Re: [CAD_CAM_EDM_DRO] Re: Servo heating - worn belt

vrsculptor wrote:

>Jon,
>I started looking for mechanical problems on the Y that could be
>causing the servo to work harder. My servo is belt drive with the
>encoder mounted on the screw and not the motor. I think the problem is
>that the timing belt on Y is worn and the gecko is working overtime
>trying to keep position. A worn belt looks like slack/free play to the
>system even though it is tight. I don't know how old they are, they
>came with the machine. The edges of Y's belts teeth look polished and
>not like X. Time to order new belts.
>
>
>

I use 3/8" XL (.200" pitch) belts, as that is what was on the system that I
adapted. The original belts were REALLY tight, so i looked up the
acceptable
belt tension, and found it could be put very high. I run somewhere around
50 - 80 Lbs of tension in each strand of the belt (total of 160 Lbs
between the
two axles). This is on a 3/8" belt, if yours is wider, the tension
needs to go
up. When I get it right, the new belt doesn't creak when rolling over the
pulleys. If it is too loose, then you hear it creak as the belt slips
across the
teeth. That is what is causing your wear. I also have the encoder
directly on
the leadscrew to eliminate belt/sprocket errors from the system.

My setup had a tension roller on an eccentric shaft, which made setting
the tension
fairly easy - no crowbars needed.

Jon