Not sure what to name this topic. I am trying to print a fixture part that has a feature that protrudes through a hole to act as an ejector. I modeled in quite a bit of clearance, but the gap fuses solid. The gap is 0.015in which seems like it should be enough. What can I do to get this to print without fusing? I can’t afford to increase the clearance much more. File attached.
Set.form (1.7 MB)
Hi, are you experiencing clearance fusing during printing or curing?
During printing. I’m printing in BioMed White at 100 microns. The part is fused straight from the printer. I tried to break it free before and after wash, but no luck.
Have you checked the dimensional accuracy of the part printed on the same printer using BioMed Resin?
It looks like the parts may be receiving excessive laser exposure or over-curing, which could be causing them to expand slightly.
You could try the Formlabs Fit Tuning Test to check the printer’s dimensional accuracy and see whether exposure or dimensional compensation may be contributing to the issue:
Could you share an image of the component which is fused?
Thanks for the info on Fit Tuning. Unfortunately it does not apply to biocompatible materials. I’ve pretty much destroyed the parts trying to get them freed up but I will take a picture of my next attempt and share it. I’ve added more clearance and am printing now.
The parts are dimensionally decent. I’d say they are a bit bigger than expected, but not enough to chew up that gap.
Apologies, I missed this:
Unfortunately, it does not apply to biocompatible materials.
Recently, I had to fine-tune my Form 4 for a project, so I performed a similar test. When I saw your post, I remembered seeing a similar article for the Form 3, which is why I shared it.
One plausible mechanism for why the prints are fusing is overcuring. This could be due to a higher laser intensity during printing, the laser/light source curing additional areas beyond what is intended due to light bleed through the LPU, or a resin-related issue where the material is behaving unexpectedly with the current print settings.
Now that you mention the parts are also coming out slightly larger than expected, it would be useful, whenever you get a chance, to measure them and check their dimensional accuracy. That could give us an idea of how much they are oversizing and may provide some insight into why the features are fusing.
but I will take a picture of my next attempt and share it. I’ve added more clearance and am printing now.
Please do, I think the community and Formlabs Support Team will find it useful to provide you insights.
Apologies not necessary. I appreciate your help.
The additional clearance resolved the fusing issue, but I’m left disappointed that so much clearance is necessary. Here are some pictures of the part. Please excuse my sloppy support cleanup. Was just trying to get this tested for function. Mostly good except for high coefficient of friction probably due to O2 inhibition at the surface. In a past life I developed a product called CUREgel for this exact reason. Time to make a new batch I guess.
Regarding dimensional, it seems that most surfaces have ~.002 extra material, so a 0.125 wall measures 0.129 for example (0.125 + 0.002 + 0.002). I have to be realistic and acknowledge that is pretty darn good. I find it unexplainable that I needed .023+ of clearance to avoid fusing. Scratching my head over that one.
Starting a 10 piece print now. Will report back in the morning on how that goes. Attaching updated model of successful design.
Set.form (1.8 MB)
I might have found the reason for your problem. I was going through the Formlabs Support Articles and found this -
This pretty much sums up the issue, another stark reminder for the stringent requirement of DFMA, don’t you think ? 
In a past life I developed a product called CUREgel for this exact reason
Very interested in knowing more about this.
Well, that says it all, and its pretty much my experience. I experienced fusing at .015in (.38mm) and not at .023 (.58mm). Ashwini, thank you for finding and sharing this. It’s funny how much better it feels to accept a technology limitation when it’s well documented/expected. I no longer feel I am fighting a process issue and can just accept the limitation.
Regarding CUREgel, you may find some history here on this forum, but I never brought it out of beta due to limited resources as I was consumed with developing the CUREbox products. Stratasys ultimately acquired that business so I moved on. Now life has brought me back to SLA and I’m immediately missing that gel. It was just an O2 barrier gel, but I designed the chemistry to be stable at elevated temperature for post-curing and added a little magic to it. It was well received so maybe I should make it again.
Thanks from me as well for sharing the guide @Ashwini! You beat me to it, and it’s great to see the community helping each other out 
You could make it 2 pieces, tighten up the clearance and assemble afterward. Looks like something to kick out a syringe. You could make the bolt/fastener in the little ‘foot-pad’ feature. I’ve had clearance issues before in the Tough2000 and 1500 resins. I just made the features separate to get around the issue.
