Re: [CAD_CAM_EDM_DRO] Re: Is this motor workable?

fj62@... wrote:

oops. I think I was comparing 55oz-in continuous to 44oz-in/amp...

I should be starting my own thinking process at the hand wheels on the
table/knee instead of at the motor. Assuming I change out my lead screws
to 4 or 5 tpi ballscrews is there a "suggested" torque requirement for the
screws on a b'port size machine? The knee would obviously have to have a
bigger motor or more reduction. Quick side question...is there any reason
to change the knee to a ball screw? Seems like there really isn't a
backlash issue on a knee.

//There is no backlash. Using a ballscrew on a knee driven Z is a waste and its not safe. There is a very little resistance in a ballscrew and if the servo belt broke the weight of the Z axis (about 800 pounds) could feed the screw in the nut and the table would fall. Ron//

>
> That particular motor has 55 oz-in continuous torque and it is also
> 6000 RPM. To get the power out of that servo you would need a
> minimum of 4-1 or 5.6 -1 reduction. More might be better, but after
> 5.6-1 the pulleys and belting become a problem. Assuming you have a
> 5TPI ballscrew 5.6-1 would give you 214 IPM rapids, that's fast. And
> you would have 308 oz-in continuous torque, plenty for a mill just
> under Bridgeport size.
>
> I think for that kind of money you should keep your eyes open for a
> servo with same torque but lower rpm�
>
> The servos Polaraligned found on ebay would be perfect for your mill.
> You could probably run them 2-1 or 2.5-1 and have fast rapids.
>
>> Here are the motor specs:
>>
>> Torque constant: 44oz-in/amp
>> Voltage constant: 32.5v/1000 rmp
>> Peak torque: 600 oz-in, or 37.5 in-lb
>> Nominal voltage: 40vdc
>> Maximum voltage: 60vdc
>> Demagnitization current: >20amps
>> Terminal resistance 2.60 ohm
>> Max rpm at 50vdc is about 1200 rpm
>> No-load current <.51 amp
>> armature inertia .09oz-in-sec^2
>
> Wally
>
>
>
> --- In CAD_CAM_EDM_DRO@yahoogroups.com, "vortec62" wrote:
>>
>>
>> Newbie here. I've been following along but I am still a little
> lost.
>>
>> I see lots of discussions about servos/$$$$. I starting to think
> my
>> CNC conversion project will be over budget before I even get
>> started...
>>
>>
>> I found this:
> http://www.servosystems.com/reliance_dcbrush_rdm103.htm
>>
>> It seems to have similar torque ratings that I have seen mentioned
> in
>> other posts. It has a high speed so could be used with reduction
> and
>> still have acceptable travel speeds(I think).
>>
>> FYI I have a JET JVM-830 mill that I would like to convert. It is
> a
>> little smaller that a regular bridgeport machine.
>
>
>
>
>
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