Any electricians out there???

bobg

Über Member
Any suggestions gratefully received..... I've just fitted and wired a new (to me) 1hp motor to my lathe exactly in accordance with the wiring diagram but it runs in reverse... there's been mutterings about the polarity being reversed at some stage in its life but at that point I lose the will to live?? :smile: Can anybody shed any light on a remedy ( if there is one??) please??? Someone suggested swapping the positive and negative but surely not.....

ta
 
Not a spark anymore but did the training many moons ago. The problem with your motor could be be solved by swapping the +ve and the -ve. Worth a try anyway
 

col

Veteran
As simple as it sounds,it could be the solution,put a scalextrics car on the wrong way,and it goes backwards?
 

simonali

Guru
Is it a single phase motor? If so it should have a capacitor attached and reversing the wires on this should do the trick. If it's 3 phase then just swap any 2 phases.

There's usually a wiring diagram inside the terminal cover of motors. Does yours have one?
 

gbb

Legendary Member
Location
Peterborough
simonali's right if its a 3 phase, just swap two of the phases at the terminals.

Again, if its 3 phase, there are 3 brass bridge plates that go across the terminals on the other end of the terminal block on the motor. MAKE SURE they are fitted the same way as the original motor.

There are two different ways....the wrong one will overheat the motor sharpish...i know...i dunnit :smile:
 
OP
bobg

bobg

Über Member
Cheers all. Yup its single phase and there is a capacitor fitted so I'll have a stab a reversing the + and - as suggested. Thanks for that. I have a wiring diagram and I pretty much only had to utilise the L1 and L2 to + and - respectively with an earth to the casing. Which is why I was mystified. According to the diagram there seems to be facility to fit a reversing switch by moving the brass bridging strips but thats for the future - as it is I nearly had a facefull of about 5k of 4 jaw chuck when it came close to flying off the lathe at 1400rpm due to the reverse direction unscrewing the thread.... past life flashed before me !! :smile:
 
OP
bobg

bobg

Über Member
Hi Longers. its an old ex schools Boxford metalwork lathe with power crossfeed - I got it for bike restoration/ screwcuttinng etc - theres been any number of occasions over the years when I've thought one would come in handy. As it turned out I quite fancy a go at woodturning too and the top speed of 1400rmp is just about useable - great toy but theres LOADS to lean and accessories cost the earth... Just need to get the .... thing turning in the right direction - pretty fundamental really :smile:
 

domtyler

Über Member
Can't you just stand on the other side?
 
domtyler said:
Can't you just stand on the other side?
Probably only really viable for left handers. I wouldn't like to be moving a chisel toward the chuck.

bobg said:
Not yet I'll have a stab at it in the morning - just had a couple of single malts - If you dont hear from me tomorrow I'm done to a crisp !
Don't play with a lathe if you've just had a couple of single malts.
 

stephec

Legendary Member
Location
Bolton
Does the motor have a set of terminals inside with links accross them? The manual for the motor should show which way to fit these for clockwise/anticlockwise rotation.
 
OP
bobg

bobg

Über Member
Thanks to every one for your help. I'm very grateful Just back in from the shed and all working perfectly! I tried switching the terminals and that worked, then tried moving the brass bridging strips across different terminals ( as per that bit of the wiring diagram that was on the back of the page I'd been reading yesterday:blush: and that worked too. Actually, I was confusing myself and you guys, cos it was in fact working "properly" as per the diagram,ie. clockwise but of course I needed it in reverse to push down on the cutting tool. I'd had advice from others saying that you cant fit a revesing switch to a single phase motor but judging by this, thats clearly not so!..
 
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