Machsupport Forum

Mach Discussion => General Mach Discussion => Topic started by: mlancaster on August 31, 2007, 03:15:37 PM

Title: crop circles
Post by: mlancaster on August 31, 2007, 03:15:37 PM

Can someone help? I have BOBCAD V21 and Mach 2 programs. I have used them for sometime now. On a regular basis i get the crop circles in Mach 2 after converting text into G code using BOBCAD. I understand it has something to do with the accuracy and chain gaps setting but i can't seem to find a solution for some cases.
Is there a setting within Mach 2 that can help with this?

Thanks
Mike

Title: Re: crop circles
Post by: Lakeside design on August 31, 2007, 10:20:44 PM

Here is a post from the bobcad forum by the Bird BCC tech. man

Believe it or not, the crop circles that most people get are due to the geometry used to generate the toolpath.



What happens is when you have an arc and a line that intersect and the line is not perfectly tangent to the arc, the system generates an arc move around the corner. This arc can be so small that the beginning and end of the arc have a difference that is less than 0.00005, so when the coordinates are rounded you get the same position for both the end of the arc and the beginning of the arc (full circle).

I suggest trying to use the Make Arcs Tangential command, when possible. That alone should help reduce the appearance of the arcs.

Regards

Title: Re: crop circles
Post by: Lakeside design on August 31, 2007, 10:22:56 PM

Mike if you still have an issue with them. Post a file and I'll take a look

Title: Re: crop circles
Post by: james elder on September 01, 2007, 02:42:20 PM

Mike,

changing the IJ mode worked for me.

jim

Title: Re: crop circles
Post by: Lakeside design on September 01, 2007, 05:48:24 PM

Crop circle are not a Mach 2 or 3 issue or one of I & J vs R. It is a cad issue not a cam issue. Cam only does what Cad tells it.

Title: Re: crop circles
Post by: Brian Barker on September 10, 2007, 12:38:06 PM

Most of the time the circles are do to the ILK mode being wrong.. some of the posts have ABS arc centers and some have Inc arc centers. If you have the wrong type selected you get into a bit of trouble :(

Thanks
Brian

Title: Re: crop circles
Post by: Lakeside design on September 11, 2007, 05:42:37 AM

Yes Brian if someone has not confiquire the software riight there can be some issue But that a set-up issue.They would have problem doing a simple arc. But Crop circles will appear wheather you use I.J. or R. I did recieve an e-mail over a week ago from the person who posted this question and started the thread. When he went and used the "Make arc tangent command" in Bobcad all of his cropcircle dissappeared. "Make arc tangent command" is a CAD function in Bobcad not a CAM function