G0678 CNC Conversion Thread

[martyscncgarage]

Look up thee post earlier and you'll see the exact make and model of the encoder. [Encoder Model #TRDSH2500-VD, from Automation Direct.}

We have covered this before in this same thread. The wiring is exact per the Acorn drawing, the cable has no extension and is the cable attached to the encoder which is shielded and it is grounded at the Acorn end only! It is only 6 feet long, does not parallel any other cable, enters the control cabinet in its own entry hole and has a modular plug that can be removed if I need to.

The RPM reads just fine at any speed, high or low and it is accurate! So factory wiring except for the DB9 connector! I've gone to the trouble of putting a bar into a holder in the spindle so I can turn the spindle as close as I can to a perfect 1 turn and I get 10,000 pulses on every turn. So it is not wired wrong else it would not be giving me proper pulses!

I'm pretty much down to a noise issue or just crappy encoders! If it is noise, I have no idea what or where it is coming from or how to eliminate it!

Dave C.

Please don't take offense. Some times we miss the basics.
I used the cut sheet for the Line Driver Connections: https://cdn.automationdirect.com/static ... oderld.pdf

So you are wired with a shielded cable:
Encoder Blue (0V) - DB9 Pin 2
Encoder Brown (+5VDC) - DB9 Pin 9
Encoder White (A) - DB9 Pin 7
Encoder Gray (/A) - DB9 Pin 4
Encoder Purple (B) - DB9 Pin 8
Encoder Black (/B) - DB9 Pin 5
Encoder Orange (Z) - DB9 Pin 6
Encoder Yellow (/Z) - DB9 Pin 3
Encoder Shield - DB9 SHELL

Also, the Acorn schematic for the DB9 is as you are looking at the female connector on Acorn.

If you used solder cup DB 9 male connector, double check there are no "whiskers" touching another pin?

Just trying to double check the basics.

Marty

[Dave_C]

Marty,

No offense taken! Just frustrated..

Yes, I have checked for whiskers and every screw pocket is clean!

One of the things that makes me think this may be "noise" is the fact that the rigid tap program ran twice! It would not have run at all if the encoder was wired poorly or wrong.

I ordered some snap on Ferrite beads to put around the encoder cable. It'll take a week or so to get them but I'm going to try and see if I can get to the bottom of the issue.

When something works twice and then doesn't work again it is not easy to find the cause!

Dave C.

[martyscncgarage]

Marty,

No offense taken! Just frustrated..

Yes, I have checked for whiskers and every screw pocket is clean!

One of the things that makes me think this may be "noise" is the fact that the rigid tap program ran twice! It would not have run at all if the encoder was wired poorly or wrong.

I ordered some snap on Ferrite beads to put around the encoder cable. It'll take a week or so to get them but I'm going to try and see if I can get to the bottom of the issue.

When something works twice and then doesn't work again it is not easy to find the cause!

Dave C.

Shoot, was hoping something got overlooked.
I understand. When you are THIS close and this sort of thing rears its head is definitely frustrating.
I am not sure what else to suggest at this point. I have used AD's encoders and had no issues. Never had to use a ferrite bead.

Marty

[Dave_C]

Marty,

I'm wondering if the high frequency rate of the 10,000 pulses per rev is causing some crosstalk? I've kept the encoder cable away from everything and only crossed the Z axis servo cable at a 90 degree angle to eliminate as much crosstalk as possible.

I've done some ground plane testing, with 0.0 ohms between the Acorn chassis terminal and the backplane ground.

One of my reasons for thinking I'm getting some "noise" is the RPM dances a bit on my computer display. In other words it does not lock in at a constant RPM while my Drive display holds a solid RPM reading. When I say it dances, I'm getting 4 or 5 rpm variance almost continuously.

Does anyone else have this same rpm result?

Dave C.

[martyscncgarage]

Did you compare with a digital tach?
Can you run the encoder cable direct from the encoder to Acorn rather than routing just for testing?

[Dave_C]

It's pretty direct now! I don't own a tach, I just look at the drive display and see it is stable.

[martyscncgarage]

It's pretty direct now! I don't own a tach, I just look at the drive display and see it is stable.

Hmm, the digital tach would validate what you see on the display.
I still think there is something to be found out with the encoder setup....

[ScotY]

One of my reasons for thinking I'm getting some "noise" is the RPM dances a bit on my computer display. In other words it does not lock in at a constant RPM while my Drive display holds a solid RPM reading. When I say it dances, I'm getting 4 or 5 rpm variance almost continuously.

Does anyone else have this same rpm result?

Dave C.

Sorry to hear of your troubles. My rpm reading does the same, it is never steady, minor fluctuations. My limited experiences with rigid tapping worked well. Using cheap Chinese encoder.

[Dave_C]

Update:

I decided to go over all the setting for rigid taping this morning and as I did I saw a footnote in the setup sheet stating that if a certain fault happened, then try taping at a lower spindle speed.

So with nothing to lose I just edited my code and changed the 640 to 440 RPM. Now mind this, I tried to run the code at 640 at least 4 times with my wife standing beside me as a witness and it failed on all four tries.

So after changing the spindle speed to 440 we tried it again, and then again and then the third time.

IT RAN EVERY TIME, just perfect! I made a video of the test because I know there are those out there who will have to see it to believe it and I will get it posted up later today.

So someone tell me why it works at 440 RPM and fails at 640 RPM. It fails right after the spindle makes the rapid move to the clearance height above the part. So to make it as clear as I can, the tool changes is done, the spindle starts, comes up to speed, then the rapid move to .100" above the part and then the fault happens. (before it starts to thread)

Changed spindle to 440 rpm and all goes as it should.

Video is on its way!

Dave C.

[ScotY]

Curious what your minimum spindle speed is set to in the Wizard. I had mine set to zero but Keith mentioned it should be set to something higher. Forget the number he mentioned and don’t know the reason why it shouldn’t be too low. Perhaps this has something to do with your mystery? Anyway, I’m guessing they will want to see a report.