I am in to making American Flags on my Shapeoko 4 XXL. I’d prefer to use a v-carve bit to cut the stars. I really like the look of the v-carved stars. When I test the bit…using 90 degree or 60 degree bits, the stars are rounded on the points. I do not get sharp points on the stars also they look bigger when cut on the material (soft pine). When I view the simulation in CC the stars look perfect, correct size and sharp points. If I pocket the stars they come out perfect. I’m sure it’s something in my programming. Any suggestions?
This difficulty is usually caused by not getting the Z-axis zero exactly so, or the stock not being even in thickness.
How are you setting zero?
How are you securing your stock?
I have a Bit Zero purchased when I bought the machine.
I use calipers to measure the thickness. The material is a piece of pine wood, just a flat single piece of stock measuring 10.5 x 11.75.
I secure the material with Tiger Claw clamps from the Get a Grip Workholding Kit along with the Essential Corner Square Set.
I have a couple of tips to share with you … all of which I learned the hard way.
When in doubt, set Z-zero higher as opposed to lower. This will result in smaller stars but sharper points. If you set Z-zero too low you will get rounded points, as the bit will begin plunging/retracting before the sharp point has been created.
I make my flags by laminating a few boards together and then running them through a thickness planer to get the finally assembly flat. If your wood isn’t flat this will cause problems when V-carving. Despite my efforts, pine just isn’t the most stable wood, so I check it with a straight-edge and I set Z-zero right in the center of the union, which gives me the best chance for success with the stars.
If I’m V-carving elsewhere on the flag (e.g., a logo or symbol amongst the stripes, etc.), or doing any other type of carving in which depth is critical, I export separate G-Code files and reset Z-zero in the area of the carve.
A 90 degree V-bit is not very forgiving when your surface isn’t nice and flat. A depth change of 1 unit equals a width change of 2 units. For that reason, I find a 60 degree V-bit easier to use. It’s closer to a 1:1 relationship. Of course, if you’re making a big flag (with big stars) then a 60-degree V-bit may result in the centers of the stars being too deep. It’s a tradeoff.
Thank you Jim for your response and your informative advice. I will definitely give it a try. Thank you too Will.
^ This. This is what I do with all my flags. Even then, if the wood isn’t nearly perfect, it will result in different size stars - some with sharp points and some with round “points”
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