Hardened s-7 milling?

[Gary]

I have 50 5/16 s-7 pins about 58 to 60 rc that have a cross hole dia that is about .145 dia and needs to be .153. I was thinking of taking a tialn coated 1/8 dia endmill and cicle milling it out. What do you think. If anyone has any ideas or some s&f info that would really bail my arse out on this one thanks.

[Jammer™]

Wire or sinker EDM Machine, or Carbide reamers????

[fboike]

Depends on what your machine can do.

I would try starting at 300sfm @.001 per tooth

.001 step out. and increase from there.

[g huns]

Never tried in 58-60Rc. Put in lots of blind .159 holes circle/helix milling w/.125 tialn cutters, but I keep my s-7 between 50-54Rc. I'd try a 2 flute, I like niagaras plus they're cheap, and you'll need a few. I like to take a 1/8 stub length(from Mich. Mill #NA85436 $5.85 each) and clear it so it only has about 1/8 or less of flute and helix down .005 per revolution about 10K RPM. I use air blast for cooling. Good luck.

[Quickmike]

he holes are in the correct position and only need to be opened up they could be honed. Probably wouldn't take to long and wouldn't be tying up a cnc. I would estimate they could be honed out in 3 hrs. for all 50 pcs. This is with using the roughing stones then the finish stones prescribed by Sunnen on a Sunnen hone.

[betts]

Good point on the hone, if you have that available.

We mill in this situation, 1/8 high helix, or 3.5mm, if available. Drob it through and morph out taking a tenth or so at a time. Should go quick that way.

[Gary]

thanks for the help crazy busy right now so I didn't get to try anything till tonight. I milled one and it cut good. Ran at 9500 rpm and about 10ipm morph pocketing with .0005 steps. Now all I need to do is get a decent setup for locating that hole in the morning and I will be cranking. again thanks