I built this toolholder on the Myford ML7 that it was to be used on.

 The tool bit is 3/16"HSS.

 Don't mind the hack marks. I was getting a little over my skills at the time, and the Myford Lathe, with milling attachment, had a little give to it, when the end mill dug in and grabbed. 

 tangential_toolholder1 is a profile view, LH side Decimal inch and 64ths on the 6 inch scale shown.

  tangential_toolholder2 is the top view

   tangential_toolholder3 shows the aprox. position that the tool in the holder, is in when applied to a grinding wheel for touchups. The clamp screw must be released, and the tool tip brought up to center height after this operation.

  tangential_toolholder4 shows the holder dissasembled.

 IIRC the angle used was 15 degrees. The slot was cut with an end mill, with the part offset at 15 degrees in one axis, and at 45 degrees on the other.

 This project was carried out, without benefit of drawings or measurements. I made the clamping piece a bit long, then trimmed it to sort of  fit. Then marked out the hole, drilled and tapped. Decidedly a low tech approach. 

 The material in front of the bit itself, was artfully removed with a bench grinder, and looks it. Don't care! It works very well, thanks!

 In use, the tip gets a very small radius stoned on the nose of the tool, and the holder is placed at about 45 degrees to the axis of the lathe, so that there is a bit of releif on both edges, allowing it to both face, and turn into a 90 degree corner if 
 I did not bother to offset it, as per the commercially available tool, as I could not get my head around the angles used at that time, and I also did not bother trying to figure out what I would need to do to use it to cut threads. Other tools work well 
 Questions? I frequent Rec.crafts.metalworking, and uk.rec.modelengineering. Drop a post there and I will find it, most likely.

 Cheers
  Trevor Jones