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Old 12-19-2018, 05:39 PM   #1 (permalink)
 
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Default Help with blank drilling alignment

Hello all
I have been drilling my pen blanks using my Jet 1221 lathe. Lately the holes have been elongated on the end where the drill bit first touches the blank. Happens on all size drill bits.

Is there a way to align the jaws on the tool that holds the blank? It is the spinning chuck on the left, not the stationary chuck on the right.

What else could I check?

Thanks in advance.
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Old 12-19-2018, 06:19 PM   #2 (permalink)
 
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Three points of information ...

Point 1.
At what lathe speed are you doing the drilling ? . Can you reduce the speed ?. Is elongation less at lower speed ?

Point 2.
Next, I am wondering how much your blank protrudes from the right end of the pen chuck jaws ? . Can you do anything to reduce this protrusion ?

Point 3.
Further info regarding the orientation of the elongation might help also. . By this I mean the following. . The elongation of the hole suggests that the hole is elliptical. . An ellipse has a long axis and a short axis.

Question: Is the long axis of the ellipse aligned with a line drawn between the two jaws ? . Or is the long axis aligned perpendicular to a line between the jaws.

The answer to this question would tell us in which direction the jaws are wiggling (slightly).
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Old 12-19-2018, 06:21 PM   #3 (permalink)
 
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My 2 cents:

1. Make sure your bit is sharp. I can't over emphasize this.

2. Make sure the end of the blank is square and put a dimple in it to start the bit (or use a centering bit).

3. When the bit first touches the wood, s-l-o-w-l-y advance it until the tapered portion on the end of the bit is below the surface of the wood.
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Old 12-19-2018, 06:32 PM   #4 (permalink)
 
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Start with a center bit.
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Old 12-19-2018, 08:32 PM   #5 (permalink)
 
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A couple things:
Put a 60 degree Center in the tail stock ( the non revolving end) and a dead center 60 degree in the head stock and bring them together until they touch...if they do not...that is the problem. Let us know if that is it. That is a co-planar check.

I had two of the keyless chucks over the years that were off and had that very issue.....
If the two points lined up in the co-planar check, then perform the same check using the dead center in the head stock and a smaller drill bit in the chuck.

Let us know.....
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Old 12-19-2018, 08:35 PM   #6 (permalink)
 
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I would take some calipers and check the distance between the two jaws. Just from the pic, it looks like your drill bit has a very small slope downward. And then follow Mikes advice.
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Old 12-20-2018, 08:06 AM   #7 (permalink)
 
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Is the shaft of the bit bent? Roll the bit on a flat surface and watch for wobble in the shaft end. Just an idea.
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Old 12-20-2018, 10:50 AM   #8 (permalink)
 
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And if you do not have center bits, buy one! If that fails, use a center punch to make a hole for the point of the bit to reach for when you first advance the drill . Works for me!
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