Straight Drilling Tips?

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davidrei

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I've been trying to do one of those "celtic knot" things for a while now. I have quite a few pens that look more like worm races rather than knots, a circle is big on one side, small to non existant on the other. An interesting look, but not what I wanted. The problem I have is drilling the glued up blanks straight. The biggest problem is that I see the drill bit "walk" to the left when I apply pressure, it then drills at a slight angle. Things I've tried, resulting in minor improvements:
- Making sure the blank is square & straight (so it sits in the vice square)
- Verifying the drill press table & vice are square to the drill bit from multiple directions)
- Using brad point bits
- Using a center punch or small drill bit to make a pilot hole

Would drilling at a slower speed help? Faster? What am I missing here?
 
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Deere41h

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You might try drilling on the lathe. Spin the wood and not the drill bit. I do this for most of the larger pens like the Baron and always get the most accurate hole this way. There is a picture in my photo album if you want to see how I do it(attached link). I usually run the lathe at about 900 rpm.

http://tinyurl.com/a9qk2

It does require that you have a scroll chuck and a Jacobs chuck.
 

Rifleman1776

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I use a machinists cross-slide vice to hold the blank firmly. Using brad point bits, I bring the bit down onto the blank with power off the press the point into the wood and hold (slightly) firmly. [you have to get a 'feel' for it]. At that point I turn on the power and drill. Bringing a spinning bit down onto the wood causes it to wander as it looks for the softest point of least resistance.
 

gerryr

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Frank's right about a spinning bit seeking the easiest point of entry. I do all my drilling on the lathe, mostly with brad point bits. With the lathe off, I move the tailstock so the drill bit point is almost touching the wood. Then I lock down the tailstock and advance the point into the wood a bit. Then I turn on the lathe and begin drilling. I haven't had one wander on me since I adopted this procedure through trial and error AND since I dumped my Crapsman drill chuck in favor of one from HF.
 

RPM

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Frank mentioned something that I don't think gets enough attention and thats "hold the blank firmly". I used to use quick clamps (the pistol grip squeeze kind) to hold my blank in my jig and the jig to the drill press table. After getting frustrated trying to squeeze jumbo holes into 3/4" blanks, I tried using c-clamps to rigidly secure everything.

Also, I took advantage of BB's sale on drill bits a few months back. I don't remember the brand, but its the complet set by 64ths from 1/16th to 1/2 They were pricy, but I have been woodworking for 25+ years and his bits are just unbelievable. Drilling acrylic with them is a breeze. They are not brad point, but I have not had a single problem.

Bottom line, secure your work, use good sharp bits along with the advice above, I haven't misplaced a hole in months.
Richard
 

jlindholm70

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I discussed this problem with a machinist friend of mine when I was trying to do the knot on a fishing rod handle. The longer the hole, the more pronounced the drift, so you can imagine what the elipses looked like after 6 inches or so.
He says that the drift of a drill bit is almost impossible to stop. His suggestion to minimize it is to push the drill bit in very slowly, cleaning out the bit often. Keep your drill bit sharp. One side of the bit is going to be duller than the other, causing it to pull to that side more than the other when drilling with a lathe (kinda like a flat front tire). In the end, the thing that helped me the most in keeping the bit from drifting/bending throughout the 6 inch length was to go from a 1/4 inch bit to a 5/16 bit and going VERY slowly. It's not much of a diameter difference, but it really helped out. I don't know what kind of pen kit you're trying this on, but going to a Gent or Jr Gent may fix your problem.
 

JimGo

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Originally posted by jlindholm70
<br />I discussed this problem with a machinist friend of mine when I was trying to do the knot on a fishing rod handle. ... One side of the bit is going to be duller than the other, causing it to pull to that side more than the other when drilling with a lathe (kinda like a flat front tire).
<br />
I don't get this. A flat front tire causes the car to pull to the side because of the increased friction on that side of the car, the car being off balance, etc. But a drill bit doesn't have "sides", because it rotates. I could see this problem causing an oversized hole, but I'm not sure how it causes drift, since the direction in which the dull "side" of the bit would be pulling will change at least a few hundred to a few thousand times per minute.
 

jlindholm70

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I stated that "when drilling with a lathe". When you drill with a lathe, the wood is spinning and the bit is stationary. I've tried drilling with a press, but I've had better results with the lathe.
 

vbatwork

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I agree with RPM. I too bought BB's drill bit set. They're USA made by Norseman and beat the proverbial crap outa my old off shore brad points. To be fair, my old set did get a lot of utility use and hadn't been sharpened. I didn't think they really need it until I started the tight tolerance work of pen turning just recently. Very important to have the vise secured to the drill press as well. Can't have any movement in the workpiece while clearing the flute. I haven't had any troubles drilling blanks since.

- John
 

JimGo

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Originally posted by jlindholm70
<br />I stated that "when drilling with a lathe". When you drill with a lathe, the wood is spinning and the bit is stationary. I've tried drilling with a press, but I've had better results with the lathe.
Actually, in this case, it should still have the same result in the blank. For example, if the bit were stationary and pulled directly to the left, as the wood rotated around the bit the diameter of the hole cut by the bent bit would increase as it worked its way through the wood as the bit pulls to the left. Imagine, for example, chucking up a nice 3"x3"x3" cube of wood in your lathe, and putting a parting tool at the dead center. Where the tool touches the wood, the hole will have a certain diameter. If the parting tool is pushed into the wood exactly along the plane of rotation, the parting tool will exit the far side of the wood with the same diameter. But if the parting tool is pushed into the wood on a slight angle, the hole at the back of the wood will be larger than the hole at the front of the wood. The bending drill bit is basically the same as the parting tool.

Please understand, I'm not trying to pick a fight or anything! It's just that his explanation doesn't make much sense. What I buy more is that in the kinds of woods we tend to use which have heavy grain movement, the differing densities of the wood can cause the tip, espeically of brad point bits, to wander. Regardless of the reason, though, his ultimate advice about taking small bites and clearing the bit regularly makes a lot of sense, and is very good advice.
 

davidrei

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Thanks to all for the great advice. For now, I'll stick with the drill press, my tool budget is perilously low for the chucks to drill on the lathe. I've added a few more clamps to hold the vice to the drill press table, and followed Rifleman's advice about pressing the bit into the blank before turning the drill on. So far, so good, significant improvement.
 

jrc

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If you can find bullet tiped bits it will take care of most of the drift. I have drilled over 12000 blanks with one. It was dull and instead of sharpening it I tried a different bit. Where I got said it was a very good bit and it would not drift, well it did so I sharpen the bullet and keep using it.
 
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