selfstyled

Extruder Hot End

2011-04-15T12:09:00.000-07:00

The hot end of the extruder is working. I can successfully melt ABS (thanks Neil!), I still need to make something to push the filament through it. I'm using old-school MakerBot technology right now: a Mk3 heater barrel, nozzle and thermal barrier. The heater is driven by their PWM board and temperature monitored by their thermistor board. All this was bought a couple of years ago, so it’s now a couple of generations old :-)

My test sketch in my Arduino uses the PID library to keep the temperature constant. Once the temperature was stable I pushed some 1.75mm filament in, and eventually I got some ~0.5mm coming out the bottom. It took quite a bit of force, but it did work. Next step: the extruder motor.

RepRap Progress

2011-04-13T11:38:00.000-07:00

I have all four stepper motors connected mechanically (this design, just like the Prusa Mendel, uses a motor on each side of the Z axis) and driven by EasyDriver boards. I built carrier boards with screw terminals for the motor connection and 12V supply and a 10pin shrouded header to connect to the RepRap motherboard – I used the same pinout as the standard RepRap, no need to reinvent. I wrote a test program to move every axis back and forth one revolution and they all move. OK, I haven’t put the Y axis conveyor belt on yet, and the X axis belt slips. But still....

I then tried to install one of the various firmware packages so I could test more complex patterns that just a diagonal line between opposing corners of a cube. Unfortunately my Arduino sports a 168, which is too small for any of the packages (even Teacup, despite what they claim). I've ordered a 328 from Adafruit, which will double the amount of flash I can use. I will eventually need to buy an Arduino Mega or Uno, but for now I'll get by with a $6 upgrade.

So I've started working on the extruder, which will need it's own controller (so my existing Arduino will not go to waste). I finally managed to get my thermistor and Makerbot temperature sensor board working (more) sanely. And I found some teeny tiny butt crimp connectors to join my NiChrome wire together. This means that I should have a hot end. Now I need an extruder to push the filament through the hot end. But progress nonetheless.

I will be doing the mechanical construction of the hot end today, and maybe try to energize it too (trying not to burn my fingers, literally).

Polyhedra Construction Kit

2011-03-20T15:00:00.000-07:00

When I was building the Valentine’s Dance decorations I thought a tab-A-in-slot-B type of construction would be cool for polyhedra. This idea has been stewing in my mind for a month or so, here is the prototype for a polyhedra construction kit. I will have triangles, squares and pentagons with common edge lengths so you can build whatever polyhedron you wish (although I think you are limited to convex polyhedra, because these pieces are chiral). I started with triangles because they’re the easiest to cut out. I used SymmetriSketch to draw what I thought would be an interlocking edge style. Then I printed it out and glued it (a glue stick works great) to some aluminum flashing, then cut out the aluminum with snips. This became a template for cutting out recycled HDPE from the sides of 4L milk jugs. Then I lightly scored where the folds would be.

I didn’t have enough faces to do a full icosahedron, but I managed to put 5 together. I had to use tape as the faces did not have positive locking as I hoped. That’s what prototypes are for, though. I then tried a tetrahedron, with tape on the outside. It really didn’t want to stay together.

For the next prototype, I am going to create a slot and tab on each edge instead, so there will be locking on both ends of the edge (right now these faces want to twist apart). Actually, V2 would look very similar to SlideTab (ok, exactly like). In fact, here is the PDF of what I had in mind. So, no need to do a V2 prototype, proceed directly to making the polyhedra.

Hmm, I wonder whether the laser cutter at the makerspace can cut HDPE?

Note to self: drink more milk.

1x2 RepRap

2011-03-12T22:40:00.000-08:00

I've been trying to build a RepRap for quite a while now. The problem is that to make its parts you need to print them on a RepRap — a bit of a bootstrapping problem. Then I started to work on a RepStrap. I've done two designs based on the Contraptor system, never getting full X-Y-Z control. I always got stuck on how to control the Z axis. I had been planning on building an SAE Prusa Mendel, carefully building the printable parts out of wood, but recently I saw the 1x2 RepRap posted on Thingiverse. It’s very similar to a Prusa, with some advantages:

all connectors are made of wood
all 90° cuts and holes
non-metric hardware
hand-made drive belts

The only tools you need are a drill press and a hand saw!

Contraptor used 1/4" threaded rod (which is flimsy), this RepRap uses 5/16" (also very close to the 8mm of the official metric RepRap); the Contraptor system uses NEMA 23 stepper motors (large), whereas I have NEMA 17s. Coincidentally the 1x2 RepRap uses them too! And finally, working in wood is a lot faster than working in aluminum.

So here's an out-of-focus picture of what I have so far. I need to order at least one more stepper motor before I can get full X-Y-Z control, but I can move all axes by hand right now.

Day 28: Light table from scanner enclosure

2011-02-28T14:58:00.000-08:00

We had an ancient SCSI-1 scanner lying around, from which I had already scavenged all the good bits, so all that was left was the enclosure. I realized that a little light table would be a handy thing to have, so voila:

It needs some frosting on the glass, and another light (Canadian Tire didn't have enough sockets). But it's good enough (for me) to finish off Thing-A-Day 2011.

Day 25: QubeRs

2011-02-25T21:51:00.000-08:00

Here is my latest artwork. I call it “QubeRs,” it’s 144 cubes that can be assembled into (small) QR codes. Each cube has the 6 possible combinations of 4 black and white pixels on it. One could also use these blocks to do B&W pixel art (welcome to the 1980s!)

I originally wanted to call this the “QR construction set,” but QubeRs sounds cooler.

Day 17: Oblique Strategies Deck

2011-02-17T20:36:00.000-08:00

I've been wanting a physical Oblique Strategies deck (by Brian Eno and Peter Schmidt) since I first heard about them. I used to have a Palm app that would give you a random strategy from the deck, but I never used it because the physical experience was lacking. The idea of making my own has been running through my head for months, but I couldn't find the right weight of paper to use. Inspiration struck, and I've been working on this deck since Monday. I used a double-blank deck of cards from Murray's Trick and Joke Shop, although I really wanted to use two blank-faced decks (they were sold out). I whittled the 3rd Edition down to 104 strategies and then transcribed them onto the deck.

Day 13: a couple of sketches

2011-02-13T20:37:00.000-08:00

Day 12: prototypes for Oblique Strategies deck

2011-02-12T22:39:00.000-08:00

I'm doing some sample layouts for an Oblique Strategies deck by drawing on the backs of old business cards. I'm planning to get a couple of decks of blank-faced playing cards for the proper version so they can be shuffled.

Here are the samples so far...

I am leaning towards making them all the same (instead of trying to match their themes), in which case they'll just be hand-lettered. Perhaps a border too? Drawing the little pictures is a little too much like 1000 blank white cards. Using blank-faced playing cards and Sharpies would be awesome for that game though.

Day 11: Die for making icosahedron faces

2011-02-11T11:06:00.000-08:00

Laurie gave me lots more plates this morning for me to assemble into icosahedra. When I was only making a few of them I didn't think a jig would be necessary (especially when the first one I made was an experiment!) but now is a different story. My hand is sore from the ruler biting into it, so I cut out an isosceles triangle from some MDF and am using it as a die to pre-fold the plates in the proper pattern.

Once again no measuring is necessary, save for setting a compass to 4.5" (radius of a 9" plate). Then it's easy enough to mark the corners of the triangle on the circle. A little drilling and jigsawing later I have a tool that is saving my hand, and saving time.

Day 10: Paper plate icosahedra

2011-02-10T17:29:00.000-08:00

We needed some decorations for the school dance tomorrow night. Laurie D found a picture of an icosahedron made from paper plates and wanted a few of them to be hung from the ceiling. So I made some. At first I did some trig calculating how long each side of the isosceles triangles would be, and then realized that I could just count the ruffles around the edge! Then fold, and staple. These would be really cool to make out of interlocking pieces of plastic, and then lit from inside.

They are quite stable once they are all put together (they are geodesics after all).

Day 9: Mr Shoe

2011-02-09T22:43:00.000-08:00

Well, I started making this with Abbie, before I had to head off to group. Her new Primigi shoes came in an alligator-skin printed box, with a bunch of die-cut flat-pack card that you assemble into the head, tail and feet of an alligator which you then attach onto the box. Zoë and Abbie finished it after I went out.

This is a great idea: instead of just throwing away the box, put a little bit more inside it (they even included some double-sided tape for assembling it) and you get more use and enjoyment out of it. Maybe tomorrow I'll post a picture, right now I'd need to wake Abbie up...

Oh, as for Mr Shoe? That's what Abbie named the box once it was done (she is a Glee fan after all....)

QR Self Portrait

2011-02-08T15:12:00.000-08:00

It is finished. Here are a couple of photos of it on my wall.

This is the thing-a-day for day 8.

QRSP

2011-02-07T22:20:00.000-08:00

Now the hard part, mixing colours. I have basically only the primary colours in acrylic, so my colour theory is getting a workout. I managed to get two colours painted today. I didn't do anything after dinner, there was a Canucks game on.

Day 6: QR self portrait (still...)

2011-02-06T22:52:00.000-08:00

The background QR code has been completely painted. Here are two photos of the work in progress, the first from yesterday when I had half of the black pixels painted and the second once the QR was finished.

Tomorrow I start on the actual portrait.

Day 5: QR Self Portrait, continued...

2011-02-05T23:08:00.000-08:00

The painting is taking longer than one day to complete, but I knew that when I started it. This is one reason I'm not in the official thing-a-day group :-) Today I got the underlying QR code roughed in, and am halfway through the black pixels. The rest of the black pixels and then white pixels tomorrow, and then the fun starts: putting the coloured ones on top. I'm hoping it'll look cool when it's done...

Day 4: QR self portrait

2011-02-04T23:25:00.000-08:00

I started working on my QR self portrait today, it's going to be a couple of days painting. I printed out the QR code and the pixelated image so I can refer to them, and managed to get the grid drawn out on my canvas. I've finished one coat of the black underneath, but I don't have a shot of it here.

In the photo here you can see some of my 3x5 test cards too.

Quick Hydraulics Test

2011-02-03T13:11:00.000-08:00

I whipped up a quick test to see how hydraulics work (day 3, thing-a-day, BTW). I used two different-sized syringes that were lying around, a bit of tubing and some food colouring so the water shows up in the pictures. The large one has a swept volume of 10 mL, the small one 3 mL. I filled the large one completely and left the small one empty when I connected them up to the tubing (also full of water). Nothing like a hands-on experience to enhance the book knowledge. Here you can see the results of depressing the large one's plunger.

Of course this is all old hat to Zoë...

Day 2: sketches

2011-02-02T12:01:00.000-08:00

I carry a sketchbook and pencil around with me now, because the only way to get better at something is to practice! The last time I took an art class was in grade 8 and I absolutely hated it! Only recently have I started to draw again, so here is today's thing-a-day: a sketch.

Moon is now the new alpha male of our cats. (OK, he's the only male, but still...) We've had Moon and his sister Star for two years now. They were feral cats, rescued from behind Camosun College. They are extremely loving now, and have completely adapted to the good life. Here he is in his natural habitat, sleeping on the bed.

Sleeping cats are easiest to sketch, they stay still until you're done. :-)

Bonus sketches: Pango and Moon from before Christmas.

Meat Tray L-game

2011-02-01T13:26:00.000-08:00

As an unofficial participant in Thing-a-Day 2011 my first creation is an L-game made out of meat trays. I've long since lost my original L-game (it may be buried in a box downstairs somewhere), so now is a good time to use my hot wire cutter and use up some meat trays.

Here's a slideshow of the construction process.

My temperature sensor works (kinda)

2010-03-24T15:38:00.000-07:00

After successfully hooking up a stepper motor to my Contraptor frame, and being able to control the motion in one axis, I returned to trying to get my temperature sensor board and thermistor working. I finally discovered that either my RJ45 breakout cable or the RJ45 jack on the board is bad. My initial problem was that I hadn't stripped the ends of the thermistor before connecting to the terminals on the board (hey, I'm a programmer not an EE). Even after that, all the readings from Arduino pin 0 were essentially random. I thought maybe that port was bad (or the header), so I tried pin 1: same thing. Eventually I tried connecting my jumpers directly to the .10" pads on the underside of the sensor board. Then I was consistently reading zeros. This thermistor came with the board, but is not physically the same size as the ones that I ordered at the same time. I am going to try using one of these larger thermistors to see if I get readings that are scaled better. If I still don't, I will have to look at populating the R1 location on the board (after first figuring out what this circuit is trying to do).

Personal Fabrication Update #2

2010-02-19T23:58:00.000-08:00

I am still manufacturing Contraptor hardware, in order to bootstrap myself a RepRap.

I found a Canadian supplier of bearings (for the shaft mounts and linear bearings), and do I ever feel stupid because I knew of them all along. Lee Valley sells sealed bearings for use as guides on router bits, and they stock the two sizes needed for Contraptor components (and 608s that would be useful for RepRap, however I already bought some skateboard bearings). They also now carry more Starrett tools than before; I picked up a Starrett 819 automatic center punch (catalog #30N28.25, I had been using a Veritas automatic punch with pegboard to manufacture perforated angle but it wasn’t up to the job of punching aluminum.

Here are some useful tips for building the hardware that the Contraptor folks either neglected to mention, or figured you already knew. I’m telling you now because I did it the hard way first. If you are using paper templates to lay out your cut lines and hole locations, glue it down with a glue stick. I tried spray adhesive, but that was too slippery (and then a real pain to remove when it dried). Place the paper on your angle with light pressure, adjust to proper position and then press down. Leave it for a minute or two, and then it’s not moving at all. There is also no need to remove the template before drilling. In fact it’s easier to line things up (and you don’t get confused and drill the wrong size hole somewhere). You also don’t need to remove the template before sawing (again, I thought I’d make a huge mess and lose where the next line would be). Cutting the aluminum with a hacksaw is not such a pain (especially with a 32TPI blade and a good saw), I tried using my compound miter saw with a carbide blade, but the kerf is too thick so it throws off all the dimensioning (especially for templates).

Personal Fabrication Update

2010-01-13T22:58:00.000-08:00

I've been spending the last few evenings manufacturing Contraptor elements. Tonight I've half-finished some sliders (I need to find a source for UHMW PE channel to complete them). I'm getting faster and more accurate. Tony G. says that he cuts aluminum with his carbide-tipped blades in his saw, so I gave it a try tonight. I used the cheapie Mastercraft mitre saw instead of the Makita with the expensive blade. It's noisy but it works. The 8.25" Mastercraft blade is only 24 TPI instead of ~ 60 on the Makita, so the edge is a little rough. But it's square, and takes about 1/10 the time of cutting with the hacksaw. Especially the 6063 square tube.

I'm using the template method on the sliders, but gluing the paper on with spray adhesive. I mounted the template last night, and then did all my drilling and countersinking tonight after it had a chance to dry (I went a little crazy with the glue, but that made it easy to adjust the positioning). I don't have a 6-32 tap, so I didn't tap the holes. I may try using steel 6-32 screws as a poor man's tap. Tomorrow night.

One Word

2010-01-04T21:51:00.000-08:00

Mr. McGuire: I just want to say one word to you - just one word.

Ben: Yes sir.

Mr. McGuire: Are you listening?

Ben: Yes I am.

Mr. McGuire: 'Plastics.'

Ben: Exactly how do you mean?

Mr. McGuire: There's a great future in plastics. Think about it. Will you think about it?

Ben: Yes I will.

Mr. McGuire: Shh! Enough said. That's a deal.

OK, how about two words: Personal Fabrication.

3-D printing is getting ready to hit Main Street. Commercial machines, costing thousands of dollars, have been used as prototyping tools in industry. Now a new breed of DIY machines (RepRap, RapMan, Fab@Home, MakerBot) are available to the hobbyist. Granted, these machine are not as fully functional as a $10,000 machine, but they are a disruptive technology (cf. sustaining).

People have said to me “what would I use one for?” I don’t know — yet — but they will become ubiquitous. I think personal fabrication is at the same stage now as the personal computer was in 1975 (when the Altair 8800 was introduced), or the web in 1993 (when NCSA Mosaic was released).

I am building a RepRap. However, RepRaps are self-replicating — many of the parts are printed on RepRaps — there is a bootstrapping problem. Correction, I am building a RepStrap using Contraptor components, with which I will build a RepRap. Right now I am manufacturing Contraptor perforated angle.

Tiny Apps are a good idea

2009-11-19T21:05:00.000-08:00

I like the idea of Tiny Apps: get something out there after a night's work. But there's a bit of infrastructure that needs to be set up:

if it's a "thick" app, where do I store it?
if it's a web app, where do I host it?

I suppose there are also browser add-ins, they'd have the same issue as thick apps.

Some web apps can be run on Google App Engine, I suppose. Or I could fire up an EC2 image. How do I pay for the EC2 usage? Maybe that's step 2 after I get something that people like.