4130 Tubing as Cylinder Liner

[gmac]

I'm looking for ways to reduce the amount of boring when making cylinder liners (nominally 0.75 in ID; 1.00 in OD) and 2.0 to 3.0 inches long on my Taig lathe. I have easy access to chrome moly tubing 4130 that I'd like to try.

So two questions;
a. how easily does 4130 machine with HSS toolbits? Recommended lubricants?
B. how do you mount the tubing to machine the outside surface and bore the inside diameter? Especially given that the thru hole on the Taig is only 3/8" and the chuck must support/align the tube. Fixed steady, travelling steady, 3 Jaw chuck, four jaw chuck...? Any tricks, tips?

I need a more rigid boring bar setup before I consider boring solid steel rounds (boring the AL pistons was time consuming, the liners will be three times as deep), until then I'll try light cuts on tubing to build my first engine. As always this noob appreciates any and all comments/recommendations.

Thanks
Garry

 

[jack404]

Gary

4130 4140

use carbide not HSS for better finish and workability

lube i use a suds dispencer with sol. oil and Mobil brand cutting fluid ( label fell off so i forget the exact name)

Garry with larger tube sizes i use a pipe tail in the tail stock mount the tube in the chuck but i use a bent leg lathe dog to hold it and the section i clamp, I DONT USE . ( thin wall chrome moly still buckles)

but i'm working shotgun and rifle barrels generally so my rule is never use what you clamp hard

love it or leave it its my workshop so my rules feel free to disregard stuff i do but do watch out how much pressure you put on CM or any of the 41XX mixes of steel

it will flex a bit but then crack and because the metal is finer than usual the cracks are tiny and hard to see

4130 tube is great material to work heat treat etc but do be careful how much pressure you clamp it with if the thing is to take pressures later..

cheers

jack

 

[gmac]

Jack;
Good to hear from you again. Would you suggest HSS for the roughing cuts then carbide or go at it completely with carbide? I only have a few carbide toolbits but enough to do the job - two or three brazed bits and two new insert type - I've stuck with the HSS so far trying to learn the art of grinding HSS, getting the angles and all.

I've got a picture in my mind of your setup, but I'll have to research "pipe tail in the tailstock". As for diameters I don't see myself going beyond 1.25 inch (32mm) but I'll keep your comments on wall strength in mind.

And I'm assuming you're generally working with normalized 4130 at the machining stage(?).

Thanks Jack.

Garry
(watching the snow come down...)

 

[jack404]

Garry

actually i dont mostly, and never on barrels

why? treating 4130 and keeping it as it was is awful hard, it can and does warp

i've gotta build a induction heating system to allow me to do this without warping everything when its treated

actions and housings i anneal but barrels i cant .... they are never as straight as theyre supposed to be afterwards, actions and housings are bigger so i can slip a stabilizer into them ( stops the warpage)

i've used Valenite inserts for years

i just got a new set of tools from LMS for the mini lathe

i do know folks who use HSS on chrome moly but few and far between

the chrome part gives it away chrome being harder than HSS, its hard on HSS tools expect to resharpen them often.

for years i did all work with brazed ( chinese indian etc) carbide bits and did ok with them as a whole

but once i got indexable bits i rarely went back

i use pretty much all carbide tooling for steel ( hard stuff ) and leave the HSS for the ALU and brass
and mild steel

if your annealing the steel first, HSS should do ok,
( to be honest i forget its been that long since i played silly bugger experiments)

but i'll ask others to chip in on that ..

i have one unused bit of HSST ( extra hard cutting tool steel for Oz standards) left free

its 3/8" x 3 " if you want it, say so, i'll send it over, this stuff did ok on chrome moly back before i got the valenite tips

pipe tail is my term for a pipe centre it fits like a live centre or dead centre in your tails stock but has a cone on the front that centres in the pipe/tube. i got a set in 1" 2" and 3" for $36 a while back for the yellow lathe

excuse my uneducated ramblings, terminology catches me often

cheers

jack

 

[gmac]

Jack;
Thanks for the offer of the HSST bit - but at 3/8" it's too large for my Taig. I'll start by using HSS (for the education!) and switch to the inserts, see how it goes. First priority will be to made some good sturdy boring bars.... ;D
regards and many thanks
Garry