Were used all the time in the old days by the radial arm drillers ,the the bar which had a blind slot in it was put through the hole then the spotface cutter was inserted in the slot.

Hi Paul

Or silver solder and grind a tip on a mild steel shank to do the undercut and using an adjustable boring bar holder wind it out while it is starionary to the correct diameter then feed it back against the rear of the work while moving, I would back it up very slowly. (Some quite expensive boring bar holders will wind out automatically) but the manual version will work fine. Handy for a lot of boring jobs

Like the photo below

**LINK**

Cheers

John

Edited By John McNamara on 10/03/2013 11:22:48

I have one, the cutting head is loose and held on with a pin, it can be used normally, or the head turned over, and the shaft passed through the hole. Ian S C

Paul,
If you make one don't forget that if you are driving the shank clockwise the cutter facing the work is rotating anticlockwise.

Les.

The cutter was picked up at an auction at the railways workshop back in the mid 1980s when the government sold off the lot, I think it was made at the workshops, it appears to be HSS, 5/8" diax 1/2" thick, there are 8 teeth(I think, not going out to look at this time of night), and going by Arnold Thorp in his book "Vertical Milling in the Home Workshop" (Workshop practice series no., 2), I would suggest that you do not be too accurate indexing the tooth spacing, irregular spacing reduces the effect of chatter, you want the spot face chatter free. Ian S C