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Forum topic by blackmage77 posted 12-16-2011 10:09 PM 1715 views 0 times favorited 7 replies Add to Favorites Watch
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blackmage77

12 posts in 1834 days


12-16-2011 10:09 PM

Topic tags/keywords: question drill press arts and crafts

Hello,

This is my first forum post so please bear with me. I hope I have this question in the right area.

I have been pen turning for a while now and lately been having a problem with some of my pen blanks. The problem I am having is I mark center on the blanks drill the blank out from center and look at the other end its no where near center. I will sometimes have a major differnence from one side to another. I use a center finder to help mark center. My table is level and I have checked for square between the bit and table. I did check to see if the blanks I am getting are square and some of them are not square but I didnt think this would make such a differance between ends.

Is there anything I am overlooking? In theory if the bit is going down straight at one end of the blank at center it should come out the same spot at the other end :P. Or so i thought…..Also I am using a blank vise for pen blanks mounted to the press table.

So if anyone has any ideas of what I am talking about or solutions many thanks.

Happy holidays

Stan


7 replies so far

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Elizabeth

814 posts in 2604 days


#1 posted 12-16-2011 10:23 PM

Hello and welcome!

I have the same problem. I think it mostly happens when the drill bit doesn’t quite get centered – either it skips a bit on entry or the blank isn’t exactly parallel to the bit. I got a clamp to hold the blanks in place which has helped a bit, and I think if I got a different type of drill bit (maybe a brad point?) that would reduce the problem even further. Since the offcenteredness gets worse the farther down you drill, I have made a jig for my bandsaw to cut the pen blanks to the sizes that I need for each half of the pen, and then drill them out afterward. Twice as much drilling but more accurate results.

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TheDane

4997 posts in 3124 days


#2 posted 12-16-2011 10:34 PM

Stan—I’ve had the same problem. I’ve done a couple of things that really helped a bunch.

My drilling jig and a better quality drill press pretty much cured it for me.
Click for details

I have started drilling in a short distance (less than 1/2”), withdraw the bit, clear chips/dust, then go at again for another 1/2” or so. My objective here is to keep the bit from heating up. I think when the bit heats up it is more prone tot wandering/deflecting in the grain. The harder the wood, the worse the problem became.

BTW … the new drill press was needed because of the longer quill stroke. My old DP only had a 2 1/8” stroke, and the distance from the bit to the base (it was a benchtop) was too short to allow use of my drilling jig.

—Gerry

-- Gerry -- "I don't plan to ever really grow up ... I'm just going to learn how to act in public!"

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blackmage77

12 posts in 1834 days


#3 posted 12-16-2011 10:50 PM

Thanks for the speedy reply… Dane the jig your using is pretty close to the one I am using from Penn State. Clamped down on the table almost the same as you. I do clean out the bit while I bore but not as much as I probably should be. The wood I was drilling this afternoon was Cocobolo and was quite hard. Just bothers me that I can see its started at pretty much center and when I am finished its no where near center on the other end. After looking at the blank I can see its not square at the one end thats really off.

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PurpLev

8523 posts in 3109 days


#4 posted 12-16-2011 11:09 PM

if your drill bit sharpened properly? on center? is it sharp?

a dull bit (especially if it’s duller on one side more than the other) will tend to wander off.

I would take a test blank (some rough cheap material) and drill through it, then slice it in half to expose the drilled hole – maybe that could give you some clues as to what’s happening there if the hole changes in diameter (drill moving off center)

-- ㊍ When in doubt - There is no doubt - Go the safer route.

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blackmage77

12 posts in 1834 days


#5 posted 12-17-2011 11:13 AM

The bit I was using was a brand new 8mm brad from Penn State fresh from the package yesterday afternoon. Will check to see if I have the bit in correctly. Also will try the cheap blank trick to see whats going on. Hoping to stop by Woodcraft later today and ask thier opinion.

Thanks for the reply.

View Jim Finn's profile

Jim Finn

2409 posts in 2383 days


#6 posted 12-17-2011 03:02 PM

I make blanks for a friend who turns pens. He just had me make the blanks a little larger to avoid this problem. 7/8” x 7/8”

-- "You may have your PHD but I have my GED and my DD 214"

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Planeman40

805 posts in 2222 days


#7 posted 12-18-2011 02:33 AM

Here is what you need to do.

(1) Make SURE the blank is at 90 degrees to the drill press table from all angles.
(2) You are using a new drill which I assume is correctly sharpened. A drill bit that is poorly sharpened (sharpened where the point is slightly off center or one side of the bit cuts less that the other side) can lead to hold drift in long bores.
(3) Be sure to draw the bit out of the blank to clear the bit often. I usually only drill about 1/4” between each cleaning of the drill bit. The pressure of trapped swarf is one of the main reasons for hole drift.
(4) Remember “easy does it”. Just a little bit at a time and KEEP THE DRILL BIT CLEAN!

And one more thing. Do the first bore undersized with a smaller bit. Then come back for the final bore with the correct sized bit. Sometimes I do three bores to make sure.

This is a problem in metal too. I have a metal lathe and often make deep bores. The above is how I do them in steel.

Planeman

-- Always remember: It is a mathematical certainty that half the people in this country are below average in intelligence!

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