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John Clow's La Cucaracha refurb


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#101 don.siegel

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Posted 17 January 2016 - 07:25 AM

Scary news Pablo! 

 

We still get a pretty good choice of epoxies here in Paris, mostly under the Araldite brand (also the generic word for epoxy in Britain and here). I'll try to check out the temp ratings next time I go into a store...

 

120°F is not a lot! 

 

Don 






#102 zipper

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Posted 17 January 2016 - 11:19 AM

I'd guess ordinary slow epoxies begin to soften at 80 - 100 C and somehow work upto about 150 C. The fast ones are much worse in this respect - at least I found so. Baking the slow one in about max 150 C makes a stronger bond. In industrial Araldite products Araldite® AW 4510 / Hardener HW 4511 offers the highest spec, 190 C and probably handles clearly over 200 C.
 


Pekka Sippola

#103 Dallas Racer

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Posted 17 January 2016 - 01:23 PM

Way back in the day I rewound a couple of RC motor arms. There was an AC motor rewind shop in my area, and they sold me a jar of stuff for this. It was about a pint in a glass jar, I think it cost $8. You brushed it on and cooked it. It went on a bit thick but thinned out when heated and sucked into the windings.

 

My apologies if you already know this: That absorbing into the windings part is important. The motor coils vibrate as they are energized and rub against each other, which wears the insulation off the wire causing them to short out. It's why transformers are treated in the same manor as well. We think of it as preventing the windings from being slung off the arm, but that's just one of the reasons.

 

I googled armature epoxy and only found epoxy for balancing arms. Then I stumbled across "insulating varnish". It turns out it's not epoxy. There's lots of product options. This might work and it's pretty cheap: http://www.ebay.com/itm/231070150546 Another qption: http://www.ebay.com/itm/172055791036

 

 


Phil Smith ® ™


#104 Pablo

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Posted 17 January 2016 - 04:47 PM

No apologies needed here, Phil. I'm still learning when it comes to arm winding  :)

 

I hand wound 50 (sloppy) turns of #30 Champion wire onto each pole.

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I finally found some slow dry 2 part Devcon epoxy and baked the arm.

 

It runs :D

 


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Paul Wolcott

#105 Pablo

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Posted 18 January 2016 - 09:02 AM

John, it's ready to tear up again :laugh2: Motor runs fine, smooth and dead cool despite the fact I left the arm unbalanced like stock.

My little gizmo to keep the cracks in the EB flange from worsening appears to have worked perfectly.

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A drop of Super Glue keeps it holding onto the aluminum (I hope).

Installing the stock body is a little trickier with the pin tubes on, you just need to ease it on little by little and be patient.

IMG_9244.JPG

 


Paul Wolcott

#106 Bill from NH

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Posted 18 January 2016 - 03:42 PM

The little gizmo is known as an external retaining or "snap" ring. A special pair of pliers is inserted in the round holes & used to expand the ring's diameter so it can be placed on or around something. :)


Bill Fernald
 

My wife says I don't pay enough attention to her, or something like that.  :unknw:


#107 Pablo

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Posted 18 January 2016 - 06:52 PM

I know, I called it a 1/4" retaining ring back on page 2, but I just like the term "gizmo" :)


Paul Wolcott

#108 Bill from NH

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Posted 18 January 2016 - 07:07 PM

There are both internal & external retaining rings, but they're not interchangeable one for the other.


Bill Fernald
 

My wife says I don't pay enough attention to her, or something like that.  :unknw:






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