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Offline c30232

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Position confirmation or tracking
« on: November 23, 2014, 01:38:27 PM »
I have been successful with Mach and stepper drives.  However, I have a new application where missed steps could go unnoticed and thus have costly results.  The movement is a simple linear X plus and minus. Is there any way to monitor or confirm or alarm position via Mach?  Perhaps an encoder???  I see there is a stepper drive that will alarm missed steps, but it is a bit pricey for just that.

What about a servo system?  If I can make a stepper go, will I have the skill for a servo system?

Can stepper and servo drives by mixed within Mach?        
Re: Position confirmation or tracking
« Reply #1 on: November 23, 2014, 11:50:28 PM »
If your stepper motors are tuned correctly, and are not being overloaded for the job at hand, they are very reliable. Missing steps can result from poor tuning, electrical noise, or not up to the task for the load on the cutter.

However, if things are set-up right, you could mount a 1" travel dial indicator at the extreme left or right X position of your job, and set it to zero. Then put an M1 in the program when the axis reaches that "0" point, and the program will stop and wait for you to hit cycle start to continue.

There are Hybrid Stepper systems, and there are Servo systems with encoders. It all depends upon your wallet, and needs for the job.

The newer digital stepper drivers have motor tuning capability through a software program in real time, that offer the best stepper tuning possible. The program is called "Protune", and shows a graphic on a program screen, connected to the driver by a RJ45 connector and an XP computer serial port.  Look on the Leadshine site, or CNC4Pc site for more info.

John


Offline BR549

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Re: Position confirmation or tracking
« Reply #2 on: November 24, 2014, 12:27:18 AM »

Offline c30232

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Re: Position confirmation or tracking
« Reply #3 on: November 24, 2014, 12:46:44 AM »
Thanks.

Your dial approach seems reasonable in concept.  However, we don't always return to zero to begin a new movement.  A linear scale in place of your dial would do the job and allow monitoring throughout the full range.  The project is a fence for a gang-ripsaw.  The critical position is a rip value set form the work offset.  Thus if the scale DRO and Mach DRO match, life is good.

So far the project works well.  But as tuned as one can be, a forklift will still stall the old stepper.  If it is off by a mile, it will be noticed.  The feed rate of the saw, in Mach terms, is 1,800 IPM.  It is the 0.062" bump that would go unnoticed and rack up the dollars.

        

Offline c30232

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Re: Position confirmation or tracking
« Reply #4 on: November 24, 2014, 12:58:01 AM »
Thanks BR,

Wow, I have a Sound Logic BOB installed in another project.  The BOB is great, however, I am using a $25.00 Brand-X because the supplier of the Sound board has not been able to produce the documentation for the BOB.  Thanks for the insight and new source.

Offline BR549

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Re: Position confirmation or tracking
« Reply #5 on: November 24, 2014, 01:11:52 AM »
You may find a manual here

http://campbelldesigns.net/breakout-board.php

(;-) TP

Offline c30232

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Re: Position confirmation or tracking
« Reply #6 on: November 24, 2014, 01:19:12 AM »
Thanks,

Are you able to find a manual there?  I have not and I cannot get it emailed either.  For about a year I simply get a 404 error.  Other than that the BOB works well, but we still don't know positively what all of the I/Os are for.  I am a risk taker but I don't want to fry a happy and functioning board.

Offline BR549

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Re: Position confirmation or tracking
« Reply #7 on: November 24, 2014, 02:20:56 AM »
Yes I can download the manuals there What version board  do you have ?

(;-) TP

Offline c30232

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Re: Position confirmation or tracking
« Reply #8 on: November 24, 2014, 08:01:08 AM »
I have the Combo Board.

Does the Rogers board handle full control, or is it a supplemental board for encoder inputs only?  Can it be used as the BOB for now and then add an encoder or two in the future?

In the event of lost steps, does Mach resolve the loss and then catch up?  

Offline BR549

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Re: Position confirmation or tracking
« Reply #9 on: November 24, 2014, 05:07:15 PM »
I would suggest you read up on it yourself there is a manual for the board on the Rogers site. Yes it can be setup to correct itself on error and move back into position.

(;-) TP