"Radius to end of arc differs" problems !

[Geetar-ist]

Hi to all the g-code buffs, I really hope you can help on this one.

I make guitars and many of my drawings are very similar with only slight differences.
I have a problem with routing a pocket which I rout all the time in my other g-codes (guitars) the pocket is identical and indentiacally machined etc.

I get the "radius to end of arc differs to start on line #xxx"

if I remove the line below in bold then the code is happy and will load properly, the last line in italics is the problem line.

I have done all the usual remedies for this issue like changing IJ mode to inc in both Mach3 and my post processor..
im at a loss - I rout this pocket on almost every guitar without problems - ive even scrapped all my toolpaths and programmed them again for this particular drawing.

N364 Y-578.975
N366 X-346.525
N368 Y-590.775
N370 X-342.625
N372 G2 X-336.025 Y-597.375 I0. J-6.6
N374 G1 Y-621.775
N376 X-279.233 Y-578.975
N378 G54 F600.
N380 G3 X-266.55 Y-591.025 I12.683 J.65 F1250.

If needs be I will run with the bold line removed but I dont know the consequences of removing it... I think that G54 is my Z axis work offset and 60mm/min is my plunge rate for that operation.

Jaden

[ger21]

In Mach3, G54 is the default coordinate system, so that line shouldn't do anything except set the feedrate. Just remove the G54 and make it N378 F600.

Unless you're in a different offset prior to that call. And btw, that's 600mm/min in that line. And I just noticed that you set the feedrate to 1250 on the next line, so that line really shouldn't be needed at all. Make sure you double check what it's going to do, but i don't think that line is needed at al.

[gar]

071216-1047 EST USA

Geetar-ist:

Does your program have any G5x other than G54 issued before this problem line? Is there a G54 executed at the beginning of your program?

When you execute a G5x in a program it sets all ( X, Y, Z, etc) current work coordinates to the contents in G5x.

A step change in Z between your last move and the start of G03 might cause a program fault.

.

[Geetar-ist]

Thanks Gerry, thats a relief - taken the weight off my mind and gambling on ruining stock/router bits etc - much appreciated.

I just loaded it up in mach 3 successfully so that should be good to go - Ill hang over the e-stop for the first one though

Jaden

[ger21]

I'd run it in the air first to be safe. I don't know what the rest of your code looks like, so I can't be sure what it will do. I just told you what I see.

Re reading your first post, I see that I misread it. But I think you mis-wrote it. I thought the bold line was the problem line, and I still do.

[Geetar-ist]

Gar - there are other uses of G54 in the code but ive not had a problem since I first encountered this and read on this forum about the IJ fix.

this is the first portion of my code up to a couple on instances of G54.

and Gerry - youre right, I should cut air - ive just lost 1/2 days work and I was being impatient

N100 G17 G21 G90 G40 G80 G64 G49 G0 M05
N102 G8 P1
N104 G90 M05 Z0
N106 G52 X0. Y0. Z0.
N108 T1 M06
( TOOL - 01 DIA. OFF. - 2 LEN. - 2 DIA. - 12.7 )
N110 G54 G0 X-103.993 Y-86.258
N100 G17 G21 G90 G40 G80 G64 G49 G0 M05
N112 S18000 M3
N114 G43 H2 Z5.
N116 Z2.
N118 G1 Z-1. F600.
N120 G3 X-104.393 Y-85.858 I-.4 J0. F1250.
N122 X-104.793 Y-86.258 I0. J-.4
N124 X-104.393 Y-86.658 I.4 J0.
N126 X-103.993 Y-86.258 I0. J.4
N128 G0 Z1.
N130 Z2.
N132 G64
N134 G54 X-103.743
N136 G1 Z-1. F600.
N138 G3 X-104.393 Y-85.608 I-.65 J0. F1250.
N140 X-105.043 Y-86.258 I0. J-.65
N142 X-104.393 Y-86.908 I.65 J0.
N144 X-103.743 Y-86.258 I0. J.65
N146 G0 Z5.
N148 G54 X-328.11 Y-576.805
N150 Z2.
N152 G1 Z-6. F600.

[ger21]

What are you using to create your code? I don't think you need any of these G54's.

[Geetar-ist]

im using the default post in mastercam X
ive talked with other mastercam users and some recommend never going beyond 9...
I dont have the luxury of rolling back.