I have an SLA printed part I want to put a brass threaded insert in using a soldering iron. The insert is slightly larger than the hole so I would assume the edge will melt and re-freeze around the teeth. Are there any issues with melting SLA or this idea in general?
The plastic used in SLA printing is what is known as a thermoset plastic, as opposed to the thermoplastic plastics used in FDM printing. What this means, is that it can not be melted. The reaction that hardens SLA materials is irreversible. If you heat up the plastic it won't melt, it will just burn (if it gets hot enough). What you're planning is a bad idea, and it won't work.
There is an alternative. Use screw to expand inserts before final curing. After washing, but before curing, place the threaded insert into the hole. Use a screw to expand it into the hole walls. Curing will then 'fix' the insert into the hole. Hope this late advise is usable. TC Carr