Layers are shifting all over the place

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SgtFolley
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Joined: Tue Sep 15, 2015 9:54 pm

Layers are shifting all over the place

Post by SgtFolley » Sun Jun 03, 2018 7:10 pm

I think she's getting to that point where she needs a major tune-up. I've had consistent prints for about 2 years with her making numerous props etc. Lately, on the last 2 test prints my calibration cubes come out perfect but the prints themselves seem completely out of wack.

I've checked the filament, no change there, same OD

Extrusion seems ok, but the X and Y Axis seems to shift from layer to layer. The belts seem tight enough but I'm not sure if I should attempt to tighten them myself.

any thoughts from folks?
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ednisley
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Re: Layers are shifting all over the place

Post by ednisley » Sun Jun 03, 2018 8:54 pm

SgtFolley wrote:
Sun Jun 03, 2018 7:10 pm
consistent prints for about 2 years
Which says now's a good time for lubrication, pulley screw centering / retightening, and all the general preventive maintenance we tend to ignore while it's working.

Judging from the model, though, the nozzle is whacking on raised perimeter threads after the part separates into two towers, along that steep overhang, when two towers rejoin into one, and at various protruding features here & there.

You're likely to see nasty perimeter curling at the corners in those situations and, with a big hunk of plastic stuck firmly to the platform, the nozzle impact can briefly stall either or both of the XY motors.

Set the slicer to squirt infill first, then add perimeter threads from the inside out: with a bit of luck, the infill will anchor the perimeter threads a bit better and reduce curling. If you have just one perimeter thread, a few more can help hold the outer one in place.

Aggressive cooling may also help, although reports from folks with exotic cooling ducts seems mixed at best. If it's PLA, you can't have too much cooling.

Some folks add a smidge of Z hop during layer changes, which probably won't help for a part with the nozzle traveling between multiple islands.

And, perhaps, after a couple of years, you're designing / printing more intricate parts which make the limitations of 3D printing more obvious ...

Gwhite
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Re: Layers are shifting all over the place

Post by Gwhite » Sun Jun 03, 2018 10:19 pm

ednisley wrote:
Sun Jun 03, 2018 8:54 pm
SgtFolley wrote:
Sun Jun 03, 2018 7:10 pm
consistent prints for about 2 years
<snip>
Aggressive cooling may also help, although reports from folks with exotic cooling ducts seems mixed at best. If it's PLA, you can't have too much cooling.
Actually, I've had the best luck at eliminating warping on larger prints by turning the cooling completely off. I've got a job running now with MakerGear PLA that is about 5" by 5", and the fan stays off the whole time. No sign of any obvious warping after about 2 hours into it. I'm running with 15% infil, which I suspect helps reduce the leverage of the upper layers to pry the print off the bed. I'm printing on Kapton, and fully expected to have to revert to hairspray on glass to keep this thing stuck down. This is mostly a trial run to check some dimensions, and killing the fan was an experiment. Keeping the cooling to a minimum also helps with layer to layer adhesion.

The place where you need cooling is on small things where the PLA hasn't had a chance to cool before the print head comes around for the next pass. Simplify3D has a setting where you can turn on cooling for layers that take less than X minutes to print to try to take care of this. Bridging is another place where cooling can be critical.

SgtFolley
Posts: 6
Joined: Tue Sep 15, 2015 9:54 pm

Re: Layers are shifting all over the place

Post by SgtFolley » Tue Jun 05, 2018 4:17 am

So i think this was a senior moment, i realized while looking up how to tighten the belts that the banana clips on the glass plate have been missing the past few prints... :oops: :oops: :oops: :lol:

Will be printing a few more things to confirm I was an idiot.

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ednisley
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Re: Layers are shifting all over the place

Post by ednisley » Tue Jun 05, 2018 1:20 pm

SgtFolley wrote:
Tue Jun 05, 2018 4:17 am
a few more things to confirm I was an idiot
Those are the absolute best problems to have: they leave no doubt about cause-and-effect. A bit rough on the ego, though.

In the future, someone we'll never know will have that exact problem, find and read this thread, look over at the printer, and never, ever tell anybody.

Welcome to the club. Your t-shirt will arrive via 3D printed drone. Wear it proudly! [grin]

SgtFolley
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Joined: Tue Sep 15, 2015 9:54 pm

Re: Layers are shifting all over the place

Post by SgtFolley » Fri Jun 08, 2018 4:48 am

just closing this out, i did a little fine tuning and replaced the missing clips and she's printing beautifully.

I did get a new glass build plate with the tape applied from makergear and i'm amazed how much better my prints are with the tape instead of hairspray and glue sticks.

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