-------Original Message-------
Date: Sunday, June 02,
2002 09:15:44 AM
Subject: Re: Jog
wheel
>> >> Yours is a very common way of thinking about the
operation of a handwheel. >> It is more like the notion of the
joystick. From a service standpoint, I >>want the wheel to move
0.0100 when I command it to so that I can see axis >>
problems.
>>Ray,
>Ray, in incremental mode it
can do that, but in continious mode >it should stop when the wheel
stops turning.
>Bill
Bill,
I have never seen a wheel on a machine tool that opreates in
"continious mode". The purpose of a wheel is to quickly move to positions
without having to issue g-code commands, or to easily find the edge of a
part without having to (in EMC's case) press a key a bunch of times to jog
in .001 steps. If you want a continious mode, or feed mode aren't there
keys for that already, that continue to move as long as they are pressed?
Having used machine tools day in and day out for years, I guarantee you,
that a wheel that you have to keep spinning as long as you want the
machine to move, will quickly get tiring. Keys are much better for that
kind of motion.
I am more interested in how the machine will figure what speed it is
supposed to be moving at while the wheel is spinning? What kind of out of
position errors will be generated when it can't keep up with the commanded
position of the wheel? I have a feeling that current controllers actually
do two different things when keeping up with machine position, while using
wheels.
1. They keep track of the number of pulses, and move at a maximum
(fixed) rate.
2. They Immediately stop when the wheel stops, and ignore all stored
pulses. However, I think for this to work effectively you would need
feedback from encoders, to keep from losing track of position, unless
someone can think of a way.
Lamar |