PLA not sticking

#1
Hi,
I've got the potentiometers set properly and printed some things that came out great, using the by Gcreate supplied Rs200-GH from Colorfabb (at least, that's on the spool), using the Zen Toolworks ABS - Generic settings (t=230-235) with the fan completely off (to prevent disforming) in Slic3r for filament settings. Works great, sticks properly but my roll is about gone.

So I ordered some ColorFabb PLA/PHA filament (on the box: processing temp 190-210), used the ColorFabb PLA (generic) as Slic3r Filament settings, adjusted the first layer to 197 (tried some values between 194 and 197) but the stuff just won't stick to the acrylic plate. Sanded it and everything.

What am I doing wrong / what can I try?

regards
Jeroen
 

mwu

New Member
#2
I have not yet printed on my gMax (I am getting my hotend for Christmas which will finish my build), but I have printed on a Mendel without a heated bed.

I found that these things were important for me to get prints to stick:
  • Make sure the bed and the z-axis are completely level. For the z-axis I found measuring from the bed up to each end of the x-axis works well. Manually twist the z-axis lead screws to fine tune.
  • I used painter's tape on the bed to make PLA stick. The bed was glass so it was that or glue stick . I have not printed on acrylic and I will probably just rely on the tape as I know that works well.
  • Use the right temperature for your material. Not all PLA is the same. The temperature that works best varies between manufacturers and depending on quality, even batch. Correct me if I am wrong, but two different printers (of different models) may even print the same filament best at different temperatures.
  • Make sure your z-axis endstop is fine tuned well.

Even with all of that, I have found that I will sometimes get some edge curling on wide flat prints on the Mendel. It doesn't hold adjustments well and has a failing power supply, so I hope that is symptomatic of those issues..
 
#6
230 seems way too high for Colorfab (and most) PLA on an acrylic bed. My PLA fused to the acrylic bed when I printed at 210. I had to destroy the print to get it off and big chunks of it permanently attached to the bed. I had to flip the bed over to keep using it. My main problem with the acrylic bed is getting PLA not to stick to it. If you are successfully printing PLA on an acrylic bed at 230 then I wonder if your temp is measuring correctly. PLA will print at 230, I'm just saying that at that temp the print will fuse to the bed.

Is the first layer squishing down onto the bed? If not, that could be the problem and you have to raise the bed a touch.

I've since moved to a glass bed and use glue stick instead of painters tape. I works great and would likely work with acrylic as well.
 
#7
Hi Chris
I've set the first layer to 230 and the rest to 207. The bed and nozzle are set very nicely and leaves little room in between. The first layer is not squishing down onto / into the bed (had that before and indeed ruined one side of the acrylic bed) so in my experience so far, that went well.

I do occasionally have 'drops' in a print where the new layer doesn't really stick properly and curls up against the nozzle, dropping it later when it's a big bigger... So my idea was to now try to increase the 207 a bit. It says 190-210 C on the box.

regards
 
#8
jBrouwers, this seems way, way, way to hot for that PLA. Can you grab a picture part way thru your first layer and upload? It sounds like you may be running your first layer to thick.

Also, what is the ambient temperature of your noozle before heating show on the LCD? Assuming the printer is completely cool from the previous print, this should be close to room temperature. Mine here in Southern Cali, for example, ussually reads about 18-23 degrees. Your printer will work best if both it and the filament are kept at good room temps (high 60's at least to low 70's).

Ideally your first layer will be colder than the rest. I would suggest trying:
- wipe your acrylic down with rubbing alchol to make sure there is no body oil on it preventing sticking.
- on your slic3r filament settings, under cooling, make sure "keep fan always on" and "enable auto cooling" are both checked. Also make sure "disable fan for first" is set to 2 layers.
- I'd try setting your PLA temps to about 205 first layer (maybe even as low as 195) and 210 for the rest. I would not normally recomend exceeding the manufactures suggested temps as the PLA can start breaking down and will lead to noozle jams and/or cause the layers not to fuse properly. The one exception to this could be if you are fighting very cold ambient room temps.

Hope this helps get you on track.
 

GORDON.LAPLANTE

Administrator
Staff member
#9
Interesting information here. We have found that for Colorfabb PLA setting the 1st layer to a lower temperature of 199 and all other layers to 208 provides great adhesion but it doesnt stick too well. If you set it to 230 it will typically fuse to the bed possibly destroying the bed and your print. Al least this is what we have seen.

Make sure for the 1st layer you have the width to 150% and layer height to somewhere near 280 microns or thicker. Also make sure the fan is off. If you have to set it to 230 then something may be off with one of the other slic3r settings.