Tuesday, December 13, 2011

Cardboard snowman

As part of my company's Christmas festivities, we are having a snowman building competition.  It rarely snows in central Texas, so the only rule to the contest is that our snowman has to be made of cardboard. 

Mine is pretty much complete except for the nose and the final wiring.  He waves his arm and the corncob pipe houses an LED that fades on and off, simulating a smoldering pipe.  Here's a quick preview.

Saturday, December 10, 2011


Here's something I'm working on.  I might do an instructable on this.  More to come...

Wednesday, December 7, 2011

Iphone Tripod Mount

I wanted a way to mount the iphone on a tripod so I bought a cheap iphone case, some right angle aluminum extrusion and four 4-40 x .5" flat head screws.  The aluminum extrusion is 1 x 1 x .125" and can be found at your local hardware store.  The half inch screws are kind of long but that's what I had on hand.  4-40 x .25" would also work.  I cut two 1.5" lengths of the aluminum extrusion and drilled holes to tap the 4-40 threads into one side and 1/4-20 threads in the other side (your tripod should use a 1/4-20 screw to attach to cameras).  Next I drilled and countersunk the 4 holes into the iphone cover to mount the aluminum brackets.  When you screw the brackets on, the screw heads should sit below the inside surface of the iphone cover.  Cover the screw heads with tape to protect your iphone from being scratched.  Insert your iphone and attach it to your tripod and you're done!  Now you have a stable camera mount for photos, movies, stop motion, time lapse or whatever you want.

Monday, December 5, 2011

555 Toy Organ

I built the Toy Organ found on page 23 of Forrest M. Mims III's book Timer, Op Amp & Optoelectronic Circuits & Projects.  You can buy the book at your local Radio Shack. Part number 62-101.

I added a toggle switch for power and a LED to indicate power.  Mine uses a 9V battery. If I build another one, I'll add a pot for volume control and probably mount the buttons closer together or in a different layout.  It would be neat to experiment with different types of switches as well, like a slider instead of a rotary potentiometer, smaller buttons with less travel in the actuator would also be nice.

It's fun to play with even though I have no musical abilities.

Tuesday, November 22, 2011

Watch Case Wrench

I just made my own watch case wrench via Make volume 28, page 128. Works like a charm.

It fits in the notches on the outside edge of the case cover.  Simply unscrew cover, replace battery and reinstall the cover.

Tuesday, April 5, 2011

Goodbye MK4, Hello Paxtruder

Continuing from the last post...  I wanted to use two idler wheels to make a wider surface for the filament to ride on.  I slightly sanded the bore of the idle wheels and pushed them onto the bearing.  It wasn't a press fit, but it was snug.  There was some masking tape residue on the wheels, so I wiped them with alcohol.  Both wheels began to crack as I cleaned them, they didn't fall apart but the did split.  Goodbye idler wheel.  Don't let the door hit you on the way out.

I'm moving on to the Paxtruder because I really like the simplicity of the design.  In a Paxtruder, the idler wheel is replaced by a block that presses against the filament from the side, keeping it in contact with the motor gear.  The MK4, idler wheel was held in place by a bolt that acted as the axle, but it was tough to get it to stay in place and even more difficult to adjust.  The block in the Paxtruder is adjusted with the turn of a screw and can be done while printing.  The original Paxtruder was designed by Charles Pax and is in use on Makerbot's new Plastruders.  I decided to make my own version of the Paxtruder because I didn't want to spend much money.  My backup plan is to buy the Drop In Paxtruder for sale by Built To Spec.

The MK4 consists of 6 acrylic layers.  I made new versions of layers 3, 4 and 5.  I'm still working on it, but here are a few preview photos. They show layers 1-5 with the plastic covering intact.  This is a total hack job, done with a hacksaw, a drill press, files and sandpaper.  I bought the acrylic at home depot.  Layers 3 and 5 are .093" thick.  Layer 4 is .220". 

You can see the open space to the right of the bearing, which has the motor and gear behind it. The block slides in the space, against the filament.  The screw will come in horizontally from the right with the tip of the screw pushing against the back of the block.  I plan to curve the front of the block to help guide the filament.  
I need to cut some material off the bottom of the part with the blue tape, then make a block to fit in the slot.  The last piece will sit in the far right of the open space and will need to be screwed in place.  First I'm going to try tapping the acrylic from the edge to hold the screw.  If that doesn't work, I will make one from scrap aluminum or figure out some other way to guide the screw.  The real Paxtruder design uses delrin for the block, and the screw is guided by a nut held in place with screws above and below it.  

Here you can see the filament & the new gear behind it. 

I'm a drafter, so I normally use Autocad or Inventor for my designs, but this time I'm doing it all by hand.  I traced the parts, measured and dimensioned them.  See the scan from my notebook below.  I feel this information is very valuable when designing something, even if you end up not using it.  If I was using Autocad on this project, I would have just gone to the Plastruder MK4 thingiverse page and downloaded the source files.

I cut the parts with a hack saw.  Next, I taped them to the old parts and used them as templates to drill the holes in the new parts.  I drilled out the motor shaft hole to 1/2" because that's the largest bit I have, then filed it to size.  I have more filing and sanding to do to make sure everything fits correctly.  The hardest part will be making the T-slots that hold the nuts at the bottom of the assembly.  I'm going to bust out the dremel for that.

Thursday, March 31, 2011

Plastruder MK4 continued

The Plastruder Jack isn't working exaclty as I planned.  It works good for a while, but the filament eventually stops moving, then if you tighten the Plastruder Jack, it causes the drive gear to strip the plastic, filling the gear teeth with plastic and spinning the gear, much like a tire stuck in the mud.  I also think the wheel may be slipping to the side of the filament, removing the pressure against the filament.

Since I've been having weird extrusion problems (high temp required, extrusion curls near the nozzle instead of dropping straight), I thought maybe I had burnt plastic clogging up the nozzle and heating chamber.  This might also explain why the filament stops moving, it might be bottoming out inside the heat chamber.  I happened to have enough parts to build a new hot end, so I swapped out the new hot end for the old one.  I heated it up and did some tests. It worked great for a while, extruding a very smooth noodle that coiled up on the build platform a few inches below.  Then for some reason, it started to kink a little bit as it left the nozzle.  Maybe the new nozzle is clogged as well.

So, in summary, my filament drive doesn't work right and the hot end still extrudes funny.

I took apart the filament drive section again to see what other modifications I can do.  I have two spare idle wheels made of acrylic, so I'm going to put both on the bearing, doubling the width of the idler wheel.  This should keep the wheel from slipping to the side of the filament.  To make room for a wider wheel, I filed the points off of two of the plastruder parts as seen below.



I'm not sure if this is enough clearance for the double idler wheel.  Will work on it more tonight.

Monday, March 28, 2011

Plastruder MK4 mod (this will be boring unless you're familiar with the makerbot)

I've had a Makerbot Cupcake CNC for a year now and I'm embarrassed to say I have yet to print anything on it.  I got frustrated with my inability to update the firmware on the extruder board, as well as the poorly organized instructions on the makerbot website.  Anyway, I have dusted off the ol' makerbot and am determined to print something before a friend of mine prints on his brand new RepRap.  He's had issues with his machine as well, but he's only had his for 2-3 weeks.  He already has some decent attempts at printing.

A few weeks ago, I successfully updated the motherboard firmware, as well as the extruder board's firmware, so this got me pretty motivated.  My main obstacle right now is the MK4 Plastruder.  This part of the printer feeds plastic filament into a heating chamber, which melts the plastic into liquid form.  As more filament is fed into the heating chamber, the molten plastic is pushed out of a tiny nozzle onto a build platform.  My MK4 has problems feeding the filament into the heating chamber.  The standard MK4 design has an aluminum toothed pulley (attached to a motor) and an idler wheel to grip and guide the filament.  The idler wheel is supposed to push the filament against the pulley so that the pulley teeth can grip and feed the plastic to the heating chamber.

Two problems here:
  1. The pulley teeth do not grip the plastic well. 
  2. It's nearly impossible to get the idler wheel pressed firmly enough against the filament for it to feed properly.
To solve the first problem, I bought a new pulley that makerbot claims "provides a significant (100%) increase in push strength for the filament drive of the MK4 Plastruder!"  This pulley is designed after the wire feeder on a wire welder, it has the same concave/knurled surface to grip the filament, so I truly believe it will perform 100% better.

For the second problem, I disassembled the plastruder and cut notches across the surface of the idler wheel (much like the teeth of a pulley) with a hack saw, to help the wheel grip the filament.  I put everything back together (still using the original toothed pulley) and tried it out.  It worked, sort of.  I had to hold the idler wheel against the filament to get it to feed, but it was performing better than it ever had.  No matter what I tried, I could not tighten the idle wheel bolt in a position that gripped the filament and didn't require me to push on it.

After brainstorming with my friend with the RepRap, we realized I need a better way to hold the wheel against the filament instead of relying on the axle bolt.  I came up with a bracket I'm calling the Plastruder Jack.  Here's a preview photo.  I'll continue this post later.

Wednesday, March 23, 2011

iPhone art

Another one done in Vellum.

iPhone art

I did most of these for my niece and nephews.

iPhone art

Another one done in sketchbook express.

iPhone art

More sketchbook express work.

iPhone art

Another one done with SketchBookX.  I used this as my wall paper on my phone and it got a little confusing.

iPhone art

This was drawn with Autodesk SketchBook Mobile Express. It's a great app once you get familiar with it.

iPhone art

Drawn with the app Vellum. The app is black and white only with three different brushes (graphite, ink and scratch).

Sunday, March 13, 2011

Make: Electronics Experiment 20

I've been making my way though the book Make: Electronics and here is my build of Experiment 20.  I've learned a lot in this book and recommend it to anyone interested in learning about electronics.  I do not have any photos or documentation of the first 19 experiments to share, but you have to start somewhere, right?