1st layer problems - enable retraction?

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amcbride
Posts: 56
Joined: Thu Jan 29, 2015 9:29 am

1st layer problems - enable retraction?

Post by amcbride » Mon Jul 02, 2018 4:09 pm

Hi All,

I'm having trouble with a somewhat large print. it's an optical bench breadboard that has a bunch of holes in it. I get great adhesion for the perimeter but when it starts to print the hole perimeters, they don't stick. It looks like what's happening is that when it moves between holes, since it's not retracting, it's dragging a bit of filament with it across the perimeter of the holes and basically knocks the hole perimeter off of their spots.
bad holes.jpg
Here's a video of the process as well: https://photos.app.goo.gl/ESXAYG16dg2DUL1U8

I'm using a TAZ 5 upgraded with an Aerostruder and the modular print surface/PEI.
Filament is PolyLite PLA with the default settings (205/60)
I have tried it with a clean bed as well as with a layer of PVA glue. As I said, I get excellent adhesion of the skirt and external perimeter but once it starts printing the holes, it's a mess. Is there a setting I can change to make this work?

thanks!

-Adam

kcchen_00
Posts: 1688
Joined: Thu Feb 19, 2015 12:42 am

Re: 1st layer problems - enable retraction?

Post by kcchen_00 » Mon Jul 02, 2018 9:02 pm

Try getting the initial nozzle height closer to the bed. Maybe a quarter turn on the Z-endstop. Or use the gcode z-offset, -.1 to -.2.

I had to really work the PEI surface on my modular bed. Use a scotch brite pad, really work it so it turns hazy.

amcbride
Posts: 56
Joined: Thu Jan 29, 2015 9:29 am

Re: 1st layer problems - enable retraction?

Post by amcbride » Tue Jul 03, 2018 4:30 pm

Thanks for the suggestions. It's interesting because I setup the bed height/level the same as with the hexagon hotend and original bed as far as distance. For the most part, I've been getting good prints and bed adhesion but this print is giving the new setup a hard time. I hope it's just the bed height and I don't have to resort to scouring the surface but...I like the idea.

-Adam

Ehoff
Aleph Objects | LulzBot
Posts: 60
Joined: Fri Sep 08, 2017 1:34 pm

Re: 1st layer problems - enable retraction?

Post by Ehoff » Fri Jul 06, 2018 7:18 am

Try reconditioning your PEI sheet, and it should help with adhesion problems. The best way is to get a spray bottle and mix up 1 part alcohol and 9 parts water. Get some 1500 - 2000 grit sandpaper. Get a sanding block. Spray some of the 1:9 mixture on the bed (get it nice and wet. Just make sure that your printer is turned off and unplugged). With the sandpaper on the sanding block, wet sand the entire bed until you see a slight whitish film, then stop. Clean the bed good using the same mixture with a clean cloth.

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