How would you do it?

[JMA]

The chatter is a function of the piece whipping around though. If it was stiff enough to not have significant deflection, it wouldn’t be chattering? Those are related in my mind - am I thinking about it wrong?

When you turn a long tube supported only one the ends when cutting the middle section the cutting tool will tend to push the part away causeing the center part to end up a larger dia. then the ends. that is what I meant by deflection.

Chatter is a vibration usually caused by lack ragidity in the part or tooling.
I hope this clarifys what I was tying to say.

 

[dnellans]

When you turn a long tube supported only one the ends when cutting the middle section the cutting tool will tend to push the part away causeing the center part to end up a larger dia. then the ends. that is what I meant by deflection.

Chatter is a vibration usually caused by lack ragidity in the part or tooling.
I hope this clarifys what I was tying to say.

Yup I got ya - if the part is the thing deflecting, now its wiggling around which can only exacerbate chatter. If the toolpost or bed is deflecting, taper without chatter - I get what you mean and agree. With the amount of chatter.

This lathe had a fairly big twist set in the ways when I bought it and it took months for it to come out. I've got a 24 inch solid rod I take a couple thou off just to make sure its not still moving in mysterious ways. With the same setup (including insert) I can avoid chatter on that solid rod and get good taper number, I think this crap pipe metal is just too flimsy.

Will report back with how the multi-piecing of it goes.

 

[dnellans]

What od, id, length, and material do you want to finish with?

OD needs to be consistent, but isn't a dead nuts requirement because the bars (3 of them) are going to slip fit through two machined aluminum pieces on either end. I've yet to attempt the other piece of the puzzle, starting with this first to see if I could make the pipes. ID is totally irrelevant - its going to be passing water with no meaningful flow requirement. Material, for a home project is ideally as cheap as possible =)

 

[Steve morgan]

Yup I got ya - if the part is the thing deflecting, now its wiggling around which can only exacerbate chatter. If the toolpost or bed is deflecting, taper without chatter - I get what you mean and agree. With the amount of chatter.

This lathe had a fairly big twist set in the ways when I bought it and it took months for it to come out. I've got a 24 inch solid rod I take a couple thou off just to make sure its not still moving in mysterious ways. With the same setup (including insert) I can avoid chatter on that solid rod and get good taper number, I think this crap pipe metal is just too flimsy.

Will report back with how the multi-piecing of it goes.

Pipe is gummie. does not turn anything like dom tube.

 

[Dusty Stevens]

OD needs to be consistent, but isn't a dead nuts requirement because the bars (3 of them) are going to slip fit through two machined aluminum pieces on either end. I've yet to attempt the other piece of the puzzle, starting with this first to see if I could make the pipes. ID is totally irrelevant - its going to be passing water with no meaningful flow requirement. Material, for a home project is ideally as cheap as possible =)

How about just turning the ends that will fit into the machined alum?
One thing i can add is use a sharp hss bit not a carbide insert. The carbide likes to swage the material off where the hss actually cuts it