here's a funny thing...

[medusa]

… you can buy joint tube which is 4.75mm diameter, but it seems almost futile to search for joint files (or chenier or parallel round files) in the same size to make a seat for the tube. The closest are round files that are 3/16" which is slightly too large. Would a better way to approach it be to get to 4mm and then use a twist drill as a kind of hand file?

Or am I being too OCD about it?

[CJ57]

Is there not a round needle file in your set, I've picked up various thicknesses over the years, or there is a needle file that is rectangular but only has the file on the outside edges, that's good for grooves

[Dennis]

Using this conversion Liz there is no practical difference: http://www.metric-conversions.org/le...illimeters.htm.

You would be best though to use a saw cut, a scorer, and/or triangular/square files to start, because round files wander and tend to enlarge your groove. Dennis.

[CJ57]

There is a technique to using round needle files I find and it you start the cut with the sharpest end and then work into it further up the file that stops it from wandering. I do a lot of carving with a round file.

[medusa]

Is there not a round needle file in your set, I've picked up various thicknesses over the years, or there is a needle file that is rectangular but only has the file on the outside edges, that's good for grooves

nothing that big. I clearly need to spend money on more tools. Oh noes!

Using this conversion Liz there is no practical difference: http://www.metric-conversions.org/le...illimeters.htm.

You would be best though to use a saw cut, a scorer, and/or triangular/square files to start, because round files wander and tend to enlarge your groove. Dennis.

There is a technique to using round needle files I find and it you start the cut with the sharpest end and then work into it further up the file that stops it from wandering. I do a lot of carving with a round file.

ahh, ok both, that is really good advice. I'm working up to it!

[CJ57]

Unfortunately that file that I mentioned rectangular with smooth front and back and only file along the outside edges , I know very technical! Anyway it doesn't seem to be available anywhere which is a shame because it's great for straight channels. It either came in my set 30 years ago or I inherited it from a friend who was a machinist .