# Reversing direction of an AC universal motor

The problem: I have a table saw motor I am trying to use in a jointer and need it to spin in the opposite direction (permanently). I have had trouble finding an answer that I am reasonably sure applies. Most of the answers I have found regarding this seem to be for more complicated or different types of motors (or very vague on what kind of motor is being discussed). The closest answer I have found is this one: Reversing direction of a 115v ac motor using Arduino

The motor specs

• 110/115V AC
• 15 amp
• 2.5 HP
• 5000 RPM
• Wiring diagram below (which I think looks like it is lacking some details, but am not sure if the motor can really be that simple)
• The part referenced in the diagram as "motor" is referenced elsewhere as "field assembly" and there is an armature assembly that goes inside of it. Unfortunately, there don't appear to be any clearer diagrams than the one below.

Desired Outcome: To be able to spin at 5000 RPM in the opposite direction so I can power a separate shaft (jointer cutter head) connected via a belt/pulley in a 1:2 ratio for a total output of 10,000 RPM.

I would like the opinion of someone more skilled and knowledgable than myself on if it is possible and safe to reverse this motor. Some of the other answers I have found eluded to the motor not being safe to run or running at significantly reduced power. Alternatively, if there are some tests that I could run to evaluate these for myself, any information on what tests and how to conduct them would be much appreciated.

I like doing things without asking questions, but I also want to be safe when trying to rotate metal blades at around 10,000 RPM. Any insight and resources would be much appreciated!

• Reverse the field connection with respect to the armature. Commented Aug 24, 2016 at 2:34
• Okay, all other diagrams I have found have wires going to the field, but this one doesn't seem to (still need to fully open up the actual motor and look closer). Is it as simple as just reversing the white and black leads or is there anything else I need to be aware of? (Also, all this assuming that there are no wires missing from the diagram, will try to open up the motor tomorrow evening). Commented Aug 24, 2016 at 2:40
• What they all said: The key point is that all current flows through field and armature & direction depends on relative polarity & when fed with AC both change together so relative polarity is retained. SO by reversing current direction in one or other but not both you change direction of rotation. Add a locknut and/or split pin and or ... to shaft nut . Commented Aug 24, 2016 at 10:45
• Russell McMahon & John D: Thanks for your input and tips! Commented Aug 24, 2016 at 13:23