PetG print separation

[TomR]

I have only had my M2 for a little over a month so please forgive me any obvious mistakes. One of the reasons for getting the M2 was to print quadcopters. My prototype body design was printed with PetG from Esun and was in the form of a hollow cylinder type vase. The print came out great. It held water so looks like it will be waterproof. For strength test I threw it up in the air and it bounced great. I then threw against the pavement and it cracked. My question is the way it cracked. It appears the layers separated and cracked along the extrusion lines. My impression was that the petG layers weren't adhering very good when they should. Please look at the images. I tried to use the settings recommended on this forum and had the wall thickness in the design set to 2mm and 3 layers thick when printed. Temp was 250 extruder and 100 bed. Extrusion width .45, extrusion multiplier 1.04, infill 100%. Is this breakage normal or are my settings off.
Thanks for any insight and hints.

[jimc]

Ahhh yes. It looks like the layers bonded well since it didnt crack aling those but your perimeter walls seperated. That means your underextruding. Your not putting out enough filament. You need to measure the dia of the filament in a few places and be sure that is set right. Once that is right then you fine tune with the multiplier.

[TomR]

Jim, Thanks for your response. Both rolls of PetG from Esun were right at 1.75 so I will increase the multiplier to 1.1 and see how that works. I just wasn't sure what variable should be changed. This forum is just invaluable!!! We are so lucky to have so many great posters with such a wealth of experience

[jimc]

are you absolutely sure? i have 6 spools here and every one of them come in at 1.71-1.72mm. your multiplier seems quite high. with my dia set exactly to the filament dia my multiplier is .95. i have never found a filament yet where my multiplier was as high as 1.1 if the dia was set correctly. not saying what you have is wrong, just saying to double check it. what is going on is your real world extrusion width isnt matching what is set in the slicer so the lines your printing are coming out thinner and not touching each other. if your filament is actually 1.71 and you have it set to 1.75 this would be why your light on material and now trying to compensate with the multiplier. there isnt anything wrong with doing that. i know some people always leave the dia setting the same and just tweak the multiplier for each spool of plastic they use. i just feel thats not a good practice and harder to tune everything.

[TomR]

I just rechecked the thickness and it was between 1.75 and 1.77, never below 1.75. I saw where you and some others had slightly lower readings but thought since I just received mine and you had gotten the initial batch that they had improved the quality control. Could my extrusion width be off? I have the .35 nozzle. Would lowering it to .4 from .45 help? I also notice that when I measure the finished print, it is a little larger that file, usually about .3 to .5mm.

[jimc]

wait, i didnt ask, are you using s3d or a different slicer? as for you dia size ...yes thats fine i just wanted you to double check and be sure. lowering the width would not help.

[ednisley]

Could my extrusion width be off?

Indeed!

Have you printed a thinwall box, measured the actual thread width, and adjusted the Extrusion Multiplier so that matches what the slicer expects to produce? That's how you get an accurate extrusion, which is what you need before you can figure out what else might be going on.

viewtopic.php?f=10&t=1719#p6771

Apparently you can produce a thinwall box from a solid box by using zero infill and one perimeter layer, but I have an OpenSCAD model that builds a model to match the slicer settings:

http://softsolder.com/2014/04/18/revise ... on-object/

The Extrusion Multiplier will generally be around 0.9 to 1.1, so you can get close by guessing, but this is where your digital caliper comes in really, really handy.

Because things like temperatures and speeds can affect the results, you should recheck the thread width after making any dramatic changes to your printing process.

[TomR]

Thanks for all your replies. I will work on this today and yes I use the s3d slicer. Just for general knowledge, if certain settings work for a stock M2 for a specific material, will those settings also work for all stock M2's with the same setup?

[jimc]

they should be in the ballpark but there are always slight differences from machine to machine and from one spool of filament to the next

[TomR]

Thanks for all your help. I was finally able to print a one layer thick calibration cube. The slicer would not slice correctly the sample one I had so I took the advice in the link from ednisley's post and made a 20x20x20 solid cube and printed with no infill, 0 layers on top and bottom and 1 layer for side. Printed great. The value I got for the extruder multiplier is .87 which gives me for an extrusion width 0.42(auto value), widths of .43 to .44. Now I'll see it that fixes the layer adhesion problem.

I really appreciate all the help and knowledge shared on this forum.