Sunday, December 16, 2007

Extruder Kit

I started on the extruder head kit (thanks Zach). The body is made from molded parts based on the RP'd extruder. Things I've noticed so far:

On the plastic parts, some holes weren't completely clear. Easy enough to drill out, though. One of the motor mounting holes was missing entirely. I temporarily mounted the motor using the one hole, lined it up and drilled the second hole using the motor as a template.

The feeder screw assembly refused to solder. I ended up using JB Weld instead. Currently curing.

I realized a bit late that I was supposed to cut down the braided wire to fit the distance between the motor and screw. Fortunately, I figured this out before the JB Weld had hardened. Note to self: Test-fit everything first.

I've avoided soldering the wires on the motor for now. Not exactly sure which direction the filament will go under power, so I've just twisted the wires on until I'm ready to test.

Not sure what I'm going to do about the bearings. The ones that came with it have fairly thin walls. I'm wondering if they'll slip out of place under axial load. Options: 1) Use the supplied bearings. 2) Use Vik's washer configuration. 3) Grind down a piece of brass stock to fit. I'm leaning toward option 3 since it'd provide the most support. Maybe I'm overestimating the forces involved here, though.

The bolt to tighten the barrel clamp is a bit too long. It butts up against the extruder body. Options: 1) Cut a chunk out of the extruder body. 2) Cut down the bolt. 3) Find a shorter bolt. 4) Stack a bunch of washers under the head.

I can see a Home Depot safari in my future.


Zach Smith said...

hey, just wanted to comment on the intent of some of the parts in the kit:

1. the kit comes with small bearings + CAPA. melt a bit of capa with a hot air gun (hairdryer should work.)

first, cut the bearings in half with a dremel. use the bigger half from each.

put a blob of that in each place for the bearing, put the bearings on the blob, and then put the drive screw on the bearings.

arrange this assembly so you are looking across the extruder and can see how far the threads are sticking out. push down on the screw assembly until the threads are only slightly sticking out. allow this whole thing to cool.

i'd recommend superglueing or jbwelding the bearings to the CAPA. they would slide out otherwise.

2. sorry about the extra long screw. you can either cut some of it off with a dremel, or dremel out some of the clamp. either way works.

Steve DeGroof said...

Thinking you must have this blog on an RSS feed. :-)

Yeah, gluing the bearing would probably do the trick. Hadn't thought of that.

No problem about the screw. Easy enough to work around.