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It prints!

Posted: Wed Jan 23, 2013 11:37 pm
by SnapFracturePop
Yes, I know others have gotten this working ages ago, but still I figured I'd post my experiences. Plus a video - everyone likes videos.

The Qu-Bd extruder was a pain. The insulation crumbled off, the thermistor wouldn't stay in place, and I had trouble getting either ABS or PLA to run reliably. Everything finally started to work when I made 2 changes - I ground a flat spot on the stepper shaft for the gripper gear's set screw, and I used Arctic Alumina thermal epoxy to install the thermistor into the hole intended for a screw to hold the thermistor. I didn't even bother replacing the insulation - I might, just to keep from burning myself.

With the Acme screw mod, my Slic3r start G-code looks like this:

Code: Select all

G21 ; MM
M92 X173.579 Y173.579 Z1515.60 E128 ; calibrate steps/mm
;M106 ; turn on fan
;G28  home all axes
For Octave ABS off Amazon, 240 degrees worked well. For blue PLA from Inventables (I think), 220 degrees. Both were at 45mm/min. I couldn't get the ABS to stick without a heated bed, so I printed with the PLA (which also doesn't smell as bad). 0.35mm nozzle, 0.28mm layer height.

I had a couple of clogs at the beginning of my print - the PLA expanded/compressed in the barrel. I pulled the filament out, cut, and re-inserted, missing ~5 seconds of fill each time. I had this problem with the next few objects I printed as well, but got pretty quick at it. I managed to print the shark (build surface wasn't clamped down & shifted), a gear (fast movements & dual motors at 12v jarred the Y axis repeatedly - very bad print until I upped the power) and both pieces of the Qu-Bd spring loaded filament latch (perfect!).

And a picture:
2013-01-22_21-37-45_385.jpg (164.42 KiB) Viewed 4908 times
Have fun!

Re: It prints!

Posted: Thu Jan 24, 2013 12:51 am
by WillAdams
Very cool!

Could you document your mod on the wiki?

Re: It prints!

Posted: Thu Jan 24, 2013 1:33 am
by SnapFracturePop
Happy to.

Re: It prints!

Posted: Mon Jan 28, 2013 7:22 am
by SnapFracturePop
Slight delay in the Wiki-fying process. I'm trying to tune the thing to print reliably before posting the settings. After the first day I've had so-so luck printing. Turns out that reducing the layer height from .28mm to .15 really crushes the reliability. So, back up to .25. Also, the extruder becomes unreliable at slow speeds. I'm amassing quite the pile of Minions ( with problems around the eyes because the extruder slows down to allow the previous layer to set. Still fighting with that.

In the mean time, I did the insert nut mod - very easy & cheap, highly recommended.

Re: It prints!

Posted: Mon Jan 28, 2013 11:36 am
by cvoinescu
The slowdown doesn't really work. Even though Skeinforge says that the "Slow down" was recommended, "Orbit" works much, much better for me. With "Slow down", the heater block hovers just above the layer that's trying to solidify, blocking airflow and keeping it hot -- exactly the opposite of what you need...

Re: It prints!

Posted: Thu Jan 31, 2013 2:46 pm
by alpha
You may want to think about installing a fan. I'm using this fan right now:

Re: It prints!

Posted: Thu Jan 31, 2013 4:16 pm
by SnapFracturePop
Looks good, though my biggest issue right now is the filament clogging the barrel. Once I get that fixed I'll look into that fan.

Re: It prints!

Posted: Sat Apr 27, 2013 3:27 am
by WillAdams
On another forum, the suggested fix for the barrel clogging was a silicon insert.

Re: It prints!

Posted: Sun Apr 28, 2013 5:30 pm
by jluther
Hey nice post!

I was just curious about the piece of angle stock you're using to connect to the dremel tool mount. Right now I'm running mine using a hacked off shelving bracket (that happens to fit the NEMA 17 motor beautifully) However, I can't hold two motors my way and I have 2 extruders.

A couple things with my experience in the Qu-bd world...

High Temp RTV works good for putting the thermistor in that hole as well (just as messy as epoxy, but easier to remove if you want to change a thermistor that something bad happened to). Also, it can be used as an insulater... however, it isn't as good as the ceramic, and if it gets bumped it will fall off the aluminum unless it is very thick... When I first looked at it I never even tried to mount the thermistor outside. At those temperatures that aluminum is going to have a fairly stable core temp, and any air movement around the heater would bork up the temperature reading.

As far as plugging the nozzle a few extra things I noticed it can be caused by...
1) shavings of ABS from the drive gear jamming in the barrel
simply check for shavings around the drive gear and in that area

2) inconsistent temperatures it a little warmer or get a better thermostat, could hook up a different thermistor too. The in the hole location will be consistently warmer than the nozzle tip.
Also, if there are different feed speeds, the extrusion will extrude at different temperatures (the faster the extrusion the cooler the filament temperature) So if you run great at lower speed, and then try and extrude fast without a change in temperature, the extrusion will be cooler, and require more torque to extrude.

for me, I'm running a velleman thermostat (mostly because I had one and I didn't have to think to get it working) and a different thermistor that's a lot more accurate than my current off the shelf thermostat can do. Also, this works fine, I have it set a bit warmer than necessary, and I run the same extrusion speed for each section right now.

3) motor reversing too far to destring,
simply turn it off

4) not enough or too much grip on the filament...
complicated... However, when I was having problems with jamming I noticed if I was too loose, the filament would strip. If I was too tight, I'd stall the motor. So the motor stalls when it doesn't have enough current (current spikes happen in a motor, but the driver doesn't necessarily compensate for this. So if you have a cheap driver like me, adjusting the microstepping, checking the power supply, and testing different driver current settings can help get all the torque you need. Enough for me that I actually deformed the filament and it pinched off and it fed back up through the other side's filament hole. I had grooves about halfway through the filament... Which if the filament doesn't track into the tube will cause a jam as well... but your motor should break it.

The motor speed can also be a factor in this. If you tell it to move too slow or too fast it won't step and it will stall, but not because of insufficient current max, but incorrect power/signal delivery.

Anyway, maybe it helps someone, maybe it doesn't...

Re: It prints!

Posted: Sat Apr 26, 2014 4:10 am
by alexzheng
So Amazing