This post is really about some of the manufacturing detail I’m going into as I make the part. As I’m sure you know, the sensible route to getting a composite component is:

1. Make the part you want out of any old stuff so you have to get the right mock-up shape. I’m using kingspan and covering it in glass. I also like kingspan because it sands really well with an orbital sander, and till take bog (body filler) nicely both as a glue and as something to put on the surface when building complicated shapes.
2. Cover the part in glass so that it is rigid and all the foam is separated away because of course you can’t take a mould straight from foam – they will become one and we all know what happens when two become one.
3. Where I can, I’m cladding the part in pre-made sheets of 450g chopped strand matt glass which I made on a pane of glass. The reasons are that firstly the sheet made from glass has a reasonable surface finish and secondly it’s a lot less faff to clag this on than wrap the whole thing in glass, set in resin and then flat and polish, flat and polish FOR EVERRRR until I have a sensible surface. Thirdly these sheets, being quite flat, mean I can trust the angles I have them in at so I can reduce the chances of mechanical lock.
4. Where I can’t clag, I’m putting body filler in, which is great for filling the gaps, but must be recessed slightly back from the overall profile. The filler will then be coated in resin. This is because you can’t go body-filler straight to mould surface – when you pull the part from the mould you will leave the filler behind. So, for the want of a little deft work with an artist’s brush and some resin, I can avoid this.

As ever, this is easiest explained with pictures:

Here is the joint between two panels. Both panels have been cut and bogged down and while the bog is soft a bit of a push allows the bog to squeeze out into the gap, Add deft work with a lolly stick and the gap is scraped out.

You can also see a big gap between the panel and the part. This will be radiused back so I don’t have any right-angles into which I can’t get cloth.

Rivets are handy to stop the panel sliding down the part on the bog. whilst it’s claggy stuff, it still has a propensity to flow. I suppose this is another odd reason why kingspan is so useful – you can stick rivets into it.

Here is the bottom of the tank with the three panels attached. What you can’t easily see is the slight angle the tank tanks to follow the fury transmission tunnel, which is angled.