Currently, any spinning weapons are banned in UK heavyweight arenas. Pretty much everything you might want to use counts as a spinning weapon, the only exception is: "Full body spinning robots with an eccentric mass, are excluded from this section unless they spin over 500 revolutions per minute." FRA Build Rules, Section 11.

Also, 99% of robots do not use off the shelf saw blades, they are just to fragile. There are some that do, namely robots like SOB and Gloomy, both American bots, but there are currently none in the UK.

A final note, if this is your first robot build... don't build a Heavyweight. Start with a Featherweight, or a Beetleweight. The costs tend to spiral out of control on your first few builds and building a HW, even when you know exactly what you are doing and can call in a few favours, will cost at least £1000, usually triple that. Start with a FW or BW and then that way you can build whatever you like as we have a Class 1 arenas for Feathers and Beetles, ie: Full Combat with Insane Spinners, Flippers, Crushers etc. Much more fun!