Problems printing on anything but the center part of the bed
As long as I stay inside the outer couple inches of the bed, I have no problems.
But for larger prints or when I load the bed up with parts, I’ve had nothing but problems, particularly in the lower left corner. I’ve ran scores of first layer tests, but cannot get a live level value that will work across the entire bed.
In desperation I did the nylon mod, and managed to get it dialed in to where I have no more than +/- 0.01mm anywhere across the bed, although when I do if I put a machinist straight edge across the bed there’s a good couple MM of delta across the front and left edges of the bed, so something is obvious wrong, despite what the probe is reporting.
I ran the bed cailbration print several times, and have manually overridden the nyloc mod values to get the corners as close as I can but I still am having no luck getting a zero layer to work across the bed unless I slow the print speed way down and manually adjust the live z on the fly to deal with the corners.
One of the pics above shows the mic’d thickness of each of the test squares.
Is this a probe out of cal or do I need to adjust it’s height? I set it to the “middle of the zip tie” and redid it again when adding the MMU2 upgrade. At this point I’m thinking either the bed support or the bed itself has got to be warped beyond what the 49 point calibration can deal with.
As I said before as long as I”m not hitting the outer 1-2” of the bed I’m fine.
Yesterday I literally spent 14 hours running 1st layer test after first layer test, starting in the middle making 0.05mm live z adjusts until I had that completely dialed in. However when moving to the whole bed tests, at full speed I can’t even get the first border to completely without the corners balling up the filament and dragging it all over the bed.
Printer is an MK3S + MMU was built last week of Nov 10, 2020, and has amassed just short of 31 print days with 1800m of filament ran through it. Firmware is 1.06-372. Measured skew is 0.06. Help!
Thanks.
Mark
RE: Problems printing on anything but the center part of the bed
Your Frong left and front right corners are particularly bad,
Could that be due to finger grease contamination?
I give my textured build plate a really good scrub with hot water and a little dish soap (Dawn or fairy dish wash detergent)(Nothing Fancy)
I rinse well with hot water and dry immediately ,
then I print on the clean surface at 70C with no other surface preparation...
regards Joa
I try to make safe suggestions,You should understand the context and ensure you are happy that they are safe before attempting to apply my suggestions, what you do, is YOUR responsibility. Location Halifax UK
RE: Problems printing on anything but the center part of the bed
I was just about to post almost exactly what Joan said, I can actually see your finger print marks (oils) in your images, make sure you clean the sheet well, and try not to touch the edges after, and run your test again.
The Filament Whisperer
RE: Problems printing on anything but the center part of the bed
@joantabb, @swiss_cheese
The finger prints are from handling AFTER the print was completed.
I do the whole dawn scrub followed by 99% IPA pre print. No abrasives, just dawn / water / hand scrub in blue nitrile gloves.
The really bothersome thing is even after the NYLOC mod and dialing that with no greater than +/- 0.01m across the board if I put a machinist straight edge on it, there’s a good 2 mm of variance (daylight under the machinist straight edge) across both the front and the left sides of the bed.
I *think” that has more to do with the problem. I have no idea why the probe is reporting a good level on the nyloc mod yet you can visually see the distortion on the plate even without the $300 straight edge on it.
When I realized that I “overrode” the nyloc mod values bringing the front left corner up to get it more in line visually with the straight edge, and it DID help. Still getting what you’re seeing above.
RE: Problems printing on anything but the center part of the bed
It has been commented that IPA simply moves the oils around. So as a precaution I use a paper towel and IPA but only wipe left to right and front to back. So that if the theory is correct (I have zero evidence that it is) whatever contamination is present will be on the right and rear border.
RE: Problems printing on anything but the center part of the bed
@towlerg
Jo Prusa used to recommend Paper Coffee filters for this task, as they are mildly abrasive as well...
regards Joan
I try to make safe suggestions,You should understand the context and ensure you are happy that they are safe before attempting to apply my suggestions, what you do, is YOUR responsibility. Location Halifax UK
RE: Problems printing on anything but the center part of the bed
It has been commented that IPA simply moves the oils around. So as a precaution I use a paper towel and IPA but only wipe left to right and front to back. So that if the theory is correct (I have zero evidence that it is) whatever contamination is present will be on the right and rear border.
When I do use IPA, I puddle a good squirt of it in the middle and wipe it outwards away from the center of the bed. As Joan notes though, the BEST clean is after a Dawn wash with NOTHING else, including IPA wipes.
RE: Problems printing on anything but the center part of the bed
@bobstro
Well Bob, you’re kind of my hero these days. I’ve poured over all you notes on your site, some of which I knew, others I didn’t. I took the “clean plate” thing to heart as result of your notes, hence the box on nitrile gloves (probably ocd) I use when taking stuff off the plate.
I do the Dawn thing every 4-5 prints, and always before any large long time print.
Still puzzled as to why stuff in the middle of the plate except the outer 1-1/2” is always flawless but the second I get to the edge this stuff all shows up.
RE: Problems printing on anything but the center part of the bed
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@joantabb @bobstro
Ok so here’s a fresh “Bob” STL print.
Z @ -1.570 (although I realize it’s relative from machine to machine).
Started with fresh dawn job on the plate, and redid the Nyloc Mod level back to +/- 0.01 across the plate.
No Z adjusts were done during the print, did that to show the variance across the middle part of the plate.
Is it normal to have that much surface variance over even this small an area of the build plate?
I haven’t pulled it off to mic the thickness yet but based off what I found yesterday I’ll probably weigh in between 2.35 and 2.5 if yesterday’s tests are any indication.
Thoughts?
RE: Problems printing on anything but the center part of the bed
Try to go a little bit lower.
Pei sheet and powder coated sheet, the powder coated sheet I find needs to go a little lower.
Try to print a little hotter? first layer or the whole print.
Try different filament, different company or roll.
RE: Problems printing on anything but the center part of the bed
@peter-m-3
Thanks. Yeah it can stand to drop, the value this morning was the last value I used last night trying a test on one of the edges, and that was too high so I upped it just to try to get the edge single layer test to hold.
Hadn’t tried messing with the temps yet, I’m running each filament at the hottest I can get it on a temp tower without excessive stringing.
As for the filaments, this is a brand new roll of PETG, and I’ve had excellent luck with the CC3D brand PETG across many rolls. The problem isnt’ TYPE of filament, or Brand, or even color, it does this on everything I throw at it once I get outside the center sweet spot.
However I’ll drop it a bit, up the temp a bit and see what that does for the center area before trying the edges again.