Printed object warps and comes off the "Raft"

[SeattleDavid 0]

In Cura I am using the "Raft" option. The raft sticks perfectly to the baseplate. But the printed object is so weakly attached to the raft that it comes off sometimes during printing.

What setting would allow me to better attach my printed design to the raft? There must be a setting that determines how well connected the object is to the raft.

Thanks!

[gr5 2,094]

I'm not a fan of rafts. This is an older technology that you shouldn't need anymore. Is the bottom of your part flat? anyway I recommend you print on glass and here's my details of how to get parts to stick like hell to glass. I hope you consider it strongly but if not maybe someone else who used rafts "back in the day" can help you:

lifting corners, curling corners, part sticking to glass

1) Make sure the glass is clean if you haven't cleaned it for a few weeks. You want a very thin coat of PVA glue which is found in hairspray, glue stick, wood glue. If you use glue stick or wood glue you need to dilute it with water - about 5 to 10 parts water to 1 part glue. So for example if you use glue stick, apply only to the outer edge of your model outline then add a tablespoon of water and spread with a tissue such that you thin it so much you can't see it anymore. wood glue is better. hairspray doesn't need to be diluted. When it dries it should be invisible. This glue works well for most plastics.

2) Heat the bed. This helps the plastic fill in completely (no air pockets) so you have better contact with the glass. For PLA any temp above 40C is safe. I often print at 60C bed.

3) heat the bed (didn't I already say that?). Keeping the bottom layers above the glass temp of the material makes it so the bottom layers can flex a bit (very very tiny amount) and relieve the tension/stress. For PLA 60C is better than 50C. 70C is even better but then you get other "warping" like issues at the corners where they move inward but if you are desperate it's worth it. For ABS you want 110C (100C is good enough).

4) rounded corners - having square corners puts all the lifting force on a tiny spot. Rounding the corner spreads the force out more. This is optional if you use brim.

5) Brim - this is the most important of all. Turn on the brim feature in cura and do 10 passes of brim. This is awesome.

6) Squish - make sure the bottom layer is squishing onto the glass with no gaps in the brim. The first trace going down should be flat like a pancake, not rounded like string. don't run the leveling procedure if it is off, just turn the 3 screws the same amount while it is printing the skirt or brim. Counter clockwise from below gets the bed closer to the nozzle. Don't panic, take a breath, think about which way to move the glass, think about how the screw works, then twist. This may take 30 seconds but it's worth it to not rush it. You can always restart the print.

If you do all this you will then ask me "how the hell do I get my part off the glass?". Well first let it cool completely. Or even put it in the freezer. Then use a sharp putty knife under a corner and it should pop off.