I'm drilling a fair number of 1-5/16 holes in birch at an angle of 39
degrees to normal and the drill press chuck keeps coming loose. The bit
is a new LV saw tooth bit. When the bit is entering the work there will
be some lateral load but I can't avoid this until the entire bit is in
I've cleaned the male and female surfaces of the taper so that there is
nothing on them, to the point of wiping them down with organic solvents.
Any suggestions as to how to keep the chuck in place?
For the morse taper, look for any burrs on the shank and stone them off. For
the spindle, a morse taper reamer - hard to find and expensive, but also
usually not required. There are morse taper cleaners, a plastic device like
That often clears things up for me.
Same rules apply to a jacobs taper, however I've not seen a jacob's taper
Angle drilling or for that matter, any side loading can and will eventually,
work a Morse Taper loose.
However, a resetting (slight blow from a brass hammer) after each initial
angle is cut should help to keep the chuck and bit from flying off into
You might also check that the tang is not bottoming out. Some of the import
DP are notorious for short spindle holes.
I'm guessing you may be talking about a Jacobs taper instead. Female taper on
chuck / male on spindle?
Make sure the mating surfaces are not just clean, but free from burrs. Then
you can seat the chuck by hitting it with a mallet (with the jaws fully
retracted), or pressing it with a wood block.
If you heat the chuck to 200 degrees or so before seating, it will shrink onto
the spindle and grip a bit tighter.
In the end, though, you may always have problems. Tapers were not meant for
why not trying to make a jig so that side load is minimized .
Bore a 1-5/16" hole in a piece of say 1" board then cut the base of the
board at 39 degrees.
clamp the board to the work at the prescribed positionand bore the hole .
The jig should take the side load off of the taper also can be used as a
guide to position the hole......mjh
"RB" < email@example.com> wrote in message
as a work around try this:
take a block of something slippery. it could be umhw, delrin, lignum
vitae, maple soaked in motor oil.... whatever. drill the hole in it at
90 degrees. either drill it with the bit hanging over the edge or cut
through the hole after drilling it. in any case, you want to end up
with enough solid material on the non half of a hole end to hold on
to. now, when you go to start your angled hole, use the gizmo you just
made to apply a balancing load to the bit- pushing in from the side.
you'll probably only need it for a moment at the start of the cut.
be very careful doing this.
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