How to Remove a Broken Tub Drain

While attempting to remove an old tub drain with a dumbbell wrench, the drain spindle broke. Does anyone know how to remove a tub drain with no spindle inside of it? Any assistance or advice would be greatly appreciated!

I do this all the time. You use a Sawsall and 24 tooth blade very carefully. You cut the drain flange in 2-3 places through where the threads are but not cut the tub and as much of the flange as possible. Then pry up with a screwdriver until you can grab it with a pair of channel locks then back and fourth until it brakes. then there will be enough play to get the rest out. You have to be very carefull.
I'll bet I have done this 50-60 times on old tubs. I have only scratched 1 tub and that was very minor. I always get home owners permission first. I explane that I have no other way to do it and if I scratch anything I'm not responsible. If anyone knows a better way I'm all ears.

Ridgid model 342 internal pipe wrench

or this

Job completed...Thanks!

I used a reciprocating saw as suggested and cut a 1/2 inch notch in the drain. After that I tapped the remaining threaded sides with a hammer and chisel. The drain loosened and I was able to unscrew it. Thanks for the advice.