I’m printing a small 2-peice servo enclosure using Black resin with a Form 2 printer. It’s coming out pretty good, but I have a problem. When the two pieces are screwed together they are meant to fit flush to each other and close into a tight little box. But along the edge of the cases, where the two halves come together, the material is curling back (contracting). It’s not a square edge. It’s a very uneven rounded edge. So it’s leaving unsightly gaps between the two parts. Note: When I print these two cases, the outside of the case is facing down. The inside of the case is facing up (toward the build platform). The parts are supported by a whole bunch of supports that are recommended by the PreForm software.
I would try to rearrange this part like this
This way you dont need to support the critical edge.
Dont forget a hole at the bottom to allow the air to escape. Otherwise the air will make a hole in your part automaticly
Thanks for your reply. The reason I didn’t do it that way was because that would put support marks all over the visible outside of the case which would be very difficult to finish/sand because of the ridges/complexity of it. I was hoping to keep the supports on the inside of the case where the dots are not visible. Is there a way to support it without having any supports on the outside of the case?
You mentioned the hole in the “bottom”. When you say bottom, do you mean close to the bed? (which seems like the top to me) (Sorry, I get the lingo confused because of the inverted position of the bed).
Here is the way I printed it. Will tilting it at a 45 angle help (while still keeping the outside of the case pointed downward away from the bed)? Or should I should I manually add a bunch more supports to support the flanges?
You could try like that with more supports, but odds are it will still not give you what you want. The issue with no angle there is that it will do what it does to cups and cylinders, create vacuum. Also, there won’t be a lot of support to keep the thin first few layers from being shifted by the peel. I’d suggest at least a 10-15 degree tilt which will also help give it more to build on without needing tons of outside supports.
OK. Thank you for the information. I’ll put it on an angle and see if I can get the supports in places they won’t cause visible marks.
Please see the marked area.
It is not the point about the angle which creates the vacuum. They way “cbeatty” arranged the part won’t cause the vacuum effect. The problem of parallel arrangement is that the flat areas without support will be pulled down by the gravity causing sink marks on the parts. The structure can’t support itselsf without an angle
Tilting it at an angle will almost certainly correct the problem. Faces oriented to be co-planar with the bottom of the resin tank experience maximum stresses during peel. Those faces cannot help but be distorted. Besides the curling, you might also notice “puckering” around the support contact points. I’ve found that the best orientation of the model will have no large surfaces completely parallel with the built plate.
Flat-to-the-build-surface is an FDM printer habit that is actually counterproductive on the Form printers.
Let PreForm orient your objects. If you don’t like the resulting orientation because of where supports will be making contact, just tell PreForm to reorient again. I have my suspicions that PreForm orientation has a high degree of random element to it. Click Orient again and again and again, you never see the same orientation twice (at least, that I’ve noticed). I’ve gotten to the point I get better results if I orient manually, but I used to just let PreForm do it and I’d just iterate until, for example, most of the support contact points were on the bottom of the print where they’d be easiest to clean…
Looking at the pictures you posted above, it appears you’re both positioning the model and adding supports by hand. If so, that’s a double whammy of problems. The “ears” of your cases are completely unsupported, it is not at all surprising that they are distorted. So besides letting PreForm orient the model, I’d also recommend you let it add supports automatically.
If you let PreForm add supports and that’s what you got, even though the orientation is not optimal, PreForm should have put supports on those protruding features. In which cause you might want to submit the file to FormLabs for them to take a look at.
Preform isn’t great at orientation or supports, it can easily miss areas that are unsupported, you can always get a better result by orienting yourself and manually placing supports–when you do that you can make sure to get parts that Preform would miss along with placing supports in a way that is easier to remove and causes the least amount of damage to the surface of the model. But it does take some practice to learn what the best way to print something is–basically the top of the model will turn out the best but you also have to consider how easy it will be to clean up the surface where the supports are.
This but rotated roughly 45° should be optimal. You’ll get few supports on your outside surface (especially if you are thoughtful about which way to rotate it. For example the sawtooth ridges on the top surface would become local minima if you rotate it clockwise but would be well-supported if you rotate CCW.
This topic was automatically closed 14 days after the last reply. New replies are no longer allowed.