Ti for shafts/piston?

[jtrout13]

Hi,

As I am building Elmer's Fancy engine (and really making it fancy by the way), I'd like to get opinions on using Titanium for shafts and pistons? I'd like to give machining it a try, and I have access to a good deal of it in the shop in various sizes.

What do you think?

 

[Dave G]

I've thought about it myself but haven't tried it yet. Ti has a tendency to gall from what I have been told. That's why I haven't tried it but who knows, give it a try, we may all learn something. Dave

 

[stevehuckss396]

I have used Ti for connecting rods. Use HSS and dont be afraid to take a heavy cut. I dont know if it will wear well as a shaft or piston. The way it cuts, I wouldn't try it myself.

 

[Chaffe]

Ive got a bit of 5 series titanium at home, we used to use quite a lot at my last place, not dissimilar to duplex to machine, very abrasive in my experience, but easy to get a good finish and size with. As for pistons, im not sure any benefits could be had. But for connecting rods and other stressed reciprocating parts you will struggle to beat its strength/lightweight properties.

 

[MachineTom]

I've made a number of pieces from Ti, you can feel the pressure needed to cut it when you crank in the cross feed. Making some .600-.700"D pieces 2K rpms gives a nice finish. Ti is a poor conductor of heat, any cut will make the Ti hot HOT. Chips come off red hot. For turning you will need a stiff lathe and some power. Cobalt drill bits work well, its tough on regular HSS bits, start with sharp bits, any dullness will lead quickly to problems, work hardening++

 

[kf2qd]

Ti for pistons may cause some problems with balancing. Most designs take the weight of the piston as a given and use it to balance the offset in the crank. It may also affect how smoothly the engine runs as the lower mass will have different acceleration characteristics as compared to a Cast Iron or Steel piston. If Ti is replacing aluminum it will probably not have that musch of an effect other than being harder to machine.

 

[precisionmetal]

I'd echo what others have said: probably not ideal for shafts, but excellent for other applications.

When machining, the most important thing is to NEVER NEVER dwell with the tool -- it will work harden almost instantly.

I've cut lots of it, but I cheat: I cut it in my wire edm machine where it cuts considerably quicker than steel.

 

[Omnimill]

Careful with turning commercially pure Titanium - twice I've had Ti swarf catch fire on my lathe ...

Vic.

 

[xpylonracer]

If you use for connecting rods be sure to bush the big and little ends, use phosphor bronze, titanium running on steel will gall and seize.
Emgee

 

[spuddevans]

Careful with turning commercially pure Titanium - twice I've had Ti swarf catch fire on my lathe ...

Vic.

I've had that too, it burns incredibly bright, you shouldnt look at the flame or you will be seeing spots for a few secs after.

Tim