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If by burst velocity you mean max RPM a cutting wheel can operate at safely, all cutting discs/ blades have their max RPM on them as far as I am aware.

have you tried your local scrap merchants, they will probably sell odds and ends for a little over scrap value, also fabricators etc might have stuff suitable in their scrap bins, even exhaust places...

229584
Something like this

And your blade will effectively be a wheel, with the work piece as a brake.
High rpm with low torque won't be terribly effective I don't think.
If I was going to do something like this I might use...