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Premium Member
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Discussion Starter · #1 ·
I've bought my first resin body, a Hillman Imp Cali, for the Wolves Ocar event.

How strong are the bodies in relation to their thickness?

It weighs a ton and so want to machine away some of the casting.... How far can I go before I loose vital strength?

I take it they aren't as resilient as a plastic body?

Thanks
 

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Jon Grainger
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3,825 Posts
Hi Jim

Hope your well mate, been a few months!

Yes-so, resin bodies are usually pretty strong, I mean they can chip a little if you explore the barriers too much, as can plastic shells. Any thin areas can be strengthened with a length of piano wire epoxied in place, on the back of the shell.

With regard to thinning out, use a Dremel sanding disk, and I usually thin my bodies until they are 1.5mm thick, and I've never had one break. You could maybe thin it a bit more along the sills if you feel confident.

Post some pictures when your done,

Regards
Jon
 

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Senior Slot Car Mechanic
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Do not under any circumstances use a dremel tool on resin. Resin dust is VERY TOXIC. A friend of mine has severe liver damage from doing this.

Using a mask doesn't help that much either, because as soon as you take the mask off, the stuff is in the air anyway. Dremel tools creat very fine resin dust which stays suspended in the air, and, the fan in the dremel tool, blows this all over the place. It gets all through the house like second hand smoke, so, everybody in the house is breathing it.

The only safe way to thin resin castings, is to scrape them with ground up files. Scraping takes out larger chips of resin, which drop out of the air quickly, and, mostly end up on the floor, instead of in your lungs. These are easily swept up and disposed of.
 

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QUOTE (bwaminispeed @ 5 Aug 2012, 17:42) <{POST_SNAPBACK}>Do not under any circumstances use a dremel tool on resin. Resin dust is VERY TOXIC.

Well, you can do the same as firms do: Take a vacuum. I have built a simple holder for the hose of the vac, built a little cone from cardboard and fixed this at the end of the hose. When I use a minidrill to cut / lighten anything I hold the part and drill into the cone. So the dust is sucked in to the vac resp. spun in the cone and not in the air.
To see if it works I have a sheet of black styrene lying under the holder.
Btw - I wouldn´t use a dremel but a somewhat weaker minidrill. And I would work at as low rpm as possible to avoid the dust from being launched with too much force. It works with resin, styrene, but also with cutting discs and 1mm spring steel sheet.

Roland
 

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Premium Member
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1,207 Posts
Discussion Starter · #7 ·
Thanks chaps.

Im sure Chris will be along (CJA) - the first thing he told us beginners at the club was to be ultra careful when machining this stuff.....perhaps they ought to come with a warning to advise those less in the know?
 

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Discussion Starter · #8 ·
QUOTE (ferraif40 @ 5 Aug 2012, 16:13) <{POST_SNAPBACK}>Hi Jim

Hope your well mate, been a few months!

Yes-so, resin bodies are usually pretty strong, I mean they can chip a little if you explore the barriers too much, as can plastic shells. Any thin areas can be strengthened with a length of piano wire epoxied in place, on the back of the shell.

With regard to thinning out, use a Dremel sanding disk, and I usually thin my bodies until they are 1.5mm thick, and I've never had one break. You could maybe thin it a bit more along the sills if you feel confident.

Post some pictures when your done,

Regards
Jon

Thanks Jon yeah all ok here mate hope you are well - busy building several cars for the upcoming Trans Am and Wolves pre 80s. Really enjoying the builds but the wallet is taking a beating!
 

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Premium Member
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On the slushcast resin shells I've used they're incredibly strong; they will take several falls off a table (onto carpet) at speed. They're usually around 2mm thick and I'm amazed at their strength even compared to injection moulded bodyshells.

Some flat parts like the roof, bonnet and sides can be made very thin, I'd leave the front a bit thicker and any areas where the body mount posts, that's where the heaviest knocks will get transferred to the shell. Don't skimp with the epoxy on body posts.

Interesting about the resin dust, I advise to do it outside with a mask but perhaps a vacuum is a good idea. Perhaps it comes down to how often you're exposed to it, if it's once a year the risk might be very different to once a week? I'd welcome any facts from a manufacturer's datasheet or something.
 

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Nobby Berkshire
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2,015 Posts
Resin shells are seriously heavy things. You'll never get it as light as plastic, and if you do it will be a very weak bodyshell.

Different resins have different strengths and the mechanics of different body shapes from model-to-model will make certain structures weaker or stronger. Despite what's been said you will find that resin does not have the same flexibility as modern slotcar plastics so it tends to snap and crack more easily. Ideally 1mm to 1.5mm is likley to be the best thickness.

George Turner Models make the finest resin bodyshells in the world and he does a Hillman Imp. If it's like the other shells I've had from him it will need no scrubbing or carving out at all. And he won't rip you off a fortune to buy one.

btw don't forget to wipe it all over with white spirit or lighter fuel before you paint it as resin is famous for having yucky oily muck all over it that resists paint.
 

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QUOTE (bwaminispeed @ 6 Aug 2012, 00:42) <{POST_SNAPBACK}>Do not under any circumstances use a dremel tool on resin. Resin dust is VERY TOXIC. A friend of mine has severe liver damage from doing this.

The only safe way to thin resin castings, is to scrape them with ground up files. Scraping takes out larger chips of resin, which drop out of the air quickly, and, mostly end up on the floor, instead of in your lungs. These are easily swept up and disposed of.

Thanks for the heads up on that, I must admit to using a dremel on resin before. (Although at least it was outside) but will certainly refreain from doing so in the future. Good tip about making scrapers out of old files.
 

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re member
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I thin resin bodies using dremel power.
As previously described I do it in the airflow of the vacuum cleaner nozzle and at low speed.
My dremel has a flexi shaft so the motor is well away from the body being worked on.
Another tip is to use a tungsten burr.
Dremel makes a few shapes of these and they take larger chunks off so the dont float in the air the same as sanding dust.
 

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mac pinches
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2,154 Posts
Some good advice among these posts.
There is however a couple of things to consider, will the car be used in
the rough and tumble of club racing or for one off open meetings.
If its a club racer, you can afford to leave a little more "meat" in the shell
to take a few knocks.
With an out and out race car remove as much weight as pos.
Most saloon shells have the bumpers moulded into the shell as road cars,
if the full sized car is raced the bumpers are removed, so with you shell
a big saving can be made with the removal of these chunks of solid resin.
Drill out the lights and replace with light plastic lenses, a bit more gone.
Any part of the moulding that can be removed and replaced with a lighter
materiel ie exhausts, wing mirrors etc all helps.
Keep the body mounting posts as light as pos as these are just added weight.
With saloon cars you can afford to reduce the roof to the extream as there is
little chance of it being damaged, it also keeps the C of G low.
As has already been stated use burrs to remove any exess resin, this keeps
the dust down, plus if you have one, use a extention shaft on your dremel.
In the past iv used one or two Ocar shells, with a little work they are quite
usfull shells but in out and out race cars i have remoulded the shell, then
slosh moulded a very thin racing shell, making two for the event just in case
one gets damaged.
Hope this is usefull to you or anyone else who is going down the "off the shelf
shell " road
good luck with your racing.
Mac p
 

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Discussion Starter · #16 ·
I attacked the Imp today and have gone from 40g to 13.8g......result!

I will post pics when the build gets more interesting!
 
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