Filtering

[Gmbill]

I am using MC v9 with the mpmaster post with a few minor alterations to suit a centurian 6 controller on a 3 axis mill. If I try to filter the output code to create arcs rather than jumpy lines mastercam tends to mix up G03 and G02 so the arcs go in the wrong direction. You do not see this error on screen but it machines incorrectly and looking at the code produced it is wrong. Am I the only one suffering from this problem? Is there any way to adjust the post to not allow this error? Even just filtering in the x,y, plane it will make this mistake the odd time.

[Zero]

I have had this problem in the past too. I think that it might be your post. I think that your creating some arcs that are too small for the post to recognize so it makes them go the opposite way. Try looking in your .pst file for a line that says arccheck. If it's there change the value to 1( 0= off, 1=length, 2= angle, 3=both) Then change the ltol (which should be pretty close to arccheck line) value to something like .1 or something (I have fixed mine with a value of.01 when the default was something like .002). This will make the post change any arcs with a length less then .1 back to lines.

If your post does not have an arccheck then look for a line that says= minimum arc length?, and give that a value of something like .1 (which is pretty high but better safe then sorry).This has worked great for me. I was having trouble with arcs in the xz and yz planes doing the same thing.HTH

 

Oh ya, 1 more thing, ALWAYS BACK UP YOUR ORIGINAL POST BEFORE ALTERING IT (Just in case).

 

[ 05-03-2002, 09:43 AM: Message edited by: Zero ]

[Zero]

I just checked my V8 Mpmaster .pst and it has arccheck and it's already set to 1. 2 lines beneath it is the ltol which is set at a value of .002. Change this value (or the ltol_m value if you're using metric) to something larger and it might help you. HTH

 

[ 05-03-2002, 10:10 AM: Message edited by: Zero ]

[Mike Whitten CAD/CAM Contractors]

I found a problem while filtering pocketing operations in the middle of March. QC says that they will have the fix in the next service patch. This patch is due any day now. It wouldn't hurt to try something like MPFAN though and compare the g-code in the problem area.

[Allan Brown]

The Centurion control has a parameter to select the G2/G3 directions for the G18 plane. By default, it doens't jive with the industry standard G18 arc direction standard. Something to look into.

[Gmbill]

I made the changes suggested by Zero and the mistake percentage has improved. The latest mistake I have seen is right on the screen toolpath doing a simple 2d contour using the ramp down feature. I had 10 pieces on the screen 6 were correct and on 4 of them the toolpath took off into the part on one end of the piece. The difference this time is it showed up on the screen. When I shut off filtering the toolpath was correct. My controller is set to G18 is xz plane which corresponds to the mpmaster posts

 

[ 05-03-2002, 12:05 PM: Message edited by: Gmbill ]

[Allan Brown]

Unless you consider XZ and ZX to be two different plane definitions, it's the arc direction within the G18 plane that I'm concerned with it. Actually something tells me that plane definition may indeed by how the manual handles the parameter...

[Allan Brown]

Some fresh info here. I had a user send in an apparent Mpmaster bug. On investigation it seems that this may be an Mp.dll issue rather than a post issue. Mpfan avoids the potential arc issue by using arccheck : 3 rather than arccheck : 1, although the change shouldn't be necessary. I've sent this in to CNC Software, but will update the Mpmaster posts on this site in the meanwhile.

 

[ 05-07-2002, 04:29 PM: Message edited by: Dave Thomson ]

[Allan Brown]

Still not sure if it is directly related to the issue decribed at the top of this thread, but MP V9.04 has released. It features some additional arc checking logic.

[Gmbill]

Hey I'm back: I just downloaded the latest v9.04 and changed arccheck to 3 in the post. I am pleased to say my problem has disapeared. I will keep you informed if I encounter this situation in the future in some other file. Thanks

[Gmbill]

Have more info on this problem. On the mc. handy codes card that comes with the software G18 is listed as zx plane where the mpmaster post uses xz. This is important because it reverses the rotation of arcs screwing up the job. I backplotted a job watching the colours to see the direction of the arcs and mc. definitely uses zx not xz. I then switched my centurian 6 controller to zx instead of xz and it now machines the arcs the right way. I have to say though I am afraid to filter because its like a box of chocolats you never know what you are going to get.

[cadcam]

Now you say you are afraid to filter because of the output arc issue.

 

then I suggest not outputting ARC's and fillter if it is a large surface job to save on the code.