I am in the process of making some curved molding for a client. I used the two rail sweep in Aspire to create the files. Because of the curves, I want to run the finishing toolpath in offset so it follows the direction of the curve. I started running some sample of the molding in a straight piece just to determine feed rates, speeds, etc and I have some strange things happening.
I have a Buddy standard with the Porter Cable router, z axis is perfectly plumb to the table, table is perfectly flat, I used Andrew's mod with the roller blade wheels to hold the table flat in the cutting plane, brand new bits, perfectly milled S4S wood.
Finishing toolpath:
1/8" tapered ballnose bit (starter set)
running at 4 ips
router speed 13000 rpm
roughing tool path done with .03 machining allowance
I am 100% sure that the roughing toolpath is not cutting deeper than the finishing.
At every high point in the curves of the molding, it is leaving a flat spot. It also left a nasty ridge in the top at the exact spot it starting the offset cutting. If you watch the control box, it clearly changes depth on every pass, maybe 1-3 thousandths but it is not running multiple lines at the same depth. Looking at the toolpath file in editor, every line shows a different z depth, indicating that is making a curve, not a flat spot. When the CNC is carving, I can see that the finishing bit is actually cutting lower than the roughing in every spot.
If I take the exact same file and change it to raster, everything comes out perfect.
Any suggestions on what might be happening here?
Phil