Friday, April 22, 2011


New Extruder Design

I have (finally) finished my 1.75mm filament extruder design for RepRap.

I say RepRap - in fact, by simply changing its adapter plate (called base_plate in the design), it should go on virtually any 3D printer.  The standard design fits Mendel (both the standard one and Prusa).   I will shortly do a plate for Huxley too.

It features:
  1. Very compact high-torque NEMA 11 motor
  2. Active ducted fan cooling for high reliability
  3. Wade-style hobbed bolt filament transport
  4. Wing-nut drive to spread the torque loading on the plastic gears
  5. Push-fit hot-end parts - no thread cutting
  6. Easily replaced PTFE liner for the hot end
  7. A single M3-threaded rod cut to lengths makes all the fixings
  8. Lightweight: 420g (about 60% the weight of this extruder)
  9. Compact design (110 mm x 90 mm x 80 mm)
It's all here on the RepRap Wiki.

And here's a video of it printing itself:

RepRap Universal Mini Extruder from Adrian Bowyer on Vimeo.

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I've been using shorter lengths of Peek insulator and Brass extruder. Looking at other extruders like the Up, Ultimaker, E-Makers extruders they are also using shorter parts.

I've searched the WIKI for formula to define/calculate the length of these parts the REPRAP extruders seem to be quite long. This reduces the maximum print height.

Is there a specific reason for these parts being longer?
As they are, they only just reach through the standard X carriage.

The PEEK needs to be a reasonable length, I think, if it fits in a reprapped part at the top - you don't want that going soft. Machined parts can take higher temperatures, of course.
Thank you, that makes sence I have been using MDF and Perspex to mount the Peek through.
The Huxley E-Maker Extruder seen at MakerFair had printed parts in very close proximity dont think it had an insulator either.
Will you at some stage, alter it to utilize a NEMA 17 motor?
Just so that it can still be just as ubiquitous as the Wade extruder.
Not sure I follow. Why would one size of motor make it more ubiquitous than another? And a NEM17 would be pretty overpowered, as well as bulkier.
NEMA17 seems to be the cheapest size. Both bigger and smaller get more expensive.
Instead of going to a smaller (more expensive) motor I'm pushing towards a direct drive system, mostly caused by the difficulty that gears creates for all the machines that I have (Darwin, Sells mendel and a vik mendel). Anything which eliminates gears is my objective.
Hello Adrian,
One of the big problems I faced here in NZ wen putting together an extruder, was the lack of easily obtainable parts.
I got a set of parts for your your earlier extruder, bt I couldn't justify procurring a brass spline from overseas.
Which is why I went with the Wade extruder, the parts were easily obtainable (except for the hot end, still no real easy place to get those bits).
This new design, which I like uses parts which aren't really obtainable locally, like the Nema 11 motor, and the bearings.
Nearest supplier is in Australia.
Which is why I am wondering if you would alter the design to use locally available non replicatable bits.
Rather coincidentally I am currently in the process of fitting my Wade extruder with a NEMA-17 motor on my huxley x-bar carriage...

I am certainly looking forward to your OpenScad or STL-design files huxleys x-carriage to mount your smaller form-factor extruder on the Huxley.
Hi Grogyan - I fully take what you say about part availability. But I was trying to make a small light extruder...

However, it shouldn't be too hard to hack the OpenSCAD design do that the motor size is a parameter.
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