"hovering" – a little trick against warping even without heated bed

[fuh 1]

I managed to print some critical shapes by letting them "hover". That is, not letting them touch the platform level anywhere but having support structure under the whole part. That way, the support structure elasticity is used to absorb the tiny shrinkage movements that would else lift the corners or edges, sometimes invisibly at first but causing a bend that would escalate in the next couple of layers. So I may still get some slight distortion but it will not substantially bend a layer, and thus not escalate. For example I have applied this to nylon material which has severe warping problems else.

In order to not let the part be automatically adjusted by the slicing program to begin at z = 0, I use to place some additional, tiny "dummy part" a bit below the needed part in my design.

Maybe a nice feature candidate for Cura that a model can be shifted interactively in z direction, too, to achieve the same effect?

 

 

[IRobertI 520]

Isn't this what the raft option does?

 

[gr5 2,172]

That's what I was going to say. Raft is a great way of dealing with warping. Except the bottom surface ends up rough. But if you don't mind that then it's great. And much easier than trying all those silly techniques to get it to stick better. Another way to deal with it is to have the temp well above the glass temp (try 75C). That way the bottom 5mm or so is so soft, any pulling forces won't make it down to the bottom layer.

 

[fuh 1]

Yes, obviously both work on the same principle. You could say, I'm misusing support as raft.

Hmm, trying to remember why I thought it would be better than a raft... I think a thin raft can absorb much less contraction than a support structure. And it is my experience that a raft is hard to remove, but maybe that has changed? For parts without a flat bottom there is no transition from raft to support. I found an almost flat bottom is not easy to print without my trick. Or is it? But support generation strategies change all the time, and my experiences become worthless, I need to keep experimenting.

So I could imagine an integrated support/raft structure with adjustable minimum height could be best.

All this is just meant to be brainstorming.

 

[gr5 2,172]

All this is just meant to be brainstorming.

 

Which I enjoy! If you have a picture of what you are talking about that would be interesting. Maybe a screenshot from Cura of raft versus support for the same part.

 

[fuh 1]

If you have a picture of what you are talking about that would be interesting. Maybe a screenshot from Cura of raft versus support for the same part.

 

I'll have a look if I can find a good example..