First Time Cutting Tool Steel

[JohnLucas]

I'm reducing a section of 1/2" drill rod 2.4" long to 3/8" for a tee slot cutter. The stock is mounted in the chuck on rotary table and supported by tailstock.

First time I've cut drill rod and can't get a feed and speed that does not vibrate!I've tried (with a 1/4" HSS cutter):

- Cutting from above, using bottom of cutter, rotating 360 then shifting sideways
- As above but going end to end then 10 degree shifts (for roughing)
- Going end to end using side of cutter (Y axis to set depth of cut).

Calculated values at 1100 rpm of 6 in/min with a 0.01 cut.

Best results I can get are a 0.003" cut at 15 in/min and 1100 rpm but surface is still rough and light vibration while cutting. I tried other speeds and any deeper cuts just make it worse. Cutting using the side of the mill seems best but I'd really appreciate some advice from others who may have tried this.

Thanks

[neilw20]

A carbide cutter will work much better.
Have you thought of mounting the drill rod in the spindle, and mounting a tool in a vice and using the mill for a lathe?

[JohnLucas]

Thanks. I'll get a carbide cutter on weekend. Did consider vertical lathe but no way to hold 1/2" stock.

[JohnLucas]

Carbide cutter definetly helped. Still some minor chatter so am experimenting with feed rate. Much better than before. Thanks.

[BobWarfield]

John, are you able to see the chatter marks on the workpiece?

If you can see them well enough to measure the distance between them, you can use the chatter pitch calculator in G-Wizard to figure the optimal spindle speed to minimize the chatter.

Best,

Bob Warfield