Posted by Douglas Johnston on 25/06/2016 10:56:04:
When I got my original toolholders I got fed up with the mess the screws were making on the top of my homemade carbide insert tools, which were not hardened. I inserted brass pads into the ends of the screws and this made all the difference.
I was taught to use a packing strip on top of a tool bit to spread the load of the screws.With the T00 holders the screws are usually Allen type which are tough rather than hard but on larger sizes and with old style 4 way tool posts the screws were probably left pretty hard to minimise wear to the square head and mushroom effect on the tips. I do not like to see screw marks on boring bars or tip holders and it is little trouble to keep some strips to take the marks rather than the tooling. With solid HSS tools they do not mark easily but to spread the contact area is probably good on small bits to avoid the possibility of fracture.
Mike