Ignoramus16651 wrote:
On 2010-04-09, Karl Townsend wrote:
Once your control box is empty and you've pulled the resolvers off
the servos (check you may get lucky and have encoders) you'll only
have about 30 wires to figure out.
Why do I need to pull resolvers off?
obsolete, encoders used today.

KO, how do I get those encoders, are they a standard item?

If the motors have Harowe Controls resolvers in the NEMA size 11
package, it may be hard to fit encoders in place, as they are 1.1"
(28mm) diameter. I have a resolver converter that makes them look just
like encoders to the CNC control.

Resolvers are not obsolete. They were the top choice when cost was no
object and optical encoders had light BULBS in them, as you got a servo
runaway when the bulb burned out! Now they are just more expensive, but
will run underwater, fully filled with oil and coolant, and at 150 C.
They are nearly indestructible.

If you mean linear encoders from DROs, the problem with them is the
general DRO-class encoders have low resolution, typically .01mm ~=
..0004" This is really not good enough for CNC motion control. You
generally want 10X the encoder resolution compared to displayed
resolution. I have 50 uInch resolution on my X and Y, and 25 uInch on Z
on my Bridgeport mill retrofit. You can get higher resolution linear
encoders, and now 1 micron resolution is becoming pretty affordable, but
they will still cost several hundred $ each. If your machine has
resolvers and good ballscrews, just keeping that system and using the
resolver-quadrature converter may be the easiest way to go.

Jon