Strange Toolpath

[BobA]

Has anyone had this happen. I made a program in VCarve to a wood part 14" wide at the top tapered on both sides to 6" at the base and 17" tall. The material was 3/4 thick. I did not catch it at first but when I did, I noticed that the machine was slowly going down while moving in the x and then y axis. It really came to my attention when I was cutting and noticed Z axis was .250" about 2/3 around the first path. I had set my tool path to cut .075" per pass and when I noticed that I was already .250" deep I paused the machine. I began checking my depths around the perimeter of the part and sure enough the cut was progressively deeper. I stopped the machine and went back and looked at my VCarve program and the Z depth was moving down frequently in .001 increments. I went back to my program and reran the tool path and this time the program came out okay. I do not know what happened. Does anyone have a logical explanation.

Thanks
Bob

[Buc]

Bob"A",

When I set-up my profile tool path and add ramps to tool path, check radio box (SPIRAL) it will start the tool path above the material and slowly increment down .001" all the way around tool path. It will only feed down the distance I have set in the plunge depth per pass. If I have a material thickness of .75" and my plunge is set at .250", it will take 3 passes to reach .75" and it will take a finish pass at .75". So actually it will take 4 passes to complete the tool path. This is my experience with this type of action.

Buc