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Thread: Can you instruct me...

  1. #1
    Join Date
    Oct 2008
    Posts
    79

    Can you instruct me...

    Monty, can you please instruct me with what and how to tie down the wires under the commuatator? Thank you.
    Alvin blair

  2. #2
    Join Date
    Jun 2002
    Location
    Victorville, CA
    Posts
    1,725
    Al,

    The material varies with manufacturer. ProSlot, Viper/RJR, and myself use Kevlar thread of suitable guage (mine is approx. .020"). Koford and PK use a synthetic blend thread (nylon-polyester), and Camen has used strands taken from fiberglass cloth for 40 years or more!

    The problem is that all of these will fall off the first time the armature runs if they weren't held on by the epoxy which is also saturating the wire windings. This also varies by maker and can be one or two part. If 2 part, the mixture must be blended relatively acuurately by weight according to the suppliers directions. Most are cured by heat, often in a multi-step process of increasing temperature. Hot epoxy thins in viscosity and this helps it seep into windings, but most makers will improve the saturation process by applying partial vacuum which causes internal air to boil out. upon releasing the vacuum, epoxy is forced deeper into the windings.

    All this processing is the 'real' work in armature making, and can take just as much or more time than winding and brazing them.

    It would be helpful to know the nature of your project: repairing an arm that has lost threads? Winding a new one just to be able to say you did it? I can tell you right now that it isn't practical to replace commutators (not enough slack in the wires to hook them up), and I WON'T help you brew up an armature that may end up in a class it isn't legal for.

    Adding thraed wrappings to stock Chinese 16d or S16d improves the reliability of the arm a ton. This may or may not be legal where you race, so you need to find out. This is problematical if USRA rules are in place, since the domestic armatures with wrappings are already legal as replacements.

    You will probably have more questions. Just ask.
    A clean slotcar is a happy slotcar!!

  3. #3
    Join Date
    Jan 2008
    Location
    mechanicsville Virginia
    Posts
    364
    A related question: I'm about to send a few arms out for balancing and stack grinding. The Proslots seem to have minimum epoxy on them. How common is it to add epoxy before the rebalance?

    I don't think any windings have actually moved but it sure looks like they could...I'd like to be able to SEE some epoxy on the dang things.
    Anything worth doing is worth overdoing

  4. #4
    Join Date
    Jun 2002
    Location
    Victorville, CA
    Posts
    1,725
    Don,

    While SOME of the reconditioning services have the technical means to re-epoxy armatures, none of them will do it automatically. You can request it from those services that can do it, generally at additional charge.

    Who can perform this service? Any of the reconditioners who also make armatures. I can only speak for myself: yes I can add epoxy, cost $3 more per arm.

    Monty
    A clean slotcar is a happy slotcar!!

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