H-1 dribbes before it shoots

[markotime]

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

[Fiero2M6]

Have you tried the "lift z" feature in Slic3r?

What is your print speed?

[markotime]

Thanks for the reply. Lift doesn't help with the leading-edge dribble, just drops it earlier. Have tried many speeds from crawl to outrageous. The latest version of slic3r does a high speed jog back and forth between the pillars in the test cube, leaving threads and little drips.
A strategy worth considering is to suck back during traverse rather than all at once before starting to move. I'll pass that on to the slic3r folks.
one of the other slicer programs does a "wipe" before moving, which might help a little on nearby moves.

Tried a fan last nite, helped with the stability of the 4mm pillars (there was distortion due to not being entirely solid during perimeter and fill), and with bridging, with the latter needing more work.
Lower tip temp and/or more fan airflow just makes things worse.

I may just try even higher extruder temps - I'm wondering if the heating resistors are not in good contact - not enough foil. May try some of the termal epoxy, but don't like the mess if I have to
remove same.

thanks/m

[Jimustanguitar]

Dribbles before it shoots... Could be performance anxiety or an early sign of extruder dysfunction.

[markotime]

Yeah, wondered about that myself. The fan helps with rigidity, which reportedly reduces the urgency to "see Alice", whoever that is. <g>