Monday, 30 March 2009

Three heater barrels and a new drive

I made some extruder barrels over the weekend:
(click on the links for more pictures, design and test results)

From renoir1_extruder_quick_v0.01

quick and dirty extruder

From renoir2_extruder_v0.01

Version 2 - Welding tip

From renoir3_extruder

version 3 - wider feed channel (3.5mm through PEEK) for the filament

And I mucked around with a minimalist drive (Keep it Simple)

From Renoir1_extruder_drive

Simple - shove a screwdriver in a hole
This worked OK - as long as it was driven at a slower speed than the screwdriver default (2.4v instead of 3.6v)
I also had problems driving the screwdriver motor from the RepRap electronics

From Renoir2_extruder_drive

Version 2
used the BfB motor. Plenty of torque, but I can't drive it slow enough!
Below about 50/255 the motor stalls: above, the speed and torque is good but it stalls the filament once it hits the end and chews up the filament.
It works well (filament speed is aprox 5mm/sec at the 3mm diameter end) and as much drive as the filament can stand. The star screwdriver bits work well and seem to drive well. Perhaps I'll have to get a stepper motor and driver circuit for the extruder to get the speed down?

I'm going to try and reconnect the original BfB screw thread drive to my version3 heater barrel, and see if that drive will screw down at a slower rate.
*embarassed* I can't exactly use the original BfB heater barrel anymore- I was drilling some out stuck filament when the drill snached and ripped off the ends of the nichrome wire and threw the thermistor circuit across the garage. I still haven't found it...

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