Problem- milling Telescoping brass tubing

[jackie_burton@m]

I am having a problem with milling a slot in thin wall (.014) telescoping brass tubing. There is a .003 difference between the outside diameter of the inner tube and the inside diameter of the outer tube. They telescope perfectly before I cut the slots but stick afterwards. There is no problem with burrs so I can only assume that the tubing is being forced out of round by the milling process. Any thoughts on how to true the tubing afterwards or how to prevent this from happening?

[harryn]

A friend of mine made some thin wall parts out of brass. (hobby level, not pro machinist) He placed a wooden dowel rod sized to fit inside the tube first - then machined. It seemed to work well enough for his hobby work.

[LaserImage]

Fill it with water, freeze and machine - should work fine.

[jackie_burton@m]

Ok, as per previous response, I did try the wooden dowel approach. It didn't work. Maybe because the fit wasn't close enough.

Not sure if you are pulling my leg with the ice thing but I will try it for grins and giggles while waiting for clamps and tooling mandrel. Can't imaging someone doing it in production.

Anyway, thanks for taking the time to pass on your ideas.

[LaserImage]

Originally Posted by jackie_burton@m Not sure if you are pulling my leg with the ice thing but I will try it for grins and giggles while waiting for clamps and tooling mandrel. Can't imaging someone doing it in production.

I'm completely serious. I recently watched a Discovery show about brass musical instruments - they used that technique to bend brass tubes without deformation. I've never tried it and have no idea if it would work in your circumstances or not, but I thought it might be worth a try.

Gary

[jackie_burton@m]

Actually, that's kind of cool (pun intended). Thanks!

[ALLtra Mach]

In a production run, if small parts, have a cooler with dry ic to hold parts in.

[jackie_burton@m]

I will give it a try.