Servo Spindle motor encoder Mesa 7i76e

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29 Feb 2020 15:34 - 01 Mar 2020 12:20 #158816 by Erikcnc
Hi all,

After making good parts with my emco 220, i was able to finally try threading.

Unfortunately the thread (or should be) looks rubbish.
Did some searching and i think i setup some things wrong. Every start of new cut is shifted some how, so its off the starting point.

encoder scale in the .ini file is -1024, same as in the motor drive. could be increased if its better.

In hal scope:
Phase A works
Phase B works
Phase Z works, but have a hard time to find its spot by rotating the spindle by hand, but i get a pulse though.

Can some one walk me through it to find the problem?

File Attachment:

File Name: EMCOTURN22...2-29.hal
File Size:11 KB

File Attachment:

File Name: EMCOTURN220.txt
File Size:4 KB
Attachments:
Last edit: 01 Mar 2020 12:20 by Erikcnc.

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29 Feb 2020 15:53 #158818 by PCW
Are you sure the spindle encoder scale is correct?

An easy way to tell is to mark the spindle and hand turn
it say 10-20 turns, the spindle encoder position pin should
advance by exactly 1 for each spindle turn
The following user(s) said Thank You: Erikcnc

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29 Feb 2020 16:42 #158820 by bbsr_5a
it is always better to stay positiv in all main setups and turn a wire to get direction change
as the New interpreter is in someway getting troubled / confused on calculation
My personel expirience on the Motor setups

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01 Mar 2020 12:20 #158888 by Erikcnc

Are you sure the spindle encoder scale is correct?

An easy way to tell is to mark the spindle and hand turn
it say 10-20 turns, the spindle encoder position pin should
advance by exactly 1 for each spindle turn



so i checked hm2_7i76e.0.encoder.00.position in halshow. Marked the spindel, did one rotation, value was 0.9560***.

so, its off. if i continue o get the value to 1 its like 10mm between the marks on the spindle.

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01 Mar 2020 14:00 #158890 by PCW
That's an odd number, sounds like its miss-counting
is the number consistent? That is, do you get back to the mark
if you rotate backwards to 0?

If the count is not consistent I would suspect:

1. Electrical problems: Encoder input mode on 7I76 does not match encoder signals/wiring, wiring issues, bad levels
2. EMI issues (electrical noise from drives etc) possible fixable by adjusting the encoder filtering
3. Bad or dirty encoder wheel/optics
4. Slipping mechanics
The following user(s) said Thank You: Erikcnc

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01 Mar 2020 14:59 #158892 by Erikcnc

That's an odd number, sounds like its miss-counting
is the number consistent? That is, do you get back to the mark
if you rotate backwards to 0?

If the count is not consistent I would suspect:

1. Electrical problems: Encoder input mode on 7I76 does not match encoder signals/wiring, wiring issues, bad levels
2. EMI issues (electrical noise from drives etc) possible fixable by adjusting the encoder filtering
3. Bad or dirty encoder wheel/optics
4. Slipping mechanics


No when i rotate back, its sets to 0 just fine.
i also checked the .00.counts. one full rotation has a value of 975.
I set this in the ini file.
00.position value is now 1 at full rotation.

now 00.rawcounts value should be the same as 00.counts right? value is 1971.

for the information. W10 W11 and W13 are in differential mode. should these be in single?

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01 Mar 2020 15:15 #158893 by PCW
975 is a very odd number so I suspect something is still wrong

The 7I76E encoder jumpering must match the electrical interface on the encoder
Differential encoder interfaces will have 6 signals instead of 3:

Differential:

A, /A B, /B Z, /Z

TTL/single ended:

A,B,Z
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01 Mar 2020 19:51 #158906 by Erikcnc

975 is a very odd number so I suspect something is still wrong

The 7I76E encoder jumpering must match the electrical interface on the encoder
Differential encoder interfaces will have 6 signals instead of 3:

Differential:

A, /A B, /B Z, /Z

TTL/single ended:

A,B,Z


oke, well that confirms that the jumpers are right.

i set the encoder scale in my .ini file back to 1024. in program run its wait for spindle reach.

this is really weird what cause this.

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01 Mar 2020 20:51 #158909 by PCW
To check if its a bad encoder, you could rotate at a constant speed and plot the
encoder velocity with HALScope. A bad /dirty encoder wheel will show up as a repeating dip in velocity
The following user(s) said Thank You: Erikcnc

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02 Mar 2020 15:00 #158977 by Erikcnc

To check if its a bad encoder, you could rotate at a constant speed and plot the
encoder velocity with HALScope. A bad /dirty encoder wheel will show up as a repeating dip in velocity


Found it!

Nothing in linuxcnc or drivers.

There is a difference in the poly v belt wheels. A deviation of 5%
I get the same offset in the drive. So i was questioning my self why also the drive counts where off.

Now, I might add a encoder on the spindle its self (as it was original but one puls).
I would like to have also a quadrature encoder on it, so i can also ridgit tap.

Or, i replace the v belt wheels to timing belt. Might be more work, but then i can use the servo motor as i intended.

Any suggestions?

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