More on the transmission tunnel mould

Wow – this mould is becoming a saga but it’s worth it to get it right.photoSo, as you can see from the phototwo pictures, the mould is finished and ready to pull a part.



So, the plan to get a part out of this mould was as follows:

  1. do a trial bagging session to understand how the bag falls in under vacuum and get a good handle on the pleats. write off the bag afterwards.
  2. lay in the first two layers and set them – this gives me a chance to examine the the quality of the finish and lets me decide if I like it before continuing. If I like it, I can put the part back into the mould and infuse the further layers into it.


The mould isn’t remotely air-tight. I think it boils down to a fundamentally bad assumption on my behalf, namely that the wood I ordered would be vac-tight. It’s not. I did a test on a patch of it and couldn’t get it to hold vac at all. And that’s before I go investigating the other bits of it where it mates and the flanges for the three-piece aspect of it.

So, rather than faff about for a week and get nowhere and waste a load of bagging material, I called Warren for suggestions.

His idea was a step beyond my initial one (throw it into the skip) which was to lay a chopped strand mat part in there (no need for a vacuum seal with simple wet lay) and then take a mould from that.

This has many advantages:

  • 3 layers of 450g CSM is cheap
  • I can trial fit the part to the car. It’s not going to be anything like the final part (13mm thick) but will give me ideas
  • it’s a one-off, so best bet is get the part finish as good as possible and then I can use a standard moulding kit to make the final, vac tight mould.

Lessons Learned

  • I tried a hybrid technique of using part making material for mould making, which didn’t work
  • you can use any old cheap bits for pattern making but moulds require precise application of the right materials and chemistry for resin infusion
  • I have a good mould but nothing like strong enough or sealed enough for epoxy resin infusion
  • cut your losses
  • growth through pain. 80% of learning is experiential – I have learned so much getting hands-on like this.

So, I can now see a positive from this, which is I will have a part that can be wrangled into the shape I need and surface finished. Then I can make the right mould.

Feed the attention-whore