Machsupport Forum
Mach Discussion => General Mach Discussion => Topic started by: Flipz01 on June 05, 2008, 08:04:10 PM

I have the angular shortest rotary on G0 set to "ON" in the General Config settings. That's fine, but I really need this on all the time.
For example, in the code below, I'm trying to cut a square that has two rounded corners. The Aaxis should follow and stay parallel to the cut. Direction is critical, so you can't substitute A90 for A270.
G0 X2.0000 Y0.0000 F600
G0 A180 F5000 (I put this on a separate line to speed it up)
M3 (Water On)
G1 X0.0000 F600
G0 A90 F5000
Y3.5000 F600
G2 X0.5000 Y4.0000 I0.5000 J3.5000 A0 (Instead of going from 90 to 0 over 90 deg.  this wants to do a 270 deg. arc)
G1 X3.5000
G2 X4.0000 Y3.5000 I3.5000 J3.5000 A270 (Instead of going from 0 to 270 over 90 deg.  this wants to do a 270 deg. arc)
G1 Y0.0000
G0 A180 F5000
X2.0000
M5 (Water Off)
G0 Z0.0000
M30
This small square must take 23 minutes to run because of the arcs. That's one problem, but the bigger one is how to get the arcs to work correctly without having to run everything CCW  that is A0 to A90 works, but A90 to A0 does not.

I tried this code  but I got a fault on line 6, (your first G2) " radius to end of arc differs from radius to start"
I altered the line to read G2 X0.5 Y4 R0.5 A0 and this ran, and as you say showed your second arc in the wrong direction
I altered the second line using R(radius) instead of I and J and it came up on the toolpath correctly.
I always use R instead of I an J, I find it much simpler. Minus R in the same lines would give you the dreaded rabbits ears.
Whether this now affects your A position, I wouldn't like to say

Many thanks. I changed my code as follows:
Note that I used NEGATIVE numbers for CW moves and this works in both the absolute arc center and radius offset examples.
Also, to get the speeds to work better, I set "Use Diameter for Feedrate" on the Toolpath Configuration screen, and set the Rotation Diameter to 0.1" on the Settings Page.
NOTE  The DXF I used is plsted below.
N5 (Posted with Water Only.pst)
N35 G0 X2.0000 Y0.0000 F600
G0 A180
N40 M3 (Water On)
N45 G1 X0.0000 F600
G0 A90 (This works because I have “shortest rotary for G0” turned on)
N50 G1 Y3.5000 F600
N55 G2 X0.5000 Y4.0000 R0.5 A0.0001 (Note – A0.0 turns the wrong way)
N60 G1 X3.5000
N65 G2 X4.0000 Y3.5000 R0.5 A270
N70 G1 Y0.0000
G0 A180 (This works because I have “shortest rotary for G0” turned on)
N75 G1 X2.0000
N80 M5 (Water Off)
N85 G0 Z0.0000
N90 M30
AND
N5 (Posted with Water Only.pst)
N35 G0 X2.0000 Y0.0000 F600
G0 A180
N40 M3 (Water On)
N45 G1 X4.0000 F600
G0 A90
N50 G1 Y3.5000 F600
N55 G3 X3.5000 Y4.0000 R0.5 A180
N60 G1 X0.5000
N65 G3 X0.0000 Y3.5000 R0.5 A270
N70 G1 Y0.0000
G0 A0
N75 G1 X2.0000
N80 M5 (Water Off)
N85 G0 Z0.0000
N90 M30
AND
N5 (Posted with Water Only.pst)
N10 G0 X3.0000 Y2.0000 A270
N15 M3 (Water On)
N20 G2 I2.0000 J2.0000 F500.00
N25 M5 (Water Off)
N30 G0 X4.0000 Y3.5000
N35 M3 (Water On)
N40 G1 Y0.0000
G0 A180
N45 G1 X0.0000
G0 A90
N50 G1 Y3.5000
N55 G2 X0.5000 Y4.0000 I0.5000 J3.5000 A0.0001
N60 G1 X3.5000
N65 G2 X4.0000 Y3.5000 I3.5000 J3.5000 A270
N70 M5 (Water Off)
N75 G0 Z0.0000
N80 M30

Hi, Flipz01
Do you have a drawing of this, You could post.
Chip