Binary Construct

It turns out a single resistor wasn't enough to drive the extruder, so following some ideas from Makerbot I decided to create a double resistor heater. I wanted to reuse parts that I already had as much as possible, so I started with a standard heater barrel. The heater block is machined from a single piece of brass.

Here are the build instructions.

Materials Required:

• Heater Barrel
• Nozzle
• Double Resistor Heater Block
• PTFE Washer
• Heatsink
• Hybrid Thermal Barrier
• 2x Resistors
• Heatsink Epoxy
• Heatsink Grease

If you are experiencing extruder jams, here are the basic steps to follow to reduce or, as in my case, completely eliminate them! Jams can be cause by incorrect temperature settings, trash in your nozzle, incorrect extruder grip, long melt zones, poor spooling and any number of other causes. Here are some solutions to those problems and some additional tips.

 Needing a quick solution to a heated bed, I dug around my closet and found this $20 GE hot plate that I had used to do some SMT soldering.  I purchased the 8"x8"x0.25"aluminum plate at a local welding shop for $5 and covered it with Kapton tape. I used a bit of doublestick tape to hold the hot plate to the McWire platform and some more Kapton to hold everthing down.  I "borrowed" my wife's thermometer and taped it to the bottom of the plate for a quick way to measure temperature. 

 So far it has worked great and ABS parts come off with ease.  This solution isn't very elegant or complicated but it gets the job done, took less that 10 minutes to build and test and cost under $30 for all the parts including the Kapton. It probably wont fit on anything other that a McWire or gantry style machine with this size hotplate but you may be able to find a smaller one in your area.

After building two more extruders, I think I've got it down. The body of this one is constructed almost entirely of MDF, with one aluminum angle to attach it. It only took about half an hour with a hand drill and some calipers to measure where to place the holes, but it is defiantly working far better than anything I have built previously. As you can see from the pictures it is a pretty simple design but is cranking out parts as fast as I can skeinforge them.

Click for larger versions of the photos.

 More after the break, including skeinforge settings.

The new extruder is complete and here are some shots of the first build. A few settings need to be tweaked for quality, but I'm very excited as this is the FIRST time I've actually extruded an object and I've been working on this off and on for over two years.

Pinch Wheel Extruder Complete

Here is the completed pinch-wheel extruder only deviating from my plans slightly. For build details read more.

Untested for milling, works for etching

Here is a simple bracket I built to attach a dremel extension to the McWire bot. It is made from a short piece of L aluminum and a C bar extending downward. I bolted a clamp to the downward piece to hold the end of the extension in place. The grip is extremely firm, but I haven't tested it yet as I still need to get a milling bit.

The first photo is the nozzle and heater barrel for the mk 2 extruder. This photo was taken immediately after wrapping the nichrome wire around the barrel and covering the whole thing in high-temp furnace cement. The furnace cement will act as glue, keeping the heater element and the thermistor in place as well as an insulator, allowing the heater to get hotter than it could otherwise. 

You can see the leads for the thermistor poking out the lower part, and the heater element on the upper side. 

In the second photo you can see the old heater/nozzle and wooden extruder. This design had far too much friction and the motor couldn't put enough force on the plastic to keep the extruder flowing. The original design also used JB weld instead of furnace cement.

So far my attempts to make a new extruder that works for more than a day have not been successful. My goal is to build an extruder with parts I already have and without any printed parts. This extruder is based on the 2.0 extruder as well (although I'm using the old solarbotics motor).

The back plate would be made of some sturdy material (lexan / aluminum / steel) that I have in abundance. Gears would be salvaged...most likely from busted drills. The tubes would probably be steel tubes. The gold thing is an extra skate bearing I have from building my RepStrap. I have two or three nozzle/heater barrels working so that part is already complete.

The main problem I have with my design is attaching the heater to the rest of it. Another concern was the speed of the motor, the gear ratio could be adjusted; this is just a proof of concept to better visualize the design.

More after the break.