Replacing and relocating switch on B'port clone

[Investigator]

I have a B'port clone knee mill, the switch is a "FWD-OFF-REV" 3 position rotary/drum type switch located on the motor itself, you can see it here:


I will be doing some refurb on the machine, and I am concerned about the switch location. I dont like the idea of reaching up and over to get to it, and I dont like the idea of using a long handle to actuate the switch. I would like to move it. Something like the location on these:




To make it a bit harder, the switch I have has a broken face mounting plate. I could make it work, but perhaps a new one is in order. To that end is there anything special about getting a new switch?

 

[markba633csi]

Two things:
First, the switch needs to be able to carry the rated motor current plus an additional amount. I like 3x the rated current at least.
Second, the switch needs to have enough poles to perform the reversing function. 6 pole would probably be plenty. Take a look inside yours.
Amazon has lots of imported multi pole switches; I've seen several styles. If you want USA-made, you'll pay much more.
-Mark

 

[projectnut]

If you intend to locate the switch lower make sure the one you get is sealed, or seal it yourself. One reason they're in that position is to keep them out of the reach of swarf and coolant. When I got my Bridgeport from a local high school the box with the starters was on the right side of the column just below the most common table height. Even though it was in good shape coolant and swarf had managed to migrate in over the years. I had to remove the starters, clean them and the box, then reseal all the wiring ports. It's remained clan and dry inside, but still gets covered with swarf on occasion.

 

[Investigator]

So I have 9 wires coming out of the motor. 3 are tied together, the other 6 are marked U V W and UU VV WW. I assume one set is forward the other is reverse. Below is a pic of a motor plate from what I believe to be the same mill as mine, although my motor plate is totally unreadable.

 

[ttabbal]

From the motor plate, it looks like it's wired for 220V. The 3 connected together are the XYZ at the top. Those are just capped off with a wire nut or otherwise shorted. The other 3 are the phase lines. When I wired mine, it had the switch mounted lower already. Still on the head, but easier to reach. So to relocate the switch, put a junction box where it is now and use a 3 or 4 conductor wire with a strain relief to bring the switch to where you want it. If you use 4 wire line, you can bring a ground along for the ride, but you don't need to from there. You can ground the frame elsewhere. It's the safety ground, the motor itself doesn't need it to run. It's just to protect you in case something shorts to the body of the machine.

Then just run from the switch to the power source. Here you do need a ground. Don't worry about which wire is which. It will work however you connect the phase wires. If it turns backwards, swap 2 of the phase lines.

If you are going to run a VFD, the phase lines need to go direct to the VFD. No switches. The switch is low voltage and connects to the control terminals on the VFD. If you are using a phase converter, static or rotary, carry on.

 

[Larry$]

The reason for 9 wires is having two sets of windings in the motor so it can be used as 220 or 440. The connections just change it between parallel and series. Your connections will be like those shown for 220V. The dashes indicate connections between wires. I'm assuming you have 3 phase 220V (208 or 240 also work) in your shop. Wires U1 & U2 will be connected together Same for V & W. The direction of rotation is controlled by the order in which the 3 resulting wires are connected to line. Swapping any two wire locations will reverse the motor. The connections of having the Us, Vs & Ws together doesn't change. Think of them as just becoming one for each letter. The drum switch connections are made to do the changing of the relationship of any two leads. You can find diagrams online that are easier to understand.

 

[Larry$]

ttabbal beat me while I was responding. Note where he says "Those are just capped off with a wire nut or otherwise shorted. " He means connected together, not shorted to ground.