On 2017-01-05, Tim Wescott wrote:
On Wed, 04 Jan 2017 23:58:56 +0000, DoN. Nichols wrote:

On 2017-01-04, wrote:
On Wed, 04 Jan 2017 10:39:49 -0500, Randy333
wrote:

[ ... ]

What am I missing? Is there a real use for a taper attachment on a CNC
lathe?

This depends on what kind of motors are on the axes, and what
resolution they are capable of. I've got an Emco-Maier Compact-5/CNC
which has stepper motors capable of either 0.01mm or 0.001" resolution
is pretty coarse when asked to cut a Morse taper. I tried a Morse No. 2
taper with it, and it was visibly stepped -- no need to even measure it.
(Remember, 0.001" cutter steps mean 0.002" diameter steps. And since
the machine's native steps were metric, some conversions are off enough
so a 0.002" step actually works out to be 0.003".

So -- yes, *that* machine could benefit from a taper attachment.

However, ones capable of significantly more resolution can
happily cut tapers with the program. This would likely include machines
doing micro-stepping, or machines with servos instead of steppers.

So -- it all depends, but a better CNC lathe would be preferred
to one with a taper attachment.

Interesting. It's a good argument for always building your control
systems with a resolution that's better than the precision of the
device. Had they done that their tapers may not have been _accurate_,
but they certainly would have had better surface finish.

Agreed. Granted, this machine was intended as a training
device, not a production machine. As such, it had accessories like a
tool turret, but was fairly small (5" swing, or 2.5" by UK standards.)
I guess that it was small to minimize the damage to people from a crash. :-)

So, I wonder if it would have been worthwhile to turn your taper, and
then run a whetstone over it to smooth it out on the lathe? It's kinda
redneck, but might work out well if you had a good touch (and a flat
whetstone).

Hmm ... maybe, with lots of protection for the ways before
getting something like that near it. I did not trust my ability to
do that precisely enough -- and at the time did not have female and male
taper gauges for a proper blueing check. So instead, I ordered some
blanks with the MT2 on one end, and about an inch and a half of 1"
cylinder soft to turn to needed shape on the other. Using those, I made
a pair of adaptors for some TapMatic heads to my drill press. (Both
required a threaded adaptor (two different sizes), which the CNC lathe
did do fine. And it is my go-to for metric threading, rather than
rebuild the geartrain of the 12x24" Clausing. :-)

Enjoy,
DoN.

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