Bed Level adjustment

[Giterdun2]

Hey all,
I was wondering if someone could explain how to make adjustments to the middle parts of the bed plate. There are adjustment screws on the 4 corners, but none in the middle that I can see.. Whenever I do a bed level, the center part of the bed is always higher than the corners. I have adjusted the corners, but the center is still always higher.. In the attached pic,, I just did a bed level, but I haven't done any corner adjustments in a while and am also using a different plate than before..

[jeffalanmcclain]

You can't. And adjusting the corners just helps with z-tilt, not really the bed calibration...which is all sort of one big combined thing on this flash forge, since you don't have separate z-motors...

[Giterdun2]

ok thanks.. Just seems kinda strange that it can't be adjusted.. I have adjusted the corners to make them very close to zero after bed levelling, but the center of the bed is still always higher. If I try to print anything that uses the whole bed, the left side always ends up very rough, and it looks like crap... oh well... ;)

[jeffalanmcclain]

Hum...so, that is precisely what bed leveling is for. Warping of the bed plate at different temps. You can never mechanically trim those out, so you typically get it z-tilt leveled (such that a flat mesh projection has it as level as you can, which the flat mesh projection shows it is) and then the individual areas higher or lower are what the bed mesh does for you. But, that should make it so a first layer print (check out Ellis' Print calibration guide for proper first layer squish) is very nice and uniform. If it doesn't, I would argue you don't have a good bed mesh. Or, if you are seeing "rough" print on the left side on layers ABOVE the first layer, this is NOT bed mesh problem...it is probably more too much cooling from the left side bed/chamber fan running too high.

Finally, I will comment that the FlashForge macro for bed mesh is pure crap. I've revised mine (you can see my submission for a replacement that fixes at least TWO major problems with how it is run in the Pull Requests). Specifically, it waits for the extruder to cool down to 120'C before starting the bed mesh. This should normally be done as close to print temps as possible, ideally, however, because PEI can melt and be damaged by hot extruder tips, the normal agreed convention is to run it at a constant 150'C. Unfortunately, it gets even worse than that, as they LEAVE THE HOT END driver off the entire time it is running bed mesh, which by the time it finishes can be as low as 80'C...imparting OBVIOUS skew to the measurement. Anyway, give my revised bedmesh macros routine a look / try. Check out Ellis' guide: https://ellis3dp.com/Print-Tuning-Guide/. I don't see anything wrong with your bed mesh that would require mechanical adjustments to.

Hope this helps!
Jeff

[Giterdun2]

ok thanks Jeff for the explanation.. I'm just somewhat curious as to why it would look like that and not be a bit flatter.. ;) When I print something that is fairly large as I mentioned, the first few layers do print just fine, but as it builds higher up, that's when it starts getting rough, and it seems to be only on the left side, and towards the rear. It also gets noisy when printing over that area when it's rough.. I never considered the cooling fan, but that makes sense as it's closest to that area.. I will check that next time.. But large objects are a rarity anyways.. most things I print take only a small portion of the bed.. I strictly use Klippermod for levelling tho, and I level anytime I change plates or nozzles.. I also haven't updated the A5M firmware for a while due to all the issues that have been reported, and it generally works fine.. thanks again.. Just one question regarding the macros.. It says for auto bed level.. it that when you want to automatically level before a print every time, or does it work when I select Auto Bed Level in the Klippermod menu? Thanks again..

[jeffalanmcclain]

Either one on the auto bed level question. The AUTO bed level just calls the "bed level" routine with specific temps. That same routine is called when you print and have NOT already loaded a bed mesh (the little tune icon) or you can force it to run. Either way, it is not the best practice the way they [flashforge] have it running with extruder temp off. There is also a bug where you could be running a HOTTER bed temp and the routine doesn't check to see if the bed is actually HOTTER than the target bed mesh temp, which then will continue cooling as you run through the calibration, so I fixed that too, with proper checks.

Ok, so your "rough" print is NOT first layer, so that absolutely discounts it being related to the bed mesh / level. Just curious, but what filament are you printing with and what temps? I assume you have AUX fan (or the chamber fan) set to be on? Is it "rough" as in warped on over hangs or look melted or does it look like it just isn't "flowing" hot enough? All of these I would STRONGLY encourage you to work through the temp tower prints and the flow rate tuning guides on Ellis' page.

Also, take a look at this page to help identify what you mean by "rough" and looks like crap. It can help zero in on what the issue is. https://www.simplify3d.com/resources/print-quality-troubleshooting/

[jeffalanmcclain]

P.S. it is possible that you are not running hot enough on bed temp and getting poor adhesion (again, what filament and temps are you using for extruder/bed and first layers), and the part is curling or warping off the bed on the left side and causing later print layers to look bad? ABS is notorious for warping and will pull itself off the bed as you progress through the print.

[Giterdun2]

hmm.. I didn't see anything in the link that resembled my issue.. Here is a pic of a previous project to give you an idea.. This is Overture Matte Black PLA. I print it at 220, and bed at 60.. I have profiles for various filaments with their recommended settings.. As you can see most of it is fairly smooth, but the left side it pretty rough.. I print mainly with PLA, HS PLA, Silk PLA etc, and some TPU, ABS. I set the temps to roughly what it says on the rolls, and I've successfully printed a lot of things I've designed. ;) I don't generally have an issue with adhesion.. I also use various types of plates like PEI, PC, and some others I've purchased. I understand that ABS uses higher temps, and I have printed some things without issue.. This only seems to occur with larger objects..