Start To Finish

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#1

I’m making new auto parts and thought I would share a small one from start to finish. I don’t normally share what I do because I’m contracted to do much of the work I do and can’t break confidentiality.

This is a solid metal part. I had a mold but it got abused and is no longer serviceable.

Below are pictures…I’ll add more as I go. Questions are welcome but I can’t say what part it is or what it goes to, sorry for that.

The one carbon fiber part was a reject, it is just here to show what Is being made.

The glass is just a smooth flat surface to lay the plug part onto, in order to build a mold. I am waxing both part and glass 10 to 12 times waiting half an hour in between coats. The part and mold will be made of polyester gp resin. I usually opt for clear polyester resin when making this particular part. I don’t use ISO or Vinylester to make molds most times because frankly it cost more and most molds I build only need to pull a maximum of ten to twenty parts. The gel coat I use is vinylester modified that is catylized with mekp 9.

#2

I laid up the mold and forgot to take photos during, but here is the mold and a description…

I used black tooling gel coat, about 40 mils thickness, applied by brush. I let that set for 18 hours, but it’s not necessary to wait that long. I just had other projects going at the time. Also 40 mils is a bit thick, but I have seen boat hulls where the gel coat is 40 mils. I then used general purpose polyester resin and 12 layers of 2oz fiberglass mat to build up the mold thickness. I laid all 12 layers one after the other working the bubbles out of each layer before the next is applied. A fiberglass roller works well for this purpose. You can buy these rollers in many sizes and shapes to suit your project. Once the mold was pulled off the glass panel I trimmed off the excess edges and sanded it round. It’s not perfectly round border but it doesn’t matter. I noticed some air bubbles in my gel coat on the surface of the tool so I will need to grind those out with a dremel and fill them with fresh gel coat… I use a toothpick to apply the gel, then sand it flush and buff the mold. Even a small mold can take hours to build. I will have about 6 hours into this one small mold. If you are wondering how to price your molds or the value of your molds … materials, labor rate, overhead + profit margin. This mold is being done at no charge because i broke the customers mold through use.

NOTE: the longer you can let the mold cure on the plug… the better. If you can leave it set for 7 days… do that. It will help eliminate shrinkage/warpage of the mold.

#3

Thanks for sharing this. I’m pretty new to making moulds and it is good to see how the pro’s do it.

#4

I’ve built about 35 molds or so since I’ve started this as a business back in 2007. If I can help others I’m willing.