With Gusto!

Today I'm designing a clay extruder. I've taken one pass at this before, so I know a bit more about what I'd like to see in the end result:

clay should be easy to load, straight-up plunging the clay is mechanically arduous, but worth it

I want to strong arm this whole situation. The mud will fear my plunger. From the supply chain I'm going to pull a few critical components:

closed loop gt2 for first reduction bicycle headset bearings to mount a ballscrew nut, driving a ballscrew nema 17 motor & 20 or 16T pinion pulley

I'll use 2.5" ID polycarb tubes to load clay in to, with 12" (off-the-shelf length) sections, assuming 8" used height, that's about 3.5lbs of clay, which is plenty much.

1kg Carry or Tube Delivery

My first temptation is to just carry this whole thing around the machine. The laying-down is speed-limited by the process, not by the machine's accelerations... so carrying 1kg on the end of the machine is OK. It's also straightforward, and has a kind of elegance that's hard to find with tubes.

I am a bit weary of doing this to the plastic parts of my gantries. To that note, I'll also spec parts to design / build a 'bowden' type nozzle delivery... Since size will be a bonus there, I'll pick some ... 1/2" id hose and compression fittings. My notes from before:

We found that with ~ 20% water added, we could push it through a 1/4" inside diameter tube having ~ 1m of length with only 30psi.

So, straight up clay (no water), anticipating a similar (hopefully shorter) hose length ... 1/2" ID seems OK, considering the force (that I haven't actually calculated yet) that we should be able to plunge with.

Design Log

Here's the stick at June 7 2019

Ok, through some of this ...

• nozzle detail ... o-ring, and screw-to-secure, or secure somehow ?

• finish motor mount to pulley side

• consider similar structure & method (alu tabs with 3dp heatset inserts to secure) for bottom lock-in ...

• plate

• fin

• luer lock

• vol / step ? haha

• ballscrew: flip flange side,

• instead of an o-ring seal, use dam-type flange wall?

• or o-ring gets a nest, for slightly oversized o-rings ?

The McMaster Order

• 8585K31 1/8" Wall 2.5" ID Polycarb Tubes
• 9558K75 O-Rings
• bowden-type hose fittings ... barbs?
• 50915K324 Compression Fitting 3/8" and 3/8"
• 50915K195 Compression Sleeves
• 50915K169 Compression Elbows (for turnaround possibility)
• 4568K135 Turnaround Pipe