Print directly on the build surface but still have supports

Is there a way to print a part directly on the build platform, yet still have Preform generate supports only for the overhangs that need it.

I know there will be some compression occurring for the first 10 layers or so, but I can accommodate that by thickening the base.

I don’t believe there is a conventional way to accomplish this within Preform.
You could use OpenFL to remove the raft FLP layers. But that has its own challenges.

You could always draw your own supports and just print without Preform generated supports.

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There’s not currently a way to create supports that originate on the platform without a base. You can however generate internal supports without a raft. I’ve used this a few times for large bridging sections. You can go into support edit mode without generating supports and manually place points. So long as none of them need to contact the platform, a base won’t be generated.

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That is pretty cool. I didn’t realize that was an option.

That is a very neat idea, so I gave it a try, and it works, except in this particular case I still need to provide support for the bottom part of the foot.

So then I got an idea. What if I provide a surface for the supports to attach themselves to, a surface which will be discarded after the print is done. So here is what I came up with.

This is actually perfect for my needs.

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That’s a great idea. Are those flat bottom surfaces coming out well for you? I’m curious as to if you can bridge cleanly over smaller supported areas. I haven’t tried since we improved flat bottom surfaces in 2.10.0.

This is an excellent tip, there have been so many occasions when I have had to model supports by hand, and making just a base is so much easier.

@Frew , can you explain the improvements in flat bottom surfaces please? I would very much like to understand the difference it makes. Is it a difference in supports, or does it actively do something to eliminate the distortion?

I don’t know exactly the mechanisms our process team used to improve parallel surfaces but my understanding is that supported surfaces that are parallel to the platform will have less distortion and be generally cleaner.

I printed it before using full raft with the previous version 2.9.1, and the flat bottom surfaces needed some work. The support connection areas create convex dimple that needs to be sanded down.

I haven’t yet downloaded 2.10, but now that I know how to do this, I’ll definitely give it another try.

I’ll also modify the throwaway surface to have a bevel, to make it easier to remove. That’s easy to do in Solidworks, 45° outward draft will get it done…