I've got a Delta 12" drill press (11-990) with a min speed of 620 rpm.
I've got a 3 1/2" hole saw that I want to use in the drill press, but
it's max speed is 140 rpm. I've called Delta and they don't have any
other pulley arrangements that would reduce the speed. I've looked at
a router electronic speed control but the info says they work only
with motors with brushes - my drill press is a 1/3 hp induction motor
without brushes. I don't want to do this job (many holes) using a hand
drill - am I just up the creek?
Any suggestions would be greatly appreciated - thanks in advance.
I've looked at the pulley sets, and the one over the motor looks like
can be removed and another pulley put in it's place, but it's the
and it doesn't look like a much smaller one could be found. The other
pulley set (above the chuck) looks like it is fixed.
Concerning the depth of hole, I'll be drilling hard maple or baltic
1/2" thick. I'm working on making a wine cabinet and using maple or
slats with half moons removed to cradle the wine bottles. I had
make the half moons by drilling 3 1/2" holes in the 1/2" pieces and
cutting them down the center.
Yes, that has crossed my mind, but the hole saw would be
so much quicker. What do think about really securing a setup
to the table of the drill press into which I can fit the piece to
be drilled - how dangerous is operating the hole saw at 620 rpm?
thanks for your help
I generally run hole saws up to 6" at 480 rpm with no problem. I would
think that a 3.5 at 620 would be all right. Just take it easy and lift
the saw out of the piece now and then. Keep an eye out for burn marks
and ease up if they appear.
Assuming that you don't have a fence, bolt a piece of plywood to the
metal table and clamp a straight board to that at the appropriate
distance from the center of the chuck. You can also clamp a stop block
at the proper distance. That an some hand pressure should do the trick.
You will never get it centered to get 2 equal pieces.
One piece will always be a tad bigger than the other.
My guess is that existing motor is a 4 pole or 1,800 RPM base speed.
You could replace with a 6 pole or 1,200 RPM motor but that still
leaves a 3-1/2" hole saw operating at 400 RPM which is just plain
You could engineer a belt drive reduction ratio and remove the motor
to drive it which in turn drives the D/P quill, but pillow blocks,
sheaves, belts and a suitable structure aren't free.
Morris has given you the fastest and lowest cost solution.
Make a template and cut ONLY half moon cuts.
1) Faster than any hole saw. BTDT.
2) Every piece will be identical.
3) Eliminates table saw operation.
4) Cost will be minimal compared to other methods.
Cutting lots of holes with a hole saw in a drill press is a TOTAL PITA
As Leon suggests, probably time for a drill press upgrade.
Update: Some more thoughts.
"Lew Hodgett" wrote:
If you have a saber saw along with that router, you could really
Make two (2) templates, one using posterboard that would allow you to
mark a saw cut line maybe 1/4" proud with a pencil for the saber saw
and another using 1/4" Plywood for the finish router cut.
Make a simple clamping fixture that will position the part and the
template(s) while being held place with a couple of toggle clamps.
Probably trace saw cut line on maybe 100 pieces in less than 30
Regardless of where you cut a circle you will not end up with a full circle.
A full half circle for a wine bottle is not necessary. 99.5% of a full half
circle will work equally as well.
The solution for a full half circle is going way way past wasting time for
an unnecessary step and will be unnoticeable.
Not if you don't try to reinvent the wheel.
As stated in a previous post, cut a half circle with a router and a
template and the T/S goes away.
You also eliminate the necesssity of cleaning up saw cut surfaces.
Whether a full half circle is necessary is academic.
Trying to do this job with a hole saw is another kettle of fish IMHO.
Understatement Of The Week goes to...........
Those hole-saws are CRUDE! I have bought the best, cheapest, staggered
teeth, bi-metal, Swiss-made custom ground...... no matter. Drill-press
or not.. they do not leave a finished hole. A router, properly used
with proper bit, does leave a very nice hole...if it isn't too small.
I don't understand "if it isn't too small" - what's "it"?
I routinely cut large holes with small bits. For fun, I uploaded a
drawing showing the toolpath for a (large) blind hole "drilled" with a
"small" bit to
You might find it interesting that the toolpath (red, starts at center
of hole) consists only of straight line moves, marked by a circle the
size of the bit at each end, and the finished hole (green) is good to
about +/- 0.001"
I'm not sure there is a "too small" :)
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