H-1 dribbes before it shoots
Posted: Mon May 27, 2013 3:37 pm
After days of heat table and extruder temperature experimentation, I still have a couple of problems which make prints unusable (ABS) 1.75mm ABS (measures 1.65), Steve's extruder, .35mm orifice, using slic3r with Mach3.
The most troubling model is the "another hollow cube" of 30mm, and having a frame of about 4mm.
1. Pillars having a "following" blob as the nozzle departs one pillar toward the next (I think a fan may cure this as the top mm or so of each appears slightly flexible; temp lowering doesn't help).
2. A "leading" blob - although withdrawing up to 3mm before moving, a small bit of ooze hangs on the leading edge of the next pillar.
What I have done so far:
1. maximize rapid speed and accel, especially on extruder withdrawal, to minimize time spent on the "finished" element before moving to the next - this helped with the trailing edge distortion.
2. adjusted the fudge factor (in slic3r) between 0.6 and 0.9, (same as calibration fiddling) to fine tune the amount of abs being extruded
3. heat table temps - at 100C +/- 10C, no real difference. 120 seems a little high.
4. Extruder temps - My point and shoot laser thermometer (one of the best 10 dollar values ever!) gets heat table readings that match thermistor tables, but the extruder doesn't cooperate. Adjustments from "very hot" down to dragging threads - doesn't help the leading-edge dribble. (Let's call it a "wimbledon", from the book which assigns names of streets and things to various phenomena - in this case, "no matter what a guy does to shake it after peeing, the wimbledon is the drop that always seems to lie in waiting afterward".) So, I'm guessing at temps, but feel I've run the usable range without success in curbing this unwanted dribble.
5. Backlash / timing belt slack: while there's some Z axis lash, X and Y seem fine but I had some wobble in X. I elongated the hole supporting one of the idler pulleys and that helped a lot with distortion, especially with rapid direction changes (man, I can set the whole machine into the jitterbug on its rubber feet during narrow fills!).
any suggesitons gratefully accepted!~ /mark
The most troubling model is the "another hollow cube" of 30mm, and having a frame of about 4mm.
1. Pillars having a "following" blob as the nozzle departs one pillar toward the next (I think a fan may cure this as the top mm or so of each appears slightly flexible; temp lowering doesn't help).
2. A "leading" blob - although withdrawing up to 3mm before moving, a small bit of ooze hangs on the leading edge of the next pillar.
What I have done so far:
1. maximize rapid speed and accel, especially on extruder withdrawal, to minimize time spent on the "finished" element before moving to the next - this helped with the trailing edge distortion.
2. adjusted the fudge factor (in slic3r) between 0.6 and 0.9, (same as calibration fiddling) to fine tune the amount of abs being extruded
3. heat table temps - at 100C +/- 10C, no real difference. 120 seems a little high.
4. Extruder temps - My point and shoot laser thermometer (one of the best 10 dollar values ever!) gets heat table readings that match thermistor tables, but the extruder doesn't cooperate. Adjustments from "very hot" down to dragging threads - doesn't help the leading-edge dribble. (Let's call it a "wimbledon", from the book which assigns names of streets and things to various phenomena - in this case, "no matter what a guy does to shake it after peeing, the wimbledon is the drop that always seems to lie in waiting afterward".) So, I'm guessing at temps, but feel I've run the usable range without success in curbing this unwanted dribble.
5. Backlash / timing belt slack: while there's some Z axis lash, X and Y seem fine but I had some wobble in X. I elongated the hole supporting one of the idler pulleys and that helped a lot with distortion, especially with rapid direction changes (man, I can set the whole machine into the jitterbug on its rubber feet during narrow fills!).
any suggesitons gratefully accepted!~ /mark