FingerTech's Blade Hub is the best way to attach a blade to a shaft. It uses a flange nut to hold the blade tightly (like an angle grinder), meaning you can use off-the-shelf sawblades without needing to drill screw holes into hardened steel! Custom blades can be made stronger by not having those same mounting screw holes.

The stepped design allows use of blades with different bore sizes.
A clamp mount with two screws attaches the hub to your weapon motor shaft. (Remember to apply thread-lock.) (This replaces the 8-32 setscrew in the previous version.)
The hub has a 6-32 threaded hole so that your horizontal spinner robot can rest on a screw head and not be pulled in different directions when the blade spins. Also useful for supporting the hub's far side in vertical spinners.

Specifications:
- Accommodates blade bores of: 10mm, 16mm (5/8in), 20mm
- Recommended blade thickness: 1.6mm (0.63in) - 5mm (0.2in)
- Material: Anodized 6061 aluminum for high strength and low weight.
- Hub hex size: 25.4mm (1in)
- Nut hex size: 24mm (15/16in)
- Hub height: 14.5mm (0.57in)
- Clamp Screws: 4-40 x 1/2in Socket Head (requires 3/32" hex wrench)
- Bore diameter: 3.175mm (0.125in), but can be drilled out as big as 6.35mm (0.25in).
- Weight: 14g (0.494oz)

Installation Tips:
- Observe the proper spin direction (clockwise looking from the motor side).
- Use threadlock on both the nut and clamp screws. You do not want your blade coming off!
- If you can't get your 1" wrench onto the hub when installed, you will want to clamp the hub into a vice so you can tighten the blade before securing the Blade Hub to the motor shaft.
- As with anything related to combat robots, it is POTENTIALLY DANGEROUS to add a spinning weapon to a robot. NEVER power up the robot outside of a safety enclosure. Always use a safety lock and follow proper activation procedure.