I have calibrated the back left, right & front middle using feeler gauges (to 0.30mm) but I can’t get the height right at the back middle (X=100, Y=0)- it’s always more that .3, maybe .35 or even .4.
As a result anything printed within about 30mm of the back edge in the middle doesn’t stick, especially brim. I could understand a warped base plate causing the glass to be bent upwards in the middle (as mentioned in some other posts), but I would expect the glass to bridge any ‘dips’ in the plate as it is only held at the 4 corners.
I’ve got the same problem. Just impossible to get it even everywhere. Not sure what the cause is. Tried several times to calibrate it and it always seems to be out somewhere on the bed. It’s quite annoying, as it means the skirt often doesn’t stick well on one part, then it lifts and the nozzles drag it off and it then gets tangled up with the print. Sometimes I have to restart the print several times to get past the initial stage, particularly on large prints.
I just had to abort another job, actually it was slightly warped at the from to I noticed.
I recehcked the calibration again and at 200,200 & 0,200 it was actually under .3, but the middle was over .3
Front center was about .3.
I thought it was working now with the H60 settings but the print has still warped up at the back after about 3hrs…at least it goes longer before warping now
I am still trying to improve the first layer(s). If have seen a first layer that got so well glued to the bed, it was nearly impossible to remove from the bed. Also, when the temperature is too low, the printed model warps easily. Since lowering the temperature for my prints I use a brim nearly all the times, and even raise the temperature/disable cooling for the first layer. That said, I’m still looking for that ‘sweet spot’.
After 3 PLA prints my buildtak sheet was already broken. I removed it and add some blue painting tape.
Now the prints sticks like hell without a heating bed.
Those little problems are the reason why most people owning printers without heatbed (like the Ultimaker) often print with a raft. So the actual first layer will be level even if the bed is not.
@minitreintje: if you question was for me, yes I still use BuildTak and a long sharp knife to remove the prints from it. I have 2 spare sheets in stock but until now everything runs ok. In the end I will move to a heated bed but I’ll wait for some more experienced users to figure out how to do it on the 8400.
I seem to have found the sweet spot…
I calibrated again, this time using a business card as mentioned on the Buildtak page - should be 0.20mm.
I then printed the power connector http://www.thingiverse.com/thing:625825, which warped badly before, and it came out perfectly. It was a bit tricky to unstick it, but acceptable.
I noticed that the first layers were much more transparent than previously, I assume that’s a sign that it’s sticking better?
OK, I’ll see how the next prints go. Buildtak quotes 0.2 for PLA whereas Velleman quotes ‘about 0.34’. Previously I had 0.3 and problems, maybe 0.25 would be the next one to try