This is not a question about a dryer! I have a Sears 10 inch Radial Arm Saw. How do I switch the motor from 220 volts to 110??

I went google and typed in changing 220 volts motors to run on 110 volts and right at the bottom all the sites is related searches and a heading electric motor wiring diagram 220 to 110
I clicked on that and the first site shows images and hand drawn schematics on how to do the job
there are other site below that which are like forums on how to do the job
personally as power is not a diy job because of the consequences of an error I would suggest that you get in an electrician to do the job safely
reading the sites and comments , if you use 110 volts the wiring in the premises will have to be able to withstand a current of 14-20 amps but if you leave it at 220-240 volts the wire is required to handle around 7 amps
there are plenty of comments to the effect that on 220 volts the motor spun faster , came to full speed quicker and handled higher loads better than a motor on 110 volts so again get in an electrician and ask him what is best

If the motor is a dual voltage type the instructions might be printed inside the motor cover or alternatively in the saw handbook.

It is important to find the correct instructions and to follow them exactly.