boot strapping an extruder.

I have access to a lathe and possibly a mill, but i have decided to try and build an extruder from scratch, using tools and materials available to anyone and for as little cost as possible, As an apprentice i had to file steel blocks down to a thou' so this shouldn't be too hard.

I've produced a drawing of the screw holder and the polymer holder from the stl images, and they are fully dimensioned if any body wants these drawings let me know, you can have them in: turbocad; dxf; png; gif; jpeg or perhaps something else.

I making a mould to cast these parts. for the initial forms i have used plascticene, i carefully shaped the screw holder to within 0.1 - 0.25 mm (not very good), left it for a few days the temperature went over 30 C and that was the end of attempt 1.

I'm keeping the form in the freezer and slowly shaping it, i'm going to make it over size and file it down.

Plascticene is; cheap; readily available; comes in nice colours and i had a kilo of it, But it's really too soft at room temperature and hard to work on accuratly.
I've got pottery clay out the back i may try that next
feel free to make suggestions

your sculpting your extruder body out of clay, to mould and cast in plastic? is that right?

i made my CNC machine in a similar way but i prototyped parts in balsa wood and molded that. have to get molds perfect the first go because the balsa breaks as you take it out.

i attempted to make my own extruder from scratch and it didn't work reliably. They are obviously the hardest part of making a 3d printer, i think your best chance of having a reliable 3d printer is by using wades geared extruder, [objects.reprap.org]

and a nozzle like this:[reprap.org]

i have in my possession molds of the pinchwheel extruder block. wades geared extruder, and adrians. I would suggest wades, i can cast you the parts for $30? the gears were originally printed on a commercial printer, the other 2 parts reprapped. i''ll take a photo of mine later tonight. i can hob the bolt for you too but i would suggest buying this:
[cgi.ebay.com.au]