Re: Re: CNC division

> Date: Thu, 05 Apr 2001 15:52:20 -0700
> From: Alan Marconett KM6VV <KM6VV@...>
>Subject: Re: CNC division
>
>
>I'm not fully decided, but I THINK I'd rather not have the table "wrap
>around", I.E., I'll go from 300 deg to 400 deg, when I want to get
>around to 40 deg again. If I "wrap" a long rotary move to my 'Y' axis,
>it works this way. If I want to cut 3 threads, I would just go 360*3
>degrees.
>

The rotary axis is programmed in degrees and decimal degrees.
The same rules apply to this axis as to a linear axis. You must
use a system that 1) will respond to the increments that you need,
and 2) it must be accurate to more than that increment, and
3) It must repeat, or somehow compensate for backlash.

Just like a linear axis, the rotary axis can be programmed in
absolute or incremental. The direction of rotation is programmed
by the sign of the degrees. + movement is CCW and - is CW, looking
down from the + center line to the minus centerline. Some controllers
will not wind past 360, and must be reset at each full revolution.
Incremental will often fool this problem. Also some rotary axes, like
some of the Haas ones, must be unwound after doing up to about
6-10 revolutions.

Place head in spindle position, looking down at table, C axis
is + for CW and - for CCW, same for X axis & A degrees, and
Y axis and B degrees.

This is the standard, but some controllers use the W word(Ahha, EMC, Allen Bradley) in place
of the A,B, or C. You just have to know which you are using.


Best Regards, Fred Smith- IMService
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