# can I use an "X" size drill bit in place of a 10mm?



## sbwertz (Apr 6, 2017)

We don't have metric bits at the Center for the Blind.  Can I use an "X" size bit instead?  It will be a bit larger...or a 25/64 which is a bit smaller?


----------



## thewishman (Apr 7, 2017)

If the 25/64 works - go for it. The X is a decent substitute.


----------



## jttheclockman (Apr 7, 2017)

There is no written law as to the drill bit to be used. When a bit measurement is given in the instructions it is a suggestion because it was probably tested and works best. But there are woods that do not respond the same way as say acrylics or other type woods. You then either need to step up or down to get a better fit. If the tube fits in the hole with minimal play then it is fine. The use of epoxy can take up more differences than say med CA. It is also a reason people use Gorilla glue which I never liked. 

So when talking about letter bits and metric bits as opposed to a standard size bit the difference is so minimal just go ahead and make it work. How well the tube is stuck to the blank for turning and sanding purposes is the key factor.


----------



## dogcatcher (Apr 7, 2017)

I would try the 25/64, then wait a day to let the internal pressures of the wood adjust to the drilling and the heat of the drilling.   Some woods will do all kinds of things when the wood is let to sit overnight.  You have heated the wood when drilling, exposed the inside of the wood to air, and released the internal pressure of the solid piece of wood when you drilled that hole.


----------



## magpens (Apr 7, 2017)

I agree with others and would use the 25/64" drill bit as my first choice. 
Diameters, as you may know, are:

25/64 : 0.391"
10mm : 0.394"
X -bit : 0.397"

Brass tube : 0.385"

For a cigar pen kit ( which uses a 10mm tube ) the 25/64" bit is specified as an acceptable substitute for the 10mm drill bit on several instruction sheets I consulted.


----------



## Herb G (Apr 7, 2017)

dogcatcher said:


> I would try the 25/64, then wait a day to let the internal pressures of the wood adjust to the drilling and the heat of the drilling.   Some woods will do all kinds of things when the wood is let to sit overnight.  You have heated the wood when drilling, exposed the inside of the wood to air, and released the internal pressure of the solid piece of wood when you drilled that hole.



This is both true, and well written. I have noticed some oily exotic woods actually split when drilled & left overnight.
I had some Cocobolo explode once when drilling it.
I actually saw the wood bulge up before it popped like a balloon.

I have also made the mistake of gluing in a tube & waking up the next day to see it crushed because the wood swelled after being drilled.
Now I just drill it & leave it a couple of days before gluing in the tube.
Sometimes I have to re-drill the wood to get the tube in correctly.


----------



## stuckinohio (Apr 7, 2017)

I always use 25/64ths in place of 10mm.


----------



## randyrls (Apr 7, 2017)

As John T said.  There isn't any hard or fast rule to drill bit size.  When I start on a new style, I start with a drill bit that is too small and sneak up on the correct size.  I then write down that size on the instructions.  About half the time my size and the printed size are not the same.

The size on the instructions is the most COMMONLY available drill bit size, NOT the closest / best size.  

Many moons ago I got both a 115 piece set and a metric set of drill bits.  I sometimes find that an odd size bit (say 13.3mm) will fit best.

When drilling acrylics the hole will be larger than when drilling wood.  Go figure!


----------



## sbwertz (Apr 12, 2017)

Thank you all so much...that was the information I needed.  The 25/64 worked fine.


----------



## sbwertz (Apr 12, 2017)

randyrls said:


> As John T said.  There isn't any hard or fast rule to drill bit size.  When I start on a new style, I start with a drill bit that is too small and sneak up on the correct size.  I then write down that size on the instructions.  About half the time my size and the printed size are not the same.
> 
> The size on the instructions is the most COMMONLY available drill bit size, NOT the closest / best size.
> 
> ...



I bought them the 115 piece set when we first started, but have only a few metrics...7mm and a little set that goes from 1mm to 6.5mm.


----------

