Camsoft & Bobcad - problem with arcs

[mbam]

I am having trouble with Bobcad V24 and arcs. At certain parts of the program the tool will make a 180 deg or complete circle.

I have tried fanucarcs = 0, 1 and 2 (making the change in the .cbk for the R value) and setting Bcad accordingly.

I currently have fanucarcs = 0 and here is what I have in my BCad post setup

221. Break arcs into quadrants? n
222. Arc center a=absolute, b=incremental, d=unsigned inc., e=radius? a
223. Break arcs into two pieces if greater than 180 degrees? n
227. Output G40 after, rather than with, the last linear or arc move? y

Is there anything else I should be looking at?

Thanks!!

Similar Threads:

• Need Help!- Bobcad V24 & Camsoft & arcs
• Problem- Problem with Arcs
• Camsoft and Bobcad ???
• Need Help!- Problem with turning arcs in Flashcut
• New Machine Build- Autocad to Mach3 problem with arcs

[Karl_T]

Can you find the section of Gcode that produces the problem? Find out if its written the way you would hand code it for camsoft. Then you know if its a control problem or a CAM software problem. If your control has generally been working on arcs, I'd strongly suspect the CAM software first.

FWIW, I was making a part with Mastercam developed Gcode just last month that did this in one spot. i ended up hand editing the offending line of Gcode.

Karl

[mbam]

Karl, yes we can see the lines where it misbehaves, however I have no idea what the code should look like! This program is about 3000 lines.

We have been using this machine for just one job for the last couple of years and no arcs are involved.

I think I used Bobcad V19 the for last program I did that had arcs and at the time it worked fine. I'm going to run that tommorrow and make sure it still works. That should at least tell me where to look. I wish I could find the post I used with that version of Bobcad!

[Karl_T]

I've written gcode for 25 years now in all flavors. Post maybe ten lines before the offending line and problem line.

Karl

[mdonovan]

what is likely happening is the end of your arc isn't calculating out to enough decimal places and is "going around the block" again because ti fails to resolve the endpoint. it's an old-old problem with many versions of NC and CNC over the decades. TNR compensation is often involved.

Try opening up your move-complete/in-position parameter by a factor of 10 and make a safe distance dry run. If the problem goes away then you've identified the problem. You will then either have to rework your arc code or leave the in position opened up.

hope this helps!

[mbam]

It's a little stormy around here today and the lights are flickering every few minutes so I won't be able to fire up the machine until tommorrow. Thanks I will report in then

[camsoft]

In CNC SETUP there are settings to conform to several arc center styles under GENERAL SETTINGS to apply Incremental, Absolute arc centers in IJK or use R for radius and also to use metric values.

The CNC Professional version even cut arcs/circles in tilted canted planes coordinating up to 8 axis motion when cutting arcs/circles.

There is also a forum on CNC ZONE for bobcad.

Tech Support
CamSoft Corp.
support@camsoftcorp.com
PH 951-674-8100
Fax 951-674-3110
PC Based CNC Control For The Machine Tool CNC Retrofit And CNC Controller OEM Market

[mdonovan]

Yes you most likely need to examine your bobcad settings. The CNC is going to execute exactly what you tell it, even if it's wrong.

[mbam]

Ok, back at it today.

Here is a line that causes a big loop. I set the Camsoft tolerance param to .0005, it had been at .0002 - still no joy. I'm going to put something over in the bobcad forum. And educate myself on what a G3 is supposed to look like!

G03X3.0319Y-.6003I3.2584J-.1713

[Karl_T]

at a bare minium we need the line before, or even further. We need to know what the current commanded X Y Z position is.

Also, which FANUCARC mode are you in?

Karl

[mbam]

Here it is

N684G01X2.9792Y-1.3197
N685X2.978
N686X2.9778
N687Y-1.3194
N688Y-1.3172
N689Y-1.3007
N690Y-1.0142
N691Y-.6529
N692Y-.586
N693Y-.5834
N694X2.9779Y-.5833
N695X2.9785Y-.583
N696X2.9913Y-.5763
N697G03X3.0319Y-.6003I3.2584J-.1713
N698G03X3.0708Y-.617I3.1565J-.3643
N699G03X3.1227Y-.6251I3.1201J-.4715
N700G03X3.1707Y-.615I3.1234J-.5097
N701G03X3.2092Y-.5855I3.1176J-.506

This was with arcs = 0

[Karl_T]

This code backplots correctly in NcPlot and runs correctly on my CNC mill.

lets look at your G03 logic in gcode.fil Or it may be some sort of tolerance thing, I'd defer to the experts at camsoft for this.

Karl

[mbam]

DISPLAY4 {f*(\73/100)}
DISPLAY5 {s*(\74/100)}
TIME CYCLE;\4
DISPLAY7 \4
RUNTIME \4
DISPLAY8 \4
DECELSTOP ' ADDED FOR OUR STEPPERS
CW x;y;z;i;j;k
'CW x;y;z;r
-----G2
DISPLAY4 {f*(\73/100)}
DISPLAY5 {s*(\74/100)}
TIME CYCLE;\4
DISPLAY7 \4
RUNTIME \4
DISPLAY8 \4
DECELSTOP ' ADDED FOR OUR STEPPERS
CCW x;y;z;i;j;k CHANGED FOR FANUC ARC SETTING
'CCW x;y;z;r
-----G3

Here it is

[mbam]

The leading 0 in the G code doesn't matter does it? G3 versus G03?

It plots fine in my Predator backplot also.

[Karl_T]

Just a shot in the dark, add this line toward the top of your G03
FANUCARC 0

(If its changed sompleace else in your .cbk you'd get the behavior you see)

Then run just this code section.

leading 0 don't matter

Karl

[camsoft]

mbam,

We've ran the program in CNC Professional and it shows a "farmers sickle" shape where 5 arc's blend together to create what looks like a single arc. There are no circles. The math isn't perfect between arc centers, start of arc and end of arc on all of them but it is good enough to be within .001 or better.

So it must be a setting such as tolerance somewhere.

Since you have CNC Professional double check to see that the TOLERANCE is set for exactly .0002 under the LOCK ICON in AS3000.

Then double check be sure your FANUCARC style set to 0 and that your TOLERANCE in the CNC SETUP is set to .001 and that you have pressed SAVE on the CNC SETUP window and have exited the CNC and then came back in, before you load the G program and run again.


Tech Support
CamSoft Corp.
support@camsoftcorp.com
PH 951-674-8100
Fax 951-674-3110
PC Based CNC Control For The Machine Tool CNC Retrofit And CNC Controller OEM Market

[mbam]

Thanks, I'll try it in the AM and report back.

[mbam]

OK, set up as above but no joy. I even went as far as to set the tolerance in CNC setup to .01.

Yes the AS300 is set at .0002 however I am not using it. The drawing was supplied as an Adobe Illustator file which I exported to a dwg, then imported into Bobcad.

I just made a drawing from scratch in Bobcad, used a post that had arc centers set to absolute and it did not work. So I did it again using fanuc arcs = 1 and a post with arc centers = incremental, and it ran OK. I'll try the big drawing again in a few minutes.

There are a couple of other Bobcad questions I have, I will ask them in the Bcad forum.

[mbam]

I just ran our program again using the same setup as my test above. Still have problems. I'm going to poke Bobcad a bit.

[mdonovan]

Ok, back at it today.

Here is a line that causes a big loop. I set the Camsoft tolerance param to .0005, it had been at .0002 - still no joy. I'm going to put something over in the bobcad forum. And educate myself on what a G3 is supposed to look like!

G03X3.0319Y-.6003I3.2584J-.1713

edited my post because I didn't read the other responses first and you already are past my advice.

good luck!