Re: hot servo motors, heatsinks??...maybe another redesign

Thanks to the group for the excellent information. Based on
Mariss' post, It sounds like I am mis-applying the servo motors.
Oh well, this has all been a good learning experience for me.
I will probably end up replacing the the servos with steppers and
different drivers (gecko stepper driver).

I really want to keep the direct drive for simplicity. I am
using helical beam shaft couplers which are a neat device that
allows for axial and parallel misalignment. I originally just
had brass rod couplers which I thought I would shim into alignment,
but quickly gave up on that. With the helical beam shaft couplers
(essentially an aluminum rod cut into a spiral, sort of like
a spring), I can turn the shaft with my fingers without much
effort, so I dont think the friction of the assembly is excessive.

I have six of the motors which I got for pretty cheap. They are
globe servo motors. I am very happy with their motion and speed
of drive, but it sounds like they will "burn up". I will still
probably try three of them out (xyz) and see how they work in short
spurts. Also see what the spec sheet says for max operating temps.

I actually have a RF35 mill/drill I was originally converting with
belt and pulley style reduction. This is based on plans from
homecnc.info. Great plans, but I finally decided that due to limited
time available to go with something smaller and simpler. I rolled
my own design, but with many redo's. Hot servo motors, case in
point. Oh well, its all for learning and fun anyway.

Thanks for the input,

Eric


--- In CAD_CAM_EDM_DRO@yahoogroups.com, "etauch" <erictauch@a...>
wrote:

> Greetings,
>
> I am currently at the point where I am testing my CNC
> conversion. I notice that the servos get quite hot
> after about 5 min of running. Not so hot that I cant touch
> them, but if you grab one, you can only hold on comfortably
> for a few seconds.
>
> I know they are running at low RPM, so this is probably one
> of the causes (higher I^2R at low rpm?). Also, I am dumping