Dottie wrote:
....

... How do we make a "collar" so
that after we drill the first hole and get it right, we can put on the
collar and do the other holes uniform size?

http://www.rockler.com/product.cfm?page=10617

Is one style of purchasable ones -- actually one of the nicer as they
clamp on the overall bit diameter, not like some that have just a set
screw that sets on the bit itself...these, you see, are made for a range
of bit sizes.

To make your own, two basic choices --

1. Drill hole in a block or the right size or slightly larger and
adjust the bit in the chuck in combination w/ the wood thickness to get
the right depth. Rarely is the depth so critical as that closer than
1/8-th or 1/16-th at most is required for accuracy and lots of times not
even that -- all you normally require is to not blast through some piece
so anything that prevents that is "good enough"...

2. Use a little more effort in the construction and model them after
those in the link -- add a lock screw to one by drilling through from
the side. Doesn't take much to hold in place and it's easy enough to
thread a block of wood using a bolt or screw and in side grain w/ a
piece of hardwood it'll hold quite a bit.

Normally, unless there's a real problem in seeing what I'm doing I'll
take the simple expedient of a piece of masking or electrical tape
around the bit at the right place and just wing it -- again, it's rare
the depth has to be exact to much precision...certainly from something
you've described can't imagine it would matter much at all.

HTH...

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