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No Kevin I wasn't aware, I'll have to go do some
'googlein' and check it out. CNC has come a long way from the good ol'
days of punch cards and reel tapes :-) While its nothing in comparison to
McDonnell, the control I'm using on my machine runs at over 4Mhz per axis,
that doesn't sound like much when we have comp's running in the Ghz but,
thats 4 MILLION resolved position calculations and movement commands per
second.The tool will pass through 12 million resolved points per second at full
rate [when runing 3 axis at full rate and can drive up to 6 axis at this
rate if desired] I don't ever plan to run it that fast or to that high of a
command rate as its not needed in my case. As you'd stated machining a huge
titanium bulkhead would need a higher performance system which can hit these
resolutions and stop if an error is found. I have no idea what Titanium is
worth, but I'm sure I don't want to have to foot the bill for a buggered up
part :-). The gantry on my mill isn't that heavy, its only about 3/4 ton but
that was enough :-) moving stuff like that around in your own shop w/ little to
no heavy lifting gear can be a challange for sure. A twin gantry mill would sure
be a site to see, I can't imagine writing the code for that, even w/ a proper
CAM. It's always exciting to hear of others who have done the same thing and had
success.
Thanks!
Jarrett
----- Original Message -----
Sent: Wednesday, January 31, 2007 8:50
PM
Subject: [FlyRotary] gantry mill
Jarret - when I worked at McDonnell-Douglas
they had a twin gantry mill. the bed was like 40', but the newer
fighters had no pieces over 15' so they added another mill. the gantries
were huge, weighing many tons. a secondary, independent computer would
run while parts were being milled, checking for any errors (not good on say
titanium bulkheads that take 2 months to mill). if it detected an error
it could shut the gantry down within less than thousandths of an inch.
they told me that it sounded like an explosion when all that tonnage hit the
wall. these machines had footings the volume of a 2 car
garage.
I was in the home built soaring club for a
while. there was a man building a plug doing exactly what you
outlined. he was connected with a university and used their
equipment. maybe his plane is the "lighthawk" I believe? he was
proud of his ability to produce many parts that all fit to tight
tolerances. I didn't know if you were aware of this project.
kevin
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