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Discussion Starter · #1 ·
hy guys, does any body know where in the uk, i can get small quantitys of clear or translucent high temp resin. its got to be over 300c for coating some 26swg rewinds i,ve done. i can get potting compound but its solid black and the usa cant supply the resin because of their rules. as an aside would adding powdered glass to the mix improve the heat bearing quality of a 200c epoxy. i,ve googled and searched but i cant find anything, so this is a last resourse long shot for the chemists on the forum. john
 

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Tony
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That's gonna be a hairy old motor with 26swg windings, I always used to use plain old aradite when I used to rewind armatures, never had any problems. I have some old 24 turns of 24swg armatures in my box, it was like driving with an on/off switch.
 

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Same here, regular slow-curing araldite, but I've only gone to a 29 size wire - not quite the same thing, heat-wise!

Like Phil, I cure in oven, also slightly preheat arm so epoxy will penetrate better into the windings.

Try contacting Andy at ABSlotsport to see if he has any ideas - there may be a few more dealers in the UK familiar with this stuff.

If you want to get into the more sophisticated, hairy stuff. try the Rewinding thread by John Havlicek on SlotBlog - he studied the whole epoxy thing in detail, but is US based.

Don
 

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I can remember racing Gp20 arms in 12 hour races at Northampton in the late sixties/early 70's, when the polished stacks ended up a strong straw colour. This equates to a temp of around 200/250, so wanting a temp range of 300 is just being cautious. Also the scars take a long time to heal if you accidently touch the arm when you pick up the car! In those days I always used high melting point solder for the pinion and motor wires as well as elephant ear heatsinks. As for magnets, if you use samarium cobalt those temps won't be a problem, use ceramic and you might need to remagnetise them on a regular basis.

Mike T
 

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hi, John
From what I'm reading, most epoxy resins are good for shorter periods (30 mins or less) as long as the temp stays below about 268 C. If you feel it likely that you will be closer to 300C for longer periods, I'd recommend calling 3M and asking their advice...they have excellent technical support. If you need someone in the US to send it along, let me know.

John

PS you asked about adding glass...from what I'm reading, the problem is that the temp breaks some of the epoxy's bonds and gases are released. Adding glass would increase
structural stability at temp, but not prevent the breakdown over time.
 

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QUOTE (Phil Kalbfell @ 26 Aug 2012, 12:44) <{POST_SNAPBACK}>I only ever use Araldite also, but only apply very thin and cure in the oven!

I second what Phil has said. Ive only ever used araldite and bake in an oven. Glass is an insulator so it will not help dissipate heat. In fact it will do the opposite.

cheers
rick1776
 

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QUOTE (John Cahill @ 27 Aug 2012, 03:11) <{POST_SNAPBACK}>From what I'm reading, most epoxy resins are good for shorter periods (30 mins or less) as long as the temp stays below about 268C.

John, where did you read that? From my recollection, most epoxy is good for about 160 to 170C, with the high temperature stuff good for 200C, I don't believe there is a substance available (varnish/glue, etc) able to handle those temperatures, which is why loudspeaker motors use ferrofluid cooling.

So even if stoner got his wish, he would have problem with the winding insulation melting. In any case I would suggest that if a motor actually needs 300C epoxy, then something is not right somewhere.

Joel
 

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Discussion Starter · #9 ·
hy! dgersh and all the guys that answered me. i,ve read john haveliceks thread[all of it] and i,ve emailed all the big companies. so it looks like good old araldite on a warm arm with a heat cure. thanks for all the answers. john
 

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Are you sure the comm and brush gear will stand that temperature ........................

Also, what magnets do you intend using for this motor ?
 

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A 26g arm shouldn't be getting anywhere near 300 c unless there's something wrong with it. Indeed you are likely to run into other problems if it ever did get anywhere near that hot.
I agree with the other posters, ordinary 24 hour setting Araldite is fine for 26g arms, I've done several that way and had no problems.

Lots off types of slot car motors use 26g and hotter arms - so brush gear and magnets suitable for that sort of wind are readily available from just about any slot racing supplier who stocks the higher end equipment.
One problem will be comms suitable for that sort of wind. As there are so few home winders working higher current motors, retailers rarely stock the comms.
 

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To the O.P. ...................... how did you arrive at a figure of 300 degC ?

I agree with everything the last poster has stated and will clarify my opinion on the choice of magnets too.

SAMARIUM COBALT ..................
 

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Discussion Starter · #13 ·
koford and the likes use 800c epoxy on their arms. be it a 23g 16t arm or a 26g 40t arm. samarium is not as strong as neo, but has a higher heat tolerance. a group 27 qualifying motor is lucky to last 2 laps of a king track. the race motors are a little les wild. they need to last, but they all use motor coolers between rounds. i only play with different rewinds, because i can and it gives me pleasure. Eddie at accuflow is sending me some clear epoxy, that will tolerate 300c in shortish runs. john
 

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Best of luck with your arm John.
Where are you going to run it?
Epoxy that will tolerate 300c in shortish runs means you don't need to worry about the epoxy temperature.

Koford claim "800 degree epoxy which is available nowhere else".
Is that degrees C or degrees F ?
 

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Tony
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One thing you haven't said is what motor you are going to run it in. I have run 24/26swg armatures in a strap setup in 5 minute finals. Ok they do get hot but not the sort of temps you are talking about. Mind you there isn't much to a strap motor and the armature is virtually revolving in the open air. I think your biggest problem is going to be balancing it, static balancing won't do at the revs it will pull. You'll have to get it dynamically balanced. You could also try one of those old heatsinks that used to push onto the free end of the motor shaft.
 

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Discussion Starter · #16 ·
thats about 10 arms for different motors ready to epoxy. i run the cars on my big mdf home track. so i can please myself. ive got a lot of cars in 1/24-1/32 scale that wouldn,t fit into any club class. we,ve only got one club in the whole off cornwall, so i,d better pay them a visit and build a couple of cars that are legal for the classes they run i dont honestly know whether its F or C being quoted, i have a gut feeling that its farenhight. john havelecek welds the wires to the com using pure silver. i think the melting point for 5* silver solder is above 400degrees F. so it shows how hot some of his arm run. john
 

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I agree with Bigtone that they would go better with dynamic balancing.
There are several dynamic balancing services around, Won o Won and Missile are UK based, the others I know of are outside the UK.

I didn't have any problems with ordinary solder on 26g home rewinds, although the extra security of higher melting point solder sounds a good idea.
Most of the higher end bought arms have welded or crimped connections to the comm. That connection certainly seems more than adequate - the wires normally stay attached even when the comm explodes!
 

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In my opinion DYNAMIC balancing and diamond comm truing is absolutely essential if you want to achieve maximum performance and keep the heat down.
What cars do you intend to install these motors in ? A photo or two of your track would be interesting ..............
The 'King' tracks they have in the US have, as I'm sure you know mostly banked corners. For very good reason ! !

This is all very interesting and takes me back to the late sixties ! !
 

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Discussion Starter · #19 ·
tiger, it goes without sayin a balance and com true are essential. some of the motors are going in plastic chassis cars some in pianowire & brass chassis and 2 are earmarked for grp chassis and a carbon fibre chassis i,m playing with. i,d love to post pictures but i,m to lazy to learn how, i never seem to have the time. there allways seems something more important to do. john
 

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John,
I fail to understand why you think you need a 26g wind to power the chassis you have mentioned. How will you transmit all that power to the track ?
I have 24th scale Eurosport cars with 29g strap motors that are 'faster than the human mind', provided you have a large enough, smooth enough, grippy enough track for them to show their absolute performance. NONE of the motors get anywhere near the sort of temperatures that you mention.
You will also need a power supply capable of delivering about 40 amps per car, otherwise you will not achieve maximum power on acceleration.
My advice is start with some 30g or 32g rewinds and when you have sorted out all the problems of getting them to work. Then try some heavier gauge wire if you feel you must ..................... it'll save you wasting your very valuable time !
 
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