Hi Ashely

I did try some rubbery foam but it was difficult to cut and carve to shape. The silicone bumpers I made for the the Boxkite were OK. Funnily enough the first one came out better than the second but that's often the case isn't it?

I need some more practice I decided and once you have the mould making spares is a doddle.

Tim R

Next to make the mould.

I know it's OTT but it's just stuff I have to hand.

Bits of pine chopped up to make the mould case.

Here the waxed pattern is stuck (with wax) to the waxed glass.

The mould case is placed over the pattern.

The pattern and mould is partially filled with epoxy thickened with micro-balloons to a consistency that will just flow.

When the epoxy has cured sufficiently (but not fully cured) the rest of the mould is filled with random bits to glass in epoxy to provide a strong back-up to the mould surface.

A quick coat of fast drying sealant and the recess waxed and the mould is ready for pouring.

The mould is filled with liquid silicone catalysed at 5%. This particular silicone will give a Shore hardness around 25 which is nicely squidgy. This time is very very careful to mix the liquid and catalyst very gently to avoid trapped air. I was also very careful with the filling to bring it just to the edge. On the Boxkite bumper I underfilled one so it ended up with a thin wobbly edge. The second I overfilled and both gave me a really hard time trimming.

This one is as-poured and you can see, the top is nice and flat. Another observation is that there are tiny "ears" on the silicone. This is where there were tiny pinholes in the epoxy mould. If you look closely you will see some black dots and these are where more prominent pockets were filled with polyester and dressed to shape. Having female features in a mould (ie small recessed blemishes) is not the end of the world as they will be male features (bumps) in the product and can be easily trimmed out. Have male blemishes in a female mould is not good as it will leave hollows that are much harder to deal with. I am sure there is a metaphor in there somewhere!! When I was learning to be a pattern-maker we were taught a lot about genders!!

So here we have the faithfully reproduced product – another metaphor!! and complete with a little ear to be trimmed.

It is very bright white so I looked up to see if there where pigments for silicone imagining there had to be. I found an American company that do a fluorescent orange which would be perfect. Many full sized racing boat have day-glo orange bows because they are designed not to sink but float with only the bow sticking out above the water. Lots of photos on the internet.
I am thinking of ordering some pigment as the same system will work on the two Cigarettes I am building to Ray Woods design.

And here we have it. Nitrohammer with its nice new shiny white nose.

Look out stone walls of cisterns as we can now drive it like a hooligan.

Tim R

Hi Chris

Thanks as always for your encouraging comments.

What happened was that as I set of for a second run, one of my pals stepped in front of me. For a moment I couldn't see a thing but knew that the wall was coming up so steered to port, or so I thought. When my view cleared it was heading straight for it. I only had time to cut the throttle but that made little difference. I just put it down to bad driving. When I found the disconnect later I realised that I had actually tried to turn but that wasn't happening!

I found a new bolt in my spares box and it is fixed with Loctite. The version that you need heat to disassemble.

Can't wait to try it again and get the engine fully run in and tuned. I made a few mods to make it faster and they worked!

Tim R