im wowing at this.... its an insainly nice print and great design work going on there... The thumb wheel is a great touch.
I use Reynolds Advanced Materials (Smooth-On) Products. For most molds I use Mold-Max 25. For casting resin I use Smooth-Cast 300. While both have spec'd shrinkage I have found it to be far less if used properly. Which means don't over-catalyze and don't heat cure. Thick parts will tend of shrink a bit more than thin ones due to exo-therm (heating up while curing. Another trick is to let the silicone mold sit for a week before demolding from the pattern. Yes, the instructions for the material say it can be demolded in 24 hours, and I do for some non-critical parts, the mold will last longer and seem to have less shrinkage if left to cure for a week before using.
As far as clearances, those can vary from .003" to .0075" depending on the part and function. For pivot holes, like the one in the thumb wheel I print the part slightly undersize and ream out on a drill press to the proper end size.
This is SUPER helpful! Thanks Dave!
I've made a point of building adjustable tolerances into all my models, and even done some experimenting with shrinkage rates in moving and connected parts printed in generic DLP resin, but I have far less experience with the galaxy of options available from Smooth-On for when it comes to molding and casting.
I spent the better part of a day extracting data out of their website and into a spreadsheet just so I could directly compare different attributes of their resins and rubbers (I didn't find their built-in tool was "data centric" enough for me). But the product and procedure recommendations that come from years of hands-on experience was what I really wanted!