Opening the Bit

I believe needle files are what you're looking for.

I have a set I used to do the very same and I got them at Home Depot

I used to take apart the pipe, and very carefully (slowww!) run a 5/32 drill bit through the shank into the bowl. And then through the mortice to the mouth bit. Depending on how thick your mouth stem is, maybe go a size less than 5/32nd... needle files to make the round hole a bit more oval at the mouth end. You may not want to try this unless you've got a bit of tool experience, but it's not too hard.
I've improved some low end pipes dramaticly that way (for my likes.)
Also only works on straight pipes, heh! I'd leave it to a professional if it is a bent pipe.

Sorry - forgot - either use a drill press of some kind to spin your drill bit (slow as possible, ramrod straight), or do it very carefully by hand. I wouldn't use a hand drill - waaay too fast, far too easy for it to get out of alignment. One method is to put the drill bit into a bench vice, clamp it in there tight, and gently rotate and push the piece by hand.

The needle files mentions are great. I reshape or fix buttons and also open the draw and bit opening. They have been very useful tools.

However the bit is restricted. Is it really true that they make files small enough to get into a very small opening so as to sand it and obtain a more open draw?

Click to expand...

The files may take care of only part of the problem. You can open up the button end to make the slot deeper and wider,and if you're not very careful break the button.

The airway through the stem may be part of the problem. What size is it? How large is the tenon? Opening up the airway on a small tenon will make it thinner-and weaker. Also the airway in a lot of stems is not centered along the length. The stem can be thicker on one side than it is on the other.If you drill it out to much the drill can break through the top or bottom of the stem,usually within an inch or so of the button. You need to measure( with a caliper etc) the thickness of the stem,determine the size of the airway in it and subtract the airway OD from the thickness to determine how much material is there and how much you can open it up. You should measure the stem about 1/2" or so in front of the button,where it really starts to thin out.

I like to use a tapered 5/32" drill bit. The point tapers to about 1/16"-5/64" ( I forget exactly) but it is quite small. You should stop drilling when you reach the funnel and work on the slot and funnel with the files or a 1/16" drill bit in a Dremel.