Convert a manual grinder to auto feed?

I spent all of yesterday and most of today so far researching Steppers drivers and controllers. There are so many options that it makes my poor little brain spin.

I did find a lot of Audrino solutions, but I am worse that terrible at programming. The closest that I come to programing is playing around a bit with LISP to create functions in AutoCAD.

Now don't this look like just what the Dr ordered? 7500 Rupee is equal to USA ~$106.74
www.tinycontrols.com

2-Axis Surface Grinder Controller

Specifications 20x4 alphanumeric LCD 16 bit controller Two Opto-isolated pulse Inputs Easy to use Menus
www.tinycontrols.com www.tinycontrols.com

I just need to add the motors, drivers and power supply, which are also available from the same place as a matched set. Then make a bunch of brackets and pulleys to fit it all together.

I have a digital torque meter that I borrowed from work, this weekend I will see if I can hook it to the the SG to measure just how much torque it takes to move things, so that I have an idea of just how much stepper motor I need for each axis. In the x my biggest concern is the starting and direction reversing for the x axis. the table moves asy enough that just the weight of the handle on the crank will always move the table while the handle drops to the bottom of rotation.
 
That's a cute little controller, never seen one before. Too bad they are out of stock, I would buy one just to play with it.

Steppers produce maximum torque at near zero RPM, and the torque drops off rapidly as the RPM increases. At a constant speed, it sounds like almost anything would drive your table, but you need to accelerate/decelerate the mass at the ends of the stroke. When accelerated too rapidly, steppers will magnetically decouple and just growl at you.

Steppers are rated by Holding Torque. When specing steppers I normally go way over the theoretical torque requirement (3 or 4 x), and try to run the stepper below about 600 RPM. You can always turn down the power on a oversize stepper, but it's pretty hard to get more power out of an undersized motor. Having said that, in a NEMA 34 stepper, going over around 1300 oz/in is rather futile because you lose too much performance in the higher RPM ranges because of the steeper torque curve.

In all cases, use a power supply that outputs near the maximum rated voltage of the drive. I normally only buy drives that will take 70-80 VDC input. All drives are not created equal, some work better than others and this is normally proportional to the price. Leadshine and Wantai on EBay seem to be good quality mid-range products. Automation Technologies also seems to have good products. Automation Direct sells top of the line steppers and drives but they are expensive compared to the others.
 
What a great idea! I have no interest in CNC'ing my mill, but I did consider briefly putting a digital lead screw on my lathe. On a surface grinder, doing even a single axis (for the long feed or the Y feed - would be a substantial improvement!
 
I did send them an email to ask when or if this SG controller will be back in stock and to see if they give package discounts if I buy a complete controller, 2 drives and 2 motors package. Their drives will take 18-80VDC.
For power supply I do already have a 24V 100A, 36V 50A, and a 48V 50A regulated power supplies that will hold those amp outputs all day.
 
Flyinfool said:
I spent all of yesterday and most of today so far researching Steppers drivers and controllers. There are so many options that it makes my poor little brain spin.

I did find a lot of Audrino solutions, but I am worse that terrible at programming. The closest that I come to programing is playing around a bit with LISP to create functions in AutoCAD.

Now don't this look like just what the Dr ordered? 7500 Rupee is equal to USA ~$106.74
www.tinycontrols.com

2-Axis Surface Grinder Controller

Specifications 20x4 alphanumeric LCD 16 bit controller Two Opto-isolated pulse Inputs Easy to use Menus
www.tinycontrols.com www.tinycontrols.com

I just need to add the motors, drivers and power supply, which are also available from the same place as a matched set. Then make a bunch of brackets and pulleys to fit it all together.

I have a digital torque meter that I borrowed from work, this weekend I will see if I can hook it to the the SG to measure just how much torque it takes to move things, so that I have an idea of just how much stepper motor I need for each axis. In the x my biggest concern is the starting and direction reversing for the x axis. the table moves asy enough that just the weight of the handle on the crank will always move the table while the handle drops to the bottom of rotation.
Click to expand...


Your previous posts had me curious about what is available for stepper controllers these days. That certainly looks like the PERFECT controller for what you want to do! I came across quite a few stepper controllers just looking around to satisfy my curiosity... I think that is the first one that I have seen in the ~$100 and under area that actually HAS A MANUAL YOU CAN DOWNLOAD. Looking at the manual it looks like that controller was made almost specifically for what you want to do.

For your application a toothed belt between the stepper and table handle shaft might be a consideration. It would allow you to gear up to get some mechanical advantage.

P.S. I didn't even see the "2 Axis Surface Grinder Controller" title until now... it was designed to do exactly what you want to do!
 
I was thinking that I would have to use a belt drive for both axis so that I can keep the handles. I do not want to give up the manual option for those quickie jobs. That is the ONLY, SG specific controller that I have seen anywhere in my 2 days of looking. In India they are all in bed right now. I hope that by tomorrow they will answer my email and let me know if it is just out of stock and when it might be back in stock, or if it has been discontinued and gone forever.

If discontinued, I may see if I can buy the design and make my own. I have done that a couple times with discontinued products that I want. I once bought an injection mold for a discontinued item for the scrap value of the mold, $15. I found a local molder that needed some fill in work that would set it up and run me 50 parts for not much more than the product originally cost. I was able to sell enough of the parts to at least break even on the whole deal.
 
I look forwards to hearing the outcome! Hopefully they have one on the back bench somewhere that they can sell you.
 
As close as I can guess at the moment, is that it will be under $400 for all of the electronics parts for 2 axis (using their biggest motors and drivers) if I get it all from the same place. Getting it all from the same place kind of insures that it will all play together and all the connectors will match. I know I can source the drivers and motors for less but then have to mess with getting it all to work together.

I am still sore from the last stint on the grinder spinning the wheel back and forth for 2 straight days. I will also raise the whole machine up about 3.5 inches so I do not have to be bent over as much while working on it. But as long as the sore back persists it will keep me motivated to automate.

If this all works out I will try to do a build thread. I am not good at build threads, I get on a roll and forget to take pics along the way.
 
Something to be aware of. If you manually move the motor using he handwheels through the belt, it generates EMF that can damage some controllers. A friend of mine bought a CNC converted mill, and he can't use handwheels at all because of this.
 
I had not thought about that but I can fully agree. I will have to be sure that I have some form of protection in place.
 
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