Author Topic: running single phase motor backwards  (Read 19079 times)

Offline jim

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running single phase motor backwards
« on: September 18, 2009, 11:21:10 AM »
i've got an old pillar drill motor, already got one on the bench running polishing mops, but it runs "the wrong way" ie, i'm having to work left handed.

the new motor runs the same way :scratch:

its a single phase one, with a starter thing on the side.

i've read that swapping some wires over will get it to run backwards, but i can't see which ones :scratch:

if i can't run it backwards, i can probably put the cooling fan on the other end, but i'll be running a much thinner out put shaft.

can anyone point me inthe right direction, please :thumbup:
if i'd thought it through, i'd have never tried it

Offline Darren

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Re: running single phase motor backwards
« Reply #1 on: September 18, 2009, 12:01:33 PM »
Can you take a picture of the wiring connections...a clear one please

It's easy to change the direction, just want to see the wiring before giving any advice as it can be different between types of motors.... :thumbup:
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Offline Bluechip

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Re: running single phase motor backwards
« Reply #2 on: September 18, 2009, 01:28:49 PM »
J-o-c

If you look on the inside the connection box cover, there is often a diagram pasted there. Although they do have a habit of falling off.

Otherwise it's Darren & a Pic.  :D

Dave BC
« Last Edit: September 18, 2009, 01:31:38 PM by Bluechip »
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Offline jim

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Re: running single phase motor backwards
« Reply #3 on: September 18, 2009, 03:58:06 PM »
thanks Darren, i'll get some photos done :thumbup:
if i'd thought it through, i'd have never tried it

Offline John Hill

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Re: running single phase motor backwards
« Reply #4 on: September 18, 2009, 04:49:57 PM »
Yes, it should be easy but maybe not depending on if the makers ever intended for it to be reversed.  If it is clearly marked inside the terminal box then go for it but double check and do before and after photos for showing here (before turning the power on!), otherwise put the motor under your arm and take it to an electrical repair shop for a verdict.  

Safety first.
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Offline jim

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Re: running single phase motor backwards
« Reply #5 on: September 19, 2009, 03:58:31 AM »
i've took some pictures, looking at it i think i may have to press the motor windings out :scratch:




if i'd thought it through, i'd have never tried it

Offline Darren

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Re: running single phase motor backwards
« Reply #6 on: September 19, 2009, 04:42:25 AM »
My pillar drill motor is wired like that, (but I was expecting to see more connections on yours) my guess is to swap the live/neutral wires around.

You don't need to strip it down, just change at the connector block. Just make sure you have a good earth.


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Offline John Hill

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Re: running single phase motor backwards
« Reply #7 on: September 19, 2009, 05:44:25 AM »
Ummmmm, errrr, does it have a centrifugal switch in it?
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Offline jim

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Re: running single phase motor backwards
« Reply #8 on: September 19, 2009, 05:59:37 AM »
i've been thinking about switching the wires on the starter, not sure if thats a good or bad idea :lol:
if i'd thought it through, i'd have never tried it

Offline Darren

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Re: running single phase motor backwards
« Reply #9 on: September 19, 2009, 06:08:26 AM »
I have a sinking feeling this motor can't be reversed because we wanted to see four connections really.

If you try swapping the connections to the windings  at the motors connection block you will soon find out.
If you want I'll try it on my motor first and let you know.

Nothing will be damaged, it just may turn the same way that's all.
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Offline Darren

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Re: running single phase motor backwards
« Reply #10 on: September 19, 2009, 06:13:49 AM »
Thinking about it the motor leads are the new wiring colours, I guess the motor is fairly new.

The fact that they have not used two black leads to the motor and instead used brown and blue makes me think that this has been done so the guy assembling it gets the connections the right way around for the machine it's fitted to.

So it may well be reversible, only one way to find out  :zap:
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Offline Bluechip

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Re: running single phase motor backwards
« Reply #11 on: September 19, 2009, 06:27:05 AM »


What you appear to have is a Cap. Run motor

You need to identify the ends of the windings, and, on the diag.

EITHER  reverse A1 and  A2  OR   Z1 and Z2.

The designations are common, but not universal, on UK motors.

The motor will not reverse by swapping the AC input.

If you have ANY doubts, as John H. said ... Get an Electrician to do it.

Dave BC

I have a few modest talents. Knowing what I'm doing isn't one of them.

Offline Darren

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Re: running single phase motor backwards
« Reply #12 on: September 19, 2009, 08:43:12 AM »
Dave's right, as usual, swapping the wires over will do nothing for you..... :doh:

My motor has four wires, yours has only two so the connections you need to get to are inside. Might be more trouble than it's worth.
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Offline jim

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Re: running single phase motor backwards
« Reply #13 on: September 19, 2009, 08:50:42 AM »

thanks for the replies. :thumbup:
its looking that way :doh:
i'd swap the wires on the "cap", but i can see that going pop!!!

i'm not going to try pressing out the windings as i'll bust sumat i'm sure :lol:

i know i could just go down the diy stores and buy a new bench grinder for about £15, but they are only 150W, this motor is 500 or 600W. i need the power as i'm using solid "scotch brite" wheels for deburring/first polish on stainless.

i'll just have to run a new spindle on the fan end.

i'll let you know how i get on :thumbup:
if i'd thought it through, i'd have never tried it

Offline Darren

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Re: running single phase motor backwards
« Reply #14 on: September 19, 2009, 08:52:15 AM »
I doubt the cap has a polarity as it's seeing AC mains ?
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Offline klank

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Re: running single phase motor backwards
« Reply #15 on: September 19, 2009, 08:59:05 AM »
Is it not possible to turn the rotor round end - to - end in the case and change the end caps round with it? Will the direction of rotation then also be reversed?
Or is this too simple - just a thought?

Peter

Offline jim

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Re: running single phase motor backwards
« Reply #16 on: September 19, 2009, 09:22:09 AM »
Is it not possible to turn the rotor round end - to - end in the case and change the end caps round with it? Will the direction of rotation then also be reversed?
Or is this too simple - just a thought?

Peter

already tried that :thumbup:
if i'd thought it through, i'd have never tried it

Offline Bluechip

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Re: running single phase motor backwards
« Reply #17 on: September 19, 2009, 10:16:56 AM »
j-o-c

Sent u a pm @ 15 18 BST UK

Dave BC
I have a few modest talents. Knowing what I'm doing isn't one of them.

Offline jim

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Re: running single phase motor backwards
« Reply #18 on: September 19, 2009, 10:29:53 AM »
j-o-c

Sent u a pm @ 15 18 BST UK

Dave BC

thanks, i'll ring you at 4 :thumbup:

i'll get the motor ready now
if i'd thought it through, i'd have never tried it

Offline jim

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Re: running single phase motor backwards
« Reply #19 on: September 19, 2009, 10:56:13 AM »
great joy :) :)

the motor now runs backwards :) :)

thanks for all the info and offer help, it was all appreciated :mmr:

all i've done is pop the shaft out with a BFH

shoved it back in the other way round, the drive shaft now spins the corrcet way, how i didn't think of that before :doh: :doh: :doh: :doh: :doh: :doh: :doh:

now i cna get on with making me shaft for the polisher
if i'd thought it through, i'd have never tried it

Offline Darren

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Re: running single phase motor backwards
« Reply #20 on: September 19, 2009, 12:41:14 PM »
Brilliant, you were lucky you could turn it around....  :clap:

Dave, perhaps you could help me solve a little problem that I can't seem to fathom.

My drill motor when switched on from cold spins up fine. If it's switched off, allowed to come to a stop and switched back on again it just hums.
But if you leave it off for 10 seconds or more it will spin up fine.

I originally suspected the start cap, changed it and there was no difference. So I changed it again for another known good one and still no difference.
I'm lost as to what it could be. Not a major problem, just a slight inconvenience.

Any ideas?
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Offline Bluechip

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Re: running single phase motor backwards
« Reply #21 on: September 19, 2009, 01:47:52 PM »
Darren

If it's a motor with a start switch, I would do this:

Next time the sod acts the goat, while it's a-buzzin, give the chuck a twist.
If it starts, it's yer start circuit. So:

Caps are usually not the culprit, in my experience, go for the centrifugal doings.
If you ever have a shufti at these cheapskate devices, you will see an unlikely arrangement of bits of bent metal and a couple of springs.
These are VERY prone to temporarily jamming up due to fretting rust on the bearing surfaces.  If you find this, clean 'em off and lube with a bit of 3in1 on a matchsick.

T'other source of grief are the contacts, any 'pip & crater' they aren't usually fixable. There ain't a lot of contact alloy, if your're down to base metal, you are done for. Look at the connections on the paxolin plate that all the things attach to. Particularly the brass 'rivets' that take the phossy contact springs, I have seen a number where there have been poor grip leading to heat cycling and looseness.

Another idea I have used, good if you suspect the switch is sticking, is to get a rubber mallet, and administer a sharp wallop or two.
Or more if you're feeling particularly narky..

If it always runs OK afterwards, the windings are almost certainly OK. A dead winding is usually forever, not just for Christmas.

Just look for poor/loose  push-ons etc. usual things that screw up any elec. device.

Bout it really

Dave BC

Edit No it ain't about it! Check the sliding bush on the motor shaft.  ::)

Also, when the motor stops, you can usually hear the switch click, followed by a quiet 'hiss' as the motor stops. Does it do that?
« Last Edit: September 19, 2009, 01:57:08 PM by Bluechip »
I have a few modest talents. Knowing what I'm doing isn't one of them.

Offline Darren

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Re: running single phase motor backwards
« Reply #22 on: September 19, 2009, 02:06:48 PM »
Blimey that was comprehensive.... :bow:

When it hums you can spin it up by hand

"Also, when the motor stops, you can usually hear the switch click, followed by a quiet 'hiss' as the motor stops. Does it do that?"

Yep does that, quite a good positive "click" too and the hiss

The rest I'll have to check. It's been like this for 10yrs or more, never got any worse or better, rain or shine.

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Offline Bluechip

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Re: running single phase motor backwards
« Reply #23 on: September 19, 2009, 02:23:34 PM »
Darren

Sling it out. Replace with  a 1000cc JAP vee-twin ..

Much more fun    :D

Dave BC
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Offline Darren

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Re: running single phase motor backwards
« Reply #24 on: September 19, 2009, 03:21:13 PM »
One of my mates rides one of these.....SP1 when he's not riding his full power Hayabusa



when he's not riding his full power Hayabusa

http://www.extremesportclips.com/video/2054/A-Hyabusa-Over-240-MPH.html

And he plans to turbo it next year.....he's 50yrs old btw.....

Never too old as they say......I really miss not having a bike....this was mine....no stone unturned, 140bhp at the back wheel by 5,000 rpm 170mph....



If you know anything about bikes you'll also know that is far from factory spec..... :thumbup:
You will find it a distinct help… if you know and look as if you know what you are doing. (IRS training manual)