Drilling a 1/4" hole in the center of a 1/2" dowel....

[Bill Huber]

I spent the afternoon yesterday working on get a 1/4" hole in the center of a 1/2" dowel, sounds easy but I sure had a problem with it.

I made V blocks, I use a vise with a V slot in it, I drilled a 1/2" hole in a block and centered it under the bit clamped to the drill press table. For some reason I could not get a consistent hole in the center, I guess it could be that my 40 year old Craftsman drill press just couldn't handle it or something.

So today I came up with another way to do it and it worked great. I took an 8/4 (1 7/8"), 5"x5" block of hard maple I had, clamped it to the drill press table. Then I drilled a 1/2" hole into the block that was 1 3/8" deep. With the block still clamped I changed to a 5/16" bit and drilled the rest of the way though the block. ( see attached image)

Now with a 5/16" outside diameter bushing in the little Dewalt router and 1/4" bit installed I set that on top of the block and seated the bushing in to the 5/16" hole, it was a very tight fit which held the block on the router.

Now with a 1/2" dowel locked into my bench vise I set the router with the block over the dowel and seated it down all the way. Set the depth of the router, plunged it down and there is my hole center right where it should be, in the center.

I don't know if anyone else would ever need to do this but the method worked very well and could be used with different sized dowels.

This is an Xray view from SketchUp.
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[Prashun Patel]

Sniff, sniff, I smell a $100 tool tip.

(although, something tells me I've seen this before).

[Grant Wilkinson]

Good tip, Bill. I cheat. I chuck the dowel up in my collet chuck, put the jacobs chuck and bit in the tail stock on my lathe and drill away. :D

[Rod Sheridan]

I cheat and put it in the lathe............Rod.

[pat warner]

Clamp scrap to drill table.
Drill 1/2" hole in it.
Move nothing, insert 1/2 dowel.
Chuck up sharp 1/4 brad point. Will be auto-centered to dowel.
Drill @ <250RPM.

[Bill Huber]

Good tip, Bill. I cheat. I chuck the dowel up in my collet chuck, put the jacobs chuck and bit in the tail stock on my lathe and drill away. :D


I cheat and put it in the lathe............Rod.

That would work if I just had a lathe, the problem is I don't.

[glenn bradley]

Great stuff Bill. Thanks!

[Bill Huber]

Clamp scrap to drill table.
Drill 1/2" hole in it.
Move nothing, insert 1/2 dowel.
Chuck up sharp 1/4 brad point. Will be auto-centered to dowel.
Drill @ <250RPM.

That is what I tried and just never could get it to come out centered each time. The other problem was holding the dowel, it would want to spin after about an 1/8" in to the dowel.

I even cut a kerf in a block so I could clamp the dowel and then clamped it down, drilled the hole but I still could not get the holes to be consistent and I was using brad point bits that had been used very little. I think my old drill press needs to be replaced but this got me though on what I needed.

[pat warner]

Also have drilled a hole for a set screw though the thickness.
Drive the set screw against the dowel, that will keep it from spinning.
Did you change the table ht. at any time during your first scenario?

[Bill Huber]

Also have drilled a hole for a set screw though the thickness.
Drive the set screw against the dowel, that will keep it from spinning.
Did you change the table ht. at any time during your first scenario?

I did not change the height at any time, it was set and I did not move it. When the drill press is on and I look at the bit the point is in one place but then it walks or something, just don't know what the problem was.

[pat warner]

Bad chuck or bent drill.

[John Downey]

Drill bits will wander to a surprising degree, there's nothing wrong with your bit or drill press. I do this sort of thing all the time, with blocks of wood rather than dowels.

280512

One that I do often is a 3/4" hole about 3" into a block, then a 7mm hole continuing through to the other end of the 5" block. I have a long bit that would reach, but it is way too flexible, comes out 1/8" off at least. I just made a steel sleeve to go in the 3/4" hole with a 7mm bore through it. With any luck, that will help guide my longer bit and keep the hole straight.

[John Coloccia]

Drill bits will wander to a surprising degree

Yup, they do. Next time try it with a Forstner bit. Getting a small twist drill through any significant depth of wood in a straight line is an exercise in frustration. These kinds of things are a job for something with a more or less solid shank, in my opinion.

[Brian W Smith]

Drill geometry would be my first hurdle.Once that's where you want it....fixturing becomes much less critical.

I would want some way to "clamp" the drill guide onto the 1/2' dowel.So slots on guide would probably be on the list(the beginnings of a collet system).The 1/4" end of guide needs to remain a "constant".......it's the range in the 1/2" dowel's OD that would be of concern.

[Mike Heidrick]

I have been center drilling 6mm stainless screws with a 5/32 drill for a few months now making 3D printer barrels and then installing PTFE tubing in them. Using a metal lathe and a center drill before the 5/32 drill are the only way to fly. Never tried a center drill in wood but I bet it would work too.

http://i39.photobucket.com/albums/e169/BloomingtonMike/Ord%20Bot/PA230023_zps8ec058bd.jpg

[Jim Matthews]

http://i39.photobucket.com/albums/e169/BloomingtonMike/Ord%20Bot/PA230023_zps8ec058bd.jpg

Dude, you need to start using Sunscreen.
Your palm looks like a Prada handbag...

[Garrett Ellis]

x2 on center drills. especially helpful for small holes.

[John Coloccia]

Just one thing...

Center drills are really designed to drill for a lathe center. The best tool to use is a spotting drill. It will have a much larger angle, allowing the tip of the twist drill to actually contact the center of the hole you wish to drill. Drilling after a center drill is done, but the outside edges of the twist drill will contact the sides of the hole first, and if things aren't perfect it will still knock it off line. A spotting drill is essentially a solid chuck of metal with a wide, V shaped cutting profile....no flutes. It's strictly made to guide a twist trill and get it going perfectly.

[Mike Heidrick]

Dude, you need to start using Sunscreen.
Your palm looks like a Prada handbag...

I knew that red office chair was good for something.

John, I will have to give one of those a try. Thanks. The 100+ barrels I have done so far have been perfect to even in stainless steel but I am always trying to learn the correct ways to do this metal work. This is work on a 12/36 atlas craftsman commercial lathe from 1981 - not even a crazy south bend heavy 10, or Logan, or Hardinge or other commercial lathe smaller lathe.

[John Coloccia]

Dude, you need to start using Sunscreen.
Your palm looks like a Prada handbag...

I knew that red office chair was good for something.

John, I will have to give one of those a try. Thanks. The 100+ barrels I have done so far have been perfect to even in stainless steel but I am always trying to learn the correct ways to do this metal work. This is work on a 12/36 atlas craftsman commercial lathe from 1981 - not even a crazy south bend heavy 10, or Logan, or Hardinge or other commercial lathe smaller lathe.

Even machinists spot with a center drill many times, but they also consider our standard Jobber length drills to be "long" and tend to use very short drills on very solid machines going into very homogenous material. With our typical woodworking drill presses, long bits and inconsistent wood, we can use all the help we can get :)