I bought a Bay-Com "diamond" tool holder quite a while back, it uses standard 1/4" HSS bits, for an Atlas lathe and now have it in a quick change holder for a 9X19 Grizzly. As commented above it doesn't do everything but I find myself reaching for it more often than any other tool. It is expensive, but, every once and a while I just bite the bullet and spend what it costs and hope for the best. In my opinion it was money well spent.
If you do some searching for "tangential tool holder" you will find references to this type of tool. There are several "shop made" ones out there and some would probably be better than the Bay-Com, and certainly are cheaper. I have seen some that hold two bits at a time which would be very handy. I bought mine a long time ago and wasn't looking at the machine forums at that time (my loss!)
The biggest obstacle to getting one for me was deciding if it was worth the rather high price they were asking, and in retrospect, to me it was. The following are some observations on the Bay-Com holder that may help you decide:
When the tool is rotated just right the angle of the point is less than 90 so it will turn and face at the same time. This makes turning to a 90 degree shoulder a no brainer.
You can cut a new bit in half and sharpen both ends of both pieces and have four sharp cutting ends in a very short time, I find I will switch instead of working with a dull bit.
If the bit is rolled in the sharpening fixture 180 when you swap ends it puts the points on opposite corners, this lets you put two different radiuses on the points. This is very easy with a diamond stone, you round of the length of the bit so the radius stays the same everytime you sharpen it.
Sharpening it is very fast, no need to finish "just one more cut".
Essentially no skill needed for sharpening it, and very fast once the initial sharpening is done, you decide whether this is good or bad
The angles generated will cut most materials pretty good, not as good as a purpose sharpened bit, but for most things, good enough.
If you have a wreck and hit the chuck jaws or overrun a cut (this has NEVER happened to me
) it will generally force the bit down in the holder and cause less damage.
Some of the cons:
It is designed to cut towards the chuck, you can sometimes get it adjusted to cut towards the tailstock but it is not designed for that. Really depends on how long your workpiece is. This would be a consideration if deciding to make one (make a left and a right, or one that holds two bits).
It can be set to turn and face at the same setting but does a slightly better job if you rotate it so the cutting edge is at right angles to the cut, it just depends on what you are trying to do, some times I move it and sometimes I don't.
The cutting angles provided are not perfect for all materials, like all all things where "one size fits all" it doesn't fit anybody perfect. I do "flatten" the top of the point when cutting brass but that is by hand, the sharpener fixture does not do that automatically.
It is not suitable for making form tools. (other than radiusing the point)
In my opinion, I use it all the time and if it disappeared today, I would fork out the cash and order one tomorrow. it is a very convenient general purpose tool and I like it very much. I realize this is kinda long, so I hope it is worth reading.
Thx
MikeR C