I recently put a used Mitutoyo DRO on my Bridgeport and thought I'd post a few picks of the install. Before I got the mill, it had this exact model of DRO on it, so the holes for the Y axis were already there, which was convenient. I am at a loss as to how they had the X scale mounted though, since there were no holes drilled on the back side of the table (maybe they had it mounted on the front t-slot ).

Anyway the first order of business was drilling and tapping two holes to mount the reader head on the saddle. They needed to be 1/4-20, 1.125" apart, and .750" down from the bottom of the table. I thought about using the right angle head, but the saddle doesn't move in the x axis, so there would be no easy way of getting the 1.125" spacing. So I decided to mount my bench top drill press to the table and let it do the drilling. I measured the distance from the spindle center line to the post of the drill press, then subtracted the thickness of the mill table and the .750" measurement (how far down the holes needed to be from the table) and found I needed to elevate the drill press .588" from the table. I proceeded to make two blocks with a radius matching the diameter of the drill press post that would elevate it the needed .588".

The first pic is showing the setting of the radius on the boring head. The adjustable parallel is set at the diameter of the drill press post. The fixed jaw is found with an edge finder and the table is moved so the spindle center line is at the center of that measurement. Then the boring head is adjusted (about as far out as it could go actually) until the cutting edge catches a piece of paper against the fixed jaw.

The thickness of the paper is accounted for and the radius is machined on both pieces until the correct thickness was reached (measured with a tubing micrometer).

Then the drill press is clamped down lightly, indicated in, and tightened the rest of the way so the holes could be drilled. I had to remove the belt guard from the drill press to make it clear the mill ways, and also had to take off the table and base. These are easily the two most labor intensive holes I have ever drilled.

Continued in the next post...

Anyway the first order of business was drilling and tapping two holes to mount the reader head on the saddle. They needed to be 1/4-20, 1.125" apart, and .750" down from the bottom of the table. I thought about using the right angle head, but the saddle doesn't move in the x axis, so there would be no easy way of getting the 1.125" spacing. So I decided to mount my bench top drill press to the table and let it do the drilling. I measured the distance from the spindle center line to the post of the drill press, then subtracted the thickness of the mill table and the .750" measurement (how far down the holes needed to be from the table) and found I needed to elevate the drill press .588" from the table. I proceeded to make two blocks with a radius matching the diameter of the drill press post that would elevate it the needed .588".

The first pic is showing the setting of the radius on the boring head. The adjustable parallel is set at the diameter of the drill press post. The fixed jaw is found with an edge finder and the table is moved so the spindle center line is at the center of that measurement. Then the boring head is adjusted (about as far out as it could go actually) until the cutting edge catches a piece of paper against the fixed jaw.

The thickness of the paper is accounted for and the radius is machined on both pieces until the correct thickness was reached (measured with a tubing micrometer).

Then the drill press is clamped down lightly, indicated in, and tightened the rest of the way so the holes could be drilled. I had to remove the belt guard from the drill press to make it clear the mill ways, and also had to take off the table and base. These are easily the two most labor intensive holes I have ever drilled.

Continued in the next post...

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