Thursday, December 25, 2008

Extruder Design


After successful lashups, I've completed design for a "prototype" version. I have the materials, just need to construct.

In addition to minor fixes from the lashup, the main difference is use of an aluminum housing instead of the cement board. The hope is that the housing will dissipate the heat by operating as a large heatsink.

This extruder design aims to work towards eliminating the PTFE part. This version still uses the PTFE, but not as a structural element. Later, I hope to cool the inlet and avoid the PTFE.

6 comments:

Arvin said...

Any further development? Pictures?

Dave said...

Hi, Thanks for posting. No, unfortunately no further development, as I have a 3-month old in the house that takes priority at the moment.

I do have the materials i need, so its just a matter of getting back to it....

Marc said...

Hi There
Very intereseted in what you have been doing as I just bought a small CNC router and would love to drive an extrusion head and then machine back the top surface for finished surfaces.

Ooooh just thought your three month old is now walking, I may have to wait another 17 years for an update. (I have two of my own)

You start with having no spare time anymore and as they get older you then seem to have no spare money anymore??? But love'em.
Cheers
Marc

Dave said...

Hi, Marc:

Thanks for posting.

I have been making some progress. Construction is nearly complete on a new cnc machine that has a much larger envelope and higher speeds.

My old cnc machine was stepper based and could only do 40 in/min. I want to do 250 in/min at least so that i can achieve fdm deposition rates of 1 cubic in/hour, so i needed a new machine.

The new one has envelope of x,y,z = 22"x14"x7", with rapids about 250 in/min. it is servo based and all aluminum construction so it is taking a while...

whosawhatsis? said...

Instead of the machined PTFE barriers designed to be a structural part of the extruder, consider using a short piece of PTFE tubing, like the ones used for bowden cabes. In my limited experience, if you stretch the end of one of those enough to thread the heater barrel into it, it makes an excellent thermal transition zone.

Also, if you plan to have a metal case that acts as a heat sink, be sure to only attach it to the cold end of the heater barrel. You don't want to sink heat away from the hot end.

Dave said...

Hi, thanks. Actually, i have a different design that i've not taken the time to post yet.

The new design does not use any PTFE barriers at all.

I'll see if i can post a picture of the solid models for the newer design.