Scratch build electric tethered car racer

[Roog]

It’s been a funny day, I’ve not been to my shed at all, this is almost unheard of, I have been working out how much GRP resin to buy and where to get it as model shops are a dying breed in the UK and even the old sailing and canoe supplies shop ‘wet and windy’ seems to have either moved or has shutdown. :0(

I’ll call someone on line tomorrow to see what they suggest for my ‘up turned boat’ like project.

 

[WickedFog]

When I was building fiberglass subwoofer enclosures I got my supplies from an automotive paint supply store.

 

[Roog]

When I was building foberglass subwoofer enclosures I got my supplies from an automotive paint supply store.

Yes that’s a good idea, I noticed that most around here seem to be roofing supplies.

 

[Roog]

Fibre glass mat and resin on order, memories of the smell have come flooding back and the fun of trying to remove half set resin and bits of chop strand from both hands!

 

[ahr43]

Fibre glass mat and resin on order, memories of the smell have come flooding back and the fun of trying to remove half set resin and bits of chop strand from both hands!

Ahh, the memories. Helped my dad in repair of fiberglass boats, mat and chop lay-up late 1950s, early 1960s. Keep a supply of acetone at hand. It helps in clean up. Nasty stuff though. Use care with it.

 

[WickedFog]

Ahh, the memories. Helped my dad in repair of fiberglass boats, mat and chop lay-up late 1950s, early 1960s. Keep a supply of acetone at hand. It helps in clean up. Nasty stuff though. Use care with it.

I always wore nitrile gloves when I was building speaker boxes. Acetone dries my skin out something fierce.

 

[Roog]

Well the kit of GRP bits included tools, gloves and acetone, warmed my shed up with an electric heater and set to work.

I decided to try the chop strand mat because I remember it was better at going* around corners. I have some fine woven mat for the top layer

One layer down with a second to go, now all I can smell is resin.

Image above is as seen from the rear, I stopped taking photos because everything was getting sticky and there was a risk that my phone might become part of the moulding. Finish is as anticipated rough, it’s going to need a fair bit of sanding, then the woven layer and more sanding.

Well at least it still resembles the original shape and not a giant sticky ball of chop strand fibres.

With the heater on in the shed (I took it up to 20 deg C) my machines must think that summer has arrived early, the oil I coat them with to minimise rusting certainly got mobile and pooled in the chip tray.

 

[Doom!]

Lookin' good. Kind of makes me want a burrito.

 

[Roog]

Yes it reminded me of a half baked loaf of bread

Some progress today, I marked the edge to cut and trimmed it with a Dremel, sanded it down to expose fibres and applied a coat of resin by brush. The trimmed edges were of the order of 2mm to 2.5mm thick so I decided not to add the third woven layer, may be next time, one layer of chop strand and a top layer of woven.

Plan is to give it a light sanding and for this to provide a key for the paint, plenty more chances to sand it although it is never going to be great.

 

[Roog]

The GRP 'loaf' is currently sitting along side me in my home office and has cured very well. I get to pat it like a dog in between moments of actual work!
It now has a nice smooth semi matt finish and feels quite tough when tapped. I am not looking forward to the further sanding that is required.

It should do a reasonable job of keeping the flys off the car during a run and maybe affording the motor and battery some protection in the event of a mishap?

I have decided to cut it shorter to reduce the overall length. I am no aerodynamicist, but I might leave the back open, I have a gut feel that closing it off won't help anything.

 

[Doom!]

Give that loaf a couple of extra pats for us.

 

[WickedFog]

Have you managed to release the shell from the mold?

 

[Roog]

Have you managed to release the shell from the mold?

I was tempted, but I’m going to leave it in place ready for the last sanding.

I managed to move it when I trimmed it, but after sanding the second layer I applied a coat of resin which has glued it back in place!

 

[Roog]

I sanded to body shell on the plug until I got fed up sanding and the fibres started to show!

It’s shiny because I’ve just wiped it down with white sprit

Then released it to mark trim edge

Once trimmed I gave it a coat of primer, being impatient as usual I put too much on in one coat and have runs, so I have more sanding to come

There are blemishes in the surface of the fibre glass shell, but I’m not too fussed

 

[Tunedfrog]

Lookin' good. Kind of makes me want a burrito.

I was waiting for a slice of homemade bread but it hasn't been baked yet.

 

[Roog]

I was waiting for a slice of homemade bread but it hasn't been baked yet.

No bread as yet.

I weighed the shell before trimming the rear part off to length and before painting, it came to 650g or 23oz so it is quite heavy.

I have just realised that I should have sorted out the mounting points before painting !

 

[WickedFog]

I have just realised that I should have sorted out the mounting points before painting !

Easy fix. Especially if doing the studd/nut mounting. Just get you some blue tac and put a little ball on top of the body mounting studs. Gently set the body down, trying to line it up. Then press it onto the blue tack. It should stick to the body and not the stud, especially if you lube the stud.

You could also grind some points on those pins and screw them in upside down and put some masking tape under the body. Set the body on the chassis and line it up. Then press down to imprint the tape.

 

[ahr43]

Wondering if this body might be a candidate for a Kamm effect rear? Earlier on you were wondering about what to do with the rear of the body. Ferrari used it successfully on its 'bread van' body in the 60s as did the GT-40. Just a thought. Your tether project looking great. Two thumbs up, mate.

Lots of articles on this. Here's one FYI:

Kamm Effect

 

[Roog]

Wondering if this body might be a candidate for a Kamm effect rear? Earlier on you were wondering about what to do with the rear of the body. Ferrari used it successfully on its 'bread van' body in the 60s as did the GT-40. Just a thought. Your tether project looking great. Two thumbs up, mate.

Lots of articles on this. Here's one FYI:

Kamm Effect

Thanks @ahr43 i love the long tapering rear body work, I was worried that the car was a
Ready far too long so short butt is what we have!

Easy fix. Especially if doing the studd/nut mounting. Just get you some blue tac and put a little ball on top of the body mounting studs. Gently set the body down, trying to line it up. Then press it onto the blue tack. It should stick to the body and not the stud, especially if you lube the stud.

You could also grind some points on those pins and screw them in upside down and put some masking tape under the body. Set the body on the chassis and line it up. Then press down to imprint the tape.

Good call, tbh I’m not too worried about the final finish, it’s going to get scuffed up in use, I’m just annoyed that I didn't think of the sequence before getting the rattle can out.

I am an Impetuous fool.

 

[WickedFog]

Good call, tbh I’m not too worried about the final finish, it’s going to get scuffed up in use, I’m just annoyed that I didn't think of the sequence before getting the rattle can out.

I am an Impetuous fool.

I can't tell you how many times I was 2 or 3 coats into a paintjob before I realized I forgot to mark the pin holes. But that trick is something I came up with for mounting hardbodies, and it works surprizingly well.

You mentioned the body being heavy. After some testing, I bet you could lighten that chassis quite a bit with some strategically placed machined pockets here and there

You're lucky I don't live close to you. I'd be dropping by unannounced all the time to give you a hand with this beast. It's just a killer project.