On Feb 16, 10:58*pm, GeoLane at PTD dot NET GeoLane at PTD dot NET
wrote:
What depth of cut is safe to take with a HSS end mill of 1/8" dia, and
how fast can you feed in mild stee without breaking or quickly dulling
the end milll? *The ROT of that I'd read in a book years ago was 1/8th
of the end mill diameter as the depth of cut (0.015 for an 1/8" mill)

I don't have power feed, and have never had coolant, except flood
coolant (what a mess) the few times I ran the horizontal part of the
mill. *[1940s vintage Hardinge Universal horizontal mill with a
Bridgeport C head in the overarm hole for vertical milling - not very
rigid, but it's what I have] *Any technique to use to do hand feeding
of the table?


Most of the info already given is quite sound.

Some further thoughts...

If you're making a full-width slot with the cutter, use coolant to
remove chips. You need to remove those chips. If you don't get the
chips away from the cutter, you'll likely break the tool from the
chips jaming in the flutes of the cutter. Use a 2-flute endmill!

Make sure the machine is pretty tight (this is *always* important!).
If you can't tell, use an indicator on the table, and give the table a
good tug. If you can see more than perhaps a thou or two of play, you
should consider adjusting your gibs. If the machine isn't tight and
you change your grip or something, you run significant risk of
breaking the cutter. I typically snug the table lock until just before
the table won't move.

Always make sure to lock all the axes which aren't moving! You must
*always* do this! If you don't lock your axes, the cutting forces can
drag the axes enough to break the cutter (or at least start cutting
where you don't want to cut).

What you're attempting is pretty standard stuff and you really
shouldn't have trouble. Machining isn't magic, but it's also not very
tolerant of sloppiness either. If you don't follow standard
proceedures (like outlined above), you're never going to get
consistantly good results.

Good luck.

Regards,

Robin