Wiring new motor
I getting a new motor for my lathe.
When I bought my lathe 4 years ago the old wiring was totally rotten.
I labeled everything and replace it exactly as it had been previously wire.
I have a 1953 SB with the Furnas Drum switch, the existing motor is 110 only, the new motor is 1/2 HP and can be wired 110 or 220.
I have both outlet right at the lathe.
My lathe is currently wired with the power cord attached to the drum switch, but I'm open to moving that cord to the motor.
Here's a drawing of how the drum switch is currently wired and also a picture of the wiring diagram for the new motor which I don't have yet.
Like I said I can solder and crimp and I'm game to starting over but electrical theory gives me a head ache, so any help would be appreciated.
I can't draw either.
Looks like that switch should work. Does this drawing help?
PS- The "L" on the right side gets jumpered to the 120V "Line" input wire. I should have drawn that better.
Last edited by Paula; 07-17-2010 at 06:17 PM.
Reason: Oversize image
I'm not sure?
Are you deleting the jumper wire between the 2nd and 3rd poles on the right side?
No, that was what I meant by the note to connect "L" on my drawing to the "LINE" wire. Looking at this again, the two drawings (your and mine) are electrically the same, but I think I had my switch rotated 180deg compared to yours when I sketched it. Maybe this second drawing will make more sense.
One other thing I'll point out- in your original it looks like you are switching the neutral lead from the wall, not the hot lead. The lathe will run either way, but you want to run the hot (line, black) lead through the switch instead of the neutral (white) lead as shown in my second drawing.
If the motor spins the wrong way for fwd/rev, swap the locations of the T5 and T8 leads from the motor.
This drawing is clearer.
As I said I redid the original wiring exactly as it came to me.
Would this diagram be correct if I decide to wire for 220 volts instead of 110,
as I said I have both outlets present at the lathe.
BTW. I switched the Hot and Neutral leads in my switch, and it still works. LOL
In that last drawing for it to work in the reverse position 1-3, 2-4, 5-6 will have to make for it to work right. The way it is showing wired in the reverse position the start winding will start in the same direction and the main/run windings will never get power.
I'm a wiring dummy..
Originally Posted by SB10L
If this won't work you need to draw out how it should be wired.
he has reversed the numbering scheme in the drawing. in the top two drawings of the switch he has the numbers going 1,2,3,4,5,6.
on the bottom drawing the numbers go 6,5,4,3,2,1.
If you've transposed the numbers, basically turn them 180° on the switch portion of the last drawing it should work properly. 6 = 1, 5 = 2, and so on.
The drawing is correct, he just labeled part of it wrong. the labeling on the bottom drawing of the switch should equal the top two drawings.
Thanks, I knew the top 2 drawing were upside down.
1 other question, I've had some rubbing and crowding issues with the wiring in the switch, especially on the middle of the left side..
Does anybody have a picture of how they routed the wiring inside the switch.
Also what size wire should I use, I'm going to use liquidtight conduit and individual wires.
You can use AWG 18, 16, or 14. I would not go any larger than 14 as it is rated way above the total amps of the motor at 7.4 on 120 and less on 240V.
To run at 220/240V, you put the two run windings in series instead of parallel as shown below. And yes, its a lot of wire to pack into the drum switch body. I added a single gang junction box to my motor so I had a little more room for the splices etc. Then I ran liquid tight to the switch and ran #14AWG from each switch terminal. #16AWG would be OK too, but, but may be harder to find?
I'm not sure I follow you? If you swap the wires at terminals 1+3, then swap 2+4, then swap 5+6, you wind up with the same function/circuit. I drew this circuit a bit different than the standard, but I was trying to match as much of Bob's original wiring. To swap rotation of the motor, you would swap the connection of the T5 and T8 motor leads at the 1 and 4 terminals on the drum switch.
I wish everybody would draw out circuits so we electrically illiterate could understand them.
I'm actually going to be starting over, I'm going to move the power cord off the switch and move it to the motor, then run all the new wiring from the motor to the drum switch through a liquid tight conduit.
yes if we all had 3-phase at home it would be much easier....packrat2
One can set up a standard drum switch like that for single phase 240 volt service
for a motor like that. The trouble is however in doing so the usual way, one only
interrupts *one* of the incoming hot leads, as only one pole is available for this - the
other two poles are used up reversing the start windings.
This seems to be a common problem for those who want to run on the higher voltage.
One common apporach is to simply live with the code violation where the internals of
the wiring are hot even when the motor is not running, another is put a safety switch
inline before the drum switch.
If you are willing to go into the guts of the motor and bring out wires that are not
usually available, it can be done legally with a drum switch like that, for motors
that are dual-voltage. Those, when wired to the higher voltage, return the start
winding connection to the center-tap on the run windings. This allows the following
trick to be used:
As shown, the upper and lower drum switch poles simply energize the run
windings when switched on to either position. The center pole on the switch
connects the free end of the start winding to either hot leg, alternately, for fwd
or rev operation. It's clean and uses a minimum of wires inside the drum switch,
a plus that many here will appreciate!
Well no one has said how the switch terminals are configured on the switch to be used but here are a couple of drawings I made of some common ones I have used and not sure why you have to have a hot anywhere past the drum switch until it is either in reverse or forward position. There is also another one where you remove the jumper for 240V but I did not do that one. Unless I have missed something I have no hot in the motor circuit when the switches are off. One even has an extra terminal that is not used. I would not want a hot anywhere in the circuit myself other than the feed coming into the drum switch when it is off. You should only have 4 wires from the motor (5 with the ground) on the lower voltage and only 3 wires (4 with the ground) on the higher voltage.
As for the 3 phase I am still using that motor on my lathe with 240V single phase and an inverter along with the drum switch inputting into the inverter and an external potentiometer. I really like the setup so for and it does so many different things like takes care of the over-current protection the dynamic braking (bringing the spindle to a stop in a specified time that you set) straight from forward to reverse without stopping if that happens just to name a few any speed from 0-1800 and can be set to go more if wanted. It has about 125 things you can set up on it. If we all only had 3 phase at our houses now... how nice.
Those look good. But it does point out that there are at least 2 (maybe 3) different internal schematics for the drum switches.
Jim- the SB diagram you posted looks like it has 9 terminals (a 3 pole, double throw switch). I pulled apart the switch on my 9C at that's the switch installed there (Cutler Hammer #5441H27A)
SB10L- the internal schematics on your two switches are slightly different. One matches the circuit I copied off a Dayton drum switch. The other is different again. I agree that's a better way to connect the 240VAC power supply so you kill both leads to the motor when the switch is off.
Bob- so if your lathe/motor works, you are all set. If it doesn't, you may want to compare the internal drum switch schematic to the ones presented here to find the right interconnect, or maybe you have schematic #4?
The drum switch schematic you drew matches the one on the inside cover of the switch.
Your's is much easier to read and understand.
I've had to change the way the wires were hooked up in the compressor and table saw in the shop where I used to work to run them off 220 volts instead of 110, and your drawing make clear what's actually happening in the motor.
Changing the motor runs from parallel ton series.
Now I just need to get a few thing and wait for the new motor to arrive.
Got my new motor install Wednesday.
Luckily I double checked the configuration of my drum switch against the different wiring diagrams I was provided with.
Turned out Chris drawing was upside down on the reverse side compared with my switch, so I used SB10L's diagram.
I was tracking my shipment and usually get my UPS in the mourning so of course it didn't arrive until 2:00
By the time it arrived I already had to old motor and wiring removed.
Only had 2 small problems, those bottom motor mount bolt are hard to get started, if I was doing it again I would have used studs and nuts in the bottom holes.
The other problem was the motor came with a nice big die cast box for the wiring but only had 2 predrilled threaded holes, 1 on the end perfect for the power cord.
But the other was on what would be the bottom if the motor was mounted base down, but was the top in this configuration right under the belt.
There was a blank space on the side so I dismounted the box an drilled a 7/8th hole with my smallest hole saw.
Not a big deal unless you don't have the proper tools, I just think there should have been holes on all 4 sides.
Once I got the box remounted I hooked up the liquid tight conduit ran all my new wiring hooked everything up according to my diagram, double checked to make sure all the wires were hooked up proper plugged it in and turned on the switch.
Everything works perfectly and I want to thank those who helped, I've got a better understanding in how motors run and how drum switches work.
The motor is a WEG 1/2 HP TEFC, it's wired for 220, I got it new off E-Bay and paid about half what a Baldor or Leeson would have cost me.