Prints curling, ripping off print bed

Wondering if someone can help me.

I have been printing fine since the weekend i got the printer. obviously had the small niggles like everyone else but ive hit a brick wall.
The other night i was printing all night, lots of different prints and everything was fine. i was so impressed everything was working..

The next evening i go to print again and nothing will stick to the print bed, it does one layer and it starts curling, then the air ducts or the ir sensor rip it off the build platform.

The kapton tape is clean with isopropanol alcohol. im doing exactly the same as i have been doing but nothing is working. ive tried putting the nozzle lower but it scraps it off. ive tried higher but the filament doesn't stick down at all.

ahhhh

I had this problem too. I started a new spool of filament and was able to do a number of prints. But later (I think it was next day), I just couldn't get it to stick to the Kapton. In the end, I switched to a new spool of filament from a different supplier. That was about 2 weeks ago, and adhesion to the bed has been good since.

I no longer print on Kapton, I print either direct on glass, or on solvent cement, depending on the nature of the print. Direct on glass works well for prints that have large, mostly rectangular outlines (you need to heat the bed to 70C-80C and wipe it with vinegar). However, when printing items with small outlines, sometimes these outlines fail to adhere to the glass when printing the first layer. For these prints, I use glass painted with solvent pipe cement, at 60C. Adhesion to the pipe cement is extremely good, so the pipe cement comes off the glass bed when removing the print - but it is very easy to patch up.

I've recently received some 50mm Kapton tape, so I'm going to try printing on Kapton again, but applying it using the wet method this time.

Edited 1 time(s). Last edit at 02/07/2014 01:38PM by dc42.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

If you haven't read it already, the new part in [forums.reprap.org] that lowers the nozzle a bit with respect to the IR sensor is a great start. You might also be able to get the IR sensor a little higher, and you can adjust the bearing on the back of the X carriage to get the fan duct a little higher.

I'm experiencing big improvements in the curling department on large objects after I added a 5 mm raft in Slic3r. Turning off the heated bed seemed to improve the issue too, although I'm using blue tape instead of kapton.

It strikes me that if the nozzle temperature is too low, perhaps the extruded filament has too little time to stick to the bed before it "dries up". There is a separate Slic3r setting enabling you to set a higher temperature for the first layer.

Some people report that a stable temperature (i.e. no draft) around the printer helps -- I haven't got any conclusive evidence, but a few thoughts about what curled and what not, point in that direction... The thread at [forums.reprap.org] has a couple of solutions for draft caused by the fan.

Finally, I think it is possible to get the first layer too low....

My prints has been much much harder to remove after I smoothed (or made rough actually) the kapton over with a sanding block P400 to level out the small dimples from nozzle crash, could be worth a try?

Erik