Wednesday, April 20, 2011

Twist Drill Shank Modifications

I'm on record as having praised K&S Engineering's telescoping brass tubing product to the sky for its usefulness and versatility, so I feel obliged to exhibit new uses that I find for it. There's one example of a use here, where I used it to sleeve an oversize bore in a barbeque's valve knobs that I was repairing. Following is an example of the converse, where the tubing serves to increase a diameter rather than decrease it. Here's a photograph that explains a lot.

Pictured is my elderly Craftsman 3/8" drill, with a modified 1/16" drill in its chuck. There was a little problem with chucking a 1/16" drill in this drill's chuck -- the chuck is worn and will no longer close down to 1/16". (I needed to drill a lot of small pilot holes for 1 1/2" finishing nails to do a problematic baseboard installation job -- long story.)

Brass tubing to the rescue.

A short length of 3/32" outside diameter tubing (just over 1/16" inside diameter) glued onto the shank of a 1/16" twist drill with CA adhesive gave me a means of chucking the drill securely in the worn chuck. The arrangement worked nicely and got the job done.

A variation on this sort of drill modification can be helpful when what you need is not so much a longer than normal drill, but a drill with a longer than normal reach. You do the same as what I did to make the 1/16" drill fit the worn chuck, but you use a longer length of tubing. Here's an example of a 'lengthened' 3/32" drill.

The tubing's outside diameter here was 1/8"; hence, its inside diameter is a slip fit over a 3/32" drill shank.

The tubing and the glue bond are entirely strong enough for the drilling of small diameter holes in wood. But if a more robust extended-reach drill is needed, one can be made by using steel rod instead of tubing. here's an example of an extended 1/8" drill.

That's 6mm diameter rod salvaged from an old laser printer. These are easy to make if you have a lathe. Just use the drill that you mean to extend to bore a hole in the end of a length of rod, degrease the parts with lacquer thinner and assemble with CA adhesive. The adhesive bond will likely take anything you can dish out.

Should you ever want to take one of these apart, just heat the glue joint gently with a propane torch. CA adhesive is not all that heat resistant. It will soften and let go.

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