Steel grade to be used to make a spindle?

[rnr107]

Hi all,
I am in the process of making a small indexer (4th axes for my CNC mill).
And I have not much experience in metalurgy...
So, my question is: What grade of steel would you use to make the spindle?

I must be able to machine it with a nice smooth finish (for bearing mount) on a lathe as I don't have access to any cylindrical grinders.

Ta,
Laurent

[Geof]

1045 or any medium carbon steel would be fine. Problem is these can be difficult to machine on a small lathe, at least to get a good finish. Your best approach would be to turn the bearing sizes about 0.001" to 0.002" oversize and then carefully finish them to size with a fine file and emery cloth. It will take several miuntes and you need to creep up on the final size gradually because you need a tolerance of 0.0005" or so.

Take care not to get hung up on a spinning chuck with either the file, the emery or the sleeve of your shirt and only run at 200 or 300 rpm for the filing and polishing.

[keebler303]

I've never finished it but I started a spindle from 4140 Prehard. I was using a small atlas bench lathe. I was using carbide and it produced a great finish but I could only cut 5-10 thou at a time due to the limited power available.

Matt

[rnr107]

Hi Geof, keebler303,
Thank you for the replies! :-)
What about the inner bore? Would it be do-able?

Ta,
Laurent

[TOTALLYRC]

Hi Geof, keebler303,
Thank you for the replies! :-)
What about the inner bore? Would it be do-able?

Ta,
Laurent

Hi Laurent,
the inner bore should be very doable. When I have had to do bearing fits both internal and external the key is as, Geof says, is to sneak up on the final size with some emery cloth and patience. Just take your time and make sure you don't sand it as a taper. If you have never done this before it may be worth while to practice on a test piece or two.

Mike

[rnr107]

Thanks Mike! Time is not an issue... :-) Even if it takes me a month, that's fine... :-)