Table Saw runs in reverse

[Phil Tomlinson]

OK this is a new one for me.
I've got a 2-year-old Powermatic PM 2000, 3HP, wired for 220.

Today after running the saw for a while, I stopped, changed a blade, and when I went to start it back up, it ran backwards for a second and then tripped the breaker. Two more tries, including hand-spinning the blade in the proper direction, it did the same thing.

Switch? Motor? Capacitor?

Anybody have any ideas?

Thanks
Phil

[Mike Cruz]

Gremlins...

[David DeCristoforo]

??? I'd put that other blade back on.... Quick!

[Ken Fitzgerald]

Phil,

I would bet it's the capacitor.

The starting capacitor's main use is to insure the motor starts and starts in the proper direction.

[Karl Brogger]

I've heard of that with three phase after a power loss. Never in a 1ph scenario.

No clue.

[Mitchell Andrus]

Phil,

I would bet it's the capacitor.

The starting capacitor's main use is to insure the motor starts and starts in the proper direction.

Ditto... STARTER cap, not run cap. They're different.
.

[Phil Tomlinson]

Ditto... STARTER cap, not run cap. They're different.
.

Thanks for the advice! Will check it out, and report back.

[Joe Wiliams]

What would be real freaky is if someone put the blade on backwards when that happened:eek::p

[Harold Burrell]

I've got a 2-year-old Powermatic...

Yeah...it's that "Terrible Twos" thing. My kids did crazy stuff at that age too.

(Sorry...I'm being silly. Hope you get it figured out.)

[Tom Veatch]

One more vote for a defective start capacitor. A new one should be available locally for something in the neighborhood of ten bucks. Be sure the voltage and MFD specs on the new match the old. Also be sure the physical size of the new capacitor is compatible with the enclosure on the motor.

[ken gibbs]

Your problem can be fixed in five minutes at no cost. Disconnect your feed power. Hook up the red wire where the black wire is feed to the motor. Hook up the black wire where the red wire used to be attached. This will cause the motor to run in the opposite direction.

[Myk Rian]

Your problem can be fixed in five minutes at no cost. Disconnect your feed power. Hook up the red wire where the black wire is feed to the motor. Hook up the black wire where the red wire used to be attached. This will cause the motor to run in the opposite direction.
Ken;

That only works with 3 phase power.

[Rod Sheridan]

Your problem is that the starting winding isn't in the circuit for some reason.

The starting winding provides the direction control on a single phase motor, if it isn't working when the motor is energised, the motor won't have a directional bias, nor will it be able to start.

Your motor problem could be;

- a broken wire

- an open start winding

- an open centrifugal starting switch

- an open starting capacitor

I would check al of the above with an ohm meter/ mechanical inspection before I started replacing parts.

Regards, Rod.

[Phil Tomlinson]

Two things I confirmed with the Powermatic rep on the phone this AM.

One is that the original switch on the saw has insufficient overload capacity, so they are sending me a new switch [guess they figured that out after I bought mine], and

Two is that the starting capacitor is bad.

Will report back after installing the new parts just to close this thread.

Thanks for all the help everyone!

Phil

[ken gibbs]

Ken;

That only works with 3 phase power.

Switching the red and black hot leads worked for me on 220 power that is not phased. No such as single phase power.

[Jason White]

What side of the saw were you standing on when this happened?

:D


OK this is a new one for me.
I've got a 2-year-old Powermatic PM 2000, 3HP, wired for 220.

Today after running the saw for a while, I stopped, changed a blade, and when I went to start it back up, it ran backwards for a second and then tripped the breaker. Two more tries, including hand-spinning the blade in the proper direction, it did the same thing.

Switch? Motor? Capacitor?

Anybody have any ideas?

Thanks
Phil

[Peter Quinn]

Switching the red and black hot leads worked for me on 220 power that is not phased. No such as single phase power.

I may be confused, but not about this. There should not be a red wire on a 220V Single phase circuit. Switching the two hot leads on the line side of a 220V single phase circuit should not do ANYTHING at all.

There should be a red wire, and a black wire, and a white wire, and hopefully a green wire, on a 220V 3 phase circuit. Switching any two of the red/black/white leads WILL reverse the motor direction.

Perhaps Ken you were in the motor control block and rewired the start circuit relative to the run circuit? That would change direction on a reversible motor and might involve a white and red wire depending on your motor.

[Myk Rian]

Switching the red and black hot leads worked for me on 220 power that is not phased. No such as single phase power.
Single phase 240 volt is your standard household feed. 3 phase is an industrial feed.
If I switch the wires on my 240v dryer, it does not run backwards. Same with my jointer, table saw, drill press, garage heater, etc.

[Phil Tomlinson]

Two things I confirmed with the Powermatic rep on the phone this AM.

One is that the original switch on the saw has insufficient overload capacity, so they are sending me a new switch [guess they figured that out after I bought mine], and

Two is that the starting capacitor is bad.

Will report back after installing the new parts just to close this thread.

Thanks for all the help everyone!

Phil


Conclusion:


Installed new starter capacitor and switch.

Tablesaw is back to normal!

Thanks for all the input.

Phil

[Mark Engel]

??? I'd put that other blade back on.... Quick!

Now that's just funny.

Glad you got your saw fixed.

[Bill Dufour]

Ken;

That only works with 3 phase power.
Well he did say 220 volt so most likely he meant 208 three phase.

Single phase has been 120/240 volt in North America for longer then most posters here have been alive.
Bill

[Wade Lippman]

Single phase 240 volt is your standard household feed. 3 phase is an industrial feed.
If I switch the wires on my 240v dryer, it does not run backwards. Same with my jointer, table saw, drill press, garage heater, etc.

I have seen 240v motors that could be made to run backwards by changing how the incoming wiring was attached. I didn't pay much attention to them, but I think it was more involved than just changing two wires.

[Bill Dufour]

Home wiring color code is pretty simple white is neutral, may be missing in a 240 circuit, bare or green is ground. All other colors are hot. Normally hot is black and maybe red or blue.
three phase... green or bare is ground. all other wires are hot. normally all just black wires going to the motor.
Bill

[William Shelley]

Well he did say 220 volt so most likely he meant 208 three phase.

Single phase has been 120/240 volt in North America for longer then most posters here have been alive.
Bill

Most people don't know or don't care that saying "110v" or "220v" is wrong. I might be a jerk for this but I correct people EVERY SINGLE TIME if I'm talking face-to-face with someone.

[Bruce Page]

This is a 7 year old thread. Hopefully Phil solved his problem long ago.

[Andrew Hughes]

My Davis and wells table saw has a Dayton motor single phase that can be wired to run Cw or Ccw.
In fact it was running backwards with a very cheap miter saw blade on it when I rescued it from a Life of cutting MDF for signs.
Im pretty sure the person wasn't thrilled about the saw running that way.Looking at the bright side of things at least the dust was shooting away from the operator.:o
Heres a diagram that proves it.

[Jerry Wright]

Some trades use regular blades installed backwards - example is vinyl siding installers. May work on mdf also. Once saw high temperature, refractory round fire brick shapes reduced in diameter by turning with the square back end of a tool bit. Sharpened end wouldn't touch it:)

[George Makra]

Some where you had a phase reversal. Was there a power outage or work recently done?
if you have 220 3 phase then there is no run or start capacitor turn of the power and switch any two leads on the load side of the contractor.
That should take care of the motor reversal

[Lee Schierer]

Guys this is a 7 year old thread........:eek:

[Ken Fitzgerald]

Lee,

Post #21, Member Kelly Hanna was given a saw and has the same problem.

[Andrew Hughes]

Ya Lee,We are trying to help Kelly :p

[Alan Schaffter]

Just so we don't leave this 7 year old thread with any misconceptions- yes, you can rewire a 110V (120V :rolleyes: ) or a 220V (240V) single phase induction motor to run CW or CCW, but only if it is a bidirectional motor in the first place. Also, you don't do it by rewiring the incoming line voltage wires - forget about switching black & white or black & red (that only works w/3 phase motors). What gets rewired is the internal motor wires which may be color coded and/or marked with number bands- see the motor plate photo in Andrew's post (#26). Rewiring changes the direction the start capacitor and start winding cause the motor to turn initially. By the way, without those, you can spin a bi-directional induction by hand so it will start and run in either direction.