Large part... nozzles tripping over?

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kanDO_Bryce
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Large part... nozzles tripping over?

Postby kanDO_Bryce » Tue Jun 07, 2016 6:29 pm

I have had no end of problems trying to print this part... this is attempt 4. Before running this print I cleaned out the nozzles, replaced the PTFE tubes inside both hotends, re-tensioned the belts, and re-calibrated the z height around the bed as best i could.

But it appears to have tripped over itself and slipped a tooth on a belt (or belts?) two or three times as the part has been built upwards. Should have set up some sort of camera to watch what was going on.

Printer was run in a heated cabinet at around 50degC.

Any thoughts?

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Qdeathstar
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Re: Large part... nozzles tripping over?

Postby Qdeathstar » Tue Jun 07, 2016 7:10 pm

I cant see the images, but i am having a simular issue with large parts during the first layer.

Qdeathstar
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Re: Large part... nozzles tripping over?

Postby Qdeathstar » Tue Jun 07, 2016 7:12 pm

Yikes, i was able to look at the pictures. That looks like a lot of different issues rolled into one. I suspect your calibration isn't correct. larger parts exponentially expose bad calibration.

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Qdeathstar
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Re: Large part... nozzles tripping over?

Postby Qdeathstar » Tue Jun 07, 2016 7:13 pm

are you doing ABS and do you have a fan on the print? (you should not for abs)

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gestalt73
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Re: Large part... nozzles tripping over?

Postby gestalt73 » Wed Jun 08, 2016 6:37 pm

There's alot going on in that photo, and I have some spare time, so here's what I'd try if this happened to me with a print.
(It looks like you're printing in ABS, and you're using an ABS slurry, if that's not the case then some of this won't apply)

Your main 2 issues appear to be:
(1) bed adhesion
(2) delamination

Either one of those will cause the steppers to skip as they get caught on an edge that has warped upward.

There's more going on, perhaps the extrusion multiplier, retract and prime settings as well, but it's a distant 3rd on the list of problems with that print.

Here's what I'd recommend for you to try (It's what I do and seems to be the magic sauce for ABS prints)

(1) bed adhesion
- prep your plate in 2 steps, first apply a single layer of PVA gluestick to a cold build plate, and once it dries apply a single layer of your abs slurry
- (fyi, your abs slurry is really thick, try a ratio of at least 10:1 acetone to abs, should go on and dry almost clear)
- crank up your bed temps as high as they'll go, I set mine to 100c, and won't start a print until it reaches as least 80c
- set up mattercontrol to use a 10mm brim, with a first layer of 0.3mm. If using KISSlicer, use 10mm brim, 0.5mm high, set plate roughness to 0.1mm
- keep drafts to a minimum, no ceiling fans etc, and no layer fans with something this large.
- watch your first layer, and cancel the print if you need to recalibrate your printer, your prints wont stick if you have a part of the bed where you're printing too high because of bad bed calibration

(2) delamination
- you're printing either too cold and/or too fast
- slow down your print to 20-40mm/s maximum,
- bump up your print temps. I know people are going to disagree, but I wouldn't have a problem printing ABS at 245c, and even higher with an all metal hot end
- there's a balance between print speeds and print temps, you need to print hot and slow enough to give the new layer a chance to slightly melt the layer below it

(*) bonus advice
- large ABS prints are tricky, and large solid ABS prints are next to impossible because of warping and splitting
- for something that size, I'd just print it in PLA
- if you must print it in ABS, I'd print it with very light settings, 2 perimeters, 0.8 ceilings and floors, 16%-20%infill

kanDO_Bryce
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Re: Large part... nozzles tripping over?

Postby kanDO_Bryce » Wed Jun 08, 2016 11:08 pm

I discovered (at least partly) what the the problem was here... the nozzle for the support material had managed to unwind itself about 2-3 turns from the hot end, so it was hanging significantly lower than the ABS nozzle. This would have caused ever-worsening crashing / collision problems between the support nozzle and the printed part, as the nozzle unwound itself further and further.

And... Crashing -> belt slippage -> print being offset and on funny angles. Bugger.

@gestalt73 - thanks for the advice on the ABS slurry. That batch was made in a hurry, as I had been having great results straight onto glass up until that point. I am printing relatively slow, and at 247degC for ABS onto a bed at 104degC. I had one attempt at this print that was almost perfect, but a power cut thwarted it. Much annoyance...

@Qdeathstar - no fan on the print, just coolign onto the peek section of the hot ends. Cabinet is heated to about 50degC.

ZionPhil
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Re: Large part... nozzles tripping over?

Postby ZionPhil » Thu Jul 07, 2016 8:10 pm

No one is addressing that he is still using the Steve's Extruder? You are still using that correct? That is the biggest source of your issues right there.


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