Mold Repair Questions and Options - Example Pictures

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#1

Hi Everyone. I finished another mold this weekend but when I pulled the parts out a couple small pieces of the mold broke and came out with the part I was molding. This mold has 4 parts which all go together. 3 of the 4 are great and ready to go. The 1 broken part will need to be repaired or redone. I was hoping to get some help on how to best repair this. As you can see from the pictures the pieces can be put back into place.

I was thinking of just adding epoxy and basically glueing them back in. Then I can sand the finish smooth. I have also thought about using something like Gorilla Glue to make sure the pieces stay in place. My fear is that if I fix the mold the pieces might break off again.

What does everyone think? Can I repair and have it last, or do I need to make another mold?

Thanks!

#2

I would CA the bits back in. CA is cyanoacrylate. It’s essentially super glue…but you want to use a good quality CA. Most hobby shops will carry some good stuff. The advantage over resin is that you could glue them in and start sanding almost immediately.

Due the nature of the shape, it’s quite likely that they will break off again.

If I made that mold, I would have used shorts cuts of carbon fiber tow to reinforce them and made the surface coat as thin a possible…or stuffed some carbon tow into the dimples right after the surface coat was applied. This way you’ve got some longer fibers in there to reinforce the resin

#3

Thanks!

Would you recommend trying to repair? It do you think I am just setting myself up to have to fix the mold multiple times?

#4

How it going just finished rear spoiler I will send email off pics,any holes dan you really need to fill using microfibres,high density filler it’s just like filleting.

#5

It’s really hard to say. Will the parts be more flexible than your master was? Are the sides of those little dimple vertical?

Also, the demolding technique could really help. Ideally, you want the laminated part to come straight up off the tool. I would start the demolding by getting the ends loose, put a Popsicle stick under each end, and pry up both ends simultaneously. This will help the laminate come straight up rather than trying to lever the nubs off. If you pry on only one side the nubs will receive leverage which will increase the forces applied.