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Jerry Glickstein's Tool Holder (Adapter)

I prefer to have my toolbit right side up, 
and at the front of the work, so I can see what I am doing. 
So, I took a piece of aluminum 3/4" (.750") by 1 1/4" (1.250" Square).
Set the piece up in a vise,  so that you can cut a close fitting slot of .250" 
wide" by .250" deep, across what will be the front of the adapter.  This slot 
has to be located so that .625" is left at the top of the adapter. The side 
view in the photo make this very clear.

Now turn the piece over so that the .250" slot is facing away from the front 
jaw of the vise, and nearest the movable jaw.  Mill a tongue that will be a 
close fit for the slot at the front of the Compound Slide.  This tongue has to 
be .312" wide by .281" high.

It has to be located .312" from the top of the adapter, and leave .625" at the 
bottom.

Now, put the adapter in the vise so that the .250 slot is against the solid jaw, 
and the top of the adapter is facing forward. Use the front of the adapter, and 
pick up (locate) the edge. Move in .125".

Now, pick up (locate) the left end of the adapter, and move in .187".  At this 
location Y = .125" and X = .187", Center drill, drill, and tap through to the 
.250" slot.

Stay at the Y dimension, and move the milling  table .875" along the X axis.
Center drill, drill and tap through to the .250" slot. You are going to drill 
and tap for 8-32 Allen Socket Head Cap Screws by 3/4" long.  The recommended 
tap drill size for aluminum is a # 30 drill ( .1285" diameter) for 75% thread,
or a # 29 drill ( .136" diameter ) for 70% thread.
Deburr the adapter, and you are in business.*
 
*Note, it is important that the top of the .250" slot coincides with the bottom 
of the tongue milled on the opposite side of the Adapter. Why? In order to get 
optimum use of the toolbit,the cutting edge has to be on center of the lathe, 
or not more than .003" to .005" below the lathe center.   Then, the clearance 
angles (rake) ground into the toolbit will be correct. Anything more or less will 
cause the toolbit to "dig in"(more),  or "heel and rub" (less), instead of cutting 
correctly.