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View Full Version : V Carving Speeds, Stepover, Stepdown



blaz_in_az
02-24-2007, 10:56 AM
There are a lot of newcomers to Shopbot, with questions on which bit, speed, etc.

There are chip load tables and other support materials, but I have to see things for myself, and offer my method experimenting as a learning tool for a new Shopbot user.

My first attempt at carving a 4" x 5" wolf's face took 45 minutes. (As a new user, I assumed the V tools speeds, stepover, stepdown rates in the tool bit database were automatically set to their optimum.) As I watched the cutting of the wolf's face I thought maybe some parts of the cutting procedure could be speeded up.

I set up an experiment to determine if I was right about speeding things up. The results were amazing to me and taught me a lot about the ShopBot through practical experience. After using this technique, I reduced the cut from 45 minutes to less than 20 minutes, with better quality cut results!

The experiment was a test file created with a rectangle 0.5" x 0.25". (I use ArtCam Insignia) I then distorted it by making one end an arc and the another corner more sharp. I then replicated it about 20 times.

I set up five rectangles for each bit, (45, 60, 90, 120 degree V bits) and changed the stepover and stepdown rates beginning with the rates included in the tools list in Insignia. I increased the step down in each case and was amazed to see that greater stepdown rates not only increase cut speed significantly, but improved quality (fewer tool marks) of each cut. (I used solid birch for test cuts.)

The photo may not be clear enough to see the final results, but it is offered as an example of what I did.

I hope this is of help to others and I thank you for your indulgence in my ramblings.

Tim


6169

Test Board, 11" long. Cut 1, top left has over 10 tool marks, cut 5 had one!