On Mon, 19 Aug 2013 08:10:54 -0400, Joe AutoDrill
wrote:

On 8/15/2013 1:21 AM, PrecisionmachinisT wrote:
In either caser, Sfm (rpm) is dependent mostly on material and tool
diameter; (or workpiece diameter if turning)....

--tapping is typically done at slower than the optimum rate mostly because
of machine/ operator/ cnc controller restraints.

That said, drilling at a moderately reduced rate typically causes no
objectionable results other than perhaps a slightly higher per-hole
cost...(oftentimes this balances out into the positive since this all
involves having to actually calculate cutting tool cost proper, labor cost
to replace said tool, downtime, and so forth)

As they shout in Catholic churches... BINGO!

If the customer isn't in a rush, the slower tapping RPM can usually be
used for the drilling process with no negative side effects.

If you add in the scrapping or rework costs every time you break off a
tap inside a part - either the cost to dig it out and save it, or to
scrap the half-done part...

Slowing down the feeds and speeds a little, using a proper tapping
head that will clutch out before breaking the tap when it jams, being
proactive in changing the tapping tool for a sharp one at the first
signs of sticking or tripping the clutch on less than a full stroke,
and using proper lubricant and cooling... will pay off big-time.

Unless you're in the business of making scrap metal - most people I
know only get paid for shipping the finished good ones to the
customer. The bad ones are a waste of both good materials and time.