Precision hole drilling

[LCHIEN]

wow i impressed myself.
Here i drilled a 1.5" deep 17/32" hole in a 9/16" thick piece
If you calculate that leaves a 1/64ths thick wall in either side providing you drill exactly in the center AND you keep the bit and the workpiece precisely parallel...

Came out almost perfectly.... It broke out the side just a little on one of them at the very bottom.

Procedure:
Make sure to cut the pieces squarely as possible so the ends are perpendicular to the length.
Mark the workpiece center from both edges so you can identify the exact center as halfway between them if they don't coincide because your measurement is not perfect or you set the square off just a hair. This requires four marks on the each end.
Use a 1/2" brad point bit as this will ensure the center location and also prevent wandering off on the end grain which frequently happens. Besides I don't have a 17/32 brad point bit.
Clamp the work in a 8" wooden handscrew clamp laid flat on the DP table. This will make the sides of the handscrew clamp perpendicular to the table surface lining up the work. Make sure the end of the workpiece is lying flat on the table and there are no wood ships under it before clamping into place.
Drill out the hole to 17/32 using a bit bought purposefully for doing oversized 1/2" holes.

[atgcpaul]

I'm impressed but what's it for?

[Relative]

Would a doweling jig such as this one have helped with the alignment for your project?

http://www.harborfreight.com/self-ce...jig-41345.html

I use it whenever I absolutely need to have a hand-held drill aligned at 90 degrees to the target and it's just not worth the time to set up for the drill press.

Mike

[LCHIEN]

Would a doweling jig such as this one have helped with the alignment for your project?

http://www.harborfreight.com/self-ce...jig-41345.html

I use it whenever I absolutely need to have a hand-held drill aligned at 90 degrees to the target and it's just not worth the time to set up for the drill press.

Mike

well, it would never have worked... the minimum width of material of that jig is limited by the black piece of metal in the middle which has 4 holes in it. The walls of those holes is more than 1/64th to start with and you really need to put the guides in it so that increases the wall even more, FInally 17/32 is not a standard dowel size so there's no guide that would work for my bit. I'm sure the guides are only the standard sizes. I think 1/4, 5/16, 3/8, 7/16 and 1/2"
according to the web page.

In this thread Durango dude gives a not so glowing review of it and DBHost who says its OK after tweaking.
http://www.bt3central.com/showthread...ight=dowel+jig

I think there's little substitute for a drill press for precision drilling. Somtimes you can't get the drill press to it but I have found its usually not worth taking short cuts. I do have some drill guides
http://www.leevalley.com/us/wood/pag...at=1,180,42311
for when I need to make a 90 degree guide and can't get the drill press to fit. I use the drill press to make the guide template.


PS I guess I could start with a 1/2" hole for which there is a bit and guide... like I did ...and enlarge it to 17/32" ;ole I did, but that still leaves the minimum thickness issue.

[mpc]

What about starting with thicker stock, drilling the hole, and then ripping (or sanding or hand-planing) the stock to final width on either side of the hole? That way the drilling operation, with the potential for bit walking and/or wobble, doesn't have to be so precise/exact. And if the hole doesn't end up exactly 90 degrees to the sides you can use a taper jig (or hand-plane) to adjust the workpiece sides to match the hole.

Though what you did is a pretty good test - "can I do this?" and "are my drill press settings accurate?"

mpc

[LCHIEN]

What about starting with thicker stock, drilling the hole, and then ripping (or sanding or hand-planing) the stock to final width on either side of the hole? That way the drilling operation, with the potential for bit walking and/or wobble, doesn't have to be so precise/exact. And if the hole doesn't end up exactly 90 degrees to the sides you can use a taper jig (or hand-plane) to adjust the workpiece sides to match the hole.

Though what you did is a pretty good test - "can I do this?" and "are my drill press settings accurate?"

mpc

I find that the more operations the more chance for errors that eventually add up. lets say you randomly center the hole and then try and rip to proper centering and width there are two independent rip setups of which there are lets say .010" errors giving a total of .010 in final width error and .020 in centering errors...

Besides, I had this scrap that was 9/16ths wide and a perfect length and I was too cheap to use a bigger scrap, haha. I figured it was a good test of skill and if it failed I would get a bigger scrap.

[gerti]

well, it would never have worked... the minimum width of material of that jig is limited by the black piece of metal in the middle which has 4 holes in it.

Ehem... Look again.

[LCHIEN]

Ehem... Look again.

the biggest hole is supposedly 1/2".
How thick does that wall look to you?
To clamp to a 9/16ths thick piece then the black piece would have to be less than 9/16ths leaving less than 1/16th for 2 walls... e.g. less than 1/32nd each wall.
I guess its possible.
But I didn't need it.

[gerti]

the biggest hole is supposedly 1/2".
How thick does that wall look to you?
To clamp to a 9/16ths thick piece then the black piece would have to be less than 9/16ths leaving less than 1/16th for 2 walls... e.g. less than 1/32nd each wall.
I guess its possible.
But I didn't need it.

I was talking about the clamping parts are stepped under the middle part, so it CAN clamp material that is thinner than the middle part.

[LCHIEN]

I was talking about the clamping parts are stepped under the middle part, so it CAN clamp material that is thinner than the middle part.

I guess I completely missed that!
You can drill right into the jig, then... great design.