SolidCam Radius Problem

[CNCOX]

I have used the search function, both on here and Google, and have came up with nothing. Maybe it's because it's somewhat difficult to search for.

I have had SolidCam R12 for sometime and use it for simple stuff in SolidWorks 2009. Recently I have been trying to cut out stuff that has a lot of radii. When I post a program and run it on the machine, it will cut the radius with flats on it. For instance a 50mm round boss that is 10mm tall will look like a decagon. I know that in MasterCam you switch between Arc Segment moves and Point to Point moves to cure this. I am guessing there is a similar function in SolidCam. Anyone had this issue before?

I have been around programming and CNC equipment for a while now. I do not have this issue with MasterCam, and I have tried everything I know to try in SolidCam to fix this issue...

Any input or advice would be greatly appreciated!

[Brakeman Bob]

It is in the MAC file (and was changed in SolidCAM 2009) to be accessible from the CAM settings. Have a look in your MAC file for the "Arc Definitions" heading and then check the settings listed below. However, your post processor may need tweaking to produce the code you want. Tell me, does your post output G2 / G3 for arcs (assuming your control is Fanuc based)?

[mattpatt]

In the interests of keeping up to speed I had a peek at this.

My post uses G2/3 code, and produces (in theory and practice) a nice smooth radius.

In the .mac file I change:

;Arc definitions
arc_exist = Y

to

;Arc definitions
arc_exist = N

and the code comes out using linear moves, which are not smooth at all (in theory or in the simulation, not sure about practice, but I doubt it).

Now here's a thing. If using the linear method I can't seem to change the pitch (precision) of the points chosen. Let's say for example that point A to point B should be an arc (as it is if the G2 or G3 code is generated), well in this case a straight line 3.8mm is generated, which is obviously never goiung to work.

Maybe I'm missing (or not seeing) something obvious, but I can't seem to suss out how to change this precision level.

Any pointers?

Not a big thing because my fanuc control handles the G2/3 codes nicely, but it would be nice to know.

[Brakeman Bob]

Hi Matt,

I think the value you are looking for is stored in the "arc_max_chord" variable in the MAC file. As an old APT hand I know this value as "LINTOL" . I haven't played with as my G2 & G3's work fine. I have an idea that in R13 (or SolidCAM 2009 for the superstitious) you can alter this value job by job.

All the best

Bob

[mattpatt]

Bob. You are a vault of top information :-)

I changed as follows:

arc_max_angle = 3.0000

Now the linear moves max out the points at 3 degree. Pretty good for a small radius, but still shows up as a bit of a move on a larger radius. So.......

I then changed:

arc_max_chord = 0.1000, 0.004

Now the max linear move is 0.1mm, unless the rad is so small that the 3 degree max takes over and limits the movement.

Works very well from what I can see, but makes for a very long program! I'll stick with the G2/3 moves but it's great to know a bit more.

Just playing really to find out what everything does.

Matt.