loat Y axis marker

[BrianP]

I had problems with the machine not moving in the Y minus direction, got some good advice from "bloke" and replaced a couple chips, the machine now has movement in all axis's but a new problem has cropped up.

When I attempt to zero the machine the Z axis does fine, the X axis also zeros out fine but the Y axis attempts to zero, it goes to the limit and then reverses/backs up slowly as though its attempting to find zero then stops. I get the following message:

"Error positioning to marker on axis Y"

Any ideas as to what to do next, thanks in advance Brian

[underthetire]

Does the machine have scales or encoders?

[fasto]

When I attempt to zero the machine the Z axis does fine, the X axis also zeros out fine but the Y axis attempts to zero, it goes to the limit and then reverses/backs up slowly as though its attempting to find zero then stops. I get the following message:

"Error positioning to marker on axis Y"

Any ideas as to what to do next, thanks in advance Brian

Brian, when you jog that axis before calibrating, do you see the "marker flag" on the control? The marker flag as I call it is a decimal point after the "X" or "Y" up in the position part of the screen, like my example below on Y & Z:
X 16.0252
Y. 14.2543
Z. 12.0777
Jog the axis & see if the marker flag decimal point shows up. Do X first so you know what to look for. The marker is once per rev of the servo, so you've got to jog pretty slow or it won't show up.
On my machine the marker is about 0.0003" wide so go slow so that you don't miss it.
You probably won't see the decimal point on Y. Now you can have a look at what might be wrong. You have an axis that works and one that doesn't, so you can start swapping until the trouble changes from Y to X.
The marker signal comes from the encoder on the servo motor, so the wiring between the servo motor & the drive or the connector at the servo motor could be causing trouble.
Or, it could be the servo drive, so exchanging x & y then jogging to find the marker flag would check that.
Could be the dual-axis card, you could swap x & y 25-pin connectors there so that x is now y and y is now x - jog x on the control/y on the machine and see if the marker flag shows up. If you do this the limit switches are disabled so be very careful not to crash the machine! Also don't try to calibrate it if you switch the x & y on the control because this uses the limit switches!

[BrianP]

the machine has encoders, I will check on the on the marker flag, a person had suggested that I swap out the amplifier cards between the x and y axis but that didn't help.

[underthetire]

Most of ours have scales, thats a whole other problem ( magnet pickup on the outside of the scale). The ones we have that get that alarm with encoders its usually nothing more than the reference switch is sticky and not returning fast enough, causing the machine to miss the marker pulse on the encoder. Might try a little WD40 on the switch.

[bloke]

Another thing to try would be to set a multimeter on DC volts and measure between the brown and orange wires on the edge of the servo amp (on the connector between the board and the terminal strip).
start the servos and measure the voltage between them - it should be 0.00v.
If not, adjust the BAL pot on the board until it reads as near to zero as you can get.
Try and calibrate again. It should now find the marker.

[BrianP]

I haven't had a chance to try the fixes mentioned, unfortunately I'm not the most electrical minded individual, the stuff you guy's talk about like it's nothing gets my head swimming

I did notice something though, when I start up the machine and move the table the X axis still gives me no problem but if I rapid traverse the Y axis very fast it trips the servo, it does fine if I move it slower but will not move move more then an inch or two if the speed is up. Any idea what this indicates?
Thanks again in advance, Brian

[bloke]

By the sound of it, your servo amps may need a bit of setting up.

[BrianP]

I want to thank bloke for pointing me in the right direction in finding the problem and fixing it.

The machine will now zero in all axis's now but I still have a small problem, if I try to rapid traverse the "Y" axis at much more then 50 IPM the servos fault out. This only happens with the "Y" axis, is my amp board going bad, servo or something else that may be a cheap, easy fix.
TIA
Brian