Letter O bit alternative

[ToddMR]

So looking at a chart Letter O bit = 0.3160 and 5/16 = 0.3125, so I am curious if I could use 5/16 bit on a kit requiring the letter O bit since the 5/16 is 4 thousandths of an inch smaller roughly. I would think that small of a difference wouldn't hurt. I am going to attempt on scrap first, but thought I would ask here when searching didn't turn anything up.

 

[Russianwolf]

Todd, I don't follow directions any more. I use my calipers to measure the tube, then find the appropriate bit. Given that,

Drill the hole in a piece of scrap, you want the tube to slide freely in and out of the hole but not wiggle around a lot.

 

[mrcook4570]

I use 8mm and O, whichever I happen to locate first. The 5/16 may work - test in scrap first.

If you are making only one of a style that calls for a drill size different than what you have, you can always use a size that you have that is just slightly smaller than necessary. Then use a file or dowel wrapped in sandpaper to enlarge the hole. Just be careful to file the hole evenly, or you will get an elliptical hole. I would not attempt this for multiple pens, but for a single pen as an experiment, sure.

 

[Andrew Arndts]

If you ain't cheatin', you ain't tryin'... Good luck and report back.

 

[Monty]

Todd, I don't follow directions any more. I use my calipers to measure the tube, then find the appropriate bit. Given that,

Drill the hole in a piece of scrap, you want the tube to slide freely in and out of the hole but not wiggle around a lot.

Ditto.
I've found that the "recommended" bit is not always the best fit.

 

[LarryDNJR]

You can borrow my O bit if need be.

 

[ldb2000]

If the kit is calling for an O bit , the 5/16" is going to be a little tight . The 8mm kits that I have done that required an O bit use very close to a 5/16" tube so a 5/16" bit won't work without some sanding of the hole .

 

[Polarys425]

What pen kit is this for? I remember subing a bit for a pen kit, and cant remember which one. Letter O sounds familiar.

 

[ToddMR]

Yeah we will probably just borrow Larry's bit. I know I have used some other bit on other ones. This is for the classic American ball point from WC.

 

[randyrls]

I have a loose leaf notebook with the instructions for every pen style I have ever made. I write the size bit I used on the instructions. Sometimes not the same as the printed instructions.

I often drill a blank with an undersized bit. Keep the blank in the vise, lathe, etc and test the fit with the tube. If necessary, use the next larger bit.

The instructions often specify a larger bit then needed, and use the next larger commonly available drill bit size.