Thread: Saw bolt countebores.

Up till now I have been using the smaller pilot counterbore to seat my saw bolts. left of photo above. It does a very fine job but there is one frustrating draw back when using it.
Because the correct depth is governed by the base of the depth collar making contact with the handle surface, wood fibres quickly get trapped between the inner sleeve of this collar and the drill spirals. So much so that after boring 1 of the seats for the saw bolts, the drill bit needs to be removed from the chuck and the wood fibres cleared out, before refitting it within the pedestal drill chuck to continue on. Earlier correspondence with Isaac Smith he pointed out that the solution was to use a spacer plate with the pilot counterbore as this would negate the need for the base of the depth collar to make contact with the surface of the handle at full depth.

There was no problem making up a spacer plate, but the smaller pilot counterbore would not be a suitable option.

The solution was to use the longer length pilot counterbore seen right of photo above . After an initial trial, I ended up modifying it by removing an inch of the split shank at the top of the drill bit, as well as reseating the grub screw so it would be flush to the outer dia. These changes would facilitate an easier fit within the pedestal drill chuck.

The spacer plate I made using 1/4" thick brass. The hole drilled has clearance of 2mm over and above the 1/2'' dia. of the counterbore. The plate size is 75mmL x 63mmW.

photo's.







Stewie;