/diy/ - Do It Yourself

>>1944957
The rough surface of the printed parts and their lack of flexibility makes them really uncooperative for making molds directly. The only success I have had are the following.
1. Making the mold a single-use destructive item. Add splits and seams in the print so that the mold can be put into a vice after the resin cures. You then use pliers or wrenches to split the mold in order to free the part. This being needed really depends upon part geometry and I mostly used it for dished shapes.
2. Print the positive masters and pour 2-part silicone molds around those.
3. Using a rigid master for pouring flexible parts, or dummy masters for making finer detail parts. The rigid master can be touched up with sanding, epoxy putty, or bondo if you need to remove the texture of the printed surface.

I've mostly cast parts from higher durometer polyurethane, or from bisphenol. And all with a pressure pot to avoid having bubbles in the final parts.

>>1531056
The quality and accuracy of the resulting parts will depend heavily on the resin system used, the stability of your molds, and whether or not you cast them under pressure. Using a pressure part is GREAT, especially if you intend to cast any clear parts, or parts with higher durometer ratings. The pressure helps to crush any bubbles in the resin mixture down to a fraction so tiny that they are imperceptible. It also allows the resin to be shoved into areas of the mold that it would have trouble filling as a result of surface tension or air entrapment.

>>1465041
>Can I just leave it on a flat surface, or will the polyurethane resin leak out from underneath? I guess I could bolt on a removable plate on the bottom so it's sealed up, but I don't know if that's even necessary. Any help?
Use polypropylene sheets as the surface you are setting your mold face down against, then put some heavy weights on the mold. Alternatively use aluminum ductwork tape to adhere the polypropylene sheet to the mold.

I used silicone molds and simply overfilled them with the resin, then added a sheet of silicone or polypropylene, then placed another mold on-top and filled it. I repeated this until I had a stack with a weight on top that would fit inside a pressure pot. Which I then closed and filled to 40psi.

>>1294781
Very few of the products on offer from any of those companies even list Izod impact ratings. I compared 18 different products across 5 different brands. I was considering Innovative Polymers but their system is twice the price per unit of volume compared to anything else, and it's harder to find suppliers for.

But anyways, I'm not likely to go back to casting because of how time-consuming and messy it is to have to pour molds, pot them, pull molds, pry parts, sand/drill parts to tolerance, and then have to deal with however many reject parts I produced. I didn't get anything from the cast parts that was of a worthwhile benefit over just scaling up my printing operation.

It's infinitely cheaper in time and money to buy another printer than to try to scale up casting. If I were making much smaller parts, with much finer details, and less of a requirement for dimensional accuracy it would be a different story.