Drilling Troublesome Blanks - A good use for Corian..

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Timbo

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The following was written with drilling on your lathe in mind.

If you're like me, you've run into problems when trying to drill a centered hole into pen blanks which are spalted, highly figured, or segmented. The problem is that there is a lot of uneven variability in the density of the wood, including at the entry point, this causes the bit has a hard time finding and staying centered. Even if the bit is perfectly aligned after locking down the tailstock, harder or denser areas of wood causes the bit to want to wander towards the softer, or less dense areas. This will manifest itself as wobbling or vibration of the bit.

My solution is to provide a good entry for the bit, and a guide to help keep it on track throughout the drilling process. Corian to the rescue! I found that gluing a 1/2" thick piece of Corian to the end of the blank prior to drilling eliminates most of the problems with drilling these types of blanks. Here's my process:

1 - Get a piece of that 1/2" thick Corian you will never use for a pen because the color is just yuck. Cut it into strips slightly narrower than your pen blank. Cut little squares from that. Use medium or thick CA to glue the little square of Corian to the end of your blank. Make sure the edge of the Corian square do not overlap the edge of the blank. Why...Later we will want to cut the Corian away, we'll want our blank to still sit flat for sawing. Here's what mine sample looked like:

View in Gallery

2 - This is a blank for a cigar pen which requires a 10mm bit. I use that bit to drill into the Corian a little more than 1/2", until I just start entering the wood. This is what it looks like (sorry about the over-exposure).

View in Gallery

View in Gallery

3 - Next I replace the 10mm bit with a smaller bit, then finish drilling through the blank. The smaller bit is only used to clear the way for the larger bit, reducing resistance, lessening tear out, lessening the chance of a blowout, and makes it easier for the Corian block to act as a guide for the bit shaft.

View in Gallery

4 - I then replace the smaller bit with my 10mm bit and redrill the hole to the correct size.

View in Gallery

5 - The last step is to slice off the Corian block using whatever method you prefer.

I've used this method with a lot of success. Give it a try if you think it could help you.

Tip 1 - If you don't have any Corian you could substitute a piece of fine grain hardwood, like Sugar Maple, acrylic, or a scrap Tru-Stone.

Tip 2 - This method will also work for longer single barrel pen blanks that you might want to drill from both ends. Glue a piece of Corian to both ends of the blank. Make sure the blank is square prior to drilling so that when you reverse it in the chuck, the drill holes will line up.
 
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ericofpendom

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Jun 6, 2012
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Bolton, England
Timbo, as is often the case it's the simple solutions that are the some of the best. Great tip and thanks for sharing, it sure will help people be less frustrated.
 

Blackwood

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Apr 27, 2014
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Bayville NJ
Great system, will give that a try on my next spalted turning. now if I could just get it to stay round when it hits the punky part.

Baron
 

lwalper

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Mar 16, 2014
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Lancaster, TN
Why not use a center drill to start the hole????? P.

I do that, but the larger bit still tends to wander around when it hits the harder spots. This looks like a great idea or adding a guide collar to the blank. I've tried step drilling too with the smaller holes drilled at a lower speed and the final bit being just a light pass at a higher speed. That sometimes seems to work, but not if the small bit has wandered too far off center.
 
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Timbo

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Kill Devil Hills, NC USA.
That is an really cool idea and very helpful. If you cleaned off the glue you could use it again (same size hole) William

Thoughtful idea, but it would be almost impossible to realigned the Corian piece with the centerline of the blank. Even if you're a little off the bit will wobble or vibrate, defeating the purpose. My guess is that it would be easier, faster and more accurate to just use a new piece of Corian. Corian scrape is pretty cheap, especially if you get it from one of our members (elody21).

Also, keep in mind that you don't have to use Corian. I use it because I have plenty on hand. The harder plastic, or Tru-Stone pen blank scraps will work as well.
 

turncrazy43

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Apr 22, 2012
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Marietta, GA
Thanks for the good tip there Tim. Will try it for some of my applications. Thanks for the photos as well. Always looking for helpful tips, thanks for sharing.
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