I bought a Kossel XL last year from builda3dprinter.eu. Unfortunately I’m having a lot of problems with calibration. To be exact it will work so-so for small prints, but when it comes to larger footprints, it fails miserably. I’m attaching a photo to illustrate my problem. I calibrate each tower and the middle of the platform, using the paper test, and those are fine. Even then there is this “dimple” having a whopping 0.15-0.2 mm gap there…Currently I’m trying rotating the platform to see if this issue is with the movement or with the glass somehow…I mean this is not a concavity/convexity problem nor is it a simple “tilted plane”, and thus calibration simply doesn’t help with it…Any suggestions would be appreciated. Btw, the issue is the same without the masking tape, using the heated bed. Thank you!
.15 to .2 mm gap is not unheard of. Glass isn’t '.00000001mm ’ perfect. Mirror glass is usually better. I suggest rafting large prints, and over extruding on the first layer an additional 25% or more
I have a delta too and the issue is familiar. For me the purchase of a borosillicate glass bed solved the issue, but I see that you already have glass. Not all glass is equal though… These are some other random thoughts:
* If the diagonal arms are not equally long you can get very strange non-linearity effects.
* in my experience the “thin spots” can move around if the nozzle moves the other way so also experiment with that. If that is the case your effector is not level enough and there is too much slack in the mechanics.
* Are you using a thicker “initial layer height”. For instance 0.3mm work well for me.
From my experience and your photo, I would say the glass bed isn’t flat. It looks like in the center it gets too close to the nozzle and prevents filament from flowing and then as the glass gets closer to the camera it lowers and gets too far away from the nozzle and the filament can’t stick. Obviously you could try getting a different glass bed, or you could try tilting the bed very slightly so that the part of it that is closer to the camera goes higher and gets closer to the nozzle. This should also slightly lower the other half of the bed which looks like it’s too close to the nozzle anyway.
Thank you for all your responses! I have tried tilting the glass, it didn’t help much so far.
I’m glad the possibility of altering the first layer in the slicer was brought up. It’s something I thought of but haven’t tried, I kind of needed the input, as I pretty much gave up on this thing after days of experimentation. Unfortunately I also noticed that a setting that was good for a tower a day before is totally out of whack now. In the room where the printer is the temperature can fluctuate quite a bit (3-5 degrees C), so I was thinking the long aluminium towers might actually change their length a bit. Al is prone to significant thermal expansion.
Aerospacesmith, yes the setting for the Y tower was off, but I didn’t care much, I’ve been fiddling with it for quite a long time, and I just wanted to demonstrate the issue. Unfortunately it really does seem like there is a palm sized “anomaly” there, regardless of the calibration settings. I recently tried rotating the bed to see if this “dimple” moves, so far it seems it does not. So I’m starting to fear that it has to do with the diagonal arms, as Themba suggested.
For the time being I’ll fiddle with the first layer, see if over extrusion and a higher layer thickness helps. I could also just use the “better half” of the print area for most models.
Just scroll down an please read my other post there is a link how to calibrate a delta, in your case the the firmware’s delta radius needs to corrected first in the firmware.
Just a quick update…I pretty much gave up on this printer unfortunately. I simply don’t have the time/patience to fight with this (honestly piece of shit) bed. I’d need a proper manual leveling system (three screws with springs), to have a chance. M666 sort of does…something…but it seems unpredictable, sometimes it changes nothing, sometimes it does…There is a probe on the head but that never really worked…3d printed parts for a 3d printer…from what I’ve sen so far is a bad idea. I wanted to get into 3d printing relatively cheap but that didn’t work out. If I ever go for another printer it will be a plug and play type for sure. I do love fiddling and tinkering, but this is just pure frustration !! I tried so many methods, and the results are simply unpredictable. I’m really disappointed. That’s just 700 dollars of junk sitting on my table…A very expensive learning experience for sure. I know some will simply say I didn’t try hard enough but…honestly I don’t want to at this point… Thank you for all your input! At least they probably helped others with a similar issue and a LOT more patience!
