Convert a manual grinder to auto feed?

An inexpensive DPST relay along with a SPDT limit would give you what you want.
 
As part of my further thinking I started to like the idea of using 2 SPDT limit switches at the one end of travel so that I can have them staggered by about a half inch or so. This way the Y axis can start moving just before the table reverses so that it will be done with its move before the wheel hits for the next pass.

Like I said in the beginning, I have no idea what I am doing or what matters. I am just doing a lot of thinking out loud here. If I am doing something crazy just tell me. I expect to learn a few things that will not work along the way. I may even let some of the magic blue smoke out of a few things before I get something that works. I just hope it is not the expensive shade of blue.....

Maybe I should order an extra can of magic blue smoke.....

Magic Blue Smoke Refilling Kit - TOL-10622 - SparkFun Electronics

**Note:** This was one of our April Fool's products for 2011. Sadly, it's not real. On a recent trip to South America I made a shocking discovery. Deep in
www.sparkfun.com www.sparkfun.com
 
OK, I think I now have all the bits and pieces to make a stepper motor spin and go back and forth.
I am going to whip up a test bed wit string and 2 pulleys and a block of wood to represent the table.
This way I can test my theories on connecting everything up and reversing AND get to see a stepper motor actually spin.

My new question is; Can I just use 2 conductor speaker wire to hook everything up, or do I need twisted pairs, or shielded wires, or, or ,or????
 
The key is to use a short as you can get. If you are using twisted pairs, use a pair for each power lead with the other member of the pair a ground. This gives you the best performance at the frequencies involved.
 
My latching relay finally showed up today, now I can try to make it go back and forth automatically.
 
FINALLY!!!! All of the parts are here for me to start connecting up oodles of wire to first see if I can make a stepper motor actually spin and if I can make it reverse direction on command AND not let any of the Magic Blue Smoke out of anything in the process.

This weekend I will start messing around with the wires.

This is my goal is to get all of this connected up correctly and functioning just on the bench just to see if I can make a motor spin.
This will just be for the "X" axis that moves the table back and forth, and back and forth.......

Once this is all laid out and working electrically then I will start modifying and making parts and doing the changes to the grinder to actually implement it.

Then I get to start designing what it will take to move the table in the "Y" axis, and acquiring the parts to do so.
 
Woooo Hooooo!!!!!!!

I got the fancy stepper motor to spin, AND reverse direction on command. The speed control will vary it from about 60 RPM up to around 3,000 RPM.

Now I have to start working on the electronics to make the on off switch, and the speed control to be separate from the controller board so that I can have them mounted on a nice control panel. Then I have to find and tap into the controller circuit board the direction control and interface it to the 2 direction switches that will be at each end of the travel.

I think I know how to do these things, I just have to find where to splice the wires to the controller circuit board, and which traces on the controller board to cut so that all control is external to the board.

I did not make a video because YouTube does not need another boring vid of a motor spinning with nothing but a piece of tape on the shaft so you can see that it is spinning.

OK I know that this is old hat for most of you, but for me it is exiting being the very first time I have been able to make a stepper motor spin and a mile stone in his project.
 
After more testing, I found that I can get the motor down to about 1.5 RPM by playing with the steps per revolution settings. With a 3/4 inch dia timing pulley mounted on the shaft I can not stop it just by trying to hold it. I was impressed at the felt torque from this tiny NEMA 23 x 57mm unipolar motor being run as a bipolar on 24VDC.

I now also have the table reversing circuit built and working with the actual limit switches that I plan to use, Now I just have to interface it with the controller board.

Progress is happening.........
 
IT WORKS!!!!

I now have all of the electronics assembled and playing well together. The reversing switches actually make the motor go the other way, on command even.

Now I get to start figuring out how to attach all of this to the grinder. :dunno:
 
I am now starting into the actual machine conversion. Would those watching prefer to have me just add on to theis thread or start a new conversion thread. It makes no difference to me either way, I want to do what is best for this forum and its members.


I have a set of timing pullies and a belt. The small 25 groove pulley has been reamed to fit the motor, and the big 50 groove pulley has been bored to fit the shaft on the grinder.
I have been playing with a bunch of ideas on how to put this all together.I wanted to make it "universal so that if the NEMA 23 x 56mm motors that I have are not enough torque, I can go to the longest 114mm motors to double the available torque. I decided that I will make a setup for the short motor, and have the motor on the back of the mounting plate to not have anything sticking out. I I end up having to go to the long NEMA 23 motor I will have to mount the motor on the front of the mounting plate and live with it sticking out. OR I could get a short NEMA 34 motor and still have it on the back.

For the mounting plate I have a piece of 5/16 x 4 x 8 steel plate.
The surface of the grinder is rough cast so my plan was to drill and tap four 1/4-20 holes into the machine around the shaft boss and spot face them, then put in threaded rod and lock them in with nuts against the casting. The mounting plate will be about 1.50 inches out from the cast surface and go over the 4 studs with a nut on each side of the plate, this will allow me to get it squared up with the shaft. The motor will mount on the back side of the plate with the pulley projecting out the front. The 4 holes for the mounting of the plate to the studs will be slotted for adjusting the belt tension.

I have the mounting plate squared up and a small hole drilled in the location of the machine shaft and a relief cut to clear another cast boss that sticks out of the front of the grinder.

I am planning to make a quick release to be able to mechanically disconnect the shaft from the motor in case I want or need to go full manual, like for dressing the wheel. This will be the hardest part (at least for me) as I need to make a sliding male and matching female splineish something using the machines I have to work with and NOT buy any expensive tooling. The spline will need to be big enough to put into a tube that has a 20mm ID to fit the machine shaft. There will also need to be a detent to hold it either open or closed. I am still open to ideas on how to accomplish all this. I have never even thought of trying to make matching splines.

Still working on ideas of how to mount the limit switches to the return bumpers........?
 
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