Wow – this mould is becoming a saga but it’s worth it to get it right.
So, as you can see from the 
two 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:
- 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.
- 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.
But … DISASTER.
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.