Re: [CAD_CAM_EDM_DRO] Re: I need some feedback on using wire rope for driving...

In a message dated 12/12/2007 9:41:27 A.M. Eastern Standard Time,
dave_mucha@... writes:

For a long table you could use an ACME screw between a couple pillow
blocks. pretty easy. one double angle bearing to eliminate axial play.

the screw, say, 1" dia will move the table 3.14159" per revolution.
that means you need one thread for every 3.14159 inches of table
movement plus a few more for the wraps.

5 wraps and 10 thread gives you about 30 inches of movement.

At 5 TPI, that is 3 inches of screw. For 120 inches of table movement
that is about 15 inches of screw. The screw would not bend appreciably
at 15 inches between the bearings because it is so short.

The wire needs to be able to bend at slightly less than the radius of
the screw.

A ball screw over 48 inches will be very expensive because it has to be
so large of a diameter.

For giggles, the wire drive should take an afternoon and cost less
than $100.

I plan on doing one as a means to test a long axis. I have looked at
this as a simple way to move an axis and the only drawback is that it
would go in the center of the axis. Great if you have a moving gantry
and the drive is under the table.

Dave



I must be missing something here. The diameter of the screw would have some
effect on the travel per revolution of the screw but the distance traveled
would be controlled by the pitch of the thread. For instance, if you have a
screw that is one inch in diameter but has a thread pitch of 5 TPI, then the
table would move 1/5 of an inch with each complete revolution of the screw.
Also, how could you have 120 inches of table travel with only 15" of screw
length. The table couldn't travel more than 15" before it hits the end of the
screw. As I said, maybe I am missing something but the ball screw has to be
at least as long as the table travel plus allowing for the nut and some extra
at each end.

Randy A.

I furnish technical support, repair, and other related services for your
industrial woodworking machinery. My background as Senior Service Engineer for
the SCMI Group for nearly fifteen years with factory training, combines with
my extensive background in electronics, mechanics, pneumatics, electrical and
CNC machinery to offer you needed support for your machinery.




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