Tailstock DRO for a Sherline Lathe.

I decided that a tailstock DRO would be useful on my Sherline Lathe. It turned out to quite easy to do and quite cheap.

I based the tailstock DRO on a 6-inch digital caliper. I made some cuts on the caliper with a cutoff saw. See figure 1. The two holes in the prongs are #33, which is the body brill for 4-40 screws.

Figure 1: modified 6-inch digital caliper

I then made a small bracket to mount the caliper on the tailstock. See figure 2.

Figure 2: bracket

I made the bracket out of 3/32 aluminum sheet but 1/16 would work just as well since the bracket is not the subject to much stress. The part of the bracket on the right with two holes will get bolted to the back of the Sherline headstock. The holes are #28 which is the body drill for 6-32 screws. The hole on the left part is #33, which is the body drill for a 4-40 screw. A 4-40 screw will pass through this hole and through a #33 hole in the right prong on the caliper shown in figure 1. The angle of the bend is to let the caliper lay back so it is easier to see, you should pick an angle that works for you.

I then drilled and tapped two 6-32 holes in the back of the Sherline tailstock. See figure 3.

Figure 3: Sherline tailstock with tapped holes for bracket.

The DRO works by fixing the body of the caliper to the tailstock and fixing the slider of the caliper to the front of the tailstock’s spindle. The front ¼ of an inch of the spindle can be used for a bracket since it does not not interfere with the function which ejects things that have been put into the MT0 taper in the spindle.

I first mounted the bracket to the tailstock with two 3/8” 6-32 round head screws with lock washers. I then manually lined up the fixed caliper prong with the bracket to figure out where to drill a hole in the bracket and a matching one in the prong. After drilling the holes, I bolted the caliper to the bracket with a 3/8” long 6-32 round head screw, lock washer and nut. I used a single screw to hold the caliper to the bracket so that the system would have some flexibility if the position of the caliper was a little bit off.

I made a ¼” thick disk out of a piece of 1 ¼” diameter aluminum bar that I had around. The disk has a hole in the center that fits tightly over the tailstock spindle. I put the disk onto the tailstock spindle and put some layout fluid on the disk so that lines would show up. I then scribed the side of the caliper’s sliding prong so that I would know where to shape the disk so that the prong would fit against it. See figure 4.

Figure 4: disk marked showing the edge of the caliper prong

I cut off the side of the disk with a band saw & a disk sander. I then mounted the disk on the tailstock and lined up the caliper prong to figure out where best to put the hole for fastening the prong to the disk. After figuring that out and drilling a #33 hole in the prong I reinstalled the caliper and used the hole to mark where the matching hole needed to be drilled in the disk and then drilled and tapped the disk.

I then drilled and tapped a 4-40 hole for a set screw to hold the disk to the tailstock spindle. The hole for the set screw is positioned so that the set screw goes into the slot in the tailstock spindle. Then I shaped the disk with the band saw and sander to make it look better.

I put the disk back on the tailstock spindle and bolted the sliding prong onto the disk using a 3/8” 4-40 screw and lock washer. Then I screwed a 4-40 set screw into its hole to secure the disk to the spindle. Then I put the tailstock back on the lathe.

Figure 5 shows whole thing put together and mounted on the lathe.

Figure 5: Tailstock DRO mounted on the lathe showing the shaped disk

Figure 6 is another view of the DRO.

Figure 6: DRO mounted on lathe

2024-09-05