$20 shaft encoder

[systemslave]

I just completed version 2 of my $20 shaft encoder project on my Sherline lathe. It has index and phase A. Phase A has 16 divisions because I am using Linux CNC to track the pulses in software and that limits the possible resolution.



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[LeeWay]

Do you think it will regulate the speed well enough for threading? I imagine that may be why you installed it to start with.
I have been considering going with a servo spindle on my lathe. It now has a DC motor controlled by Mach 3, but not nearly well enough for threading.
I do have an encoder that I bought several years ago and never installed. I may see how that works out first.

[systemslave]

From what I have read a real encoder has too much resolution for software pulse tracking. The computer can't keep up with it and loses pulses. I have an encoder on the bench as well, but set out specifically to build one with low enough resolution for LinuxCNC to track without hardware support. A real encoder on a board with hardware support is clearly superior to this solution. That said, I thought that this had to be a very inexpensive problem to solve. I do hope that it provides enough resolution to do threading. I have read of several people who claim to do threading with just an index pulse. This solution has many times that resolution.

The next step will be harder for me but probably little challenge for most of the folks on this forum. I built the encoder out of parts I had laying around. In fact, I looked at a sensor and thought "I should use that to encode my lathe spindle". Now it has passed all of the electrical tests and as you can see from the original posting LinuxCNC feels the tiny heartbeat of the index and phase A inputs. It is time to test it in the physical world. I have a lot less experience with that. I got my lathe and mill to fulfill my electronics hobby. I have never threaded on the lathe before. Right now I am looking for software to generate the g-code so that I can test the threading abilities of the lathe. Since the whole idea of the project was that this should have an inexpensive solution, I am looking for cheap or inexpensive software for simple threading. No doubt you Gurus would just hand code it. I don't have those skills, but I can make some interesting circuits.

BTW this unit is not Sherline specific. It should work with almost any lathe.

[Al_The_Man]

From what I have read a real encoder has too much resolution for software pulse tracking. The computer can't keep up with it and loses pulses. I have an encoder on the bench as well, but set out specifically to build one with low enough resolution for LinuxCNC to track without hardware support. A real encoder on a board with hardware support is clearly superior to this solution. .

Pretty much true for Mach, 1 pulse/rev is about all it can keep up with, with a advanced system like a motion card (Galil etc) or industrial CNC, the Z axis servo is geared to the Spindle encoder, the spindle is not usually as precisely controlled, so by gearing the Z off of it, what ever the spindle is doing, the Z tracks precisely.
I believe Kflop can do it also?
Al.

[systemslave]

Hey, look! I put threads on a rod! I still don't know what I am doing, but I'm having fun.