Cnc router and mould advise needed

So I ordered a cnc router from China but I got impatient waiting so tried to make a mold the gelcoat and fibreglass way. It didn’t go so well, I could probably use it but it’s a bit warped because I used a heat gun to try get all the paint out of it and overall it’s a bit shit, now the cnc has arrived so I don’t care, I can start again and life will be easy! One issue though, how does it work? It came with no instructions or software. It does have a dsp thingy with a usb hole and internal memory so I’m thinking I just need software like vcarve pro, learn how to use it, save the code to a flash drive and I’m good to go…right?

Cheap mold
I’m thinking if I cut the mold out of mdf, leave it on the machine, paint it with glue (pva or epoxy) the mdf will swell, then when it’s dry run the finish cut again to remove surplus glue, swelling and furry bits. Then wax the heck out of it. Will this work? I’m probably going to try it anyway but any tips would be appreciated.


That should work well. However, MDF soaks up wax really well and doesn’t swell from wax like it does from epoxy or resin. So if you can get a smooth cut it makes a perfect mold surface because of how well it holds wax. The denser outer surface doesn’t soak up as much wax (but it soaks up plenty) while the core takes more coats before it stops absorbing so much. So if you can get a smooth fiber free cut with just wax that’s a perfect mold surface. I’ve found that a router leaves a more fiber free surface than other cut surfaces so the CNC might create that same type of surface. Try a small test piece. If you aren’t able to get the surface you want on the cut surface with just wax then try what you said (on a new wax free sample). Polyester resin works well. Keep saturating it till it won’t suck up more resin. Allow to cure and run the final cut again.

The high density outer surface with a softer core creates a potential problem with warping after removing the dense layer on one side. A larger outer perimeter would probably allow it to lay more flat.

Hey, thanks for the advise, it’s good to know I’m on the right track. Good point about warping, I might laminate it to another piece of mdf to keep it flat. I got the router working and got it cut today, I’ve already put resin on it so I can cut again tomorrow. It’s looking good so far.


beautiful, thank you.

Progress update.
The moulds worked well. I was trying to get some pva release but all the shops around me that sell it were shut this time of year. As a very impatient person I looked for alternatives and found hairspray was sometimes used, so I got some, tried it and it worked great. It’s also good for spraying on finished parts to stop resin sticking where you don’t want it to. Hairspray is my new best friend.
The mast is done and extremely stiff, quite heavy though.
Mast mount is well underway.
Currently I’m fitting the Chinese foils.

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I’m thinking about buying one of these same machines too on aliexpress.
Now I want it even more, this is a clever idea to make molds with this beautiful cnc machine.

very nice work!
how much did you pay for the cnc?

The machine was US$3600, that was with all the extras like the dsp and 4th axis that I’ll probably never use but wanted anyway. I don’t know what brand it is as it was a bit of a weird transaction. We were buying another cnc machine from China so it was a referral to a guy that spoke hardly any English. My experience with Chinese machines has been largely good, they use the cheapest of everything to put them together (so you may as well get the cheapest one you can find) but they work and parts are cheap. Neither this machine or the much more expensive one we got at the same time was earthed so it pays to have them checked before you plug them in if you’re a fan of living. The dsp and vectric software (NZ$1200) have made it really easy to learn to use.