I am using MakerJuice castable resin in open mode. My first build with it produced a part the full usable Z height and didn’t fall off. Then I had another two builds that didn’t fall off.
But my latest attempt only printed to about 20mm in height before it fell off the build platform. It is essentially the same job as the previous build that didn’t fall off (identical geometry and orientation only 2% larger). I’m not sure why the first prints worked and now it is falling off. Any ideas?
Any tips how to make the build stick better to the platform? Should I rough it up a little with sand paper or something?
That 2% apparently increased the surface area enough that the peel pressure exceeded the adhesion force. (Sticktion is the official term for that )
In Help -> Fine tuning drop the build platform 0.2mm in Z and try again. If that fixes it, cool. If not, try another 0.2mm drop. If it still falls off, retry the previous scale part you did that worked and see if that still prints. If that fails too, then there may be other issues, like the resin needs agitating, or the PDMS is cloudy or something. You’ll probably want to open a ticket then. But, if the previous part succeeds, you may want to try re-orienting the bigger part to try to minimize the total surface area at any layer, and or drop another 0.2mm. In any event, slow and small changes are best to isolate and correct the issue. You’ll get a feel for what to do.
Roughing the build platform might help, but I have never needed to do this. Plus, having an overly rough platform could acellerate the demise of the PDMS, and make part removal more difficult.
If it’s due to the layer being large enough to make it hard to separate you might try using a material preset with a lower exposure time–for instance the lighter resins. That will make it so that it doesn’t cure as much.
Note though, since you’re not using Formlabs resin, they can’t help you
I don’t think the extra 2% caused the issue since a part with far more shear force exerted printed fine.
Thanks for the the tip about lowering the build platform - I didn’t know that was there.
I am trying again after lowering it 0.1mm and I also coated the build platform with a dab of the much stronger non-castable resin (I figured that it might help since the part that survived despite having much stronger shear forces had some of the other resin on it - I didn’t wipe it clean first build of the castable resin).
I think you misunderstood - its not too hard to remove - it fell off mid-build.
Christopher suggested that the print surface area is getting large enough to where the layer is difficult to remove from the bottom of the tray, which could put stress on the base of the print as it tries to separate it, that’s why with the Form1 they recommend having parts be hollow to reduce surface area during the print and reduce stress when during layer separation.
What I was saying, if the surface area is an issue, then using a lower exposure preset could reduce how much it wants to stick to the bottom of the tray and therefore reduce stress on the base that could make it fall off.