We have a bit about this here:
https://my.carbide3d.com/gswso/12
https://my.carbide3d.com/gswcc/08
There’s a bit about angle and how it relates to font/feature size at:
- V-cutting — special purpose, used for engraving or chamfering, or cutting parts w/ angled sides. Identified by the angle of the V — 90 degree bits can be used for mitering. Sharper angles will cut deeper for a given width of cut. Engraving bits with a single-flute (look like half cones) are able to cut more deeply w/ a single pass.[19] Most V-bits are unable to clear chips, so require slower speeds.
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If work cannot be completed in a single pass, some operators will grind the tip to a 0.5–1mm radius ball point so as to minimize stepping (esp. when cutting wood). Discussion here: Steps in V carve file
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the # of Passes — Size guidelines for adding a radius at the tip (may vary based on bit angle and material):
- <10mm — one pass
- 10–20mm — ~0.5mm
- 20–35mm — ~0.75mm
- >35mm — 1mm radius
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The tradeoff is feature size vs. feature depth — an acute angle allows one to cut a smaller, finer feature w/ more depth, while a more obtuse angle allows one to cut a larger area w/ a single pass and while having a single bottom, as opposed to a ragged set of scallops.
- Recommended bit angle for a given text size:
- <1" 45–60°
- 1–2" 60°
- 2–4" 60–90°
- 4–6" 90°
- 6–10" 90 to 120°
- >10" 120° or greater
- Recommended bit angle for a given text size:
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Material guidelines:
- hardest timber available
- use conservative plunge and feedrates even when doing more than one pass
- avoid overlapping V-cuts — tends to cause splintering at the top edge, leave a ~0.5–1mm gap at the top
- use a cutter w/ centered/symmetrical geometry
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Formula for calculating the effective diameter of a V-bit at a given depth in Excel this is:
=TAN(RADIANS(B3)) * B4 * 2
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Where B3 is the angle in degrees and B4 is the depth in inches
Site to calculate offsets/depths: Angular Size Calculator [22]
Excellent image noting width considerations: Carve letters depth - #5 by JaredHooper
This thread discusses it as well
and has an image which shows width considerations
Like anything else, start with the feeds and speeds in Carbide Create as a conservative guideline and use a technique such as: Calibrating Feeds and Speeds When Using Carbide Microtools to work up optimal settings for your endmill, machine, and material.
The elephant in the room is that Carbide Create doesn’t account for an inability to carve wider than the endmill diameter, so a too large square will become a four pointed star — you can work around that by insetting the geometry twice, and carving as a V carve using the inner and outer geometry, and cutting the in-between as a pocket at the depth which the V carve will reach.