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.

Before:




After:

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?