Engraving tools - angle

Hi,
I need to purchase some cnc engraving tools. Most often the shape is in 30 or 45 degrees V-angle, but I have seen other figures too.
Why different angles ? and how do I choose the right angle for non ferrous metals and plastic ? Thanks.
Gianlepri
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V angles are just for decorative purposes. When you are trying to do a vertical wall, you run into the problem of the molded material clinging to the sidewalls, either the roughness or grain of the wall or the mold release fluid keeping the molded material from coming out due to a liquid seal. I've usually used angles of about 2-3 degrees for moderately shallow molds and had good results. Other materaila may want to have other angles. Note that interior angles (ones that the material will shrink onto) are a lot more important than the exterior angles which, if properly polished and inspected, can attain 0 degrees.
-- Yeppie, Bush is such an idiot that He usually outwits everybody else. How dumb!
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The narrow angles work well in soft material like plastics, and the wider angle works well in metals.

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Thank you guys.
Gianlepri
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