Print not at all flat
I'm still working on dialing in the settings for my MK3, and while it's close to great, a few things still aren't quite right. One of those things is this:
Notice how the flat bottom is basically boat shaped? What on earth would cause that?
Print is in Hatchbox PLA at 0.15mm layer height 20% infill out of PrusaControl. Firmware version 3.1.1. It was printed on the bed with two other parts and was pretty close to one of the bed edges. Another part that was printed in the middle of the bed doesn't appear to have the same problem.
Thanks in advance for any advice you can provide!
Re: Print not at all flat
Bed adhesion issues. The edges of the print are coming unstuck from the bed and bowing. You need to increase adhesion to the bed. To do that you can do a few things; Lower Z, higher bed temp, slower first layer. Also, cleaning the bed will help, and you can always use the provided glue stick! I am actually battling the same issues right now. I am going to put buildtak on one side of my sheet.
Re: Print not at all flat
Bed adhesion issues. The edges of the print are coming unstuck from the bed and bowing. You need to increase adhesion to the bed. To do that you can do a few things; Lower Z, higher bed temp, slower first layer. Also, cleaning the bed will help, and you can always use the provided glue stick! I am actually battling the same issues right now. I am going to put buildtak on one side of my sheet.
Thanks for the quick reply! I'm pretty confident my Z height is spot on based on the test prints I've done, at least in the middle of the sheet (I'm using .615):
The bed is cleaned before every print with alcohol. The prints in the middle of the bed definitely stick on well, I have to flex the sheet to get them to pop off. If I remember right, this piece at the edge came off really easily though.
Which of higher bed temp or slower first layer would you recommend trying first?
Re: Print not at all flat
A few things:
1) Check that your z axis is level. Move the z axis all the way to the top and make sure both sides touch.
2) Check to see you don't have something under the removeable bed. I had this happen once and realized a small piece of pla was wedged inbetween the bed and the sheet. If its not right at the 9 spots the probe tests for level, it may not trigger any difference in the probe height.
3) Clean bed. Acetone once a week and IPA 70% before each print
4) Bed temp. The Prusa beds do a decent job for uniformly heating, but you can still have lower temps on the edges. You can increase the temp a tad if you're printing on the perimeters of the bed, but the middle will get hotter so you can't go too high. <-- You should not need to do this. So far print have stuck well for me and have been easy to remove. My PEI sheet still looks new despite printing just about every day since I got it in December. My MK2... low flat prints kill those sheets in no time since I have to use tools to remove parts.
Re: Print not at all flat
I am finding 70% alcohol not enough to fix adhesion. I had no issues at first, now things dont stick right. Using 70% has done nothing, so I ordered acetone to use once per week. So OP if your using JUST 70% you should move to 90%+ or do acetone every once in a while. Slower first layer is always good, (50%) speed but most slicers do this automatically. Temp should probably be a max of 70(which is pretty high for PLA). Honestly, PLA should not have problems sticking, (I never had issues with my buildtak surfaces) So I think its just a matter of cleaning/prepping the PEI correctly.
Re: Print not at all flat
I'm using 91% Isopropyl Alcohol to clean before every print. I'll double-check the Z calibration and ensure it's level and will try with a slower first layer. I'll report back!
Neil
Re: Print not at all flat
I've decided to go with the simplest solution to start:
1. Give the bed a good cleaning with my 91% alcohol
2. Adjust the first layer z height to .630 instead of .605
A test print with the "life adjust Z" model at .630 stuck well in the middle* and didn't show any ripples from being too close. I'm re-printing the above part now, we'll see how it goes after the first few layers.
* How can I get that test print to print at the edges of the bed? I tried loading it into PrusaControl but since it's gcode PrusaControl won't let me re-position it.
Re: Print not at all flat
Sometimes you just have to print with a brim and trim the part afterwards. I generally do this with all large prints these days (because of the wasted time if it lifts)
Re: Print not at all flat
I just stopped the print a few layers in at .630. It was STUCK on the bed. However it showed waves, so I've backed off to .625 and am trying again. Seems like this is the path to success, just have to get the first layer z height a little closer.
Re: Print not at all flat
I've had that happen on a different printer when I've been in to much of a hurry. Not saying it is what happened but remember to wait till your print cools down all the way before removing from the build plate. I've removed a couple things form a heated plate as soon as they were done and they warped even though they printed flat.
Re: Print not at all flat
This was running overnight and finished sometime around 1am so it had plenty of time to cool, but good reminder for my future prints. Thanks!
Re: Print not at all flat
Thanks to everyone for their suggestions! After some tests I came up with the following print (new on left, original on right):
Much improved! The changes I made were:
I'll run like this for a while and see if it continues to work well for prints on the edges of the bed.