Anyone here know anything about switches?

[Mike G]

Can you help me Bob?

This thing.......



...........won't turn off my bandsaw any more. Or it will, intermittently, but so rarely that I tend to just switch the power off at the wall. It switches on OK, and it clicks a few seconds after I switch off at the wall to indicate that it has switched off with the lack of voltage.

Is there anything I can do for it (I've had it apart and cleaned it up, but no improvement)?

Thanks.

 

[Rod]

Perhaps a trip to Toolstation for one of these?

Rod

 

[9fingers]

Failing to turn off is unusual but generally these low power nvr switches are unreliable and Rod is exactly correct to suggest replacing with one that will protect the motor as well. About £30 free delivery from TS

Remember to order the correct overload relay with a current range that encompasses the current rating on the motor plate.

Bob

 

[Mike G]

So, I can't just use an old light switch in its place? :eusa-whistle: :eusa-whistle:

 

[9fingers]

So, I can't just use an old light switch in its place? :eusa-whistle: :eusa-whistle:

NO, a light switch is not rated for the huge starting current, you will soon weld the contacts closed.

If you must bodge it, then use a 20a isolator switch but you will lose all NVR protection.

If you do purchase the correct device, here is the wiring diagram to follow.



hth

Bob

 

[Mike G]

Brilliant Bob, thanks.

 

[Wizard9999]

Mike, apologies for :text-threadjacked: but I had wanted to ask this question and this thread presents the perfect opportunity and I think you have the answer you needed.

What is the purpose of an NVR? My router table will be right next to the power socket I will use for the router so why not just switch it on and off at the wall with the router plugged straight into it (I guess equivalent to Mike's proposed light switch arrangement). From what I have read the NVR will stop the router restarting if power is interrupted, so if a power cut for example, but does it perform any other function? I'm not trying to be clever, this is a genuine question demonstrating my complete lack of knowledge .

Now if I do want / need one why do all the ones I see only work for tools up to 2000w? I know there is a debate over measuring at input versus output (or something like that), but my Triton router claims to be 2400w, so surely none of the NVRs I am seeing are suitable anyway.

The Toolstation one seems a bargain (£20 if I am looking at the right one) and looks like it is man enough 3kw or even 4kw (is bigger always better for just an extra £1). But that doesn't call itself an NVR, is it the same thing?

Terry
Who must continue to amaze with his total lack of knowledge about anything electrical.

 

[9fingers]

NVR is the term more used to describe the function ( No volt release) but has become the name associated with the little versions put on lower powered tools and typically limited to 2kW as you say.

The toolstation type (usually used with an overload relay as per my diagram for another tenner) is known a DOL starter (direct on line - a method of starting medium power motors up to say 5hp (4kW))
This offers the NVR function as well as motor overload protection and in my book is important for induction motors.

The DOL starter also has the ability to have a remote emergency off switch wired in to be foot or knee operated in the event of a problem

It is questionable whether an overload relay will be fast enough acting to protect a brush motor which tend to have such lean designs that the smoke can be let out both easily and quite quickly.

So for the router table you have a choice. In a 1 man shop where you are in total control, maybe using the switch on the socket is OK especially if you have soft start on the router (otherwise the inrush current on start up will kill the socket switch in time).
However it is more normal practise to have an NVR in some form and the TS one (of either power rating but with the correct 240v coil) is an excellent low cost example. I've fitted 10s of them on mine and other peoples kit and only had one dodgy one in possibly 10 years?

Whichever set up you decide on, always unplug the router from the wall when changing a cutter a good habit to get into (do as I say not as I do! :lol: ) is to put the plug in your pocket and get used to feeling that discomfort when cutter changing.

hth

Bob

 

[DaveL]

Terry,

A NVR is just nought volt release, in the case of your router table it provides an easier to operate and to reach switch. What Bob has recommended is a direct online start switch which provides NVR but also has protection for the motor using a current monitor.
The cheap NVRs fitted to lots of kit use the start button to move the armature of the relay in to the operated position, once there the holding coil will keep the contacts closed.
A DOL on the other hand uses a switch to turn on the holding coil, as well as one to release it. This can be extended to provide extra switches on a machine, some planer/thicknessors have switches on both sides of the machine to cope with feeding from opposite end for the two operations.
The NVR on the blower I have just fitted to my dust collector has the coil feed on a separate connection to allow the use of a thermal cut out mounted in the motor, but it's still not as good at protecting the motor.

 

[Wizard9999]

Thanks Bob and Dave.

So, if I understand correctly the better option would be to use. Toolstation DOL, but as the router has a brush motor no benefit in the overload protection. But not a disaster if in the short term I use the socket switch (router is soft start).

In terms of changing bits, yes plug out seems the only way to go. But as often mentioned the Triton is clever in that it allows for above table changing, but can only be put into that position with the power switch turned off. Still no point taking any chances.

Thanks again,
Terry.

 

[9fingers]

I'd still put my trust in the plug being out than some sort of interlock in the router itself.
There is no way you want a router starting up with a partially tightened cutter in it!!

Bob