Wednesday, August 13, 2008

Zeroing In

After months of trying to get the original extruder working, I finally gave up and got a new one. Someone (I won't mention who, to avoid them being inundated with requests) took pity on me and sent me a fully-assembled and tested extruder. This one has a number of refinements over the original:
- the drive screw is straight, no flexible shaft
- the motor is geared down to improve torque
- the nozzle is smaller, machined from brass stock instead of an acorn nut
- all wires are soldered to a 15-pin D-sub connector

Another thing I noticed is that the springs are much heavier on this extruder. I'm not sure how important this is to the operation of the extruder but I suspect it's responsible for at least some of the problems I had.

I haven't opened it up yet but I suspect the bearings are done better than I managed as well.

Once I wired in the new extruder (I had to get my hands on a female 15-pin D-sub), I tried a few extruder tests, calibrated the heater and measured the extrusion rate.

The extra gearing makes a huge difference. The motor isn't under as much strain and the flow is much smoother. I'm currently extruding ABS (from McMaster) at a leisurely 3mm/s. I could probably go faster but I don't want to strain the PTFE barrel.

I need to update the PIC firmware and host software at some point but I want to print a complete model first. Trying not to change too many variables at a time.

Last night, I managed to get an entire shot glass printed. My infill is a bit too loose, so it leaks. It also looks like the Y axis slipped a bit part way through the build.

It's close, though. I suppose I should pick up some scotch at the liquor store, just in case.

1 comment:

Zach Smith said...


i wish i could say the same about my extruder. its ugly and hacked and falling apart.

i'm hoping the new lasercut design will help me out.