Drilling pen blanks

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Markus666

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Aug 12, 2016
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Hi all. I'm hoping you can help me with a blank drilling problem I keep having.

I drill both wood and acrylic blanks using the bit sizes specified in the assembly instructions (from PSI). I drill with a Jacobs chuck on the lathe at around 500rpm and I back out the bit several times to remove scrap from the hole and the bit. When I dry fit the tubes, the drilled blank holes are always too big, forcing me to wrap the tubes in masking tape prior (to snug the fit) to gluing them in. Does this happen to other folks too or am I doing something wrong? Is masking tape a reasonable solution or should I be doing something else?

Thanks so much for helping out a fellow turner.
Mark
 
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mecompco

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Yup, somethings not right. I've only had that happen with one 12.5mm bit--replaced it and all is good. Now how oversize is the hole? I'm not thinking I'd trust the tape trick to last. I always use epoxy and you can goop enough in to fill holes that are slightly over-sized, as sometimes happens and all is good.

Regards,
Michael
 

randyrls

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I drill both wood and acrylic blanks using the bit sizes specified in the assembly instructions (from PSI).
Mark; I often find the sizes of drill bits that give me the best fit are NOT the ones on the instructions. The drill bits specified are the closest most common available size.

I have a 115 piece drill bit set and a 25 piece metric set. When starting on a new style/model, I drill a hole that is smaller than I think is correct. If the tube doesn't fit, step up to the next size larger until the tube just fits. Then write down that drill bit size on the instructions for the pen. There are several drill bit size charts in the Library.

Oh; added later, drill no more than 1/2" at a time.

Hope this helps...
 
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mark james

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G'Day Mark,

All the suggestions above on drill sizes and drilling technique are all excellent. I can only add to combine those thoughts with the first suggestion posted by Skip... Check your Tailstock. Make sure your headstock and tailstock are in alignment, and that the tailstock is able to be tightened accurately. After that - yup, check your drill technique and the drill dimensions.
 

Dale Allen

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If the bit shakes or moves from center while drilling then something is not aligned right as stated above. You should feel almost no vibration or movement of the drill bit and drill chuck when drilling.
 

Bob Kardell

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One thing to think about is when you back the bit out don't loosen the tailstock. I made the mistake early on of loosening the tailstock each time I backed out the bit and each time you do that there is a chance that it will not tighten in the exact location and this will cause the hole to widen.

When the tailstock has been extended as far as it can go and you have not gone completely through the blank - back out the bit without loosening the tailstock, stop the lathe, loosen the tailstock, move the bit forward into the blank, tighten the tail stock again, then start the lathe and start advancing the bit again. The longest blanks should only need to have the tailstock reset once ....

Hope that helps.


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jttheclockman

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All good suggestions above. I will add also when you have the drill chuck in the tailstock, just snug up on the holding lever. And as you advance the drill bit hold the chuck with your left hand to steady it as it enters.
 

TonyL

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Please forgive the "simplicity" of my suggestion: is it possible that the bits are slightly bent or they are bowing while drilling/penetrating the blanks? No need to answer...just trying to eliminate all of the variables.

Another simple one is to ensure that the drill bit is centered and even held by all of the jaws of the Jacobs chuck; I messed-up a blank that way.
 

Markus666

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Thanks. I was loosening the tail stock several times per blank to back out the bit. I tried your suggestion and the drilled holes seem to come out MUCH better. Thanks so much for your great suggestion. I think my problem is solved. I did check alignment first and it was fine.
My sincere thanks to all my fellow turners for helping out a turner in need. Anyone want to buy some masking tape, cheap?!
 

jrc

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Drill

I drill antler on my lathe and have to stop to clear the bit, sometimes a few times. If I leave my lathe running clearing the bit and putting the blank back on the bit the hole is larger than the bit. It reams the hole bigger. Try stopping the lathe and unscrew the blank from the bit to clear it and screw the blank back on. Sometimes I do not have to this with antler. Here is how it's done. I always use a pilot tip drill bits

https://www.youtube.com/watch?v=SAEEaF8z2jM
 

Herb G

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One thing I will add here is to make sure the blank is seated properly in the correct jaws before spinning it. You'd be surprized how easily a blank can shift when snugging down the chuck key.
Also, make sure you have the correct jaws on your chuck to begin with.

Roll your drill bits on a known flat surface & check for wobble. If there is any wobble or deflection, you know the bit is bad.
 

NLAlston

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One thing to think about is when you back the bit out don't loosen the tailstock. I made the mistake early on of loosening the tailstock each time I backed out the bit and each time you do that there is a chance that it will not tighten in the exact location and this will cause the hole to widen.

When the tailstock has been extended as far as it can go and you have not gone completely through the blank - back out the bit without loosening the tailstock, stop the lathe, loosen the tailstock, move the bit forward into the blank, tighten the tail stock again, then start the lathe and start advancing the bit again. The longest blanks should only need to have the tailstock reset once ....

Hope that helps.


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Wow....you really DO learn so much, here.

I'm a relatively new turner, who absolutely loves turning pens. But I see, now, that I had been doing the 'bit clearing' movement wrong. I would always retract my bit from the blank with the lathe running; sometimes coming all the way out, to be sure that I pulled as much particles out of the hole, as I could. I did notice that the bit would catch, a bit, on the rim of the entrance hole when I would return the spinning bit to the blank. I had thought it was the norm, having been of the mind that I was doing it as (I felt) it was supposed to have been done.

Thanks for sharing.
 

Woodchipper

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When the tailstock has been extended as far as it can go and you have not gone completely through the blank - back out the bit without loosening the tailstock, stop the lathe, loosen the tailstock, move the bit forward into the blank, tighten the tail stock again, then start the lathe and start advancing the bit again. The longest blanks should only need to have the tailstock reset once ....
I brought up the same thing on another thread a couple of days ago. The quote is how I'm doing it with modifications suggest by others. I plan on practicing on scrap wood to get the best way to drill and have the hole the same size from one end to the other.
 

needastick

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May 7, 2017
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Tailstock alignment

Hello Mark,
I'm a newbie and I'm reading this thread in order to glean some tips from the experienced turners.
I find drilling an accurate hole can be quite a challenge as there are so many possible variables.
One of those variables is tail alignment. Back in the day when I started to turn metal I made a simple jig to speed up re-setting the tail( after taper work) . This proved quite accurate for my standard of work.

http://www.penturners.org/forum/attachment.php?attachmentid=163944&stc=1&d=1495133604

You will see that there is a very tiny hole drilled at the exact centre point. I made this by sliding the jig up to a rotating drill held in a small chuck. The jig can then be slid anywhere on the ways to confirm the tip of live centre will enter the hole.
The same would confirm the tip of your drill bit was centred, though not necessarily the back!

http://www.penturners.org/forum/attachment.php?attachmentid=163945&stc=1&d=1495134033

The main use for this is for checking the height of cutting tools as you can see in the second pic.
An inexpensive project, may be of help to someone.
 

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needastick

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May 7, 2017
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I made the jig from 1/4"" brass sheet and some stable Teak stock. The wood hasn't moved and I machined it parallel and a tight fit to retain consistency.
Regards, Tony.
 
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