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Author Topic: how to connect/wire a rotary encoder?  (Read 520 times)

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how to connect/wire a rotary encoder?
« on: September 09, 2020, 08:37:29 PM »
Let me first say that I am totally green when it comes to building CNC machines, but I picked up an older CNC lathe that I want to run with Mach 3.
I have all the stepper motor connections figured out, but I am stumped as to how I'm going to connect an encoder to my breakout board.

The encoder I'm using is this -->  https://panasonicsensors.com/index.php?route=extension/module/product_downloads/get&did=259

This encoder came originally on the lathe,

The breakout board I'm using is this one --->  https://www.pmdx.com/PMDX-122

My end goal is to be able to cut threads on this lathe, but I'm not sure if this even possible with Mach3.
Any help would be greatly appreciated. Thanks



Online Graham Waterworth

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Re: how to connect/wire a rotary encoder?
« Reply #1 on: September 10, 2020, 05:51:54 PM »
The PMDX-122 has no input for a high speed encoder, you are best to put a single pulse input from a hall effect sensor and set the index input active.
Without engineers the world stops
Re: how to connect/wire a rotary encoder?
« Reply #2 on: September 10, 2020, 09:06:00 PM »
Thanks for the reply Graham.
The machine came with the rotary encoder already installed, so I would like to use it. I got the PMDX-122 for free, so if I need to replace it , it's no big deal.
What do I need to look for in a breakout board so that it will be compatible with my rotary encoder?
Is there a certain brand and model you would recommend?
I would use the single pulse input, but my end goal is to be able to cut threads.
Thanks again.

Online Graham Waterworth

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Re: how to connect/wire a rotary encoder?
« Reply #3 on: September 11, 2020, 04:30:06 PM »
The encode may have an index pulse, called the Z channel on some that you could put into a normal input on the PMDX-122.

The smoothstepper has port 3 for this use or CS-Labs can do it as can Hicon some of the later PMDX boards too, you need boards that can read high input rates most spindle encoders are 1000 PPR and more so that x RPM is way above most basic boards, you need one with on board processing.


« Last Edit: September 11, 2020, 04:33:56 PM by Graham Waterworth »
Without engineers the world stops
Re: how to connect/wire a rotary encoder?
« Reply #4 on: September 11, 2020, 04:48:51 PM »
Thanks again for your help. I'm an old retired Tool Maker and got into this CNC lathe to try and keep my brain active, and it has done that for sure. Been learning lots over the past few days.
I will look into the "Z" channel on my encoder, but if it doesn't I will just go with a single pulse pickup for now.
Dan

Online Graham Waterworth

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Re: how to connect/wire a rotary encoder?
« Reply #5 on: September 11, 2020, 05:23:18 PM »
Without engineers the world stops
Re: how to connect/wire a rotary encoder?
« Reply #6 on: September 13, 2020, 04:18:10 PM »
Still having issues, and I'm totally lost. The spindle control is the last thing I need to do, and have spent the whole weekend trying to figure it out. Frustrating !!!
I understand my encoder wont work because it puts out 200 pulses per revolution.
I have proximity switches here, and was hoping I could use one for the pickup. What I'm worried about, is that these proximity switches only work on 12v , and I think that will be to high for the signal back to the breakout board.
This is for a lathe, and I will be turning on the spindle remotely. I just want Mach3 to recognize the spindle RPM so that it displays it on the DRO, and hopefully be able to cut threads.
What are most people using for a pickup?

I tried watching a few videos on this, but most pertain to routers and mills. Its difficult to find details for Mach3 turn.
« Last Edit: September 13, 2020, 04:20:13 PM by hemi43 »

Online Graham Waterworth

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Re: how to connect/wire a rotary encoder?
« Reply #7 on: September 13, 2020, 07:20:00 PM »
Without engineers the world stops
Re: how to connect/wire a rotary encoder?
« Reply #8 on: September 16, 2020, 07:19:46 PM »
Ok, I received the Hall effect sensor today, and have it Installed. Everything seems to work, except that the readout is wrong. When the spindle is spinning approximately 1600RPM, the DRO only shows around 800, yet at low RPM the readout is accurate.Another issue is when the spindle is stopped, the DRO reads around 140.
I’ve watched numerous videos on how To do this, but nowhere have I seen how to calibrate the spindle output. Hopefully this is the last time I need to bother you for help.
I appreciate it Graham.
« Last Edit: September 16, 2020, 07:28:39 PM by hemi43 »
Re: how to connect/wire a rotary encoder?
« Reply #9 on: September 16, 2020, 08:43:08 PM »
Edit; I didn’t want to delete the above post in case someone else is researching the same problem.
All is working good now. Originally, I was using a single small 3/16” diameter magnet on the spindle. This worked fine at low rpm. But at high rpm I don’t think the signal was long enough. What I did was add 3 more magnets beside the first one, so that there was an increased time that the Hall effect sensor will see the magnet(s).