I sure do learn a lot from these forums! Thank you.
Instead of using a camera, I scan the slab of wood on a scanner. It works well for the small bowls I make.
I'll attach the directions. I hope they make some sense.
This Is How I Make Bowls From Firewood
1. Obtain a dry slab of wood. I cut a small log into 1” thick pieces and let it dry for two years.
2. Draw a vertical line of a known length down the center of the slab, and make a line across it where the center is. This step is crucial for size, design and proper placement for milling.
3. Scan the slab on a flatbed scanner. Use previews first, to adjust until the center line is vertical. Start a folder called “log bowls”. This is where you will store all related files and toolpaths.
4. Start a new drawing in VCarve. Make it large enough to accommodate your slab.
5. Import the scan of your slab. Adjust the size of the scanned slab so the vertical line from step 2 is the same as the one on the slab.
6. Draw a vertical, and horizontal line on your work area that intersect in the exact center of your work area.
7. Jog the jpeg of the slab so that the center that was determined in step #2 is moved over the intersection of the lines drawn in step #6 (There are other ways to get the same result. I simply chose this one.)
8. Trace around the inner bark area of your slab, then offset inward by .5”. Use Bezier curves to smooth the vector if needed. Delete the original perimeter trace.
9. Turn off the bitmap layer.
10. Delete the horizontal line from step #6.
11. Select the vertical line from step #6, and use the circular array tool to make 300 copies around the rotation center at X:0 Y:0. Total angle =180
12. This will give 300 lines crossing at the center of your drawing.
13. Select all 300 lines and use the trim tool to trim all lines to the perimeter vector determined in step #8. (Clear outside boundary.)
14. Select, don’t group, the 300 lines. (At this stage, you should be checking to see that starting points are on the same side for all vectors. Adjust using node editing if necessary.) Select the fluting toolpath. Input the depth of the cut. (I use the full depth if less than 1 inch. Or, within the cut length of the bit.) Ramp at start and end. Select the length of the ramp. (I used 1.5”) Check the Use Vector Selection Order box. Ramp type is smooth. Calculate
15. This step is real important! At this point the bowl vectors will be cut with single passes to full depth. This will create lots of problems for the first cut. The first cut needs to be cut in shallower passes down to the full depth. Subsequent passes will be full depth, but only cutting a little off the side of the previous passes. To find the first pass, use this feature: . It will preview one pass at a time. On the preview, locate the start point of the first pass, and note the X Y locations on the lower right of the screen. Record these coordinates and use them to locate a small circle in your drawing. This small (.01”) circle will then be drawn near the end of the first vector. Create a fluting vector for just this one vector (Not the circle. It was just used to identify the proper vector.). I used .0625” passes for this vector. Preview to see if it is in the right place. Adjust if needed. Be sure to move this first vector up to first position in the toolpath menu. Slow the preview down to be sure that cuts are being made in the proper order.
16. Save these two toolpaths as one. Put it in the folder from step #3.
17. Save your crv file in the folder from step #3.
18. Setup your slab on the cnc so that the vertical line drawn in Step #2 is parallel to the Y axis. Set X Y Z zero based on the line drawn on the slab.
19. When making the cut, I start with a FRO of about 30%. This gives time to react if something was done wrong…Like setting XYZ zero, then forgetting to tell the controller. Or forgetting to match the slab center with the job center, way back during the design stage.
20. After determining that the cut is working properly, increase the FRO.
21. It has averaged 45-60 minutes to cut a bowl.