Rigid Tapping Trouble <resolved, wrong encoder>

[PFM Dave]

Keith,

Went out this AM to check. Parameter 34 is set to 8000, M3 motor turning clockwise as in normal drill bits cut material, PID count grows or increases. The only thing for me that may be odd is the N* on the count line, not sure why an asterisk. See picture.

Still getting the 438 Spindle Slave position error when attempting to rigid tap with Parameter 36 set to 1.

So if we assume for a moment that 34 needs to be 8000 what is next?

Thanks again to all trying to help,

PFM Dave

[tblough]

The asterisk denotes the index pulse. It should only come for a very short while on each rotation. If it is on all of the time, then you have something wired incorrectly on the index lines, or your encoder is bad.

An oscilloscope would be best, but you can use a DMM to check the voltage across the Index differential lines. If you turn the spindle very slowly by hand, you should see less than 0.3VDC for most of the rotation with a small blip around +4.5VDC when over the index mark.

[PFM Dave]

tblough,

Thanks for the reply, lets please expand on this. I recall the * as up on display most of the time. My encoder is E6B2-CWZ1X, data sheet attached. I see the Z Phase for this model is inverted compared to some I see. Could this be the problem?

There may be light at the end of this tunnel. Wiring change to the 9 pin or new encoder?

Thanks again to all.

PFM Dave

[tblough]

Nothing on that datasheet shows Z being inverted. If Z is staying on, then it's a wiring error or bad encoder. The data sheet says Omron, but unless you paid $400 for it, chances are it's really chinese junk. Omron is counterfeited by almost everyone over there.

The fact that it's staying on could very well be the problem.

[cnckeith]

Nothing on that datasheet shows Z being inverted. If Z is staying on, then it's a wiring error or bad encoder. The data sheet says Omron, but unless you paid $400 for it, chances are it's really chinese junk. Omron is counterfeited by almost everyone over there.

The fact that it's staying on could very well be the problem.

good catch by Tom! i agree i think the whole time the encoder z index has been ON all the time vs once per revolution. therefore stopping the tapping cycle from running. install another encoder~!

[cncsnw]

Keith: did something change in the rigid tapping cycle?

It used to be, the cycle would wait for the index pulse, then begin feeding Z down in proportion to the A/B counts.

Once it had started feeding down, there used to be no dependence whatsoever on the index pulse.

In the current software, what is the mechanism whereby invalid signals on the index channel could cause "438 Spindle Slave position error"?

[PFM Dave]

All,

Not so sure the encoder is "bad". If you look at the spec sheet supplied above the Z output is High and goes low one time per revolution (page 3 last encoder). The other encoders on this same sheet all start low and go high. If I turn the spindle by hand I do see the asterisk "blink".

Is there a way to invert the Z input in software the same way would invert any other input to Acorn? Just asking as it would be a very simple solution if my thinking is correct.

CNCSNW you are beyond my understanding but... if your tapping function took multiple "pecks" to tap a deep hole would the Z or index pulse not be needed? Yes I am asking because I want to learn from my mistakes.

Is there a full spec for the usable rotary encoders? I see NPN, PNP and "line drivers" The latter using 8 wires as I see on diagrams to wire the Acorn 9 pin plug.

Again MUCH thanks to all who have helped to resolve this journey.

PFM Dave

[suntravel]

Swap the Z /Z wires in the DB9 plug and try if it is ok.

Uwe

[tblough]

All,

Not so sure the encoder is "bad". If you look at the spec sheet supplied above the Z output is High and goes low one time per revolution (page 3 last encoder). The other encoders on this same sheet all start low and go high. If I turn the spindle by hand I do see the asterisk "blink".

The spec sheet shows the opposite. Z-not is high and goes low. Z is low and goes high. It's a differential encoder. The asterisk should blink on, if it blinks off, it's wrong. If it does blink off, Uwe is correct and you have your Z and Z-not wires swapped.

[cncsnw]

Unless something has changed that I am not aware of, "peck" tapping is simply a series of full G84 tapping cycles, with successively greater Z depths.

After each "peck" cycle, Z would return to the R plane above the surface. Then the control would wait for the index pulse to come around again before starting the next "peck".

A faulty index pulse would potentially cause the threads in successive pecks to be out of sync with the previous ones, so you would get bad threads. There is no reason I know of that a faulty index pulse should cause a "438 Spindle slave position error" condition.