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Re: using a spindle encoder w/ Mach 3
« Reply #10 on: January 21, 2008, 04:09:25 PM »
a lot of commercial rotary encoders have an index pulse(one pulse/rev) that is used for synchronization, look at the label and search google for wire colours
Friedrich
Re: using a spindle encoder w/ Mach 3
« Reply #11 on: January 21, 2008, 05:39:54 PM »
I have an older DOS-based cnc lathe that I'm looking to upgrade to Mach 3 using my existing g100/mach3 setup. The lathe uses a KVM style spindle motor controller and so I was planning on using the digispeed XL board, however, the spindle uses an encoder (see attached image) and I'm trying to find out how I might be able to take advantage of the existing encoder arrangement by configuring mach rather than swapping it out for a pulse generating indexer, etc...

 Can this be accomplished with the g100 and mach combined or can mach even be configured to at all to take advantage of a spindle encoder like this one?

 Thanks!!






Hi,

Does the encoder you have contain an index pulse output? A lot do. If so you could use that.

Cheers,

Peter.
----------------------------------------------------
Homann Designs
http://www.homanndesigns.com
email: peter at homanndesigns.com
Re: using a spindle encoder w/ Mach 3
« Reply #12 on: January 21, 2008, 06:12:21 PM »
 Yes, the encoder outputs a separate indexing (Z) channel that pulses at 1 ppr. I have the wiring diagram available for the encoder so it's not a problem to hook it up for a test. However, I'm trying to determine the output voltage before I attempt that. It appears to be 5v but I'm being cautious and waiting for verification before I proceed cause I don't want to risk frying my Grex.  :'(

 Hood thinks the pulse from the indexing channel may be too short for mach to read through the parallel port (as he mentioned above) so I'm going to check into running it through the grex/ethernet port and see if that might help. If that doesn't cut it then I might have to find an alternative.

 On the subject of the smoothstepper; does anyone know how many drives/axis it can support?

Re: using a spindle encoder w/ Mach 3
« Reply #13 on: January 21, 2008, 06:38:56 PM »
Hi,

Yes, you could be right, and you may need to go to a single pulse encoder. Have you seen the engineering notes for hooking sensors to the DigiSpeed-XL?

The DigiSpeed-XL has signal conditioning circuitry to allow the use of very simple opto-interrupters;

http://www.homanndesigns.com/EN001.pdf
http://www.homanndesigns.com/EN002.pdf

Also, as far as I understand, the Smoothstepper can control 6 axis.

Cheers,

Peter.
« Last Edit: January 21, 2008, 06:40:36 PM by phomann »
----------------------------------------------------
Homann Designs
http://www.homanndesigns.com
email: peter at homanndesigns.com
Re: using a spindle encoder w/ Mach 3
« Reply #14 on: January 22, 2008, 04:03:33 PM »
 I hadn't seen those engineer's notes for the digispeed although I've already read the manual. Thanks for the info Peter... I appreciate that!
Re: using a spindle encoder w/ Mach 3
« Reply #15 on: January 26, 2008, 08:20:29 PM »
 I was told by the manufacturer that the encoder is designed to run at 5V (and only 5V) for both input and output. He also mentioned that the lathe was originally setup to use only the A and Z channels of the encoder; where the A channel (60ppr) was used for speed control and the Z channel (1 ppr) was used threading.

 
Arduino Diecimilia baord??
« Reply #16 on: January 29, 2008, 04:46:46 PM »
 Has anyone tried using one of these Arduino usb microcontroller boards:

http://www.arduino.cc/en/Main/ArduinoBoardDiecimila

 I should be able to easily program it to have the short pulse that's generated by the encoder trigger a delay or another signal of greater length so that mach can then read it. It's $35 so it would be overkill for this app however it includes 14 digital input/outputs (6 of which can be used as PWM outputs) and 6 analog inputs so it could prove worth the investment.

 Anyone have any experience with one of these boards?

vmax549

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Re: using a spindle encoder w/ Mach 3
« Reply #17 on: February 03, 2008, 03:59:48 PM »
If you are planning on using the encoder setup in the picture to also be a timing signal I see a BIG problem.

THe drive motor is not using a timing belt to drive the spindle. IF it slips(and it will) the spindle will be OUT of synch. With that setup you will need to use a signal that is timed to the spindle itself.

It apperars that the encoder is there JUST to help control motor speeds.

(;-) TP
Re: using a spindle encoder w/ Mach 3
« Reply #18 on: February 03, 2008, 08:22:26 PM »
 I'm not sure I completely understand what you mean. I realize that the motor is not using a timing belt to drive the spindle, however, the encoder is attached to the spindle shaft and not the motor shaft so it is getting it's reading directly from the spindle - not from the motor. I don't see how this would be a problem, maybe you can you explain?

 My understanding of the original encoder setup is that the 60 ppr (A) channel was used to measure speed and the 1 ppr indexing (Z) channel was used for spindle positioning (threading). The B phase was apparently bypassed altogether.

vmax549

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Re: using a spindle encoder w/ Mach 3
« Reply #19 on: February 03, 2008, 09:57:09 PM »
OOPS MY mistake it looked to me like what is the spindle housing looked to be the drive motor.

Sorry (;-) TP