Screw Top Container

I’ve been trying to create a small container with a screw top to no avail.
I used Autodesk Fusion 360 which does thread just fine.

The section that I included in this post works great on my FDM printer, which is less precise than the Form3, but the Form3 cannot seem to duplicate the print. I’m using clear resin because I want to see the color of the container contents.

I have to say that I’m disappointed in the printer being that I use this printer for smaller detailed parts.

Here is the cross section of what I’m trying to print. The gap between the male and female threads is .26 mm.

If you are trying to print them together .355mm is the magic number for gap distance. Any smaller than that and you will risk it being fused together. Another thing is post processing is extremely important here. You must remove all the residual resin before curing. Again if you are printing them together you need top put holes in it to blow air into them to get the excess material out. It is a lot of work. But it can be done successfully.

If you are printing them separately then you need to add tolerances into your thread profiles based on the orientation that you are printing them in. I highly recommend printing them parallel to the build plate. If printing them parallel then you need to add your layer height to the pitch (.1mm). Then split the difference in the hole and shaft diameters of the thread for the (X,Y). So the hole add (.355/2) and the shaft subtract (.355/2). Doing this should make the threads come out perfectly, after properly cleaning and washing. I recommend that you print them separately.

One last thing, your galvos, main optical mirror, optical window (both sides), and the bottom of your build tank need to be spotless. Really try to avoid any supports on the threads, they will ruin them. Let me know how it goes good luck.

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A little background to how I know this. I did it. I designed a connector for one of my clients that used 3D printed M13 threads that did not need tapped in post processing. It mated with a commercial metal component directly out of the curing machine. It also printed as a solid piece that needed broken to loosen the outer ring that was used to secure the threads on the mating component. It looks like i Mayan calendar inside because i used compressed air to remove all the excess material from the threads and locking mechanism. That is the only way this will work.
The information i gave above is what i learned from this project.

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I am trying to print them together but separately o the build plate. The picture was just to show the gap I have which was .2 mm.

So I finally gave up and switched to a container lid which was a tight fit without any threads. I found that at $175 I didn’t want to waste the resign fighting with it. But I’ll try the .355 mm next time.

I switch to the standard grey resin and printed with the bottom of the container on the build plate. This of course gave me the cup error, which I feel is in error because if I print it without the cub errors then it pools all the material in the bottom of the container. It printed fine with a cup error and I could place all the supports so they were not a a thread.

Thanks a lot.

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Interesting. I wouldn’t suggest doing this because even if you’re able to print them seperately, you’ll have a small amount of resin in the gap that you won’t be able to get out without target IPA application.

Lessons learned by printing micro-fluidic parts.

Oh, and if you do still do this, you then need to clean the IPA from the interface. Surface tension can be a pain sometimes.

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