Re: [CAD_CAM_EDM_DRO] Re: Bridgeport retrofit servo questions

Not sure why you replied with your comments about leadscrew axial thrust. My
statement was only a general statement that a PDMC motor should not have
more then .005 because of the effects on encoders. It was meant as a heads
up for when they are looking to purchase a PMDC motor for use in any servo
applications. You are correct that motor bearings should not be used to
handle the axial load of a leadscrew.

Dan

----- Original Message -----
From: "Jon Elson" <elson@...>
To: <CAD_CAM_EDM_DRO@yahoogroups.com>
Sent: Sunday, January 30, 2005 5:02 PM
Subject: Re: [CAD_CAM_EDM_DRO] Re: Bridgeport retrofit servo questions


>
> Dan Mauch wrote:
>
>>2. What is the end play of the motor shaft ( if more than .005 could cause
>>damage to the encoder)?
>>
> You should NEVER depend on the motor bearings to axially constrain the
> leadscrew.
> The motor bearings are not designed for these large axial loads. I used
> 1000 Lbs of
> linear force as the design goal of my servo retrofit on a Bridgeport.
> 1000 Lbs would
> punch the armature right through the end housing of the motor! Even on
> a Sherline,
> the leadscrew force will eventually wreck the motor's bearings, if you
> try to use the
> motor as a poor man's thrust bearing. (This is true for steppers, too,
> of course.)
>
> Jon
>
>
>
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