Mr. G. Brettin's Slow Motion Leg Hump

gbrettin

Started in on sanding the hood and let me tell you this, tooling gel gets hard AF! I started off with my 400grit sanding block and quickly went down to 60. You are looking at 3.5hrs of sanding. There's a LOT more sanding to go as well. I'm going to try doing some surgical hits with the death wheel tonight to reduce arm fatigue. I will also need to do a skim coat in almost all the areas and do another knockdown with fine grit. Eventually I will make it up to 1500 wet sanding. Last step is polishing, distant horizon at this rate. Like I said, this mould is workable and will take a lot of work.

If anyone is curious about the weight of the mould, the weight is around 75 -100lbs. lol

This Saturday I'm going to start in on making the cowl. I'll need to come up with a bone structure made out of wood. It will look similar to the cardboard structure I made previously but have widths as well as height. The wooden structure will give me stop points for my tungsten carbide sanding block.

Cardboard will sit around the wood structure and on top while it is sitting on the hood. This will allow the foam to take the shape of the hood, encapsulate the wood structure and then rise up to the top of the cardboard. Relief holes will be cut into the top of the cardboard so that the expanding foam doesn't bust through like the Kool-aid man.

The cowl needs to come in close to perfection. I'm glad I started with my hood and have worked through all the repairs. I've seen with my own eyes and connected the dots why certain aspects went well and other items turned out like garbage.

Most important of all, I've always wanted to make a meaningful composite part stretching myself into new areas. Honestly, I can't suggest starting on a hood. Personally, I go head first into projects so it is what it is; however, I think that's been well f*cking established how far I'll go off the beaten path.

Good thing I have the hood because I am currently waiting on my order of wastegates, blow off valves, couplers and v-bands. The wastegates, BOV and couplers are all VSRacing. VSRacing recently had a design change and look REALLY nice. The shop bought a few for a twin turbo sandrail and was able to inspect them before I ordered. Vband clamps... That has got to be one of the biggest kicks to the balls. Ordering a handful of clamps was a rude awakening.

Guess my post is a little bit wordy today yet needed. Hopefully you can see the same path forward as I'm seeing.

madwi

When you get good at sanding try your hand at finishing a plastic injection mold for clear plastic part like a headlight. I never had the patience to sit there but the guys would sand with 220 and work up to a finish with Charmin toilet paper, and it had to be charmin.

gbrettin

I have a buddy that polished metal die sets for injection moulding. He said that the metal had to be absolutely mirror finish perfect and would spend weeks sanding to absurd high number using diamond paper. THAT would be terrible. He said that he would find flaws for some reason or another late in the process and need to kick the part back to milling. That meant starting over.

JLarson

Less text, more boost noises!!

Looking good man. Cool to read about a different kind of fab project than normal.

__________________
2014 370z Touring Sport Magma Red MT // BP Single Turbo 6467 // 63mm TB's // Z1 Ported Upper Mani // RJM Pedal // Zspeed Stage 3 Clutch // 526 WHP, 451 WTQ
2006 350z (Sold) // 1990 300zx (Sold) // 1985 300zx 2+2 (Sold)

madwi

Thats exactly it what im talking about, final polish was the tp. I could never do it, about an hour in and I said f this and went back to my machine. Made me appreciate them that much more and always tried to get the best machined finish to start with to save time. Ran a few extra cycles in the EDM machines crisping up the sharp corners and blending in transitions.
We made the molds for inifinty, honda and others. If you ever notice the seatbelt latch covers in a viper; I made the electrodes and burned the snake's face into the mold.

Your mold looks awesome and that cowl doesnt seem like its gonna be fun to mess with.

gbrettin

The cowl will have its own challenges of getting the left and right side mirrored, but I know I can nail the gel coat process on it. That will cut 90% of the repair work out.

I'm really considering moulding some vents into the cowl as well, so that engine bay air pressure can get out too.

On my hood, I really need a small duckbill to divert air up over the windscreen which would take care of a high pressure area that builds up at the center base. I forgot where I saw that particular 3d rendering of pressure zones on this site. The duckbill/diverter really should have been baked into the hood mould but I guess that can be a challenge for a different day. There are too many spinning plates as is.