[peter.blais]

Hi guys.

I have the need for a very specialized grinder- one which will rotate a workpiece against a grinding wheel, which will move in and out to grind a profile on the rotating work piece.

Anyways- I've considered converting a surface grinder, and several other things, but i'm sort of thinking of just building from scratch.

Speed is not a concern, just accuracy and surface finish.

What I was thinking was-

Start off with a thick granite inspection plate. Mount the rotary to one side of that. Any ideas on what type of rotary table I need to purchase? I need something which will work with mach 3 or similar- and it needs to provide .05 or .1 degree encoder steps.

Place a well made 3 jaw chuck or expanding collet on the rotary to hold the work piece through its center bore.

Now, on the opposite side of the inspection plate- put a thick piece of granite or steel, ground to appropriate thickness. Waterjet (granite) or machine (steel) holes in this to mount good quality precision linear ways. On top of those, your grinding head (type?) would be placed.

I'd probably mount all that vertically, and provide some dust protection for the linear ways / ballscrew / encoder. Mounting it vertically does two things for me- the ballscrew will always be loaded in one direction. Two, the dust will fall away from the rails, screws, etc- rather then onto them.


Any feedback?

Does this sound like something mach 3 can control?

[peter.blais]

PS:


How about this, for a rotary table:

http://cgi.ebay.com/Tormach-8-Motori...ht_1526wt_1137

My part is only 6" diameter at most, so a larger table is a problem, not an advantage. Something 4-5" would be even better.

[rowbare]

Aren't you just describing a toolpost grinder here? The easiest thing to do would be to get a toolpost grinder and do this on a lathe. You just have to be sure to keep the grit away from the ways. There are indexing attachments for many lathes. Of course if you are planning to do a lot of this, It might be worthwhile to build a dedicated machine. Then you aren't worrying about messing up your lathe.

Since you are grinding and not generating huge forces, a stepper would provide adequate holding torque. You could get a mini lathe headstock, spindle and bearings from Little Machine shop, drive that with a stepper or servo (or a dual drive, stepper for index mode and a regular motor for continuous grinding). LMS also has toolpost grinders or you can get a good used one on eBay.

This guy built a really nice 4th axis. You might get some good ideas from his videos. I think he wrote it up on the mach forums. [nomedia="http://www.youtube.com/watch?v=295Phu8GnjE"]YouTube - 4th Axis production model. Makes same test part twice as fast![/nomedia]

It shouldn't be a problem to control this with Mach. Mach Turn might be more suitable.

bob