Re: Questions?
paul womack
>They don't work in any arbitrary hole, and in fact, installing the collar is a pain in the neck - they require three different diameters for different parts of the hole, and the cost of the hole saws I had to buy for these large holes was as much as one of the holdfasts
Well, that's what you get for straying from the one true path.
When I installed my collars, I ran a 1/8 long series (twist) bit through the bench with a Millers Falls breast drill. I then used a washer cutter in a 14" sweep brace to cut and delineate the outer collar recess, which (from memory) is around 3" OD, and 1/4" deep. I used chisels followed by a #71 router to level this recess.
I made the next hole (1 1/4" IIRC) with a blacksmith made centre bit, in a 12" sweep brace.
Finally I made the (1" IIRC) through hole with a 1" Jennings auger in a 10" sweep brace.
More tools!
BugBear
Note to others; when using twists bit you may make a series of holes in any sequence; a small twist bit will self-centre in a large hole, and a large twist bit will enlarge a small hole.
But when using piloted bits you must drill the large holes first, so that each successively narrow bit has some material to hold the pilot.