Converting manual hydraulic cylindrical grinder to CNC

fmari --MariTool- · Mar 16, 2017

Tschudin grinder. Great machine but I want it to be easier to run. I want to convert it to 2 axis cnc. One servo for infeed another for the table cross slide. Also I would hook up some relays to control a drop down dresser to handle the dressing and simple macro program to apply offset comp once it does dress. I have a quote from MachMotion in Newburg, MO. Has anyone worked with them?

They quoted the controller, 2 pcs 1kw servo motors, Macro B parametric gcode capability, 17 inch monitor, pc, industrial keyboard, variable speed controller, 8 relays ( for coolant, workhead, air cylinders), and nice control cabinet. I just need to make some motor mounts and mount for the controller box.

Someone else on this forum mentioned that they converted there grinders to CNC by themselves. I hope he reads this and can share some advice. What controller, servo or stepper? etc etc.

It doesnt look like rocket science but I wonder if I am forgetting something. I dont want to spend roughly 15,000 and not have a working machine.

ewlsey · Mar 16, 2017

Why not spend the $15,000 on a used CNC grinder? I think you'll be much happier. They won't even use Mach on a Tormach anymore.

fmari --MariTool- · Mar 16, 2017

It will be Mach4, which I think is a big step up from Mach3. Any feedback on that would be appreciated.
I can't get into too much detail but even a standard CNC grinder would not have this capaibility that I want to put on this machine. I have a CNC grinder already. Toyoda Select G100. Plus I have 2 indentical Tschudin cylindrical grinders. So if this works I will do the 2nd one in the future.

Ziggy2 · Mar 16, 2017

Actually, this is probably one of the few applications that Mach will do really well in that none of the axis motions are actually continuous.

Being that you need to build a custom application, this is probably your best bet.
I would not be saying that if you were attempting to upgrade a three axis machine with Mach but grinder requirements are a lot different than what a VMC needs.

Milland · Mar 16, 2017

I didn't see anything about ball screws and thrust bearing mounts. Is that included in the conversion? Will you have any issues with keeping the screws clean and lubed?

I have a Brown and Sharpe 1020U that I hope to covert to CNC, will follow your progress with interest if you post about it.

fmari --MariTool- · Mar 16, 2017

Servo's will be attached to the handles by a small timing belt. I am thinking by a 3 to 1 ratio. So I can have some really fine resolution on the infeed. I will not be converting anything to ball screws. Infeed backlash does not matter. Just as long as the final infeed position is accurate ( final grinding diameter). Side table is gear and pinion. Any backlash or inaccuarcy I am not too worried. I will be tilting the table if I want any angled diameters so interpolation accuracy between slide and infeed is not critical.

Milland · Mar 16, 2017

Gotcha. I am hoping to control both axis using ball screws, angle dressing the wheels to match a taper. I may decide to bag that if I don't feel I've got enough good enough stick-slip or way accuracy.

fmari --MariTool- · Mar 17, 2017

That adds to complexity I am sure. In my situation I am not even concerned if 1.0 inch in the program equals to a true 1.0 Inch of movement of the wheel head. As long as its final end point is consistent part is good. Currently machine is very accurate, I can't imagine turning it to cnc will make it any less.

CarbideBob · Mar 17, 2017

I do it a lot. 2,3,4,5 up to 8 axis grinders.
Yes your idea will work.
I use Galil and Delta-Tau controllers and write my own software, you probably don't want to go this route as the cnc control side of mine is over 40,000 lines of custom written code.
I've seen it done with standard Fanuc and Siemens controllers.
You can also do it with a small PLC from someone like automationdirect but you need to think about the user interface and what you want on this end.
The timing belt method has some cyclical errors that affect doing say cam profile grinding but works fine for standard grinding and angle dressing.

One can write your part programs to approach from the same direction or back out and move during a size adjust just as you would do when manually grinding.
Some use steppers, I much prefer servos.
Sizing servo motors is a bit more complicated to avoid overshoot or hunting.
Bob

fmari --MariTool- · Mar 17, 2017

Bingo,
CarbideBob you are the person I remember a while ago posting about this. Thanks! Can you post some more info? What would you recommend for a simple 2 axis application. I do not macro programming. And I agree I would like to stay with Servo, unless you think stepper can still do the job.

fmari --MariTool- · Mar 18, 2017

CarbideBob,
your inbox is full. I am hoping to get some more info from you. Thanks.

priitm · Mar 18, 2017

Ziggy2 said:
Actually, this is probably one of the few applications that Mach will do really well in that none of the axis motions are actually continuous.

Can you explain more ?

Toms Wheels · Mar 21, 2017

I have done a conversion on my surface grinder. In this case 2 standalone Compumotor Stepper units were used, one downfeed the other crossfeed. The longitudinal axis remained Hydraulic. The question is do you want to automate the x/y movements, or be able to grind a complex profile like a cam, or a radius feature. If the first a low end do it yourself would work. The later, you need Pro, and ballscrews, and the like. Position control is then very important.

To do the X/Y, Steppers would work fine, and generally cost less than servo's. The writing of the software on a DIY project can be time killer. I spend 2 weeks learning and writing to program for the Grinder, and I continue to tweak it still. I had never written machine language before so it was a big step.A basic program as was used for the grinder is only a hundred plus lines. But all that is to control the amount of each step, and the downfeed.

fmari --MariTool- · Mar 22, 2017

I do not need any critical interpolation between the wheel head infeed and cross slide. Pretty much just side to side with certain infeeds in between and dwells at each corner and then a spark out pass.

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