tolerance implicitly stated
Since AND10387 is only valid only for replacements, there's a good chance you may never see a drawing with an implied drill tolerance. But there's always a chance an old drawing will rise from the depths. So perhaps it's a good reference to keep in the archives!

And if anyone is aware of a standard that calls out standard drill tolerances, or if you just "do it another way", feel free to leave a comment.

Lessons from a Mentor, a Quarter Century Later

2023-02-06T09:59:00.006-08:00

Sometimes, a lesson learned from long ago comes to pass.

Recently I was working on a project that required I transfer the location of four threaded holes to a piece of aluminum so clearance holes could be drilled. The question was, how to do it?

Sure I could measure out the holes, but the threaded holes were t-nuts pressed into plywood, and the holes for the t-nuts were measured using a tape measure. So the hole placement was made to more of a carpentry accuracy than an aerospace tolerance. But I still wanted to keep the clearance holes as tight as practical.

A 3D model of the T-nut that was pressed into Plywood

But I remembered watching an old tool maker when I was a young engineer fresh out of college. And if you haven't guessed by the title of this post, that was about 25 years ago.... Ouch.

He showed me a "threaded hole transfer punch". It's a small tool that stores threaded screws that look almost like set screws. However they have points in them instead of the hex that one would expect from a set screw.

I had my solution! I placed an order with McMaster Carr for the punch I needed, and I had it in my hands the next day.

They're screwed into the holes you need to transfer. You then position the workpiece that requires the holes, give it a quick strike with a hammer. And now you have marks where you need to drill.

Then it's off to the drill press to drill the holes you need.

The transfer punch tool and two of its inserts.
The inserts are stored inside the tool.
The tool also doubles as a wrench for the inserts.

The transfer punch with two punches threaded into the T-nuts

The marks left in the aluminum from the punches.
I'm afraid I didn't get a chance to get a picture of the drilled holes.

Using the tool that old die maker showed me, in the way he showed me how to use it, I had the holes I needed in no time flat. The whole process took about fifteen minutes. And that includes walking to another building where the drill press was kept!

That's a lot quicker than trying to match the holes by measuring it out.

And, in a strange case of deja vu, a young intern looked over my shoulder and asked me, "How did you mark those holes?"

So it was my turn to pass along the lesson I learned 25 years ago from an old die maker about the "threaded hole transfer punch".

Other than sharing a cool story, what's the lesson?

I would say to look for those small mentoring moments that can sometimes come from the most unexpected places. It might be from someone on the shop floor, an analyst in the corner of that dark office, or a program manager who's "been there and done that".

A lesson can be learned in a few minutes can take years to pay off. But when it does, it can be a life saver!

Wow, that lesson was twenty five years ago.... Thinking of that I'm suddenly overcome by the urge to yell at some kids to get off my lawn....

About the Author:

Jonathan Landeros is a degreed Mechanical Engineer and certified Aircraft Maintenance Techncian. He designs in Autodesk Inventor at work, and Autodesk Fusion 360 for home projects.

For fun he cycles, snowboards, and turns wrenches on aircraft.

Running Stress Simulations on a World War 2 Era Part

2023-01-11T19:41:00.000-08:00

I've been using Fusion 360 to model parts from World War 2 era parts It's a project I enjoy on the occasional evening and weekend.

But some time ago, someone asked me, "Have you ever run a Stress Analysis Simulation on one of those parts?"

It seemed like an interesting challenge. What would a part designed in the 1940s look like when tested with a modern Finite Element Analysis (FEA) tool.

So I decided to fire up the Simulation module in Fusion 360, and set up a stress test to see how a component I'd modeled would hold up.

The part I decided to use was for a P-51 Mustang, made by North American Aviation.

The part itself is the body for a "Hydraulic Landing Gear Uplock Timing Valve". I decided I'd see how Fusion 360's simulation tools would analyze this old component.

First, I set the material. The print listed the material as "24ST", which is a designation now obsolete. However the new equivalent is 2024. So I created that material in Fusion 360's material library, and applied it to the part.

An excerpt from the print.
The 24ST aluminum bar can be seen in the material column

First, I needed to figure out what pressure I would be testing for. Based on the document I found here, the P-51 has a "low pressure 1000psi system". That comes out to about 69 bar in the metric system.

For my test, I'll double that by applying a pressure of 2000 psi (138 bar). I'm using that as my burst pressure for this housing.

As for fixing the part, I used the two mounting holes in the housing.

With all that said and done, it was time to fire the simulation off into the cloud and wait for the results.

All I can say that in the engineering parlance, I'd call this part "hella strong". Even at double the expected operating pressure, the minimum safety factor is about 4.5!

Assuming my analysis setup is good, the part is probably overbuilt and could be optimized to save weight.

So why didn't the engineers at North American spend more time reducing weight?

That I can only speculate on.

But there are some things to consider. The body was created without the benefit of simulation tools. Add the fact North American Aviation was designing this aircraft in the middle of a war, one can probably see how not every part is optimized as much as it could be.

Add to that, the part measures about 3in x 1-1/8in x 1-5/16in (76mm x 29mm x 33mm), Even though weight is important in aircraft, optimizing this part probably wasn't a high priority considering it's small size.

So there we have it! A P-51 Mustang part analyzed in Fusion 360. It was a fun exercise to see what stresses on this part would look like when analyzed on a modern tool!

Happy modeling!

Jon

Acknowledgements:

P-51 Mustang print available from AirCorps Library

P-51 Mustang picture takien at Planes of Fame Air Museum

Why I chose to use Autodesk Fusion 360

2022-12-20T19:00:00.001-08:00

Part of a Hydraulic Valve for
a P-51 Mustang

Recently, I was asked why I used Autodesk Fusion 360 for my side project of modeling vintage aircraft parts. Why not use Autodesk Inventor? Or Dassault Solidworks?

Sitting down one evening, I decided to take a few moments to share my thoughts. These reasons are purely my own, as one guy cranking out models on evenings and weekends. I'm not an evangelist proclaiming my choice is better than yours. It's just that, my choice.

Also, I do pay for a Fusion 360 subscription. I chose to take advantage of one of the promotions a few years back. I know this is likely still a hot button issue for some, but in my case, I'm glad I did. I thought it was

important that I mention that, in the interests of full disclosure.

So, why did I chose Fusion 360?

Accessibility

A hydraulic housing in the
Fusion 360 mobile viewer

The first reason I chose Fusion 360 it's easy for me to get. Yes. It's as simple as that.

Even if I chose not to subscribe, there's a free version that covers most of what I would choose to do. Sure, there's a cost associated with my subscription. But my cost for a yearly subscription is less than I'd spend on a weekend snowboarding. So for me, it's worth the expense to indulge my hobby.

Sure, there are probably ways I could get an educational copy of Inventor or Solidworks. Some are probably above board, others, more "gray market".

At least in this case, I don't have to worry about stepping on anyone's

EULA (End User license Agreement).

Capability

As far as bang for the buck. Fusion 360 does everything I need to do, plus more.

Most of what I do is currently limited to the parts, assemblies, and drawings. I haven't delved into the manufacturing or simulation space. But it's good to know I can do it should the time come!

I have used Fusion 360 to create *stl files for 3D printing and dxf files for a waterjet (see that post here), and overall, I've been happy with the results.

One thing I really like is the way Fusion 360 models threads. More than once I've been able to 3D print a usable thread out of Fusion 360.

A 3D print created with Fusion 360.
The fitting is threaded into 3D printed threads.

Ease of Administration

I've configured installations for Autodesk Inventor, Autodesk Vault, and to a lesser degree, Solidworks. All these tools are incredibly powerful. But with that, comes a great deal of setup and configuation. Where are the templates placed? How are you configuring your data management system? When you upgrade, what's your migration strategy? What are you using for a server?

For Fusion 360, the server is on the cloud, so there's no data to move when it's time to update hardware.

When I purchased a new laptop, I installed Fusion 360 on my new computer, logged into my account, and had instant access to all my designs.

There was no need to migrate files or remap file locations. It was already there. In about an hour's time, I was up and running.

In Summary

In conclusion there isn't much, really.

My big reasons why I chose Fusion 360. It works for me! Does that mean it would work for you on whatever projects you're working on? Maybe, maybe not! That's for you to decide. And whichever way you decided to go, happy 3D modeling!

Using Fusion 360 to Create Parts for a B-17 Restoration

2022-08-15T21:21:00.001-07:00

A portion of the original print used to
create the model.

For many years, I've created models in Fusion 360. On occasion, I've 3D printed a few of my Fusion 360 models as "desk ornaments".

But a few weeks ago, I had a fantastic opportunity to create a model that would be used to make a part for the restoration of a B-17 Flying Fortress.

The part was a "friction washer" for use in the throttle quadrant. And the team needed geometry that could be cut on a water jet.

It started with a reproduction of the original Boeing print. Having the original dimensions made the modeling easy. It was interesting to note that even though standards have changed in the nearly 80 years since that print was created, it's not too different from the prints I work with today.

The model of the friction washer, created in
Fusion 360

Next, was to place the view on a drawing. The first goal was to dimension the drawing as a way of verifying all the dimensions were correct. Second, the drawing is what creates the 2D DXF file for the water jet.

Once the drawing is created, delete any information that isn't required for the waterjet. This includes borders, title blocks, dimensions, centerlines and centermarks, etc. You might even consider creating a second page in the drawing for this purpose.

Also, make sure to save the drawing before you export. I learned the hard way when I realized that the first file I exported still had all that extra geometry. Save the file before export!

The dxf geometry sent to the waterjet

Once I recovered from my snag. I sent the files off to my colleague for cutting.

A few days later, we had our part and it fit perfectly, making for a very satisfying little journey.

And while this little project was well worth a victory lap, there were three minor challenges that are worth mentioning.

1) Drawing standards have changed over the decades, and while the drawing wasn't hard to interpret, some information wasn't where I'd expect it to be. Modern 3D modelers have spoiled us. We can "slap down" a new view in seconds. For the drafters of old? Adding the simplest view would take minutes. A more complicated one? Hours.

The number of views was kept to a minimum. A part of single thickness, such as this one, will likely have the thickness dimension called out in a note.

2) Not only have drawing standards changed, industry standards have changed. That material specification called out in 1943? It's been long superseded by a new standard. It's even possible that the standard that superseded the 1943 standard has, in turn, been superseded itself.

Be prepared to spend a few minutes Googling the updated standards. Thank goodness for the internet!

3) Finally, how does one interpret the tolerances called out on the drawing? Symmetric, +/-.005 for example, is easy. Model to the nominal. But what about a tolerance such as +.010/-.000? Do you "split the difference"? Do you aim for nominal?

In my case, I decided to aim for the dimension as it was called out on the print. I figured that was the target dimension, after all.

And in my case. It worked! Fusion 360 gave me an excellent dxf file that the waterjet used with no issuee, and the part fit perfectly into its intended position.

It was a wonderful opportunity to contribute to a restoration. And a wonderful learning opportunity!

Acknowledgements

Print Reproduction via my Aircorps Library Subscription

Models and drawings created in Autodesk Fusion 360

My Tool Won't Fit! A Design Lesson From Life.

2022-06-07T22:16:00.001-07:00

A typical aircraft brake disk.
There's not much room for a socket!

Hands on experience is often the greatest teacher.

And, while helping work on a friend's change tires on a light aircraft.

In looking at the brake disk, bolted to the tire rim, I saw that there was no way one could get a socket, the ideal tool for the job, onto the bolt.

Fortunately, my friend, having run into this case many times before, had a wrench he'd cut to fit inside the disk. So in the end, it was job that was still very easily accomplished.

But there lies a lesson for those of who sit behind a desk and design the machines we use every day.

Just because the fastener fits, doesn't mean the tool will! So when designing, think of ease of maintenance.

The maintainers, who are sometimes your customers, will thank you for it!

About the Author:

Jonathan Landeros is a degreed Mechanical Engineer and certified Aircraft Maintenance Techncian. He designs in Autodesk Inventor at work, and Autodesk Fusion 360 for home projects.

For fun he cycles, snowboards, and turns wrenches on aircraft.

All PLA Prints the Same, Right? WRONG!

2022-06-03T08:20:00.000-07:00

I print a lot of Polylactic Acid (PLA) in the 3D printer at work. I've found it's a great material to work with. It prints easy, and generally gives great results.

A sample of a different PLA print.
Usually a great material to work with.
Sorry, the actual print is proprietary.

Almost without exception, I have great results.

At least until all of a sudden I start having problems with it!

When printing new color, silver from Amazon the PLA started peeling off the bed.

It didn't matter how much glue I put down on the bed, It would peel up after a few layers.

So what to do?

My first step was to try a few troubleshooting steps.

First, I raised the temperature of the bed from 50 degrees Celsius to 55 degrees Celsius. No luck there.

Next, a thorough cleaning of the bed with isopropyl alcohol. I definitely had a cleaner bed, but still, the problem persisted.

Finally, I found a trick that solved the problem. Move the nozzle .05mm closer to the bed. Success!

The Z setting adjustment in my slicer.
I moved the nozzle slightly closer to the bed.

What is it about the silver filament? I'm not sure. But during my troubleshooting, I did notice that the gray filament did appear to be laying down a thinner layer.

My only guess is something with the dye used to color the filament. But that's just a wild guess.

So what's the takeaway?

Keep an eye on those layers, and remember that not all filament of the same material prints the same!

Resources used for this post:

3D Printer: Fusion3 F400

Filament: Amazon Essentials Silver

Slicer Software: Simplify3D

About the Author:

Jonathan Landeros is a degreed Mechanical Engineer and certified Aircraft Maintenance Techncian. He designs in Autodesk Inventor at work, and Autodesk Fusion 360 for home projects.

For fun he cycles, snowboards, and turns wrenches on aircraft.

So Solidworks Happened at Work Today - A Musing

2022-05-10T07:12:00.005-07:00

I've spent just over 20 years working with 3D CAD programs. That experience has been nearly exclusively with the Autodesk manufacturing product line, starting with Mechanical Desktop (shortly after the earth cooled), and followed by Autodesk Inventor.

We've all seen the ubiquitous, 3D model, floating in space.

A couple of years ago, my company decided to experiment with switching to Siemens NX.

That experiment, unfortunately, failed. Siemens NX, while a good program, wasn't the right program for the needs of my employer.

A few months ago, my company announced that we would be going to Solidworks.

Other than dabbling in it a few times, I've never touched Solidworks. This could be an enormous change for me.

Or not, perhaps?

CAD Tools - Is it just
a Virtual Toolbox?

I completed an abridged "transfer training", where we were shown where all the buttons were and how Solidworks ticks. After that, we were released upon the world.

And what did I find? Were my eyes opened to a brand new world? Was Solidworks so much better that I wondered what I was missing?

Did I wail and gnash my teeth because Inventor was far better and I was being forced to use this inferior product?

No. I left that training and thought, "Wow! They're really similar."

Sure, Solidworks has an Extrude and and Extrude Cut button, while Inventor has the same options combined within one Extrude command. But they both add and remove material in the end.

There's functions where I think Inventor has it down better, and others where I have to give it to Solidworks.

In the end, I see it as an opportunity to learn a new skill, enrichen myself, and be more marketable in a competitive world. I think that's going to take me further in the long run.

So I suppose the point of my writing this is to muse about how CAD programs are tools. They're not the endgame, there the means to create our designs, drawings, and help us build our products.

And there's nothing wrong with learning a new set of tools. It can only make me a more marketable designer.

One Final Note.

If you're using Fusion 360, you can change your Pan, Zoom, Orbit shortcuts to reflect Inventor or Solidworks, among other programs?

I've switched mine to Solidworks, it may not be the same as having Solidworks at home, but it does makes it easier when I switch from one to the other at work!

The Pan, Zoom, and Orbit options in Fusion 360

The Chamfer Note. Does It Say What You Mean?

2022-03-12T07:49:00.001-08:00

Many CAD tools contain a chamfer note that I would describe as a leader style.

You've probably seen it, probably used it even.

It utilizes a leader to point at the chamfer, and contains both the chamfer distance, and angle in one simple note.

The advantage of this style is it's compact, easy to read, and especially easy to place when the chamfer is packed into a crowd with other nearby dimensions.

But this dimensioning style as a subtle disadvantage. This style of dimension doesn't identify the direction of the chamfer. So if the chamfer angle is something other than 45 degrees, the angle direction is open to interpretation.

Even though the chamfers are different, the callout is is the same.
It's also correct in both cases.

That literally means that a chamfer in either dimension meets the print. That can cause confusion, and possibly "heated debates" when a parts acceptance or rejection hangs in the balance.

The other option is to call out the chamfer distance and angle as separate, distinct dimensions. This identifies the direction of the chamfer much more clearly.

Of course everything is a trade off, and this method does take a little more room on the page than the leader style. Even on the image above, you can see that the page is a bit more cluttered, and someitmes a detail view is required to ensure all dimensions can be clearly seen.

In the end, I find I use both. The leader style is used for 45 degree chamfers, since there isn't really an angle direction to speak of. However, when the chamfer is an angle other than 45 degrees, it's time to employ the explicit style, and make sure the direction is clearly shown.

Ultimately, it's up to you which chamfer style you use. Perhaps you have the advantage of tribal knowledge to correctly identify these features. Or you have other means to make sure the chamfer is cut the correct way.

If anything, this is a good practice hailing from the time when "back to the drawing board" was a much more literal statement!

About the Author:

Jonathan Landeros is a degreed Mechanical Engineer and certified Aircraft Maintenance Techncian. He designs in Autodesk Inventor at work, and Autodesk Fusion 360 for home projects.

For fun he cycles, snowboards, and turns wrenches on aircraft.

New in Fusion 360 - Improved Thread Notes

2022-02-03T21:05:00.000-08:00

Sometimes it's the little things that make a guy happy.

A thread note placed
on an external thread

In this case, it's the improved thread annotation tool in the January/February Fusion 360 update.

In short, Fusion 360 can now create an annotation for a thread note placed with the thread tool, not just the hole tool as was the case in previous updates

That opens up the field to place thread notes onto external features. It's a capability I've personally been hoping would get added for some time.

Admittedly, applications like Inventor have been doing this for what seems like eons, so it's hardly a "ground-breaking" feature.

But it sure is a nice feature to have!

All you have to do is place the note using the "Hole and Thread Note" command, and you're off and annotating.

Locating the "Hole and Thread Note" tool

One little cool thing I noticed in my evening of poking about.

The tool works with threads created using the "modeled' setting too!

A modeled thread with a thread note.

I've been waiting for this enhancement for a while! I'm glad it's finally here!

About the Author:

Jonathan Landeros is a degreed Mechanical Engineer and certified Aircraft Maintenance Techncian. He designs in Autodesk Inventor at work, and Autodesk Fusion 360 for home projects.

For fun he cycles, snowboards, and turns wrenches on aircraft.

A Milestone Creating a Fusion 360 Title Block!

2022-01-08T07:49:00.001-08:00

I have completed the task I challenged myself with in my previous post. I finished up my reproduction of a 1940s era North American Aviation title block in Autodesk Fusion 360!

The original, and Fusion 360 Title block together

It was a little tedious at times, it's a lot of repetitive sketching geometry and inserting text and properties.

But it's completed, and ready for use. I'm sure I'll find a few more things to adjust as I test it out.

Ultimately, I was able to recreate nearly every feature of the title block. It's not an exact match. I couldn't find a solid fill to block out the box above the part number for example. But it is close, and it will serve it's purpose just fine.

As more features get added to Fusion 360, I'll update the title block accordingly.

The North American Aviation tile block finished

So now, it's time to start creating drawings! From there, I'll learn more lessons and make more adjustments!

Credits:

Title Block Sourced from my Aircorps Library subscription.

About the Author:

Jonathan Landeros is a degreed Mechanical Engineer and certified Aircraft Maintenance Techncian. He designs in Autodesk Inventor, Siemens NX, at work, and Autodesk Fusion 360 for home projects.

For fun he cycles, snowboards, and turns wrenches on aircraft.

A Trick - Creating Fusion 360 Title Blocks from an Image

2022-01-02T08:39:00.003-08:00

Happy 2022! Here's to hoping for a prosperous loop around the sun.

One of my latest endeavors has been recreating 1940s aviation prints as 3D models in Fusion 360. The drawings are available via my Aircorps Library subscription, and they're a great look into how parts and assemblies were documented nearly 100 years ago.

A piston for an actuator on a North American P-51 Mustang.
Model created in Autodesk Fusion 360

The models are the fun part for sure, but I also decided to recreate the drawings themselves too.

The first part of recreating the drawing, is to recreate the title block of course.

The title block image, ready for import into Fusion 360

It's still a work in progress, but I thought I'd spare a moment to document my progress.

It almost goes without saying, the process can be tedious. Since the original drawings are hand drawn, they have to be recreated from scratch.

The thought of trying to "eyeball" the title block wasn't very appealing, but finally an idea dawned on me that made the process much less challenging.

I imported an image of the title block, scaled it to a suitable size, and laid out the geometry on top of the image.

The title block in Fusion 360. The lines sketched in Fusion 360 are highlighted.

Overall, I felt pretty well. But there was one thing I did have to overcome

There's no image opacity setting like there are in other parts of Fusion 360. But I was able to see where my sketched lines were by highlighting them. I also extended the lines beyond the edges of the image. I can always trim them later.

Finally, I'd also use the good old, "Delete, Inspect, Undo" trick by deleting the image, inspecting, and undoing the delete.

Overall, its working pretty well. I've found the process is much faster, accurate, and less frustrating than trying to scale by using the title block in a separate window.

As I said earlier, it's a work in progress. I'll share my final product when I'm done. Give me time, it might be a while! This is an "evening here and there" project!

One Final Note

The team at Aircorps Library have done a spectacular job collecting, scanning, and sharing these vintage documents. Out of respect for their work, I won't be sharing any documents or models. Please, don't ask me to do so.

If you are really interested in their documentation, feel free to check out their site and investigate a subscription yourself!

About the Author:

Jonathan Landeros is a degreed Mechanical Engineer and certified Aircraft Maintenance Techncian. He designs in Autodesk Inventor, Siemens NX, at work, and Autodesk Fusion 360 for home projects.

For fun he cycles, snowboards, and turns wrenches on aircraft.

A Musing on Modeling Safety Wire - How Much Detail is Necessary?

2021-05-06T21:14:00.001-07:00

A question that was recently posed to me was; "How would you model safety wire in an assembly?"

Safety wire on a fuel
divider on an
aircraft engine

At first, I thought I'd write a post trying to summarize the standard, and how I've seen it approached in my travels over the years. But no matter how I tried to "summarize" the standard, it ended up too long, and so dry it put me to sleep. So instead, I'm going to try writing this briefly, and hopefully to the point.

First of all, Safety (aka lock-wire) is small diameter wire of various sizes that is used to prevent fasteners from loosening and ultimately falling out. It should always pull in a direction that tightens the fastener. It's usually twisted with 6-8 twists per inch.

Of course there are more details, but they're covered by standards. In my aviation maintenance travels, that standard is AC43.13-1b, issued by the Federal Aviation Administration (FAA). In my engineering travels, that standard is NASM33540. I'm sure there are other standards.

That's important. The standards tell the installer how to secure the fasteners with safety wire.

So when it comes time to show safety wire on a model or drawing, is it normal to show the twisted wire? Is it modeled exactly as shown in the

image to the right?

Heck no! That takes a lot of time and computer resources, which gets expensive fast. And having a standard to reference, there's little to be gained other than bragging rights for the designer.

Instead, I've seen, and used, on of two alternatives.

The first, is to use a sweep in the model, showing where the wire should go. This takes a little modeling time and dedication, but it will show up on the model, and propagate to the drawing when its created.

Safety wire shown in the model.
I've colored it in red here to make it stand out.

The modeled sweep representing the safety wire on the drawing.
A leader references the standards in the notes.

The other, is to use sketch geometry when the drawing is created. It takes a bit of time to sketch in the drawing, but the results do a good job of showing the desired result.

Sketches on the drawing calling out the safety wire
Circles and lines represent the wire's twists.

Which ever method is used, a note can call out the standard to be complied with. So the wire shown on on the drawing and model show where the wire should go, the note calls out the standard to reference.

If the installer has any doubts, the standard should be readily available for reference. I know in many cases, it's probably even legally required to be available.

The next logical question for a reader may be, "How does this apply to me?" After all, while safe wire isn't uncommon, there are plenty of users who live long, fulfilling lives without ever touching safety wire.

If you get anything out of this post, ponder if there's anything that can be streamlined by adding more or less detail? How detailed does the model of that purchased part need to be? Are you spending extra time showing model details that are covered by a standards that can just be shown by a note with a leader?

Perhaps take a few minutes to think it over. You might find you save hours!

Acknowledgements

Models created by me in Autodesk Fusion 360

McMaster Carr models used:

Round Head Screws (wire lockable) - P/N 90350A310
Flat Washer: P/N 92141A011
45 degree elbow (37 degree flare to NPT): P/N 50715K637
90 degree elbow (37 degree flare to NPT): P/N 50715K413

FAA Reference for Safetying: AC43.13-1b (See page 7-19)

NASM33540: This document is only available for purchase, so I've added a link to the old standard, MS33540. It's very similar to NASM33540, as well as AC43-13-1b

Getting Jacked - A Simple and Clever Way to Separate Parts

2021-02-11T19:06:00.001-08:00

One thing using 3D CAD programs has taught me, programs like these can make assembling parts together a piece of cake! With just a few clicks, parts can be quickly placed into position.

3D CAD systems have many ways of assembling components

But just because a constraints allow us to easily assemble and disassemble parts, doesn't mean that it will be so easy to do on the assembly line, or during maintenance.

One example is a seal, such as a gasket or packing that locks the two mating parts together. For example, in the image below, the O-ring creating the seal may cause enough friction to prevent the flanges from being easily separated.

The O-ring sealing the components could be enough to "friction lock"
the assembly, making it difficult to take apart.

One option would be taking a screwdriver or another prying device between the flanges and pry like you're opening a casket of pirate treasure. But while a tempting option, wedging a prybar between the flanges could result in damage to the flanges. If the flanges are made of a soft material, such as aluminum, the odds of damaging the parts goes up significantly.

But the designers of old did come up with a more elegant way of separating these... sticky problems.

Many times, assemblies such as these will have tapped holes that appear to go nowhere. They don't have a corresponding hole in any mating part. They just appear to.... be there.

Why were these holes put there? They do have a purpose!

That's because they aren't there for the purpose of assembling parts. They're for disassembling parts.

They're called "jacking holes". By carefully threading screws into these holes, the two flanges can be pushed apart evenly without damaging the parts making up the assembly.

Using a socket head cap screw to separate the flanges.

It's a simple, and elegant way of solving a challenge.

So if you should find yourself having to disassemble an assembly similar to what I've shown here, look for those jacking holes and see if it can make your life easier.

And if you find yourself designing a component that may present a challenge, perhaps adding a couple of jacking holes might make for a design that's easier to disassemble when the need arises!

Opposing jacking screws help separate the flanges evenly!

About the Author:

Jonathan Landeros is a degreed Mechanical Engineer and certified Aircraft Maintenance Techncian. He designs in Autodesk Inventor, Siemens NX, at work, and Autodesk Fusion 360 for home projects.

For fun he cycles, snowboards, and turns wrenches on aircraft.

Standard Parts Used on this Project

A569-343 Viton O-ring - McMaster Carr Part Number 9464K173

Buna-N -343 Backup Ring - McMaster Carr Part Number 5288T372

1/2-13 x .500 Long Socket Head Cap Screw - McMaster Carr Part Number 92185A712

Double Checking Your Work and Subverting Mr. Murphy

2020-09-13T11:51:00.001-07:00

I once saw a graph that showed the cost of making a change in the CAD model vs further down in the product design cycle

Spoiler alert! It gets more expensive as you move from design, to prototype, to production.

One need only to cases like the Takata airbag recall, or Boeing 737 Max grounding or the impact of the impact of a a production level design change in in money, company reputation, and tragically, in lives lost.

But I'm not here to write about such heavy topics. The example I'm choosing to document is a much lower stakes version of the same thing. It's just a basic hobbyist example that at worst, is inconvenient and marginally embarrassing.

It's an access panel based on something you'd find on an aircraft. It's a concept for a potential future hobby project. I built one back when I was in school.

So I happily modeled away in Fusion 360, creating sheet metal parts and placing fasteners from McMaster Carr.

After spending a couple of evenings of casual modeling, I was done! I took that moment we all love, I leaned back, looked at my work proudly, then prepared one last check before I took my little victory lap.

The completed inspection hangar, or so I thought...

And that's when I saw it.

The countersunk rivets I had installed were the wrong ones. I'm not sure how I missed it initially, but obviously I did.

So first, what's wrong with the rivet?

It's a rivet with a 78 degree countersink, which means the countersink extends to the second sheet of metal being riveted. This is a big no-no. When the countersink extends into the second piece of metal, the larger hole required in the first sheet of metal makes for a weaker joint.

The wrong rivet. I did match the countersink angle to match the rivet for clarification.

The incorrect rivet for this application. The countersink angle is too steep

The correct rivet is a 100 degree rivet. The shallower angle prevents the head from punching into the second sheet of metal. That means a stronger, and safer joint.

The 100 degree rivet, the correct one for this application.
I know in the model the rivet does appear to just clip the second sheet.
But past experience has taught me that this combination does work.

The shallower angle of the 100 degre countersink makes a stronger joint

So that's the technical aspect of it, what's the other lesson?

I suppose the first lesson is make sure to check the hardware before you put it in. But we all make mistakes. That's where double checking comes in.

A final check can help prevent the last little "oops" from slipping through. Even though we can't eliminate them all, we can reduce them with a little time.

For those of us working in industry, a second set of eyes never hurts. In some places, multiple checks on a drawing are required. It's not a bad practice at all, one I think should be taken advantage of whenever possible.

Some may argue it takes time, but it takes much less time than undoing a costly mistake.

I've worked in maintenance shops where "second eyes" is a standard policy on items such as fuel system repairs. In other words, the person performing the work checks his work, and then a second technician or inspector checks it again. There often are even signatures required to prove that this step was performed.

But that's it for today's anecdote. I re-learned a few lessons in a safe environment where the only bruise was to my pride.

I hope you can take a few lessons from this musing, and keep making cool stuff!

About the Author:

Jonathan Landeros is a degreed Mechanical Engineer and certified Aircraft Maintenance Techncian. He designs in Autodesk Inventor, Siemens NX, at work, and Autodesk Fusion 360 for home projects.

For fun he cycles, snowboards, and turns wrenches on aircraft.

Additional Resources:

A nice rundown on different types of rivets by- Hanson Rivet and Supply

A wealth of knowledge on general airframe repairs (start at page 4-31 for the Riveting Section) -Aviation Maintenance Technician Handbook

Standard Parts Used on this Project.

.125 Diameter, 78 Degree Solid Rivet (The Wrong One) - McMaster Carr Part Number 97483A075

.125 Diameter, 100 Degree Solid Rivet (The Right One) - McMaster Carr Part Number 96685A170

10-32 Floating Nut Plate - McMaster Carr Part Number 90857A129

.094 Diameter Rivet (to Fasten Nut Plate) - McMaster Carr Part Number 96685A143

#10 Flat Washer - McMaster Carr Part Number 92141A011

10-32 Pan Head Phillips Screw - McMaster Carr Part Number 91772A826

Designing for O-Rings and Reusing Design Features in Fusion 360

2020-07-31T08:40:00.011-07:00

O-ring seals are hard to avoid as a mechanical designer of any type. They can be found just about anywhere that fluid, gases, or debris needs to be kept in or out of something.

An O-Ring on the end of a flashlight

As simple as they appear, there's enormous amounts of research invested in that simple, pliable polymer ring.

How does this affect the designer? Typically by the pages and pages (real or virtual), containing tables and tables of o-ring groove dimensions.

O-Rings from a
different flashlight.

When it comes time to apply that to a 3D modeler, that means creating the o-ring grooves, including some tight tolerances. The process can be extremely tedious, especially when there are multiple o-rings of different sizes involved.

So how can a user create these o-ring glands as painlessly as possible? Sure, many of us have placed the same feature so many times we have the dimensions memorized. But why do that, unless you like that sort of pain?

While I can't speak for every CAD tool, many tools have wizards that will help create o-ring glands, as well as other common design features. Autodesk Inventor has iFeatures, Solidworks has Library Features.

Fusion 360 doesn't have a library feature as such, at least that I've found at this point. But, there is a way to create such a thing and make life a little easier.

Preparing the O-Ring Gland

The first step, is acquire the documentation with the necessary dimensions. Lately I've become partial to the Parker O-Ring Handbook myself, seeing how they know a thing or two about sealing.

For this example, I'll use a -018 o-ring. It's a static (non moving) seal, and I'll use the male gland as an example (stop snickering, that's Parker's terminology).

Gland Schematic from Parker O-Ring Handbook

Here are the dimensions pulled from the design tables

From Table 4-1

C=.860/.861

F = .750/.754

Corner break = .005

From Table 4-1A

W = .105/.110

From Table 4-2

R = .005/.015

O-Ring Groove Radius

Modeling the O-Ring Gland

Before creating any models in Fusion 360, enter the relevant values into the parameters dialog box. This seems like extra work, but I think it makes creating models with new sizes easier.

The Fusion 360 Parameters screen with the o-ring parameters started

Now, draw the profile of the o-ring gland, using the values from the parameters table.

The gland profile sketched and dimensioned.

Next revolve the profile into a solid. Now, we have a solid representing the shape of the groove.

The o-ring groove revolved as a solid.

Believe or not, that's it for creating the gland. Saving it will make it available for other components to use.

Inserting the O-Ring Gland

What's needed next is a component in need of an o-ring. In this case, I've modeled a simple plug in Fusion 360. It's similar to the threaded plugs found here on the McMaster Carr site. I've just moved the gland location to make things a little more clear.

A threaded plug

To place the o-ring gland, right click on the file in the Data Panel and choose "Insert into Current Design". This places the gland into the model

This inserts the gland into the plug. Now it can be positioned by using the Move/Copy command, or assembled using the Joints command.

Placing the o-ring gland. The Move\Copy command is shown.

After positioning the gland, use the combine command to subtract the gland volume from the plug.

Once the Combine Command has been committed, the plug is finished. And you also have a -018 gland ready to use in your next design!

The finished plug. (Don't forget to hide the original solid!)

But undoubtedly, other o-ring sizes will be needed. That's where using the parameters can come in handy. Just copy the existing gland and rename it, then enter new values in the chart.

Summing it Up

I only used static o-ring grooves for this post. There's also dynamic (moving) seals, face seals, glands that use backup rings (for higher pressures), and probably something else I'm not mentioning. I just can't get into them all, but the data is out there. It's just a matter of looking and asking questions.

As for desigining the gland, the steps I've shown here are for Fusion 360. But if you've made it this far, I hope it's the process you take away. I hope that you can find it helpful, and perhaps can apply it to what ever product you use for your design.

At the very least, I hope you walk away with resources that you can use when the time comes to design for o-rings.

And lastly, here's the list of resources I used in this post.

Parker O-Ring Handbook - PDF Download

McMaster Carr - Website

Milwaukee Penlight - From the Home Depot Website

Mag Instruments Maglite - Mag Instruments Website

Autodesk Fusion 360 - Autodesk Website

Lessons from the Shop Floor - Helical Inserts do more than Repairs.

2020-06-12T09:43:00.007-07:00

Many technicians, designers, and fabricators are familiar with helical inserts, often referred to by their trade name "Heli-Coil".

A helical insert in an exhaust manifold

These inserts are made of a coil of diamond shaped wire. Looking like tightly wound spring, they can be installed in a special threaded hole to create standard metric and imperial threads.

In my early experience, I only saw them used to repair a damaged thread. As a matter of fact, they were used for thread repair so often, the name "Heli-Coil" became a verb.

"Curses! This thread is completely boogered up! I'm going to have to Heli-Coil it! This why you always start a screw with your fingers!"

But as I gained more experience, I saw two additional uses for helical insert, and that's what I thought I'd share in this post.

Wear Resistance

A 3D model of a free running (non-lockng)
helical insert in an aluminum block

The first is to create a wear resistant hole in softer material, such as aluminum. Instead of waiting for the hole to get worn out, a helical insert is installed in the hole at the time of fabrication. The helical insert is made of a more wear resistant material such as stainless steel, although there are other materials available. This creates a more durable hole better suited if repeated installation and removal of the fastener is expected.

You might see this on a panel that needs to be removed periodically for inspection. Naturally, once the inspection is competed, the panel needs to be reinstalled. The more wear resistant helical insert lasts longer, and resists damage caused by cross threading.

And if you have a really bad day and damage the insert, it's possible to remove the insert and install a new one without damaging the base material.

Create a Locking Element

A 3D model of a locking helical insert.
Note the deformed thread in the middle.

Another element is to create a hole with a locking element in it. Locking helical inserts have a distorted thread in the middle that resists the screw backing out. By using a locking insert, the need for a screw with its own locking element, such as a nylon pellet, can be eliminated.

While this may seem like extra work for not much gain, this can be advantageous since you don't need to purchase fasteners with their own locking elements. Another advantage is in higher temperature applications where a nylon locking insert's performance may degrade to the point where it loses effectiveness.

And just like it's non-locking (also known as "free running") counterpart, it can be removed and replaced ,when it's locking element loses effectiveness.

Wrapping it up

I've written this post based on helical inserts, but there are many styles of threaded inserts. Far more than I know about, let alone discuss in one post. So if the helical insert isn't your speed, there's likely another that will do the trick.

For a sampling of just some of the different types of threaded inserts available for different applications and materials, take a look at the McMaster Carr catalog!

I hope you found this post helpful and informative.

Let's get out there and design, fabricate, and maintain some stuff!

Appendix and Credits

3D models created in Autodesk Fusion 360.
Threaded insert models downloaded from McMaster Carr
Threaded insert models are based on the NASM/MS21208 standard for non-locking inserts, locking inserts are based on the NASM/MS21209 standard, although several standards, both imperial and metric, exist.

Finally! Looking for a video on how to install a helical insert? Check out this video here!

Photo Credit: rustyheaps Repairing exhaust manifold, XK engine via photopin (license)