Re: Absolute vs Incremental 3D programming

Anthony wrote:
"John R. Carroll" <jcarroll@xxxxxxxxxxxxxxxxxxxxx> wrote in
news:QRLOf.37328$Jd.2790@xxxxxxxxxxxxxxxxxxxxxxxxxx:


Ok but wouldn't that be the case regardless.? The control has no way
of knowing where the machine is mechanically either way.
As far as I know ALL motion is an incremental vector consisting of a
length for the move and a velocity. The difference is in the math and
not the mechanics, or so I thought, unless you have set up an
absolute feed back loop to a mechanical encoder attached to the
machine tool, linear or not. If that isn't the case, how does the
machine know where it "really" is absent the supplemental feed back?

No matter, I'll ask around tomorrow when the headache I have now is
gone :>)



In absolute, the machine is checking itself against a fixed reference
point for each move (X0Y0Z0). In incremental mode, it doesn't care
about a fixed reference point, all it cares is that it moves X amount
in whatever direction you tell it from it's current position. Every
time it stops at the end of a motion in incremental mode, the current
position is the new 0 point for any future moves. So basically, you
have a new reference point at the beginning/end of every move the
control makes when in incremental mode.

That would explain something that's showing up in a test be I've got.
Ever see code that looks like this?

G90X0.Y-0.6936Z13.2294G91A0.B0.078F4233.141

--
John R. Carroll
Machining Solution Software, Inc.
Los Angeles San Francisco
www.machiningsolution.com


.

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