Drill Sizes

[bonefish]

Instead of highjacking the other thread about drill bits, I will start another one.

I made the comment that my drills in 1/64 inch increments are good enough. I think they are for any kit that I have used so far. I have never tried one of the expensive kits. Probably, if I did, and the drill I had was not the correct size, I would purchase the correct size.

I am not trying to start an argument. The point I am trying to make is who decides which drill is too large or too small, or put another way, who decided which is the right size and which is the wrong size.

A 1/64 increment is .0156 in. Remember, the drill is round, so that means that the hole will only be half of .0156 or .0078 larger on each side. A human hair is about .003.

I still don't think this additional .0078 in. + or - clearance on each side of the tube matters that much. That needs correcting. If it is minus, then the tube won't go in the hole.

A drilled hole will vary more than that in different types of wood or even the same wood with different grain structure and moisture content.

When you drill a hole with a drill press and drill bit, then use glue to hold the part in the hole, you ain't making Rolex watches.

There was something on here recently about the recommended drill size was the wrong size with a certain pen kit, so who knows what the correct size is supposed to be? Should the tube be a snug fit, or a loose fit and the clearence filled with glue?

Something else, if the tube is a loose fit and you cover it with glue, and also coat the drilled hole with glue, the tube is not going to be dead center of the hole when the glue dries, unless you use some type of precision centering jig.

I would like to know the exact size gap necessary for the strongest bond with the glue you are using, but I don't know how to find out.

Comments?

Bonefish

 

[Geo in Winnipeg]

I have absolutely no idea what the "correct" size hole is for any given pen or who determines it.
I start out by using the recommended drill size (if I have it) on scrap if I've never made the kit before. If the tube falls freely through the hole (and is not real sloppy) in the "test blank" I'm happy. If it feels tight or sticks at all I'll make the hole slightly larger. Once I find the drill that works best for ME I note the size on the instruction sheet for the kit which I keep in a 3 ring binder.
I use epoxy which is gap filling and this works for me. I've never had a glue joint fail. I don't use CA so I don't know how "snug" the tube needs to be.
You'll note the technical terminology and precise measuring I do []

 

[ctEaglesc]

Most of the markings on my bits have been obliterated by the jaws of my JAcobs chucks.
I "eyeball" the bit against the end of the tube.If it looks"close enough" I use it.
When in doubt I "Mic" the bit and the tube.
I have used "reccomended bits for certain kits(paid ridiculous prices) and the bit tube did not fit in the hole.
As I have said before, this aint rocket science.

 

[leehljp]

I have the HF set that has fractions, Letters and numbered 1-60. IIRC, the lettered ones do not go past (nearly) 1/2 inch and the numbered ones are smaller. There have been a couple of times that I chose a lettered set over a recommended fraction. One time I did not like my choice as it was a tad too tight in fitting. I also have metric in .5 mm sizes and a few in .2 mm sizes. (expensive and hard to find.)

Bonefish: A 1/64 increment is .0156 in. Remember, the drill is round, so that means that the hole will only be half of .0156 or .0078 larger on each side.

That does not necessarily hold true as the tube will settle to one side, or possibly catewampus. I notice the space, when using CA, and notice that it is not centered. Not such a problem with epoxy or GG. In the case of CA, you can have .0156 / 1/64 all to one side and for some people that will be very noticable. When I do have space like that, and I do with Sierra tubes, I use epoxy for the gap. I prefer a little tighter fit. But the next size down in my metric or letters (forget which) is too snug. Fits, but too snug.

 

[bonefish]

Hank:

I don't know how to use italics, but this was in the original post. Don't know whether you noticed it or not.

That is the primary reason that I prefer the thick and slow drying epoxy.

"Something else, if the tube is a loose fit and you cover it with glue, and also coat the drilled hole with glue, the tube is not going to be dead center of the hole when the glue dries, unless you use some type of precision centering jig."

Bonefish

 

[leehljp]

Bonefish,

Apologies. I did not read the original post. Your concerns are mine also. That is why I look for bits in (point) .X mm size increments when in specialty tool shops. Usually $20.00 each and with 5 to be had per mm size, it can add up. After the 5 mm size, most shops only offer .5 mm increments.

Over here in Japan we have a rubbery/flexible epoxy that I use for gap filing at times. I like it but it takes about 3 hours to harden enough to use.