OK, pulled out my set - I not normally use it anymore since I made myself a QCTP some 20 years ago.
I enclose a couple of pictures of the complete arrangement:
From the bottom you have a knurled, wedge-shaped washer, then the support plate for the the bit. Then there are two options:
- for a square (5 mm x 5 mm) bit, you use the flat side of the support plate up and the kind of half-round part with the dimple on top of the bit to disstribute the pressure
- for larger round bits (up to 7.5 mm bit diameter), you can use the support plate with the groove up and again use the half-round part to distribute the pressure
- normally you would use round 4 mm (boring) bits, for which there is a special excentric holder; the holder is slotted and has a cross-hole to fit the bar with which you normally lock the the longitudinal slide; with this you can turn the excentric holder to adjust the cutting edge; to distribute the pressure from the screw, there is a special piece with a matching groove.
The knurled, wedge-shape washer mainly serves to adjust the height of the cutting edge of square toolbits and may not be needed when using the excentric holder for round bits.
To answer your specific questions:
- the support-plate has a diameter of 19.7 mm and is 4 mm thick; the groove has a radius of 3.5 mm and is 1.5 mm deep
- the knurled washer has a diameter of 20 mm and its thickness varies from 1 mm to 2 mm
- the bore in both parts is 10.8 mm, which obviously is the diameter of the toolholder
- the slot in the toolholder is 5 mm wide
- the body of the excentric toolholder has a diameter of 7 mm and diameter of the bulbous end is 11 mm, the overall length being 40 mm.
Hope this helps. Feel free to ask for more dimensions, if needed.