How to fix this

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Addiction
Posts: 12
Joined: Sat Aug 28, 2021 7:01 am

How to fix this

Post by Addiction » Sat Nov 20, 2021 2:26 pm

IMG_2093.jpg
Picture of my poor print
Hello again.

For background I'm printing in an enclosure in a temperature controlled room. I keep my filament in vacuum sealed bags with silacant packs and the filament spools to the machine out of humidifier that holds the roll.

This is Amazon Basic PETG running at 250 temp on a heated bead of 70. This is my 6th consecutive failed print of a piece that succeeded before it started failing. I've tried recalibrating the bed but maybe I'm doing a piss poor job of it?

And suggestion you guys could make would be very helpful.

airscapes
Posts: 529
Joined: Wed Jan 31, 2018 11:36 pm

Re: How to fix this

Post by airscapes » Sat Nov 20, 2021 2:43 pm

no image posted so we have no idea of what the failure looks like. Most PETG print jobs I run on my M2 I print at 235C. Speed is a factor, it is dependant on size of the model and size of the nozzle. The nozzle size only comes into play with the .75 nozzle.. your max speed has to be lower
The only PETG failures I have had are when the filament is wet and you get bubbly rough extrusions. Same thing happens if temp is too high.
A dehydrator is a good investment 8 hours ate 160F will fix most moisture issues. I keep my filament in the vacuum bags you store clothes in, they still get wet after a few uses. I dry my nylon and package it in food saver vacuum bags which have the air sucked out and they are still wet when removed 4 months later.. Moisture can be a real problem. The desiccant bags need to be recharged in an oven for many hours at high temp to actually work again.. My Cousin is a plant engineer who worked for a company that makes the desiccant.. It does not last long before it need to be recharged (dried) Better to have the ability to dry the filament when it needs it.. This is the one I have, you cut the plastic layers so you can get 2 spools in it at a time https://www.amazon.com/gp/product/B008H ... UTF8&psc=1

airscapes
Posts: 529
Joined: Wed Jan 31, 2018 11:36 pm

Re: How to fix this

Post by airscapes » Sat Nov 20, 2021 2:54 pm

Everything I wrote is not your problem :-)
Not being there to see it happening hard to. Looks like inconsistent extrusion, slicer issue if you are just starting out, Z offset issue too close to bed, clogged nozzle, too thin a layer.. PETG is not something you use when printing .2mm layer.. PETG works best with taller layers. Sorry can be more hel but kind of a lot of things that could be causing this...

Addiction
Posts: 12
Joined: Sat Aug 28, 2021 7:01 am

Re: How to fix this

Post by Addiction » Sat Nov 20, 2021 3:15 pm

airscapes wrote:
Sat Nov 20, 2021 2:54 pm
Everything I wrote is not your problem :-)
Not being there to see it happening hard to. Looks like inconsistent extrusion, slicer issue if you are just starting out, Z offset issue too close to bed, clogged nozzle, too thin a layer.. PETG is not something you use when printing .2mm layer.. PETG works best with taller layers. Sorry can be more hel but kind of a lot of things that could be causing this...
The nozzle isn't blocked. I've cleaned and cold pulled it several times in this process and pushed clean filament through successfully.

I don't know how to fix inconsistent extrusion. When I align the bed, I do back it off just a bit because PETG doesn't need as much closeness, I was printing .1mm layers, I've moved that up to .28 (though I have not tried it at that setting yet.

airscapes
Posts: 529
Joined: Wed Jan 31, 2018 11:36 pm

Re: How to fix this

Post by airscapes » Sat Nov 20, 2021 5:24 pm

The data about Z offset is totally 100% incorrect. Your nozzles offset needs to be such that when you print an object at a particular layer height, the part prints exactly the right size (within +- .02mm) of the models size. A lot of data you read is from year ago when things were not as accurate as you machine is and filament was not as advanced. You slicer should have first layer height set to 100% and you z offset should be adjusted either in the slicer or in the firmware assuming you are using an M2 with no btouch since you did not say.

Petg does not print well at layer height less than .2mm, in fact I can not remember the last time I printed anything at .2.

Print the attached file which is made for the .35 nozzle with an extrusion width setting of .4. Once complete measure it with a digital calliper. It should print 3mm tall +-.02 and the wall thickness should be .8mm to +.02 then.
The height is controlled by the z offset (starting height from the print surface). The thickness is affected by the extrusion multiplier, filament diameter setting, and to some extent the Z offset if it is way to high or low. Another tool you should have is a jewlers loop to examine the layer of the finished part.

If you do not own an accurate Digital Caliper you need to buy one, I have 2 of these https://www.amazon.com/iGaging-Electron ... 7515&psc=1 and they are several years old and still working great. You need this to verify filament thinness as it is never 1.75mm and there is an entry in the slicer for the thickness which is used in the calculation of extrusion multiplier. It is needed for the above calibrations which you will find need to be done often if you change nozzles, or layer heights. Also you can not really do much 3d Modeling to copy an existing part or item without one..

2 walls at .4 EW 3mm tall.stl
(1.64 KiB) Downloaded 5 times

Addiction
Posts: 12
Joined: Sat Aug 28, 2021 7:01 am

Re: How to fix this

Post by Addiction » Sun Nov 21, 2021 1:47 am

My nozzle is .5 width. I have some calipers but I ordered the ones you linked as I've been on the hunt for a better pair.
Last edited by Addiction on Sun Nov 21, 2021 2:31 am, edited 1 time in total.

airscapes
Posts: 529
Joined: Wed Jan 31, 2018 11:36 pm

Re: How to fix this

Post by airscapes » Sun Nov 21, 2021 2:11 am

There you go.. .55 and .6 depending on what you use.
2 walls at .55 2mm tall.stl
(1.64 KiB) Downloaded 6 times
2 walls at .6 3mm tall.stl
(1.64 KiB) Downloaded 7 times

Addiction
Posts: 12
Joined: Sat Aug 28, 2021 7:01 am

Re: How to fix this

Post by Addiction » Sun Nov 21, 2021 4:27 pm

Thank you for all your help. I don't know if I did it quite the way you intended but I got this figured out and now everything is running beautifully. Weirdly one of the things that turned out to be an issue is there are tangles in this particular spell of plastic. The plastic just gets cinched cause its basically knotted. First time I've seen that behavior.

airscapes
Posts: 529
Joined: Wed Jan 31, 2018 11:36 pm

Re: How to fix this

Post by airscapes » Mon Nov 22, 2021 1:16 am

You have to be very careful never to let go of the end.. that is why there are holes in the edge of the spool. You fish the loose through so it can cat crossed. Sometimes inexpensive manufacture or resellers can mess up the spool when winding it.

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