Yet another tool!

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Jose Rivera
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Yet another tool!

Post by Jose Rivera » Wed May 21, 2008 12:05 am

Last week my son helped me changed the power switch on my Clausing mill with a brand new one that I recently posted with the reverse position safety block I made for it.

The motor is running on 110V and cannot be reversed. My son could not think of any way to have it go forward and reverse.

Anyway, I was told before that 110V motors can be reversed but not made to go on both direction with a FWD/REV switch.

So I had a nice quality made in Japan cast iron hand wheel and the idea came to mind to put a hex hole in it, a crank, and use it as a manual reverse for reversing taps by hand.
It worked great and it speed things up tremendously while tapping. I can even tap in, and remove the tap with this handle.

The handle will never be there when running under power at high speeds.
Finished handle.JPG
in place.JPG
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Post by MarkinMI » Wed May 21, 2008 9:04 am

As always, I'm impressed with your ingenuity, quality of work and application of principals to home shop needs. Cool :)

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Post by BobWarfield » Wed May 21, 2008 9:24 am

"Anyway, I was told before that 110V motors can be reversed but not made to go on both direction with a FWD/REV switch."

I don't know what the difference is, Jose, but my lathe has a reverse switch on a 110V AC motor and it works great.



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Frank Ford
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Post by Frank Ford » Wed May 21, 2008 10:18 am

Jose -

Great work there - you're a real schmarty!

I, too had a lathe with single phase and reversing switch. Unlike three phase you can't slam from forward to reverse, but you can stop and change direction.

It stuck out at waist level, so I made a simple safety interlock to avoid turning on the machine as I walked past:


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Post by CarlD » Wed May 21, 2008 10:19 am

Neat job Jose, but I think there should be a way to make a switch circuit to reverse the motor. Unless it was like the motor on my old Logan. I had to remove a cover and slide a lever one way or the other to reverse it. Since the chuck was screwed on I was not to interested in reversing the motor very often.
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Jose Rivera
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Post by Jose Rivera » Wed May 21, 2008 12:29 pm

Frank Ford wrote:
It stuck out at waist level, so I made a simple safety interlock to avoid turning on the machine as I walked past:
Frank, where do you think I got inspired for my safety devise ? :roll:
There are no problems, only solutions.
Retired journeyman machinist and 3D CAD mechanical designer - hobbyist - grandpa

Jose Rivera
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Location: Vallejo California


Post by Jose Rivera » Wed May 21, 2008 12:36 pm

Bob and Carl:

The motor does not have a inner switch.
Reading the instructions appears that the motor is reversible but my son's expertise is not with motors.

My option here is to contact Clausing since the motor appears to be OEM. So it must be the one it came with when new.

As for the handle I made I kind of like that far better than using toe motor specially for 10-32 and smaller taps.
Also I had messed parts by not stopping the motor in time and driving the tap way to deep or breaking it.

With my reflexes moving down towards snail speed as I get older, I would trust my this contraction more than doing power in/out with the motor.

I was doing it with the wrench for a while, but this does improves it 200%
There are no problems, only solutions.
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Bill Shields
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Post by Bill Shields » Wed May 21, 2008 6:12 pm

Most single phase motors are started with a boost (starting) capacitor to get them spinning in one directon or another. There are some older types that weren't but you aren't likely to see any of them around any longer.

Change the wiring of the capacitor on the internal coils, and you can get the motor to run in the other direction.

Sometimes, this requires taking the terminal box apart and cutting wires, but it can be done.

Clausing might be able to help you - but I would check with the motor manufacturer if you can find a name plate.

If you look on the inside of the motor terminal cover - SOMETIMES - there is a wiring diagram in there.

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Post by SkyboltIII » Wed May 21, 2008 7:31 pm

I have spent much time reading this site and this is my first post.

If you have a motor that can be wired in fwd/rev then with a double pole double pole switch, you can get the motor to run in both directions. It is a bit tricky as most 110/220 1ph motors have up to five terminals and you jug these to together for forward and those two for forward. I picture of your motors wiring digram would provide all you need to create a schematic.

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Post by MikeC » Wed May 21, 2008 10:31 pm

As SkyboltIII says, it can be wired to reverse, but also as Frank says, you have to wait for the morot to stop before reversing or it won't reverse. Had a little Century on the Logan at the museum wired to reverse. The SB10L had the original 1 1/2hp instant reversing 110v single phase motor on it, and it still worked great. Was just like running a three phase. You could stop it on a dime with plug reverse.
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Post by mechanicalmagic » Wed May 21, 2008 10:55 pm

I respectfully disagree.
110V AC motors, using a Capacitor to alter the phase for starting, ARE NOT always reversibile. I have a Baldor clone Carbide grinder. It is a cap start, but changing the cap to the other leg DOES NOT insure reverse rotation.

No, I have no idea why, it just happens.

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Reversing a Single Phase Capacitor Start Motor

Post by ftl » Thu May 22, 2008 12:39 am

The vast majority of capacitor start single phase induction (i.e. 110V) motors can be reversed. An induction motor can be identified by the lack of brushes or coils of wire on the rotating armature. Most 1/4 to 5 HP 110V motors are this type.

As stated in several posts above the reversal of most of these motors can only be applied when the motor is stopped. See notes on this near the end of my post.

The problem with any single phase motor is that there is no direct way to create a rotating magnetic field. All you can do is alternate the field back and forth over 180 degrees. The alternating magnetic field will not reliably cause the armature to rotate, and if it does, it will have very little torque. With a 3-phase motor, the fields can be placed 120 degrees apart and there is a true rotating field. Reversing the motor is accomplished by changing the order of the phases to cause the magnetic field to rotate in the desired direction.

Capacitor-start single phase induction motors have two separate field windings: a run winding and a start winding. The start winding is wired in series with a capacitor.

Capacitors have the interesting property that the current through them leads the voltage by 90 degrees. It is actually a little more complicated than that because the start winding is a capacitor in series with a coil, but the effect is the same as long as the capacitor is the dominant component.

The magnetic field is created by the current through the coil (start winding) not the voltage. Since there is a capacitor involved, this current will lead the voltage by some amount. Remember that the run winding is connected directly to the AC power source, so its current remains in phase with the voltage (actually it lags somewhat).

With the combination of the start and run windings there are now two sets of magnetic fields that are nearly 90 degrees apart. These can easily be wired to create a rotating magnetic field. The rotating field can now pull the armature around with significant torque.

The start winding is not very efficient and will heat up quickly, so it is removed from the circuit once the motor reaches about 70% of its operating speed. That is generally done with a centrifugal switch inside the motor, but sometimes it is done with a simple timer that energizes the start winding for a short period when the motor starts.

These motors can be reversed by reversing the leads on either the run or the start windings when the motor is stopped. When the motor is restarted, the field will rotate in the opposite direction and the motor will rotate in the opposite direction. Once the motor reaches speed, the start winding disconnects and the run winding provides the magnetic field with the physical rotation of the motor keeping it running (just like a flywheel on a single cylinder engine).

The trick in creating a reversing switch is to identify the leads for the run and start windings inside the motor. The run windings are generally fewer turns of thicker wire while the start windings have more turns of thinner wire. This means that if you are testing the windings with a DC ohmmeter, the start windings will have significantly more DC resistance than the run windings. This higher resistance is what makes the start windings heat up if they are connected for too long. If the windings are brought out to the motor terminal block it is easy. If not, you can go inside the motor, identify the windings solder wires onto them and bring them out for switching.

Since the start windings are disconnected once the motor comes up to speed, reversing the winding will have no effect when the motor is running. Reversing the run winding while it is running will cause a small blip to the motor (probably a pretty good spark on the switch as well), but it will only cause the motor to lose half a revolution before it syncs back to the alternating magnetic field.

It is possible to do a sudden reversal to the running motor by bypassing the centrifugal (or timed) start switch. Effectively you reverse the start windings, and then energize them while the motor is still running. That will rapidly reverse the motor. You must be sure to de-energize the start windings once the motor is up to speed again in the reverse direction. This is pretty hard on the windings of a motor that was not designed for this sort of abuse, but will work in principle.

Using the engine analogy, a single phase motor is like a single cylinder 2-stroke motor. It can be started in either direction by the starter motor, and will continue to run in that direction once started. A three phase motor is more like a three-cylinder motor. The motor will run in the direction of the sequential power strokes as defined by the crankshaft. It will be smoother, have more torque and can use a smaller flywheel.

All of the above comes with the usual warnings about messing with line power: It is easy to make big sparks and hurt yourself and other stuff.

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