Re: [CAD_CAM_EDM_DRO] Re: Z axis force

Wally, Its a 9 X 42 series 1. It requires 10 revs of the input shaft to raise the table 1" . Acording to Bridgeport mfg., the table, saddle and knee weigh 750 lbs +75 lb vise=825+ all three servos and mounts 100 lbs=925 +estimated drill loading (dull bit) of 200 lbs=1125lbs. Factor in resistance in screw of at least 50lbs.= 1175lbs + resistance in the dovetail at least 25lbs= 1200 lbs. Those are good numbers.

I'll try to calculate this, it's probably wrong:
3.5" dia pulley mounted on Z shaft with a 10.99" circumference. 10.99"/.100"linear travel per rev =109.9:1 reduction. Each pound of force on a 1.75" radius from the shaft would = 1.75 lbs rotational force. 1.75X109.9=192.3 lbs lifted. 1200lbs/192.3=6.24 in lb required to just equal the weight of the table. Divide the 6.24lbs/2.5 ratio=2.496 lb-in required from the servo to even begin to move it. Now it has to be accelerated to 60 ipm. Which on mine is less than a second.

Ron
cnc_4_me <cnc4me@...> wrote:


I am getting posts mixed up...Tell me again, what machine do you have
and what weight are you saying knee is...

Wally



--- In CAD_CAM_EDM_DRO@yahoogroups.com, R Rogers
wrote:

> Its an acme screw on Z.
>
> cnc_4_me wrote:
>
> /// Also, The servo is 2500 RPM. 2500 X 64% = 1600 RPM divided by

10

> revs per
> inch on the Z axis = 160 divided by 2.5 belt reduction= 64 ipm.
> Exactly, what I
> can achieve. Ron///
>
>
> Do you have a ballscrew or a acme screw.
>
> Wally

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