Re: Kostov rpm Limit

[Leon Levasseur <leon@ziplink.net>]

At 11:41 PM 1/30/99 Saturday, you wrote:
>> conservative until such time as you can pull the armature and wrap the
>> commutator with piano wire beyond the brush area and you will effectively
>> increase the rpm limit.
>
>How do you do this without shorting all the commutator bars together?
>
>Royce Chow  KF6PEO
>rufus@infosite.com
> 
Any suitable dielectric that can sustain the mechanical strain as not absorb
moisture that would reduce its insulating capacity and can withstand the
potentially high temperatures.  A .010 thickness of Mylar with a split sleeve
of G-10 (Printed circuit board material) is a reasonable combination.  The
Mylar will offset any moisture absorbed by the G-10 and the G-10 will absorb
the mechanical force of the piano wire.  I'm sure Lee can recommend other more
suitable and perhaps more exotic material that would be more suitable.
 A preheated stainless steel ring pressed and shrink fitted with the proper
insulation would be far less cumbersome than wire wrap.  I don't have my
"bible" handy, however I believe the coefficient of expansion of copper is
greater than that of steel, therefore it would become tighter on temperature
rise which is a desirable goal.  I suspect a pressed on Kevlar sleeve may also
do the trick.  I don't know the dielectric factor of Kevlar, but it may not be
very good as its composition included carbon, therefore any insular would
still
be required.  

Best regards,

Leon