An update; I don't know how I managed without this for so long. My parting off is improved due to being able to more rapidly and accurately adjust the tool height, and the ease of switching over tools has really made everyday tasks much simpler. I can't say I find the extra bulk of the tool-holder noticeable, and have not noticed any reduction in rigidity.
Agreed, there's no way I'd have a lathe without a quick change toolpost. Rigidity really isn't an issue, and even if it was, it's a small price to pay for the convenience. The amount of time saved is enormous, and means you aren't tempted to just use whatever tool is currently set up, even if it's not really suitable for the job. I too have made many toolholders, some on my old Southbend lathe before I had a mill, and later on the mill as a 3D milling exercise. It's well worth the time and effort to do this. I'm currently up to 16, and a few more wouldn't go amiss.
I sourced a mixture of second hand ones and a pair of RDG ones to see what the quality is like. They seem ok, although I had to reduce the diameter of the knurled adjuster nut flange as it was too big. Also, rather annoyingly, I had to take some of the flash off before they would smoothly fit. That being done they seem fine.
_____________________________________________________________________________________ Nice, constructive feedback welcomed and ingested, if not always acted upon.
Those adjusters do seem quite variable. Even on some second hand (supposedly pukka) ones, I've had to modify. Sometimes the skirt is too big on diameter, sometimes on thickness, or the waist is too fat.
This set of dimensions might prove useful if anyone is inclined to make further tool holders. You'll note that the adjusters don't seem to be defined in these drawings. I just copied what was on the ones I already had.
I also found that the holders weren't really big enough to hold some of the Indexable tool holders that I've got, so I made that dimension bigger on the ones I made.