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NVR switch?

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Chris152

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If I get one of these
https://woodworkersworkshop.co.uk/produ ... witch-230v
and place it between the power supply and my electronic speed control lathe, will I be able to use it to stop and then restart the lathe at the same speed or is that bad for the motor? It'd save winding the speed back to 0, sharpening, then trying to re-find the speed I need.
 

sunnybob

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What happens when you usually stop the lathe and restart?
Exactly the same will happen if you turn the lathe off from the NVR switch.

The two main purposes of the NVR is to give you a BIG target to hit if you want an emergency stop, and to prevent the lathe starting up by itself in the event of a power interruption, and subsequecnt resoration of power when youre either not there, or have your hands inside the machine.
 

CHJ

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Chris152":24c2vc40 said:
If I get one of these
https://woodworkersworkshop.co.uk/produ ... witch-230v
and place it between the power supply and my electronic speed control lathe, will I be able to use it to stop and then restart the lathe at the same speed or is that bad for the motor? It'd save winding the speed back to 0, sharpening, then trying to re-find the speed I need.
What model Lathe do you have, why can you not just switch it off without adjusting the speed control?

Are you saying your electronic control (is it Keypad or a Control knob?) returns to zero speed when you switch the lathe off with its own control switch.
 

Chris152

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Thanks both. I could write what I know of electrics on the back of a very small postage stamp - in this case, I wondered if switching the lathe off/ on with the speed control dial already on no.8 (of 10) or whatever would upset the motor or the speed control some how.

But apart from that, having an easy to hit emergency off button close to where I stand would be good - the one on the lathe is attached to the top of the motor which, with the head in the position I use it, is on the other side of the lathe from where i stand, and I have the speed control (which has its own off switch) out of the way so it doesn't get too much wood dust/ chippings on it.

I think I'll put one on my wish list. Thanks again, C.
 

sunnybob

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The average person is non-technical, and does look for possible dangerous situations. :roll:
I've spent most of my life repairing damaged machinery and rectifying dangerous situations and instructing people how to live to a ripe old age while still having the requisite number of digits (hammer) :D

What I call "panic" switches should be to hand, WHILE you are panicking. Trying to reach around or across a spinning machine to reach the on off switch while its all going to hell in a hand cart is about as life threatening as you can get (Please dont tell me you have a tie on while turning :shock: :shock: :shock: ).

No insult intended, nice people just think nice thoughts. :D :D
Not sure what that says about me though 8) 8) 8)
 

Inspector

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Before you go ahead with adding the switch check with the maker of the lathe or speed control if it is an aftermarket add on. You can damage a VFD if you start/stop a machine with anything other than the VFD. You would have to have the start/stop button go through the speed control so it still handled things.

Pete
 

Ttrees

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From what I see, It looks to be a 3 phase lathe using a VFD?
Can you clarify?.



If so you can just wire a button station in series, but not under any circumstances have any kind of switch inbetween the supply and your inverter for starting/stopping the motor.
I believe a properly rated isolator switch is used sometimes for the power supply only.

So from the switch terminals...
It should have a NC stop push button, and if you want another start button, this would be a NO button. ( NO= normally open )...
These are about 2 quid each, or push button station will be about a tenner on the bay, if you don't
wish to make your own.
Things might get a tad more complicated if you wished to install a potentiometer on the button station aswell, but plenty of folks here to help you out on that.
You might want to get the correct pot for the job, I don't know if those 10k? (I have to double check)
pots, are the correct one for the job, but if I recall correctly is what I used on my cheapo VFD for a short time, until I realised it was tripping my inverter.
I can double check this if need be.


Alternatively, you could rig up a paddle switch which could possibly be the safest option
SAM_2105.jpg
IMG_20170421_101613.jpg


Might not be the answer you were looking for, but it will save someone else having to cover it.
Tom
 

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Chris152

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Ok, I'm on the case! Not sure about a paddle but I clearly need something better than I have now. Thanks all!
 

Chris152

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Thanks Chris - I'll take a look at that and see if I can somehow fit a similar one into the space where I'm actually standing when I turn.

Inspector":3hae4umy said:
Before you go ahead with adding the switch check with the maker of the lathe or speed control if it is an aftermarket add on. You can damage a VFD if you start/stop a machine with anything other than the VFD. You would have to have the start/stop button go through the speed control so it still handled things.
Pete - the lathe is Sorby and the speed control isn't made by them, but came with the lathe from new (I can't remember the make and it's up the road). Does that sound like it'll be a problem?
 

Phil Pascoe

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I have the incoming power lead routed through two switched cable outlets before the motor, one in the middle that I can reach easily with the head turned and the other on the end so I can switch off quickly when long hole boring.
 

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Inspector

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Chris152":39ycr7d6 said:
Pete - the lathe is Sorby and the speed control isn't made by them, but came with the lathe from new (I can't remember the make and it's up the road). Does that sound like it'll be a problem?
I can't honestly say. That's why I suggested you find out. If it doesn't matter on your lathe then you are only out some time. If it does matter and you cook the speed controller how much does a repair to it or replacement if available cost?

Pete
 

CHJ

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Cutting the power supply with an additional NVR switch in the power supply line will be no different to switching off at the Mains supply socket or a power cut whilst the lathe is running. It should not damage the lathes electronic controls.
It will pose a problem in as much that you will have to set the extra NVR switch before starting the lathe with its own switch.
Although acting as an emergency stop it may be a limitation on the safety aspects of Switching ON the lathe if you have to reach over a swivelled headstock and the lathe stars up quickly.

My controls are set for a five second delay before the set speed starts and slowly ramps up so that I am standing in a working position before it reaches speed.

I have a kill switch towards the tailstock end of the bench which momentarily breaks (Push to Break) the power feed to the lathes and other machines in the shop that have an NVR. This switch does not require setting before using the machines via their NVR switches.
 

sunnybob

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There is no need for any switch between the NVR and the machine. The more switches there are, the more chance of confusion, and loose connection problems.
Fit the NVR at the front of the machine next to you, and wire out any others.
 

Chris152

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A fair bit of that went over my head! Anyway, not an NVR but I built a little stand for the speed control to sit closer to where I stand when turning. It has an on-off switch which I'll put a little paddle on and paint red for emergency use - I'm sure it'd break the switch off if used in an emergency, but it'd stop the lathe. I've switched it off and on several times (while the speed control has the lathe running) using the control switch and it seems happy - about a second delay before it starts turning again. You can see the hopelessly positioned on/off button on the motor, top right.
IMG_1959.jpg
 

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