Wiring Help for 110V Reversing Drum Switch on old Logan lathe

I've gotten myself into a predicament. I have a 110V single-phase Logan lathe which needed the reversing drum switch replaced. I got the old out no problem. I purchased a Dayton 2x440 drum switch with 6 contacts. The switch contacts are laid out as shown in this diagram I found on this site (I know this is a Dayton and not a Furnas, but the terminals and bus bars are set up the same):



The motor is very likely the original, it has 4 wires coming out of it.

In trying to rewire it, I have it so that off and forward work fine, but if shifted to reverse the breaker pops. I figure I have two wires that need to be switched, but which ones? What troubleshooting steps can I take to track down the problem?

The diagram your using is for a dual voltage motor with 6 leads. If your has only 4, that diagram can't possibly be right. To get some help, you need to show us what your working with. Post the connection diagram of the unit you have and the nameplate.

It's likely that the 4 leads you have are 2 windings, a run pair and a start pair, and a single voltage on the tag. But we can't see that from here. If you figured out the pairs, then you could use the diagram to connect them to the switch.

SAF Ω

Getting to the motor diagram is fairly difficult, as it is facing the back panel of the lathe cabinet with very limited space. Even if I could fit my head back there, I doubt my old bones would contort enough to let me.

I was hoping that given the current state of operating forward just fine, but shorting on reverse, that someone could deduce what was going on, or, if lacking that, then suggest some steps I could try to narrow it down. Like "switch wires from switch lefthand middle contact to righthand top contact" or some such.

I'n not sure it makes any difference, since that diagram only has 4 wires going to the switch anyhow, for 120/230 motor connected for 120V.

The problem comes if you are running on 230, with 6 wires, in which case reversing has to be done differently, and start circuit is wired differently because the start circuit is 120V witha 6 wire motor,. That does not apply to your situation.

My suggestion is that you look carefully for a wire trapped under the cover, or a stray strand touching ground, between the switch and motor somewhere. With 120V, if you short the neutral to ground, no breaker will blow unless if is a GFCI. But when you reverse, that short to ground is now on the hot, and breaker will open.

Decades ago I made an oath to never again run a lathe with single phase motor and a drum switch. The typical capacitor start motor can run in either direction as determined by the starting winding, which is switched off by the centrifugal switch after it gains some speed. If you change the drum switch to reverse while it is running, it just keeps going in the same direction. If you happen to catch a sleeve in the chuck, it keeps rolling you up. In a panic situation, it is too easy to slap the switch all the way over to reverse, which keeps it running in the same direction.

Some of the Clausing lathes had locks on the switch preventing it from going over. I would only use one like that or have separate on-off and forward-reverse switches.

I know that we are supposed to keep our sleeves out of the chuck, but the best of us makes mistakes.

Bill

Does anyone have a picture of the wiring inside the motor cover. I need to wire mine and want to compare ?

fileophile said:

The motor is very likely the original, it has 4 wires coming out of it.

Click to expand...

Take a step back and post up a photo of the motor and the wiring going to it, as is. If the motor
is very old it may be not reversible. If it has a start capacitor housing then it most likely is reversible
but you will need to get into to bring out the connections you will need to do so.

Would that be a Powermatic Logan with Baldor motor?

jim rozen said:

Take a step back and post up a photo of the motor and the wiring going to it, as is. If the motor
is very old it may be not reversible. If it has a start capacitor housing then it most likely is reversible
but you will need to get into to bring out the connections you will need to do so.

Click to expand...

f it is 4 wire single voltage, it should be reversible. If it is 4 wire dual voltage, it is very likely NOT to be reversible.

In the first case, the extra 2 are almost sure to be the start winding, and reversing those wires only will reverse rotation..

In the second case, they will be for a second run winding, and not for a start winding, so no-go on reversing unless you can dig out the wires. In that case, it is likely to be far easier to obtain another motor that IS reversible.
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