Here's the project:

We needed to refurbish a lapping machine table. It's approx 48" We needed to slot the table with a checkerboard .125 wide and .125 deep for the lapping compound on 1" centers. I don't know what the table was made of but I do know it was cast iron and it was tough stuff. I couldn't get a carbide endmill to last more than a couple of slots at .05"DOC . I also couldn't get the stubby endmills I asked for...

The engineer and I came up with a plan to lock the spindle with a clamp. We made a split clamp that grabbed the shank of a 4" long ER collet holder. I ground the but end of a carbide end mill into a lathe style part off tool with the proper 7*cut and 22* clearance .01" past center.

The long and short of it is the boss man couldn't wrap his head around what we were doing and shut us down before we even got a chance to try it. I think it would have worked beautifully. I had to cut it using endmills, Took almost 2 weeks. And I got yelled at because it took too long...

Side note: The machine in question is junk. I managed to stall the spindle with a 3" shell mill .04" deep in mild steel with fresh inserts.

My question is do you think our cnc mill turned scraper idea would have worked?

Yup, but you should just bolt the tool up to a skyhook support bracket and leave the quill and head out of the equation.

We looked, but couldn't find anything near the spindle bigger than a 1/4" to bolt anything to. What is skyhook?

You say the machine is junk. I think if you had tried your idea on a good machine you would have turned it into junk.

You planned on clamping the spindle in one postion and then using the machine something like a shaper. This would have meant that the cutting load from your tool would have been taken by stationary bearings in the spindle and you would have been taking many cuts. It is almost certain you would have false brinelled the bearings because you would have been applying a repetitive load in the same direction to a stationary bearing.

You couldn't have fixtured it vertically and used a slitting saw?

If it was a chilled iron casting, you'd probably be stuck resharpening your tool often, no matter what.

You could have made a split clamp that went around the nosepiece of the spindle cartridge. That way, you'd not have been brinelling the spindle bearings.

I'd question the necessity to have square grooves. I'd think V grooves would probably work just as well. You could mill those with the corner of a decent size tool held in an angle milling head. Maybe even get some Greenleaf WG300 inserts that would cut that shit.

We had to lathe turn some chilled iron feed mill rolls one time in prep for regrooving. We did not make any headway until we discovered the WG300 inserts. We used a 1/2 round one. The roll was 12" diameter, 30 inches long. We set the feed at about .03" per rev, and 1600 sfm and let 'er rip. We stood in a shower storm of cast iron We didn't realize the roll was tapered significantly until we heard the spindle loading up as the cut got deeper. The overloads tripped out on 25 hp about 3" from the end.

My gawd, those were some insert!

I agree I would never submit a real machine to this brand of torture. As for the machine in question. By hand I can get .002" out of the spindle and .01" from the Y axis

This machine has done it's time grinding quartz I don't think I could hurt it...

Which makes your Boss' intervention that much more ridiculous, I think your scraper idea would have worked at least for the first set of slots; the interrmittent cut on the cross slots would probaly have killed tools in short order. Maybe strapping an angle grinder to the spindle with a thin cut-off blade would have worked.