I though it benefiial to write a little foreword on this topic. The process looks relatively easy based on the photos and the video I have posted of the process. After the clamping and now comparing two sides against each other, there was a little more work to do than first indicated, but that being said, compared to rough cut or un-square stone. I was starting in a very good place.I purchased a 600mm Digital Height Gauge for a bargain as an Ex-Display Model. There wasn't a mark on it, and it came with a refreshed calibration certificate and full warranty. Expect to need something like this if you take on a build of this size. I haven't had to purchase many tools along the way for this build, but the ones I have, have needed to be pretty specialist, and thus not cheap. You need to budget for things like this if you don't own already. Obviously, with all the granite dust that was about to be around, I wouldn't be borrowing EMG Precisions from the Inspection Lab. I also figured it would come in highly useful for pre-setting X Axis rail heights on the gantry from directly off the surface plate.

OK, back to my original point. This process of grinding and measuring is extremely labourius. The granite dust gets absolutely everywhere! I mean everywhere! If your not a mile away from your house, expect the missus to complain about granite dust everywhere. Oh yes, Budget for flowers and fine dining and weekends away if you take on a project like this. Now there is only one principle way in which you can do this manually, and that is to measure, grind a bit away, do a full clean down and measure again. If you are not cleaning up very effectively between grinds, then don't expect to trust the results your height gauge is telling you. Expect to repeat this process anywhere from 10 times if you're lucky, to hundreds of times if you accidentally grind a little too deep. lol. Good luck. I will try to document how I found the process to work best. The key thing you should note here though is that I was able to take these measurements directly off a grade A surface plate. Obviously that has its own tolerances and isn't perfectly flat, but for this excercise it is more than enough to out perform the accuracy of the height gauge i was using. I would make future adjustments manually with sharpening stones and a 1 micron DTI. If you have quite literally been grave robbing for some granite that might be a bit wonky or worn down in places, you will have to find another way to measure the accuracy of your Y heights.

I have been hunting for photos of how I mounted the bench drill for grinding the granite, but I must not have taken one. I will have to rebuild the setup and photograph it to show you how i did it. It wasn't particularly completed though. I used the heavy 300x300mm square cast iron surface plate that i bought as a base. I then unbolted the Bench drill from its base and rebolted it to a flat piece of metal plate. I then sat this on top of the iron surface plate and simply clamped the two elements together with G clamps.

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