End mills overview and usage

[TODO: create overview of end mills in general, with specific recommendations for our spindle.]

Overview of end mill parameters

[TODO: figure out a way to organize this info in an easy-to-read way.]

• Flutes = single, 2, 3 and more
• Flute type = straight, spiral and O
• Profile = flat, ball, bull, tapered, V
• Diameter = very small (PCB isolation/micromachining) to very large.
• Direction = up, down, and compression cut
• Composition = HSS, carbide, exotic coatings

For 2D routing

In general, stick with flat profile end mills in order to cut all the way through material with minimal spoilboard penetration.

Plywood

Recommendation(s)

1/2" or 1/4" flat nose, 2-flute (spiral), down cut (or compression cut). Might also be able to use conventional hand router bits, otherwise known as single or 2 flute (straight), flat nose.

Notes

Direction Up cut can lift workpiece and/or cause ugly tearout on top surface. Down cut won't lift workpiece, but can cause ugly tearout on bottom surface. Compression cut is ideal, but more expensive. Composition Plywoods can be surprisingly tough on end mills due to resins. MDF in particular is very rough on end mills, as the fine dust can function as gritty abrasive. Use something that is cheap enough that you won't be frustrated by dulling, but good enough quality that things aren't harder than they have to be. Use carbide end mills. Avoid HSS, and save yourself money by not springing for exotic coatings.

Hardwoods

Plastics

Recommendation(s)
Notes	For softer plastics, look into getting a 1/8" or 1/4" single flute, up cut, "O" profile. Softer plastics tend to produce long curls rather than chips. Single flute "O" profile tends to keep these curls nice and long, while the up cut direction moves them away from the workpiece, preventing them from welding back onto the workpiece.

Foams

For 3D milling

• Good to use multiple end mills per job for roughing, coarse detail, and finishing passes. Recommend same end mill used for 2D routing for roughing, followed by 1/8" ball nose for coarse detail, followed by 1/16-1/64" ball nose tapered for fine detail.
• Ball nose profile
• Small diameter means finer features
• Use tapered bits to bring down effective cutting diameter while maintaining strength, allowing for higher speeds.

For detailing and engraving

• V bits are popular for classical signage, but also impose a strict (though sometimes desirable) aesthetic.
• Small diameter means finer features.
• Look into PCB isolation / micromachining bits
• Flat nose probably preferable to ball nose.
• Flutes probably don't matter as much.

Where to buy

• McMaster
• ToolsToday
• Carbide3D
• Inventables