1st layer squish printing PETG

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jferguson
Posts: 212
Joined: Mon Mar 30, 2015 7:26 pm
Location: St Petersburg, FL

1st layer squish printing PETG

Post by jferguson » Sun Nov 29, 2020 7:15 pm

This will likely be obvious to all of you except for those like me who didn't read the manual.
Printing eSun PETG, extruder 247C, Bed 87C, layers .1200
AND first layer set to 97% !!!!

I get mirror like finish on face set on the Kapton, but the prints are a bear to remove. I usually shear them off using a piece of wood and a mallet with the wood lying on the plate and pushing horizontally on the print. I design my prints to survive this procedure.

Maybe this is way too much squish, and maybe i should be setting it to 150%. Using Simplify3D.

What do you think?

Bioluminous
Posts: 17
Joined: Tue Oct 27, 2020 11:03 pm

Re: 1st layer squish printing PETG

Post by Bioluminous » Sun Nov 29, 2020 8:37 pm

I am very new to MakerGear printers so apologies if this sounds too newbie. With PETG, I have always found it much easier to work with flexible build plates. On my M3-ID, I have been using the textured magnetic flexible plate that PartsBuilt offers (not the buildtak model, the cheaper one). The other side of the plate is plain steel that is meant to be covered with another surface. I put a smooth PEI sheet on that side. I can print PETG on either the textured or smooth side with that mirror-like finish on the top layer and the prints are popping off with no issue once the plate is cooled to around 50ºC.

Honestly, coming from all Prusa printers, I really did not like dealing with Kapton or non-flexible glass plates. The extremely smooth finish on the prints is interesting with the glass plate, but working with glass plates on a daily basis was not fun for me.

Another idea that has been around for a while with Prusa printers is using Windex instead of alcohol to clean the plates prior to printing PETG. The idea is the Windex leaves a slight release layer kind of like hairspray or glue.

jferguson
Posts: 212
Joined: Mon Mar 30, 2015 7:26 pm
Location: St Petersburg, FL

Re: 1st layer squish printing PETG

Post by jferguson » Mon Nov 30, 2020 3:20 pm

HI B*,
thanks for your thoughts. I just installed a Wham-Bam removeable stainless steel with PEX build sheet system. I've been printing on the kapton glass plate the M2 came with for a few years now and PETG the last four rolls.

I confess stupidity and failure to read the "instructions" But last 6 months I'd been printing on the kapton but was having problems unsticking the prints.
most difficult were the small cases for electronic projects which have a lot of surface lying on the build-bed. I usually get them off by laying a small fiberboard "board" on the glass and up against the print and whacking the board with a mallet to shear off the part. This always works but sometimes the departing part takes off small pieces of the kapton.

I'm printing .1200 layers, temps 247 extruder and 87 bed. and I had been using 97% for squish.
I used same settings for first print on PEX and it really stuck in a couple of places enough to pull small chunks of PEX from sheet. I talked to Peter Solomon (Mr. Wham-Bam) who told me I would have better luck with a bed temp of 70C.

It looks with Simplify3D "Squish" is a function of layer height such that 97% will be .97 * .1200 or .1164. My guess is this is too squished and maybe I should use a setting for first layer more like 150%.

What do you think?

airscapes
Posts: 489
Joined: Wed Jan 31, 2018 11:36 pm

Re: 1st layer squish printing PETG

Post by airscapes » Mon Nov 30, 2020 4:07 pm

I print a lot of PETG on my M2 with Kapton. I use eSun and print at 235 and 70.
When you change your layer height you will need to adjust your Z offset for that perfect layer. This can be done in S3d or in the Firmware with M206. To do this you need to print a calibration square and measure it.
Set your first layer to 100% you want your first layer to be he same size as all the other layers
Print the attached model which is a square with 2 walls, each wall is .4mm, I am assuming you are using e .35 mm Nozzle with and extrusion width of .4 using the default maker gear setup in S3D.
When the model is cool measure the height of the wall using an accurate (as possible) digital caliper. It should measure .298mm > 3.02mm. Adjust Z offset to get within that range. For PETG shot for the high side which is going to start your first layer a bit farther from the plate. This along with 70C bed will help with removal.

This model can also be used to do a rough check of extrusion multiplier. Wall thickness should be between .82 and .84mm each wall is .4 and there is overlap. Under or over that range is not optimal.

There are other posts explaining the setting of Z offset within the firmware using Gcode entered on the terminal but I do not have a link, but know I posted them.

If you are not using the standard nozzle let me know and I will post a different model or you can make you own, just make the wall thickness 2x that of your extrusion width and a height that evenly divisible by your layer height.
2 walls at .4 EW 3mm tall.stl
(1.64 KiB) Downloaded 59 times
Last edited by airscapes on Mon Nov 30, 2020 4:10 pm, edited 1 time in total.

Gwhite
Posts: 296
Joined: Tue Jul 11, 2017 3:38 pm

Re: 1st layer squish printing PETG

Post by Gwhite » Mon Nov 30, 2020 4:08 pm

I've always had good luck with PETG using the glass side of the bed with hairspray (Garnier Fructis Style Sheer Set Ultra Strong Hold Breathable Hairspray). Prints just pop off once they are cool.

Also, with S3D, they pulled a fast one a while back. Initially (version 3 & earlier?) if you needed to improve adhesion, you could adjust the first layer height to get more squish. At some point, Version 4.? changed this. Now, if you ask for a thinner first layer, it will give it to you, but it also automatically adjusts the extrusion rate so you don't get extra material! With the current version (4.3), the correct approach to getting better adhesion is to go into the Gcode tab, and adjust the Z offset.

I spent a good bit of a day or two trying to adjust the 1st layer height to fix an adhesion problem, with NO effect, only to find that they had changed the behavior and buried that detail in the release notes. I think the change was probably at 4.0, which I skipped. When I went to 4.1 it wasn't mentioned those release notes... In fact, I think if you hover your mouse over the layer height adjustment, it still says you can use it to fix adhesion issues...

jferguson
Posts: 212
Joined: Mon Mar 30, 2015 7:26 pm
Location: St Petersburg, FL

Re: 1st layer squish printing PETG

Post by jferguson » Mon Nov 30, 2020 4:32 pm

Thank you guys,
I got the 87C setting for bed temperature from the PETG setup recommended here a couple of years ago.
I think I need to look at the offset issue, which should be revealed by looking at Z level on first pass in the Simplify3D G-Code.

Airscape, thanks for the files.

john

jferguson
Posts: 212
Joined: Mon Mar 30, 2015 7:26 pm
Location: St Petersburg, FL

Re: 1st layer squish printing PETG

Post by jferguson » Mon Nov 30, 2020 5:57 pm

My version of Simplify3D is 4.1.2
I tried setting first layer height to 100% and with a layer pitch for overall print of .1200 got .12. This suggests that it works and now the only issue aside from doing the check airscape has suggested is to arrive at what a good setting is for PEX and PETG.

PS: Just ran a print with first layer at 100% / .1200, extruder 235 and bed at 70. Prints look wonderful and popped right off the PEX and Stainless work sheet with the slight bending of the sheet which Wham-Bam suggests.

Yippee.

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