Martin,

Not the best design as it pushes so it's only relying on the two dovetail faces.

If you want to keep it simple, scrap the two push screws in the post and fit two screws in the holder one above the other.

Drill and tap them in the face just above the OL in holder, this way it will grip on 4 faces and pull back in to the dovetail.

A better design would be to reverse the dovetails, dril the same toe screw holes as above but now drill them into the post and fits a gib strip for the screws to push on.

Advantage of this is only two hles to drill and tap instaed of in every holder and the holders wil be easier to make given that they are open dovetails which means you can use angles side and face milling cutters instaed of fraginle dovetail cutters.

Edited By John Stevenson on 15/09/2012 23:43:18

You just home from the pub John ??

Having just made a QCTP, I wondered about this too.

The contact area of the dovetails is 0.625 square inches. Add the area of the piston (on my design) and the area is about 0.95 square inches.

The contact area of a typical 2" long 5/16" HSS tool is 0.625 square inches. The contact area of the clamp screws is less than that of the piston.

So perhaps anything that further increases the contact area is over-engineering?

Neil

Sverre,

Thanks for re-posting those links

The design looks very promising; and that write-up about building it is exemplary.

Definitely one to remember !!

MichaelG.