Here is the pictures of the raft issue curling :
Then, I tried to rotate the piece, and the raft is still curling at the same place. Might a calibration issue. Not a big issue, but for info :
btw : this is my enclosure, to make sure it’s kept warm :
Pilou, if you compare the little knobs on the bottom of the raft. Are they significantly smaller in the area that lifts up? I still suspect that your bed is hanging on corner. How long do you wait after switching on before you print?
[quote name=Andre]Pilou, if you compare the little knobs on the bottom of the raft. Are they significantly smaller in the area that lifts up? I still suspect that your bed is hanging on corner. How long do you wait after switching on before you print?
[/quote]
Yes Andre, the little knobs on the bottom of the raft are way smaller in this corner than in other parts of the raft. What does it mean ? I usually wait for 15minutes before starting printing.
Ok, i tried again, after loosened the front screw. Same result : the froth left corner doesn’t stick to the bed… 
Should I loosen the screw more ? (i already loosened more than 1mm)
Thanks
Put your gloves on and turn the ball screw so that the platform is almost touching the nozzle in the center position (printer off). Then move the head slowly be hand to the area where you have adhesion issues. If you see the distance getting bigger then adjust the platform further…repeat until the distance stays equal. Do that all over the platform. Make sure the ball screw does not spin when you move the head around (hold with gloved hand)
http://zortrax.com/forum/viewtopic.php?id=173
Here was topic about pulling of models instead of ‘cutting’ it from the platform I think this can be usefull
[quote name=Martin Olchanowski]http://zortrax.com/forum/viewtopic.php?id=173
Here was topic about pulling of models instead of ‘cutting’ it from the platform I think this can be usefull
[/quote]
Thank you Martin. I always followed your precious advice, and I always cut the prints with the spatula. I never pulled by hand.
The same story happened to me too - on only one object. 
It started curling after raft was done so platform in not the problem in this case.
Fan: 20%
Infill: Full
Resolution: 0.14 mm
Support: 30
I think I need enclosure!
It always starts curling after raft is done. 
Martin will tell you it is because of the platform calibration. But I think you’d better close your machine, yes. Enclosures will help.
And maybe check the thickness between nozzle and platform in different positions. You would be surprised of the result.
And I say it again…
We need conical holes and this will be a thing of the past! 
Rafal ordered a sample of the perfboard that worked so well for me… but I think they did not get to to test it yet. Rafal, any updates on this?
If you have Acetone use it. This worked for me. Take an old piece of raft. Rub it with an Acetone soaked towel. Rub the sticky residue from towel on the white part of perf board. No more problems!!! I did hit the white part of perf board with sand paper before I did this. Wipe all dust off with Acetone after sanding.
Acetone glue is kind of messy, I may try hairspray which has worked well on my QU-BD RXL.
David
Guys!!! I sanded the surface of the platform with 600 grit sandpaper and the adhesion problems are completly gone (welll, that and some calibration made the trick) I just sanded a little, the perfboard still a little shiny, after that I cleaned the surface with acetone.
Here’s an other thing that works fine for me if you don’t want to “destroy” the platform.
If the platform heating up, some material of the platform expand more than others. So if the top surface is flat before heating, it isn’t afterwards.
So my solution, i don’t fasten the screws before heating and when hot, i only fasten the screws at the back edge where the connectors are. so the platform is absolut flat during printing.
BTW don’t remove the screws your not fastening. Just release them a little!