# Drill Bit Sizes - Pen Turning



## Hesh (28 Apr 2012)

I've just ordered some more upmarket Pen Kits as I need to make a few leaving gifts for work and noticed the drill bit sizes are all in imperial. I've got a mountain of Metric bits but no imperial sizes and was wondering if the sizes are absolutely critical (if so I'll order some) or is the metric equivalent ok to use.

Sizes I need are

27/64 which is 10.7156 (10.5mm?)
25/64 which is 9.9219 (10mm?)
15/32 which is 11.9063 (12mm?)

Would appreciate any coments from all the Pen Turners out there.

Steve


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## nev (28 Apr 2012)

IMHO If you use PU glue that expands a bit on setting you can get away with the 10mm and the 12mm but the 27/64 is too tight for 10.5 and a little too loose for 11mm.
If you want a 15/32 jobber pm me your address and I'll pop one in the post. I bought a box of five when i was looking for the same and if i get to the point where I break 4 I'll give up woodworking!

If you have difficulty finding the imperial sizes funeturnz have some sets.... http://www.ebay.co.uk/itm/Woodturning-H ... 4602e35976


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## jumps (28 Apr 2012)

Steve,
I don't think there's a simple answer to the general question. A lot depends on how they arrived at their recommended dril bit size in the first place - some will be metric tubes marketed for the US market and hence quoting imperial sizes. There's also a small variation in the 'glue gap' that can be inherent in the recomendations - here I may go a little tighter if the wall thickness after turning is going to be thin and I'm confident I can drill very cleanly.

Generally I now measure the tubes when I get a new kit type and work from there. Even to the extent of testing with a bit of scrap if I'm not sure.

btw if the 27/64" is for the Sierra kit, it's a 10.5mm bit - an example of why you can't generalise!


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## Hesh (28 Apr 2012)

Nev, thanks very much PM sent and appreciate your advice.
Jumps - yes it is for the sierra and have plenty of 10.5mm bits so that's a start thanks for the advice.

Will experiment with the tubes and bits once they get here and will look at taking any slack up with different glues once completed I'll post the results.

regards

Steve


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## CHJ (28 Apr 2012)

And don't assume the next batch of kits have the same drill requirements. Not unknown for a tube with a differing wall thickness to be supplied.

And as already eluded to, best to always drill with with drillbit to hand and a sample of the wood/plastic if you have a spare sample, especially if it's one that has been sharpened, a small deviation in the web offset at the point can make a considerable difference on the resultant hole size.

In fact if you have a drill that is a fraction too small in diameter, sharpening off-centre can be employed to make it drill oversize.


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## Hesh (28 Apr 2012)

Thanks Chas, I will have to remember to check each batch and not do my normal trick of believing they will all be the same and you never know I might not waste as many.

Steve


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## Neil Farrer (29 Apr 2012)

This has got to be the most debated and repeated topic on pen turning forums. I make around 2,000 pens a year. If you would like me to justify my point of view I am happy to. Last time it ran to around two pages of A4. Simply, get the right size drill. And that means the right size drill for the tubes, not what some suppliers (not manufacturers) say. Some, including the larger shops in the uk have been knwon to do a metric conversion. Bear in mind that other than 7,8 and 10mm tubes almost all others are imperial, so if a kit says, drilll bit required 10.5mm - beware!!! similarly 14.5mm or whatever the metric conversion is for 37/64.

Inevitably you have to go to the larger size metric drill bit. If you do that and then drill a soft wood, spalted beech for example, the hole will be even bigger. It won't work. The correct size drill bits will cost you around £1.50 each. You can pick these up from any engineering supplies shop, don't order them from the woodturning supplies shop beacuse they wont have them and where they do they will be expensive. The colt drills are good, but only the bits larger than 8mm, so 11/32 10mm 27/64. Te 7mm and the 8mm suffer from deflection if there is any variation in the density of the wood or if you have any angle whatsoever on the face.

I'm sure that others will have varying views, they always do, its up to you!


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## jpt (29 Apr 2012)

Neil Farrer":ouw1ytw2 said:


> This has got to be the most debated and repeated topic on pen turning forums. I make around 2,000 pens a year. If you would like me to justify my point of view I am happy to. Last time it ran to around two pages of A4. Simply, get the right size drill. And that means the right size drill for the tubes, not what some suppliers (not manufacturers) say. Some, including the larger shops in the uk have been knwon to do a metric conversion. Bear in mind that other than 7,8 and 10mm tubes almost all others are imperial, so if a kit says, drilll bit required 10.5mm - beware!!! similarly 14.5mm or whatever the metric conversion is for 37/64.
> 
> Inevitably you have to go to the larger size metric drill bit. If you do that and then drill a soft wood, spalted beech for example, the hole will be even bigger. It won't work. The correct size drill bits will cost you around £1.50 each. You can pick these up from any engineering supplies shop, don't order them from the woodturning supplies shop beacuse they wont have them and where they do they will be expensive. The colt drills are good, but only the bits larger than 8mm, so 11/32 10mm 27/64. Te 7mm and the 8mm suffer from deflection if there is any variation in the density of the wood or if you have any angle whatsoever on the face.
> 
> I'm sure that others will have varying views, they always do, its up to you!



I dont make quite as many as you but I agree with what you say here, I have a Cromwells branch http://www.cromwell.co.uk/ close to me and if they dont have the drills in stock they can usually get them for the next day, or you can get them amil order.

john


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## Hesh (1 May 2012)

Nev: PM sent


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## Hitch (2 May 2012)

I have ruined (as no doubt many others have) a few tubes/blanks purely by drilling the wrong sized holes. Make it too tight and the tube gets half way and sticks.

Measure the tube, then make it fractionally larger seems to work for me, especially in acrylics and harder woods.

Cant remember which pen kit it was but I have a bit which I ended up grinding down a touch to reduce the diameter.


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## Hesh (2 May 2012)

Thanks Hitch, pen kits and various drill bits have now arrived so now all I need is the time to get into the workshop to go through all of the suggestions. I've turned pens before but whilst I dont mind making mistakes with the standard slimline pens I want to give myself every opportunity to get the more expensive kits right.

I'll let you know how I get on.

regards


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## Hesh (17 May 2012)

Thought I'd post the result of my first attempt with a reasonable kit which is a Gatsby from pencrafts, also the first time using an acrylic blank (woodland camoflage). The advice re drill sizes came in handy as although I used the "correct size" the bushings I bought with the kit didnt fit the tube so I had to ream the inside of the tube with a small spindle gouge.......... The blank was sanded with micromesh down to 12000 which made it glass like in appearence. The pen is a gift for my brother so no prizes for guessing what he does for a living. Anyway C&C welcome as always.

Regards

Steve


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## nev (17 May 2012)

=D> a good looking pen Steve. very masculine.
and well photographed too.


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