Sunday, 20 November 2011

Hand-drill geared extruder

I managed to break my original BfB extruder :-(. The acrylic had flexed too many times, and the top retaining bracket broke in half. The screw thread now carefully unscrews itself rather than driving the filament down :-(

So, time to update to a modern wade-style or similar extruder, using a hobbled bolt. Of course, I could have bought the gear drives from the many RepRap shops or ebay, but that's too easy :-).
Instead, I found an old cheap hand drill, with similar sized gearing. It turned out to be on an 8mm shaft.
I added a 5mm to 8mm sleeve to a stepper motor (made from a sex bolt)  and drilled and tapped a 4mm hole for a grub screw - I could then attach the smaller gear to the stepper shaft. The larger gear I cut a small square indent to match a carriage bolt, and cut some teeth into the threads using a dremmel cutting disc. A plastic cutting board and an Ikea bracket made a mount, and three skate bearings (8mm 908) made up a channel for the filament.

It's not pretty, and it's heavier than ABS gearing, but it grips the filament like anything - I can't stop it using my full strength grip, and really forces the filament through. 

I'm currently building a heater block and nozzle to add on the bottom. Hopefully this 'RepStrapStruder' will last long enough for me to print a proper wade's extruder. 

3 comments:

nomzam said...

Mate you look like really professional in this work :) hand drills are really helpful I don't understand why did you put 8mm sleeves when you needed 4mm? is there any main point?

Renoir said...

The hole was 8mm, the shaft was 5mm. The grubscrew I had was a 4mm :-)

nomzam said...

Ahan now I understand. Was bit confused lol. Will you please tell me where did you bought this Hand Drill?