Extruder Designs

Greetings,

I have been working on the design for my first extruder. I've done my homework and shamelessly borrowed some ideas from others. I think that I am off to a good start but still, I wanted to post up my work and get some feedback.

I've provided an animation for the two revisions and I hope they will do better in conveying the design than the typical single cross sectioned view. The 2nd design was a progression from the first but both are aimed to keep the unit modular. The 2nd concept body is a bit more of a complex part to machine but I'm looking forward to it. All of the pins/bolts/gears are mcmaster parts and then their are three machined parts in each assembly. I will try to post up some work in progress pictures if you guys would enjoy them- probably will only be machining the second version and not both.

I sometimes wonder how much of the conveyed design is lost through communication over the internet. Maybe I will annotate a screen shot or two to specify materials and such?

I leave for a two week vacation in a couple days- won't be getting my hands dirty with this project until I return.

Rev1:

Perspective view:

http://a.imageshack.us/img341/4583/extruderunit1persp1280.jpg

Sectioned view:

http://a.imageshack.us/img828/7296/extruderunit1sectioned1.jpg

Animation:

http://www.youtube.com/watch?v=0VG8BbzyEh8

Rev2:

Perspective view:

http://a.imageshack.us/img843/1543/extruderunit2persp1280.jpg

Sectioned view:

http://a.imageshack.us/img97/3059/extruderunit2sectioned1.jpg

Gear view:

http://a.imageshack.us/img827/2375/extruderunit2gears1280.jpg

Animation:

http://www.youtube.com/watch?v=zzOcbAw69gk

I suppose I've been ignoring this blog.

I've been itchin for a low cost/high rpm spindle solution and it sounds like others have had good results from the Proxxon IB/E. High spindle rpms are important for smaller diameter cutters where the cutting edge doesn't move as far per revolution as a larger diameter cutter would. I'll need to use smaller cutters for engraving work and to create isolation circuit boards ...so I took the plunge... and bought my very own.

The Proxxon rotary tool arrived in the mail and I went to machining a mount. The proxxon rotary tool is similar to a dremel in function but the quality feels a bit better- it features 20,000 rpm and the nose is cylindrical which make it convenient for mounting purposes.

And the pcb router bits also arrived about the same time.

My first go ahead- more of a throw it on their and see what I get.

It may be a bit hard to see in the picture but the problem is that the circuitboard was not oriented flat to the spindle. In one area the cutter would be down very deeply in the work and in others it would be grazing the surface. Deep cuts are not nice on our fragile little cutters and after a bit in the deep stuff, the tip snapped off. My first thoughts were that I had bowed the board in clamping it with the vise. That didn't help matters, but after further inspection, I found that the circuit boards are naturally bowed quite a bit in one direction. Holding the circuit board down at the edges against a tooling plate would keep it flat. I didn't have a tooling plate but I had all the ingredients to make one.