Since I posted the spider ring on Thingiverse I’ve seen it pop up in a few places, like this video on the WSJ site.  In the latest edition of Make magazine (volume 21) it popped up again on page 49 in a line up of other interesting objects from Thingiverse.  It’s a weird feeling to know that someone else has actually made something I designed and threw on the internet.  Hopefully this kind of thing will happen more and more as “home fabrication” becomes more ubiquitous!

Anyway, here are a few things we picked up while debugging the extruder to consider in addition to the instructions on the MakerBot site:

1. Don’t cross thread the PTFE!  This is relatively easy to do since PTFE is a pretty soft plastic.  If you’re worried about it, use the 3mm hex wrench as a guide when screwing the heater barrel in:
   
2. Remove the PTFE as a load bearing structural component.  This amounts to adding an M6 nut and washer in between the PTFE insulator and the fender washer.  This translates force on the heater barrel back up to the main plastruder body through the bolts connected to the fender washer.  While this won’t stop damns of plastic from forming and slowing down extrusion, it should keep the heater barrel from getting pushed out of the PTFE, stripping the threads out as it does so.
   
3. Add a hose clamp where the heater barrel and PTFE meet.  While not required, it probably couldn’t hurt and it may stop damns from forming.  I’m hoping this will extend the life of my extruder a bit.  Remember to periodically tighten this clamp up as the PTFE “flows” away from the clamped area over time.
   

Check out this entry on the MakerBot Blog for some additional info and some more awesome mods to the basic plastruder setup.

Second is the drop in Paxtruder.  My MakerBot has been down for about 2 weeks now because I cracked my idler wheel.  I decided to take this opportunity to play around with an alternative design someone posted to Thingiverse that uses a Delrin pusher rather than an idler wheel.  I modified the design a bit so I could reuse the mounts and heater components without too much difficulty.  I haven’t been using it for too long, but I love that it takes next to no time to change filament with this design and that tension is ridiculously easy to adjust.  During the short time I’ve been using the new extruder, I’ve also noticed that the gear motor noise (and presumably load) seems more consistent as well compared to the idler wheel design.

My personal MakerBot is up and running!  Above you can see it extruding that beautiful black ABS during the extruder burn in test.  I’ve printed a few objects with reasonable success after making a few adjustments and I’ll have a more detailed write up covering some post-construction thoughts in a later post.  Below you can see the printer laying down a raft for a z-crank.  Check out my Thingiverse page for a couple more pics of objects I’ve printed.

I also printed out my first from scratch object, this awesome spider ring for Halloween!  I would have liked to make my first design truly 3D rather than a simple extrusion of 2D shapes, but I’ve got a lot to do before All Hallows Eve and Blender has one hell of a learning curve!

So I broke down and ordered a laserless MakerBot kit shortly after MakerBot Industries started offering them.  I also ordered a few motor controllers for my upcoming CNC project and some nichrome wire and thermistors for some back up heater barrels.  I still want to make a version that utilizes more printed parts and more readily available components.  I have quite a few spare parts since I’ve been gearing up to build a MakerBot for a while, so I should have most of what I need to make a second bot utilizing the ‘control’ MakerBot to manufacture parts for the experimental one.  I’d really like to see if I can get comparable performance out of 0.2″ pitch timing belts and printed pulleys.  Providing alternatives for the  special order SDP-SI components and utilizing more printed parts means future MakerBots could cost less and supply wouldn’t necessarily be tied to a specific supplier’s stock of parts.