I have a 10" craftsman band saw I would like to use to cut steal 5/8 x 5/8 1/2 X 1/2 what would you recommend. If I remember correctly it takes a 1x72 1/2 " blade. Will this saw even work ?   

Depends on the blade and on the speed---how slow will it go? Also rigidity....

I have a craftsman horizontal band saw designed for metal cutting. Yours must be like mine right?

No sir mine is vertical. It was paw in law's I'm sure it's was made for wood 

Then it turns too fast and isn't rigid enough for steel. It CAN be used but the steel will wear it out quickly.

Frosty The Lucky.

They make metal cutting blades for your saw but it wont hold up long cutting heavy stock or harder steels. It would work ok for sheet copper, small brass/bronze or mild steel. The big difference between woodworkers shop tools and machine shop tools is the motors. Woodworkers tools don't have sealed motors and the motors they do have don't like metal shavings getting inside!. I have an old Craftsman circa 1970s and I use it to cut light weight, non ferrous metal from time to time but for cutting steel stick with a chop saw or angle grinder/cut-off wheel. (or of course a proper metal cutting band saw but the other two options are generally less expensive)

Dang that's what I was afraid of . It has a 5/8 motor 72 1/2 " blade  but if the rpm are on it I can't find it. But I was discribe it as fast. 

What TwistedCustoms said, use it only for thin stock (non ferrous).