Bandsaw cut out switch wiring

[scottmk1]

That makes sense, thanks. I'll be out there shortly to see if moving the black wire does the trick.

 

[rosinante]

That's better, original dwg made my head hurt, you have gotta be nearly there,
Chris

 

[rtbcomp]

On the contactor you have connections a & b and 13 & 14. I assume these are the coil and a pair of NO slave contacts, but which is which?

 

[scottmk1]

I couldnt say which is which, i can test for continuity but would that differentiate between them?

 

[rtbcomp]

There may be markings on the contactor. With the wires disconnected the contacts will be open circuit, the coil will show some resistance, but I wouldn't like to say how much.

 

[carbon]

A and B are the coil 13 and 14 are NO contacts used to hold the coil in after the start button has been pressed

 

[rtbcomp]

Cheers.

 

[scottmk1]

Ok, I've changed the black wire from the limit switch to match @carbon 's amended drawing, and replaced the fuse he mentions with a 3A spade connector type as I dont have any of the original ones (it was 2A) and as soon as I turn the main switch on the fuse blows. I have also bridged the 3 indicator lamps to complete that part of the circuit too.

 

[carbon]

Did you bridge the lamps before or after trying it as bridging the lamps will sort the transformer and blow the fuse

 

[scottmk1]

I bridged them before. Will it not just have the same effect as having bulbs in the lamps?

 

[carbon]

As far as I can see lamps are there as an indication to the state of the saw. So not required as such but it would be nice to know when its powered

 

[rosinante]

Agree if wired as amended dwg then shorting lamps will cause short and fuse to blow, they are no longer in series and links need removing, do that and try again chris

 

[scottmk1]

Ok thanks, I will try that. Any ideas on suitable fuse sizes? I'm guessing the original 2A will suffice if I'm not shorting the thing out?

 

[carbon]

The fuse only has the load of the contactor coil and the three panel lamps (if working) on it so 2amp should be sufficient

 

[rtbcomp]

I'm in the process of re-drawing the diagram as a circuit diagram, rather than the wiring diagram you already have. This should make it easier to see how the thing actually works.

Bear with me!

 

[carbon]

The switch top left turns power on to the saw, transformer is live.
Pushing the start button connects power from terminal 13 on contactor to terminal B. Once contactor pulls in power then flows through the contacts between terminals 13 & 14 to B holding the contactor in.
Pushing either the emergency stop button or the limit switch breaks the circuit stopping the saw.
Also main motor overload will break the circuit in an overload event.

As the coolant pump is connected after the contactor it can only be on when the saw is running.

 

[rtbcomp]

I think there's a mistake in the 2nd diagram - I have the contactor powering up as soon as the mains is switched on.

This is what I have so far

 

[carbon]

13 14 needs to be below the b on the coil

 

[rtbcomp]

This is how it should be - but I don't think this tallies with the last wiring diagram. I haven't put the other bits of the circuit in yet, but this should get it going. I don't see the point of using the NN contacts on the main switch to switch the indicator bulb on the transformer secondary.



PS I'm going cross-eyed so E&OE

 

[WorkshopChris]

13 14 needs to be below the b on the coil

Isn't that the same as is now as it powers when start is pushed then hold in until E stop or limit brakes?