Re: Help with Small Boring Bar
- From: D Murphy <spamto154@xxxxxxxxxxx>
- Date: 19 Jul 2008 00:18:29 GMT
JRWheels <jrwheels16@xxxxxxx> wrote in news:c1a3953c-8567-488d-96ae-
1d78c3ddb414@xxxxxxxxxxxxxxxxxxxxxxxxxxx:
This is for a True Life Test I'm going to be running and I need some
advice from the people who have done this or think they have the
answer anyway.
My question is when you have a CNC Lathe set to Metric Dimensioning,
will it truly give you smaller increment control than if you have it
in INCH dimensioning. I would think that 3 decimal places in Metric
Mode is calculating at a finer resolution than 4 decimal places in
INCH Mode.
The last week of July I am traveling to New York to help with a
project that has a .019" diameter hole drilled in it and needs a
profile (radius-undercut recess) machined .004" per side into it,
about 1/8" inside the bore. The neck diameter of this tool is around .
010" and actually has what looks to be a helical flute on it for chip
flow, if you can believe it or not.
I had Performance Micro Tool make some sample of a boring bar to
this. www.pmtnow.com is their website. If you want to see some really
small stuff check out the site and look at NANO TOOLS button on the
left side of the page.
So my question is when I want to take depths of cut in the tenths (.
0001") and feedrates possibly in millionths (.00001") can it be done
in either mode accurately?
Thanks for the help in advance, it's greatly appreciated.
It truly depends on the control and servo drive/motor system. I have a
machine in stock that has a 3" six jaw chuck that will run up to 15,000
rpm. The resolution of the machine is 0.01 micron. Or 0.00000039" if you
prefer Imperial.
Anyway, you have to consider spindle run out and vibration as well. On
the machine I'm talking about the spindle is better than 4 millionths.
The chuck is a balloon chuck and is built in with no actuator to
influence or vibrate the spindle.
The machine has nano interpolation. So the "pulses" or the minimum
increment the servo motors are interpolated at is a nanometer (a
billionth of a meter). With this set up there really would be zero
difference between metric input or "inch" input.
Not knowing the machine, control, etc. it's hard to say for sure. If it
is a late model Fanuc with nano interpolation or HRV control there is
zero difference.
If it doesn't work out on the machine the customer has, I would be happy
to arrange for you to use our demo machine for testing. With this set up
there is as close to zero influence on the results from the machine tool
as you can get.
--
Dan
CNC Videos - <http://tinyurl.com/yzdt6d>
.
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