Yeah I wondered about that. I initially tried it with positive and with it at
machine zero still moved up 2" and then back down again. Totally contrary to
logical since my machine zero is furthest from the tool and any motion towards
the tool should be negative?
Thanks
John
> -Original
That's exactly the behavior that g28 follows on industrial controls. Try
g28z2. (positive) and it'll move up without having to switch to incremental
Phil T.
The Feral Engineer
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Fanuc g code system a is for lathes. Some will use system b or c but it's
few and far between. Some emco lathes use system c, that much i do know.
You can change g code systems via parameter on most generation fanuc
controls from the last 20+ years
I'd actually like to figure a way to get
In effect the G91 incremental with a Z0 just cancels out the initial move to
the Z position.
I did try it on the mill as
G28 Z-2
All that really happens is the machine sounds like it stumbles as it heads
toward Z0 stopping briefly at Z-2.
Very strange.
John
> -Original Message-
>
I'm pretty sure all of our Fanuc machines use G91 for incremental G28 commands
and not U V W. (maybe some older Fanuc controls or controls specialized for
some manufacturers or maybe just T-series, I only have worked with Ms.)
But as to why the intermediate command, I have no idea, It's just
Make it in metal, truncate the teeth to have a larger bearing area. Pack it
with the grease used in front drive car axle joints. Wrap it in a flexible boot
with a rotary bushing and shaft seal around the rod connected to the sphere.
There you have a hip or shoulder joint for robots, with no need
A new kind of 3-dof spherical drive. This would work well for holding
parts in a mill. It would allow 6-axis work on any standard 3-axis
machine. The device would be easy to 3D print but very hard to make
precise.
What if the ball were 6" in diameter and made of hard steel?
Ah. Ok. I'll try that to see what happens on my system. Sent from my Samsung
S10
Original message From: Feral Engineer
Date: 2021-06-25 10:36 a.m. (GMT-08:00) To:
"Enhanced Machine Controller (EMC)" Subject:
Re: [Emc-users] G28 behaviour So generally speaking, there are a
So generally speaking, there are a few differences between g28 and g53. On
fanuc and mits controls, g53 is merely machine coordinate position, you can
put g53 anywhere in the stroke of axis travel. G28 is reference return
position 1, g30 is reference return 2, g30 p3 is position 3, g30 p4
position
Thanks for the explanation but I'm still curious why the intermediate point.
I suppose if I had a tool changer at the machine 0,0,0 position (or close to
that) and my A axis sitting on the left of the work I'd want to move to a
position that allows a clear path directly to the tool changer.
G28 is a return to reference using an intermediate point
G90 G28 z0 would bring the tool to absolute Z0 before returning to
reference zero (machine zero in most cases). By using g91 g28 z0, you
specify that the intermediate point is your current position and the
machine will reference return from
A friend who uses MACH3 and Fusion360 (free version) found that every G-Code
file created by Fusion for the MACH environment added:
G28 G91 Z0
G90
G28 G91 X0 Y0
G90
He's since figured out how to tell Fusion not to do this but looking at:
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