01-11-2022, 11:32 AM
JScott, great. You'll probably only really need 3/8" max shank for milling. The actual end mill size will probably be smaller than even that, though 3/8" is a common shank size.
Now you'll still have to retain your adapter to the spindle for milling. There may not be a way to put a retaining screw inside the adapter. You might also consider making a retaining collar to fit on the outside of the spindle and the adapter.
My drill is probably different than yours, so I have no idea what is available for gripping above the tapered end of your spindle. But if there's enough spindle exposed, then the ER adapter could have a flat put on the shank end. Then enclose the shank inside of a close fitting collar retaining it with a set screw.
If the collar is made long enough and bored at the other end to fit the spindle, perhaps you can use the same method of using a flat on the spindle and setscrew there. Your ability to do that would depend on how much length beyond the bearing the spindle protrudes. If not enough maybe you could come up with another method for that end.
Now you'll still have to retain your adapter to the spindle for milling. There may not be a way to put a retaining screw inside the adapter. You might also consider making a retaining collar to fit on the outside of the spindle and the adapter.
My drill is probably different than yours, so I have no idea what is available for gripping above the tapered end of your spindle. But if there's enough spindle exposed, then the ER adapter could have a flat put on the shank end. Then enclose the shank inside of a close fitting collar retaining it with a set screw.
If the collar is made long enough and bored at the other end to fit the spindle, perhaps you can use the same method of using a flat on the spindle and setscrew there. Your ability to do that would depend on how much length beyond the bearing the spindle protrudes. If not enough maybe you could come up with another method for that end.