Another motor reversing cry for help

Hi.

I have a small (1/8HP) capacitor start capacitor run motor which I have fitted to my (nearly) completed Bonelle T & C grinder.

At the moment I have it wired through two DPST switches, one for CW/CCW and the other for ON/OFF.

What I really want to do is to have just one DPDT ( centre off ) switch wired to the motor.

Below is the connections shown on the terminal lid

Thank you

Ian

Hi Ian,
Are you sure that both of the existing switches are DPST ? I cannot think of a way the motor could be reversed without a DPDT switch. I think to achive what you want you would need at least a 3 pole double throw switch. Your picture of the connections did not appear. Are you having a problem with the strange way used to insert pictures into this forum ?

Les.

No connection diagram. I do not think you have enough connections for what you want. To reverse the motor, you have to reverse the L and N connections to the start circuit (motor winding plus start capacitor in series), so this will use 2 poles (L&N) to start circuit (say R & B and B & R). But you have not got another pole to break the L to the run winding .

One way of doing it would be to get a relay with a coil that works on the mains voltage and wire it across the start circuit. and wire its contacts between the L and the run coil of the motor. So when the CW/CWW switch is in the centre, no supply to the start, relay is then off and no supply to run windings. If the CW/CWW switch is moved , mains goes on start winding and relay coil, relay pulls in and mains goes on the run winding.

Frank

Hi. Sorry about the missing picture. Here it is ?

Les. Yes both switches are DPST . I can't remember how I did !! I will go & have a look now.

Ian

Les.

Your dead right the ON/OFF switch is DPST and the CW/CCW is DPDT ( not centre off). Sorry for the confusion.

Ian

Hi Ian,
I think you will find it difficult to find a 3 pole double throw toggle switch so Frank's suggestion of using a relay is probably the simplest solution. You may find it easier to get a 3 pole 3 position rotary switch. The method you choose will depend on the space available for the switch and relay if used.

Les.

Hemingway kits sell a suitable rotary switch for reversing this type of motor, used on their Worden Grinder. Not cheap at £36 but does the job very well.

Hi Ian,
If you choose Frank's solution then CPC sell a suitable centre off DPDT switch code SW04199 and two relays that would be suitable codes SW04807 and SW02562.

Les.

Thanks all for your replies.

I've managed to find a source of 3PDT toggle switches:-

**LINK**

based in Scotland ( you can get 5 of the same off eBay for £10 free postage. but I don't need 5 !!) :- **LINK**

This seems to me to be the uncomplicated and cheapest way to go.

Having said that. Les how would I connect the switch to the motor?

Any way it's passed a cold Sunday afternoon. is it an age thing that I use to be in the workshop on colder days than today?

Regards Ian

Ian... If you want a three pole toggle switch take look at the Arrow switch website. **LINK**#

John

Edited By Johnboy25 on 01/02/2015 17:42:50

Hi Ian,
Those switches look ideal. The switches on eBay are from China so they will probably take about 3 weeks to arrive. It is probably worth buying 2 so you have a spare. I think your decision will be based on the postal charges from the supplier in the UK.

When I first looked at the connection picture I assumed the incoming power was the two vertical arrows at the bottom of the picture and they connected to U1 and Z1 but that did not make sense as in the CCW configuration the capacitor is straight across the mains. I think Z1 and Z2 are the main winding and U1 and U2 the auxiliary winding. (It could be the other way around.) IF I am correct the power would connect to Z1 and Z2 If you have a drawing of how it is connected at present it should identify which is the main winding. An alternative is to measure the resistance of the two windings. The one with the lowest resistance will be the main winding. I expect wth the present wiring that one end of the capacitor goes to the switches. When you provide this information I will draw out how to connect the new switch.

Les.

Mini-lathes use a multi-pole (4 pole) high-current centre off switch that would be ideal for this purpose.

Arc Euro sell them:

www.arceurotrade.co.uk/Catalogue/Machine-Spares/C2-Mini-Lathe-Spares

Neil

Les.

Just been and checked. My original diagram is incorrect. The mains IN for the CCW direction is across U1 & U2.

You are right in that the cap. is disconnected from U2 & is switched to U2 (CW) or U1(CCW)

U1-U2 20 ohms

Z1-Z2 55 ohms

Ian

Hi there,

For some reason (which I can't justify after all these years) I included a forward-off-reverse facility in the control box for my Tauco bench drill. This was achieved using a four-pole toggle switch with a centre off position. These toggle switches were common on the government surplus market back in the 70s and can be recognised by the luminous tip to the operating dolly.

(The control box also includes a MEMDOL single phase direct on-line starter.)

Best regards,

Swarf, Mostly!

Hi Ian,
It looks like I guessed the wrong way which was the main winding. Here is the way I suggest connecting the switch.

The diagram of the back of the switch is with the lever moving horizontaly. The letters are just to tie up with the schematic. They will not tie up with any labeling that may be on the switch. (It does not matter if the switch is turned through 180 Deg. If you decide to use the 4 pole swtch from Arc Euro you could also switch the neutral to the main windin with the extra set of contacts.

Neil,
Well spotted. I would not have thought to look at Arc Euro's website for a switch of this type.

Les.

Thanks for that Les.

I've ordered two switches from Proto-pic for less than £7 inclusive of postage.

Ian

Hi.

Just thought I would update you. The switches arrived this lunch time. I wired one up as to Les's diagram & it works just fine.

Thanks Les very much for your help & others for their suggestions.

PS Looking at the photo I need to level the ON OFF ON plate!!

Ian

Edited By ian j on 03/02/2015 17:22:04

Looks nice. Just as a matter of interest, which vacuum cleaner brand hose are you using to protect the front rail, and what sort of expansion ratio do you get please? Interested in using similar for when I fit a ballscrew to my lathe.

John.

I spent a lot of time looking for suitable bellows with out much success, I did get one quote of over £80 for two bespoke 6" extended length latex rubber ones. But !!

So for the time been I'm using the hose off a Dyson vac. It's 1.75 " o/s diameter, 12" extended compresses down to 2.75". I got mine free from a local vac. repair shop or you see loads down the council recycling centres.

Ian

Hi Ian,
I'm pleased that the switches arrived so quickly and that one worked when connected. Your grinder looks very nice.

Les.