Re: Timing Pulley Accruacy and Servo shaft runout

>>I am struggling to see if that
>>runout can cause any significant error.
>>

> It certainly will not.
> No, the tooth engagement doesn't affect accuracy much. And, the .001"
> eccentricity
> will have so tiny an effect on your system accuracy as to be only
> measurable in a
> metrology lab (6.33 x 10^-5 ")

Thanks Jon. I will not worry about it then.
I only bring this up because I have seen posts
about reboring the pulleys because they are
almost always off a few thousands.
So there is no need to rebore the pulleys.
There is no need to return the shafts.
Life is grand.....

> How it would eliminate runout as a source of error, I have no idea.

I do not really understand how an eccentric shaft will cause error.
I see it as the belt just getting a bit tighter, and a bit looser
as the pulley goes around. I was thinking it has something to do
with the tooth engagement. Now I think I understand: The pulley
is seen as being a larger dia when the error moves the motor pulley
away from the opposite pulley, and as a smaller diameter when
the motor pulley is closer to the opposite pulley. Correct me if
I am wrong.

>
> Why are you quibbling over ten to the minus 5 inch errors when you have
> so many
> other LARGE errors still in the system? You'd be AMAZED at all the

many

> sources
> of errors that add up in these machines! Thermal errors,
> non-orthogonality, bowing
> of leadscrews, axial thrust bearings, flexing of the machine itself,

and

> on and on.
>
> Jon
>

Like I said, I only have brought this up because many, including
yourself, have said you bore out new pulleys to center the shaft
hole.

Thanks,
Scott