Drill Press Depth Stop

[dgbreggin]

I saw a clever drill press depth stop recently in this HomeMadeTools topic: Drill press lock and stop nut - GIF

I really liked it, so I decided to make one for my drill press.

I selected brass for this project because of the weight (a heavy disk would spin easily) and ease of machining. I had some 1" diameter stock on hand. For the keeper pin I selected a 1/8" diameter roll pin.

I made the lower disk first. Using the lathe, I drilled and tapped the center hole and chamfered the outside edges. Then it took it to the mill and drilled the keeper holes using the DRO's bolt circle function. Holes are slightly larger than the roll pin, of course. Then I used a mandril to hold the disk on the lathe and knurl the outside.

I puzzled for some time about how to make the "D" shaped hole in the upper disk (I don't have a broach). Typically, this might done with small hole and a lot of filing, or a full-size hole and some welding and filing. I decided to try a different approach. I cut and reamed the full-size hole on the lathe. On the mill, I drilled a single hole sized for the roll pin and aligned with the lower disk hole circle. I removed the disk from the mill, placed it over the drill press threaded post, and used a straightedge along the flat of the post to scribe a line. Then I cut off part of the disk along the scribed line. I rough cut it on the band saw, then used the mill to finish the cut smooth and even. I made a strap to size from 1/4" flat strap and fastened it in place with a pair of #6 SHCS. Finally, I pressed the roll pin into the hole in the upper disk.

It works very well. The threaded post on my drill press is 1/2-20. I cut 10 holes in the lower disk, so each hole provides 0.005" depth adjustment -- much more accuracy than my drill press requires but makes it easy to engage the pin at the appropriate depth.

A few things I might do differently "next time". First, I might select 1-1/4" diameter stock. It would spin more easily, and the hole spacing would be a bit wider. Second, when I cut the flat off the upper disk, I cut slightly too much off and the disk would not slide easily on the post. I fixed this by milling a small amount off the inside center area of the strap until I got the fit I wanted. Third, the hole for the roll pin is very close to the hole for one of the screws holding the strap in place. I would probably move the pin a little further away from the flat. Finally, I had originally intended to counterbore for the heads of the 2 screws holding the strap to the upper disk. Using the 1" diameter stock, the strap was not long enough to allow counterboring. I could have switched to thinner material for the strap. Alternatively, larger diameter stock for the disks might have made the strap enough longer to allow for the counterboring.