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Power tools failing to start, or only running for a short time then stop....??

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Forum topic by TannerTurnings posted 10-24-2014 10:19 AM 781 views 0 times favorited 2 replies Add to Favorites Watch
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TannerTurnings

137 posts in 889 days


10-24-2014 10:19 AM

Topic tags/keywords: tip trick question resource bandsaw lathe planer scroll saw drill press miter saw jointer sander tablesaw problem switch

I had a slight problem with my Axminster Lathe yesterday. I would press the “power on” button, it may run for a minute or so, then just stop! It appears that this fault is down to the switch, in this case (and that of MANY power tools in the workshop) it’s a type of switch called a “None Volt Release” switch (or N.V.R. switch) These are actually a common type of switch for ANY machine that has moving blades or where the operator may possibly come into bodily contact with moving parts. They are designed as a safety feature, and I believe that, here in the UK at least, they are a legal safety requirement. The idea is, that if your power to the workshop goes off, where you could possibly be left stumbling round in the dark, if it then comes back on again….the machine will NOT just start back up WITHOUT the operator having to press the “power on” button again. These switches work on an electro-magnet type circuit, and need to be re-energized each time the machine is powered up.

Replacing these switches, although I would suggest should be done by a competent person only, is fairly straight forward, and not that expensive, for example: I have taken my lathe to a local power tool repair shop, as the switch is incorporated within the variable speed control unit, and I didn’t fancy messing anything up in there by trying to replace the switch myself, although I am also a Radio Ham (G7LPW) and fairly ok with replacing a simple switch unit etc. The cost of having this switch replaced…£35 or there about, (about $55 US) so not too bad. It just shows that we don’t always need to go back to the manufacturers own repair center (for me, that’s about a 125 mile round trip) and pay top price for them guys to fit a new switch unit…..hey! it would cost more in fuel for me just to drive to the nearest Axminster service center than it’s costing or the whole repair!!

Just in case people are not sure what these N.V.R. switches actually look like, I’ll try tagging a photo at the bottom. sometimes the backing plate is Yellow, sometimes Black, but inside they are much the same, and are not always a “product specific” part, as these switches are used on all kinds of power tools & machines.

-- Keith, Norfolk England. Why Burn it when you can Turn it??!!


2 replies so far

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doubleDD

5221 posts in 1505 days


#1 posted 10-24-2014 12:40 PM

They may seem to be a real pain but safety first.

-- Dave, Downers Grove, Il. -------- When you run out of ideas, start building your dreams.

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bigblockyeti

3667 posts in 1182 days


#2 posted 10-24-2014 01:06 PM

Here in the US they are usually referred to as magnetic switches or magnetic starters. As I find many of the safety devices that allow those who shouldn’t be allowed around anything sharper than a spoon to work semi-safely an unnecessary nuisance, these types of switches are an exception. They are prone to failure, but as a function of their design, they are usually better sealed from dust than a mechanical push button on/off switch as a very short service life would be guaranteed without doing so.

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