proper steel for impact tool ?

[yf]

I need to make a replacement piston for an elctropneumatic hammer. This piston is the one that travels back and forth and hits the tappet. Would the steel from a shock absorber shaft be suitable or the steel from a scrapped pavement breaker chisel.
Thanks in advance.

[SGW]

Just guessing, I doubt the shock absorber shaft would work, but the chisel steel certainly ought to. I bet it will be no joy to machine, though.


[This message has been edited by SGW (edited 01-03-2003).]

[spope14]

Back in college we made some real neat chisels out of shock absorber steel. The machining may be hard to do, but could be done slow and with oils and such. Carbides.

Our chisels were forged things, but I turned a little end on mine, and it did work. Still have it 16 years later, and it is the best chisel in my box.

Might try O-1 Drill rods if you have the chance, they make good impact tools. Cut fairly easy, and when done, heat it to a dull to medium red, and quench in oil. Draw down anneal with flame after polishing the piece. I polish so I can see the color change in the metal as I touch it up with the torch, and make the steel from bright to a brown then blue color.

Just the oil quench will make the part brittle, thus the drawing and annealing to add the toughness.

This is what I make center punches out of, they all work with this process.

[yf]

Thanks for the replies.

If I try a shock absorber shaft. What should I quench in, water, brine, oil?
How about a chisel steel?

Thanks

[Thrud]

yf:
I would use the pavement chisel. Obviously it is already used for nearly the same purpose that you have in mind.

Or use 4130 case harden and temper twice (double tempering makes the tool more durable - common with high impact tools.

[yf]

Thanks for the replies. I will try the chisel steel, temper twice and maybe freeze it after.

[yf]

OK I made the piston from a breaker steel
Not the easiest turning to do on a Taig.
It helps to have a real chuck. The taig chuck can't be tightened enough.

Tomorrow (or today? ) I plan on heat treating it. I plan on useing the OA cutting torch. Then a propane torch to temper.
Anyone have any tips or suggestions as to what to quench in? oil brine water soap suds etc.?

This part has a ring groove about .125" from one end. Should I worry about cracking because of the thin section?

Thanks for all the help.

[Thrud]

Yf
Hot oil.

Install a sacrificial snap ring on it and remove after tempering is done.



[This message has been edited by Thrud (edited 01-08-2003).]

[yf]

Thanks Dave.

I wouldn't want to have to make another one on the Taig. I don't have the Troglia set up yet.

BTW the breaker steels machine nicely with HSS once the outer layer is removed with carbide. Use lots of oil, make a blue chip and when it starts sparking, resharpen