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04-14-2013, 06:56 PM #1
Help wiring a single phase motor with reversing switch for my Lathe.
I'm trying to upgrade my Atlas 12" Lathe with a reversing switch. The Motor I have is a Century Motors 3/4 hp 1725 rpm Single Phase. I'm running it 110v and would like to add a Drum Reversing Switch. The motor is reversible and the switch I have is a Dayton 2x440. I have a diagram for both the motor and the switch. I'm trying to get them to post but not sure if they'll work. I'd appreciate any help from you electrical heads out there. thanks.
04-15-2013, 04:34 PM #2
I believe the following connex will work, using your connection diagram for the switch nomenclature:
Line1 connex directly to P1, neither are on the switch. On the switch: Sw1 connex to motor (P2+3)
Sw2 is not externally connected to anything. Sw3 connex to motor lead 5. Sw4 connex to motor lead 8.
Sw5 connex to motor leads (2+4) and Sw6 connex to Line2. If motor direction is wrong swap leads 5 and 8
on the switch. Be aware that motor must come to near complete stop to reverse, if you flip the lever all
the way F<->R the motor will NOT change rotation direction.
04-15-2013, 07:41 PM #3
Thanks for your reply: I didn't mention the simple on/off switch which I assume goes between the source and the drum. Are you saying that Line1 goes to P1 directly from the on/off switch bypassing the drum? Also, where does the 2nd line from the on/off switch connect to the drum? I certainly appreciate the help. (as you can tell, I'm out of my element here).
04-16-2013, 10:34 AM #4
Typicaly the rotary drum is off in the center position and you dont need a secondary on/off switch.
I suspect you machine was set up with a mechanical push button or toggle switch to start it.
At 110 v your black wire (hot) should be broken by a switch, and the white wire (neutral) may or may not be switched.
If the machine was set up to function on 220 as well as 110, both the black and white wires may pass through an on/off switch. The switch is basicly two switches in paralell with one trigger system. Both wires make and break at the same time. A switch of this type will have five screws for attaching wires, 1 for ground, 2 in and 2 out terminals. In and out for hot will be one the long side, neutral on the other.
04-16-2013, 11:39 AM #5
I've done similar with a second switch, double pole, double throw. One switch for off/on, second switch (DPDT) with it wired one way on one side and the other way on the other side. I'm wiring my mill that way, but have relays involved there, so my diagram would be way overcomplicated for this.
04-16-2013, 06:05 PM #6
thanks SCH for the plan. After drawing a diagram of your post I understand. P1 to line wired through with no contact on the Drum Switch. The 2nd lead (White/Neutral I suppose?) goes to 6. I'll give it a shot. About the On/Off switch. As Trip59 mentions, I picked up a big Paddle Offf switch for safety reasons. ***One more question. I take it the P1/Line is the Positive Black line? and the Drum switch 6 goes to the White Neutral line? Thanks all for the suggestions.
04-16-2013, 06:15 PM #7
Thanks for the diagram. I have the same problem with mounting a single phase motor on my Cincinnati #2 tool and cutter grinder and having to changing the wires to switch the rotation. I mounted the motor behind the spindle so the 3 phase motor is still down in the cabinet. One of these days I will take that diagram out to the shop and try to figure out hooking in a drum reversing switch.
My motor looks like twoluvbirds running on low voltage and having to change wire 5 and 8 to change rotation.
Should be easy but…. I have still a problem being sure how to wire it even with having the diagram. Hope it comes together when I am out in the shop. Can anyone make it even more simple
04-16-2013, 11:39 PM #8
Reversing a single phase motor with a drum switch is simple when you understand what you are doing. A drum switch has a number of contacts set up so that some reverse and others just close. Simple inspection will let you determine which ones do what! One set usually does very little and just completes the circuit the same way no matter which way the switch is turned, simple ON/OFF If the terminals were marked ABC and abc the "C" will be connected to "c" in either direction. The other 2 will result in "A" connected to "a" and "B" connected to "b" in one direction of turn and "A" connected to "b" and "B" connected to "a" when turned in the other direction. In the center none are connected.Understand?
A simple description of a reversible single phase motor is there are 2 windings, one is the main winding and the other simply to start the motor spinning in the correct direction. Most use a centrifugal switch to disconnect the start winging when the motor has reached the correct speed. The main winding will run in any direction so it will be connected to the "C" type connection of the drum switch, simply ON/OFF. The start winding is connected to the reversing contacts A and B so that you simply reverse the connection to the start winding and therefore reverse rotation. One thing to remember because of the centrifugal switch a running single phase motor will not reverse like a 3 phase motor when the drum switch is reversed. It will continue running in the same direction! Simply because at run speed the start winding is disconnected by the centrifugal switch so to reverse direction you have to wait until the motor speed drops to below the centrifugal switch "turn on speed"
Help?? I tried to keep it as simple as possible.
S_W_Bausch liked this post
04-17-2013, 07:50 AM #9
04-17-2013, 10:29 AM #10
As long as power is not applied before the centrifugal switch has closed then it will work. Otherwise the motor will continue in the same direction. A timer will have to be set for a long enough delay to assure reversal. However I would think that the "start winding" is sized to start the motor from a non rotating condition. Reversing the direction just below centrifugal switch reset might eventually burn up the start winding if done too many times. A switch that detects spindle rotation might be a better option.
Also Remember that with a threaded spindle and a brake it's possible for the chuck to unscrew and come off in normal Forward rotation, especially if there is a bit of weight it the item being chucked and the brake applied. Furthermore it will be a greater possibility if the spindle is reversed while rotating forward.
04-18-2013, 11:03 AM #11
Most of us were 18-19 year old kids and it was more fun to watch somebody new use it WRONG rather than show them the right way.
05-13-2013, 10:51 AM #12
Thanks a lot Sch Hot Rolled, it worked perfectly. I did have to swap 5 & 8, but it all runs well. Thanks again, and also all you guys who posted. I'm very fortunate to have you guys around for help.
05-14-2013, 01:45 PM #13
to motor lead P1 as it is effectively ground and the black line wire to the switch, slightly safer should the motor insulation short to the housing at some remote time.
05-28-2014, 03:55 PM #14
What is a connex?
05-28-2014, 04:13 PM #15
05-28-2014, 04:21 PM #16
What did he intend writing?
05-29-2014, 09:24 AM #17
connex is slightly short for 'connects' or 'connects to'
My phone is too primitive to text with.