RE: [CAD_CAM_EDM_DRO] Does this make sense? wasRe:BentNookballscrews ?????

Of course not, and I don't... The 0.2 is NOT a fudge factor. It
is an approximation of the range of typical values for a very
detailed equation. Go take a look at:

http://www.ruchservomotor.com/PDF/H_Ballscrews(full).pdf

It's all spelled out on page 28.


Regards,

Carlos Guillermo
VERVE Engineering & Design

-----Original Message-----
From: Raymond Heckert [mailto:jnr@...]
Sent: Tuesday, August 12, 2003 9:09 PM
To: CAD_CAM_EDM_DRO@yahoogroups.com
Subject: Re: [CAD_CAM_EDM_DRO] Does this make sense?
wasRe:BentNookballscrews ?????

You can't just use 'fudge factors' like that (0.2), unless you can
substantiate what each of the values are, and how they interact.
i.e. you
can't just add those factors algebraically, when, maybe they
should be
acted upon vectorially, or even transcendentally, etc. Myself, I
buy the
"increased torque, due to increased friction, due to pre-load"
added
(algebraically) to the actual torque required due to the cutting
loads.

RayHex

----------

> From: Carlos Guillermo <carlos@...>
>
> Kim -
>
> Just to clear this up -
>
> The coefficient I used of 0.2 is not the efficiency. It is a
> coefficient that takes into account lead angle, pitch circle
> diameter, friction angle, and friction coefficient. The range
> they give for the friction coefficient is from 0.003 to 0.010.
>
> BTW, you're applying the thrust force equation to a
> preload-torque-drag problem. Apples and oranges.
>

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