Drilling deep and straight.

[HarryH]

There are some great tips for boring shaft holes in the forums, but I am wondering how it is done for stock that will make up rudders and centerboards, etc.

Mr. Cleek and others, any tips for drilling through the edge of say 3/4" stock for a distance of 8-12", and coming out the middle of the plank thickness, same as entered?

I am using a hand drill, have made a jig to guide the 15" bit (5/16" dia) and am getting so-so results, not always repeatable..

Sure would like to feel a little more confident that I am not going to wander too near the plank surface...

Thanks...

_H

[Bob Cleek]

Easier said than done, but there are a few tips. First, like it sounds you have done, you must be meticulous in your layout. Mark the straight line that you want to follow across the whole length of the plank. Then line up your drill bit, making sure it is true on all planes. Start slowly and make sure you are dead on. The hole you start will be the hole you finish! (or almost, as you will see below.)
Some folks use a jig and others are just very confident in their own eye!

Be sure to use the proper bit. The point tapers are different for hard or soft woods. Work slowly and withdraw the bit FREQUENTLY to clear chips. This will keep the bit running true.

When you have gotten half way through the piece, turn it around and start from the other side, using that line you carefully laid out across the piece. Meet in the middle. Starting from each end cuts your chance of drifting off the line by half.

That's about it. The rest is luck and clean livin'.

[Dick Pendergast]

I would start with 2 pieces of plywood half the thickness you need. Lay out your intended boring path in pencil on both pieces as mirror images. Cut an modest groove on the two lines. Laminate the two pieces together with epoxy. The result is a slot that your drill bit will follow precisely as most of the material will have been removed.

Best,

Dick P.

[Dave Fleming]

Start with short bit in the jig and then one a bit longer and finally one long enough to bore through.

Short bit gets you started right on track.

As the Cleekster says, you should have bits sharpened/ground for the type of wood.
Off the shelf bits say, a bell hanger ( not my first choice to begin with)is too agressive.

Depending on how many holes to be bored a nice brace does a good job with a good bit.

And yes by all means WITHDRAW bit/s frequently to clear chips!

[dmede]

I notice no one ever suggests getting two boads half the thickness of the finished peice and routing out the hole (or half the hole) on each peice before glueing together. Why is that?

I'm thinking more in terms of shaft holes for props and such as opposed to drifts.

[HarryH]

Thanks for the replies, good ones all.

In this case I cannot use the two separate piece technique, with routed slot, as might be a solution for shaft drilling.

I agree some luck could be be enjoyed here Bob. If I drill from each end and miss by a tad in the middle, will the bit bend somewhat over a distance and clean the hole out enough to take a rod the same size as the drill? Or do I have to start undersize?

Dave, Bob, which type of bit would you recommend for hardwood? Softwood? Plywood?

Thanks..

_H

[Dave Fleming]

See:

Deep Hole Drilling (http://www.woodenboat-ubb.com/cgi-bin/UBB/ultimatebb.cgi?ubb=get_topic;f=1;t=010100)

[Dave Fleming]

Don't wish to sound like a shill for them but,
WL FULLER is your best all around source for drill bits.

What you are after is not just one bit but a series depending on the depth of the hole and wood.

To start a Brad Point would be my first choice,
Then move up to a long length Brad or a twist drill sharpened to accomodate the wood type.

As far as plywood is concerned I cannot recall ever drilling deep holes into end grain ply.

As an aside, we did on occasion use Irwin Auger Bits or Greenlee or gasp, Russel Jennings bits with the screw lead ground flat on one side.
The reduction of the screw drawing power did two things, allowed the withdrawal of the bit frequently to clear chips a bit easier and helped reduce the chance of the bit wandering with the grain.

[Bob Smalser]

Also:

http://www.woodenboat-ubb.com/cgi-bin/UBB/ultimatebb.cgi?ubb=get_topic;f=1;t=010983

http://pic3.picturetrail.com/VOL12/1104763/6583947/84760753.jpg

[kc8pql]

Originally posted by dmede:
I notice no one ever suggests getting two boads half the thickness of the finished peice and routing out the hole (or half the hole) on each peice before glueing together. Why is that?

I'm thinking more in terms of shaft holes for props and such as opposed to drifts.OK, here's how I did it:

http://tinypic.com/66jjb7

Hole is 2 1/2" dia. Coves were cut on a table saw using an auxillary fence clamped to the table at an angle to the blade. Cut is made by raising the blade about 1/16" a pass. If you don't understand what I'm talking about, DON'T TRY IT.

Ken

[Paul Scheuer]

8 - 12 inches is not a particularly "deep hole". You should be able to get a true hole on a drill press with some clever clamping. Sounds like you've got enough bit.

I'd clamp the work to a true square block so I could line it up properly when I move the table in the increments that the press likes.

A slightly related item from my past - I once did a really deep hole, about three feet through the butt of a mast for some added wiring. I wasn't too concerned about keeping it dead center, but I didn't want it to peek out the side of the mast. I had a small light bulb (about the size of an LED), that I cold insert in the hole on solid wires. Whenever I got worried, I'd insert the light, stand back a few feet and see exactly where the bottom of the hole was.

[Jay Greer]

The jig is known as a "Preacher". The meaning was that A Preacher doesn't lie. Holes are best drilled with a hand brack. Started with a double lipped lead screw auger and, as soon as the hole is started, a bare foot single land ships auger is changed over to. I have drilled holes six feet long by this method.
JMG

[dmede]

Originally posted by kc8pql:
[QUOTE]Hole is 2 1/2" dia. Coves were cut on a table saw using an auxillary fence clamped to the table at an angle to the blade. Cut is made by raising the blade about 1/16" a pass. If you don't understand what I'm talking about, DON'T TRY IT.

KenI think I know what you mean, the piece is skewed in relation to the blade when pushed over it. Ive seen it done for much less dramatic coves (shallower and wider). Seems like a good technique. Thanks.

[ion barnes]

What has not been said, is that the drill bit has to be sharp and the tip flutes the same length across the cutting face.