Spindle encoder and fine boring

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martyscncgarage
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Re: Spindle encoder and fine boring

Post by martyscncgarage »

I touched base with Delta on a VFD with Spindle Orient capabilities. This is what they suggested:

The option would be a C2000 series drive. The EMC-PG01L is the option card with line driver input and output, it will work with any HP C2000.

Please visit our website at www.deltaww.com for more detail on the series.
Reminder, for support please follow this post: viewtopic.php?f=20&t=383
We can't "SEE" what you see...
Mesa, AZ
cncsnw
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Re: Spindle encoder and fine boring

Post by cncsnw »

Fueler1 wrote:. I can add the braking resistor and board Automation recommended.
. The only unclear point is whether the Automation board allows control of spindle orientation via it's rpm feature.
. Perhaps can do spindle orientation with the rpm feature and the rest is PLC work or some other coding?
. Yes, I don't understand yet what is supposed to do what.
. Clear it up for me please on how this orientation is accomplished.
I think if you look on the back wall of the cabinet, partly hidden behind your GS3 spindle drive, you will see that you already have a braking resistor installed.

How is orientation accomplished?

Usually, it is handled by specialized software in the spindle drive (VFD). That is why the usual recommendation is to purchase a drive that specifically features orientation capability in the software. As Marty points out, the Delta C2000 is one such drive. The GS3 is not.
Given a drive with orientation capability in its software:
  • The CNC control's PLC sends an "Orient" command signal to the spindle drive.
  • The CNC control then sits and waits for an "Orient Complete" signal back from the spindle drive.
  • The spindle drive rotates the motor as needed to locate the encoder's index pulse; then rotates it an additional number of counts set in a parameter (to get around to a chosen orient position that is not necessarily at the index pulse); then stops there, and continues to apply current as needed to hold the motor shaft at that location. The spindle drive then closes the "orient complete" signal to the PLC.
At this point the spindle drive is running closed-loop position control, much like what your Centroid control does with the X, Y and Z axes: if you do anything to push the spindle away from the orient position, the drive will see this on the encoder, and will apply more and different current to the windings, to push it back where it needs to be.

As an alternative, given a spindle drive that does not have its own orientation software, but which (1) does reliably control speed all the way down to zero (rather than shutting off current below some non-zero minimum frequency), and which (2) accepts a bipolar analog signal to control speed and direction (so that the PLC can reverse the spindle simply by making the analog speed command voltage go negative, instead of by switching relays), then it is possible to write orientation software into the Centroid PLC program.

However, I would be surprised if the GS3 had reliable speed control ability all the way down to, and past, zero, even with an encoder card installed. You could try contacting Automation Direct to ask about that, though.
Fueler1
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Re: Spindle encoder and fine boring

Post by Fueler1 »

Thank you Marty. I will study up.

Marc,
That is the explanation I have been looking for. Thank you
I'm still amazed I could not find such a thing written down anywhere.
I will pass along to Automation your concerns and see if they can back it up.

I think you are correct on the resistor. Though barely visible I thought it looked like one.
Any idea what purpose it is providing for the current setup?
martyscncgarage
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Re: Spindle encoder and fine boring

Post by martyscncgarage »

Being a FADAL, is there a half moon divot where a pneumatic plunger presses into to lock the spindle in its orient position?
If so, there would be a sensor on it or its arm to let the control know when the plunger is in, lock the spindle an stop the VFD forward motion.
The control would command the VFD at a slow RPM with the roller pressed against the spindle until it dropped into the half moon divot, signaling the control to stop the forward motion and continue the tool change.

Marty
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Fueler1
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Re: Spindle encoder and fine boring

Post by Fueler1 »

martyscncgarage wrote: Mon Jan 04, 2021 1:01 pm I touched base with Delta on a VFD with Spindle Orient capabilities. This is what they suggested:

The option would be a C2000 series drive. The EMC-PG01L is the option card with line driver input and output, it will work with any HP C2000.

Please visit our website at www.deltaww.com for more detail on the series.
I am assuming you would like me to go with a 7.5 HP version.
Is this the correct version you (or anyone else) recommend?
Anything else I need parts wise?
Drive: https://deltaacdrives.com/delta-vfd055c23a/
Board: https://deltaacdrives.com/delta-emc-pg01l/
Fueler1
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Re: Spindle encoder and fine boring

Post by Fueler1 »

Not a Fadal Marty. Atrump B6FC bed mill with Centroid 400
martyscncgarage
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Re: Spindle encoder and fine boring

Post by martyscncgarage »

Fueler1 wrote: Mon Jan 04, 2021 4:28 pm Not a Fadal Marty. Atrump B6FC bed mill with Centroid 400
Sorry...I lose track of all the posts I look at!
Reminder, for support please follow this post: viewtopic.php?f=20&t=383
We can't "SEE" what you see...
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martyscncgarage
Posts: 7162
Joined: Tue Mar 28, 2017 12:01 pm
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CPU10 or CPU7: Yes
CNC Control System Serial Number: none
Location: Mesa, AZ

Re: Spindle encoder and fine boring

Post by martyscncgarage »

Is this a bed mill with no tool changer?
I went back through your post and didn't find pictures but I found one on YouTube


And one on ebay (Which has the Durapulse GS)
Atrump B6FC 3Axis CNC Bed Mill New Centroid M400 CNC Milling Machine https://ebay.us/4sy05W

Neither have tool changers.
What is your desire to have spindle orient?
Marty
Reminder, for support please follow this post: viewtopic.php?f=20&t=383
We can't "SEE" what you see...
Mesa, AZ
cncsnw
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Re: Spindle encoder and fine boring

Post by cncsnw »

Fueler1 wrote:I think you are correct on the resistor. Though barely visible I thought it looked like one.
Any idea what purpose it is providing for the current setup?
It enables quicker deceleration from high RPMs, giving the GS3 drive a place to dump excess energy it has taken in from the motor.

It is not a factor in final stopping.

Marty: the eBay listing you found is indeed Dave's machine. Jerry should take that listing down, since it was sold over five years ago.
cncsnw
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Re: Spindle encoder and fine boring

Post by cncsnw »

martyscncgarage wrote:What is your desire to have spindle orient?
With all due respect, please see the subject line of this thread, and see G76 in the Mill operator's manual.

The G76 "Fine Boring" cycle feeds a single-point boring tool down a hole. When it reaches the bottom, it stops the spindle; orients the spindle; moves X and/or Y a short distance as needed to pull the cutter tip off the wall (but without backing into the opposite wall); then rapids up out of the hole.

For this purpose, orientation does not have to be precise: plus or minus five or ten degrees would probably be fine.
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