Machinest help for Brass?

[Al_The_Man]

I am working on a project for a customer that requires a qty of particular electrical terminations.
The existing ones are 6mm brass with a 2mm dia copper pin x 15mm, fitted to a drilled hole in the end and silver soldered.
I am wondering on the viability of turning this pin down from the 6mm?
I know the brass is going to be a bit more brittle than the copper pin, but It would seem to be a bit more efficient to make, if this is deemed possible?
Whats the consenus?
Al.

[Geof]

Turning 6mm down to 2mm x 15mm long?

That could be a tricky one; what is the tolerance on the 2mm? You may be able to get away with it by going from 6 down to 2 in one cut with a very sharp tool. Taking a finishing cut on the 2mm dia will probably result in a lot of taper due to deflection; 15mm is 7-1/2 x diameter which is a large ratio.

Do you have a CNC mill? I have done something similar to this on Delrin where I took 5/16" diameter down to 1/8" over a length of 3/4" by holding it vertical and interpolating around it. It was even possible to use a 0.015" corner radius cutter to leave a radius at the transition for fatigue proofing; totally impossible when turning.

It was also quicker than turning because I clamped several lengths in soft jaws per machine load.

EDIT:

If you have to turn and the length of the 6mm is short, to reduce deflection when turning it to 2mm in a single pass start with a larger size. Use 10mm, turn the 2mm in one pass then turn the 6mm. This way you may be able to get away with using a tool with a bit of nose radius to get away from a sharp corner at the transition.

Incidentally brass needs zero top rake.

[Al_The_Man]

Thanks for the input, I do have a CNC knee mill, which I could try.
Unfortunately I have to use the 6mm as it is already 6mm threaded studs.
I do have a rapid change collet chuck on the Lathe.
Al.

[Geof]

Originally Posted by Al_The_Man I have to use the 6mm as it is already 6mm threaded studs....Al.

How many are you making?

Are you familiar with what is called a Box Tool?

This is a tool holder which incorporates a travelling steady to prevent deflection of the part being turned. The steady can support the material either ahead of the tool or following the tool.

If you have the prospect of doing a lot of these parts, hundreds or many hundreds, and you have a four place toolpost it could be worthwhile making a setup that works like a box tool. The 'steady' can simply be a 2mm hole in a piece of steel that is held in the front slot on the toolpost; the tool is held in the side slot.

Because the steady hole has to stay on center you cannot adjust the size by moving the cross slide so you have to adjust the position of the tool in the toolpost. Alternatively you can make a little subsidiary tool holder that clamps in the toolpost and which has a slot for the turning tool and a setscrew for adjustment.

If you are interested I could make a sketch if this description is too obtuse.

[Al_The_Man]

Thanks Geoff, I only have a few score to do, so at this point I won't invest too much time,
I now have the general idea it may be viable, and I guess I will try a few first and see how it goes.
Thanks for the input.
If I run into numbers later, I may ask you for the sketch.
Al.