View Full Version : How to mark and drill?
Tom Bender
12-11-2023, 7:52 PM
I need to drill a hole in the center of the edge of a board about 1/2" thick. Looking for a shop made solution. The challenges:
Measuring and marking within a few thou'
Hard spots in the grain push the center punch off the mark - It's oak
Hard spots push the drill bit off the punch mark
Drill press tends to flex just enough to throw off a clamped setup, especially with a wide board
Not so easy to clamp a drilling guide to the workpiece
Cameron Wood
12-11-2023, 9:31 PM
Drill a hole in a guide block, & clamp to the workpiece.
andy bessette
12-11-2023, 11:04 PM
Self-centering doweling jigs are made just for this. I've had mine for many decades.
Jim Koepke
12-12-2023, 12:47 AM
I need to drill a hole in the center of the edge of a board about 1/2" thick. Looking for a shop made solution. The challenges:
Measuring and marking within a few thou'
Hard spots in the grain push the center punch off the mark - It's oak
Hard spots push the drill bit off the punch mark
Drill press tends to flex just enough to throw off a clamped setup, especially with a wide board
Not so easy to clamp a drilling guide to the workpiece
Answering a few questions might be helpful.
1) How big of a hole?
2) Why "within a few thuo'?"
For me one of the hardest places to mark is on the end grain of hardwood blanks going to the lathe.
I start with a very sharp (shop made) scratch awl.
511912
This one has four facets. A three faceted awl would likely work just as well. This was made from a piece of HSS drill stock. With the tip and sides sharp it can actually do a little drilling. The wedging action can be used to push wood sideways if your hole is slightly off.
After the mark looks good the hole can be made a little larger with a gimlet.
511913
The smallest one in the box is about 3/32".
If you have an auger bit, the lead screw on that may be able to start the bore to make a nice start for a twist drill bit.
jtk
Jimmy Harris
12-12-2023, 9:51 AM
It depends on the size of the hole, but if you can use one, a Forstner or brad point bit does a pretty good job of not wandering in the wood with a drill press. Auger bits also work well for this.
Tom Bender
12-12-2023, 6:56 PM
Thanks for the suggestions. I'm making a jig using a machinist's centering drill. This has a short fat shank and a small point so it won't deflect. I'll run it thru a guide made from some hard maple. Once it establishes the hole it should be ok. The guide will have centering screws which will need to be adjusted. Feeling optimistic.
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