Re: DIFFERENCE BETWEEN G90 & G91?

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Ok heres me reason for asking this question. I am using Kcam and when
I bring my table all the way back to where I want to start and zero
every thing out, the machine and the program. when I start the
program it never goes where it is suposse to go. If I stop it then
zero everything out It will work right. Go figure Im stumped! Let me
say that I dont have limit switchs on it yet and im not really sure
if it is homed right if that would make a differnce? But if I change
to incremantal g code it works right every time. Maybe im just to
french! LOL This is all new to me too. I built a machine and am tring
to learn something that none of my friends know so i just cant go ask
them or have them show me. Makes it alot harder to learn. Im sure im
not alone out there. LOL



-- In CAD_CAM_EDM_DRO@y..., "yethdear0" <yethdear0@y...> wrote:

> I got 2 cents!
>
> G91 is like giving driving directions:
> From here, go 3 blocks south, turn left and go 4 blocks to the

east.

> Turn right and go 1 more block south.
> All the moves are measured incrementally from the last point. The
> pain with this and machining is you have to start and stop at the
> same point. Kind of like going around the neighbor hood and ending

up

> exactly where you started from. If you don't do this right then as
> you repeat the run, you also stack the error. Say you went around

the

> neighborhood and you came back to the same point as you started but
> you missed it by 1 foot. Then do it again, now you are off 2 foot,
> then 3. Get the picture?
>
> G90 is like plotting points on a graph. All the points are measured
> from the exact same reference point and you can start and stop from
> any one point. The machine always remembers where your reference
> point is at so there is no getting lost. From an industry point of
> view, 99% of all my programming has been in G90 absolute. Most
> machines "wake" up in G90 mode.
>
> Happy Toolpaths!
>
>
>
> --- In CAD_CAM_EDM_DRO@y..., "woodknack" <wjdupont@h...> wrote:
> > What is the difference between G90 which is absolute mode and G91
> > which is incremental mode. Can someone break down what absolute
> mode
> > and incremental mode is. Its probably very simple, Im just very

new

> > to this.