pocket issues

[dannymcic]

i am having issues when creating pocket between 2 squares . my work piece is 600 x600mm and the inner sqaure is 500x500 , so the pocket size is in between and should be 50mm from each side . im using a 16mm routing bit . when i create the pocket by vcarve pro , i end up getting a lip around the outer edge which changes my dimensions . i noticed that when i put the file on my cnc machine , my starting point shifts to exactly the radius of the bit in x and y directions and doing so ends up changing the dimensions. does anyone else face the same problem and how can i stop it

[mezalick]

dannymcic,
It's the way the program is set up.
If you make the outer square a bit larger ( 650mm) you will not have that probelm.
Michael

[tmerrill]

Danny,

If you are trying to remove all the material between the inner and outer squares to a depth of 20 mm, then the VCP file is setup correctly and it is generating the correct machine code to do that.

I can't tell if you are talking about the lip you see in the preview or have you actually cut it and had a lip be left? If you are referring to the lip shown in the toolpath preview screen, as shown in the first picture, this is because VCP always makes the previewed material slightly larger than you have specified. In your case, the outer edge of the pocket is still 600 mm square. If you want to remove that lip for the purposes of the preview, just do a quick Profile Outside toolpath around the 600 mm square and it will remove the lip as shown in the second picture.

A good tip for previewing toolpaths like this is to check the box under the Toolpath List that says 'Solid'. Now check the box next to the toolpath name and the exact area your selected bit will be cutting will be shaded in blue. If you look at the first picture again, you can see the entire area between the two squares is shaded, with the exception of the 4 outer corners where a small amount of material will be left due to the bit's radius.

Tim