Fail Safe?

[Digit]

Time for a nerve check. Shortly after I purchased my SIP TS the NVR packed up, you couldn't turn the machine off!
A replacement was supplied under warranty and I installed it myself.
It's just gone again!
Frightened the life out of me! Time for an upgrade I think.

Roy.

 

[Lowlife]

It seems that SIP have a bit of a quality control problem at the moment, when I returned my planer the other week I was told they had a large backlog of faulty machines that had been returned after Xmas/New Year, and that it would take a while for them to get around to inspecting mine.

 

[Digit]

To be fair my machine is at least 7yrs old. The failure doesn't bother me. What does bother me is that, again, it did not fail 'safe!'

Roy.

 

[Lowlife]

Yes I see your point!

 

[CHJ]

..... What does bother me is that, again, it did not fail 'safe!'

Roy.

I have seen two machines with 'stuck on' NVR's. Both had cheap mechanical latching systems.

The first was in a bandsaw cabinet, due to dust filling the switch plastic housing though holes facing upward, allowed enough dust to accumulate to wedge the latch shut. *
The other was on a tablesaw because the cheap contacts burnt and welded together.

*On my SIP I had the opposite, enough dust to stop the contacts latching.
Turned the switch up the other way so holes on the bottom and enclosed in plastic bag, sealed the door safety wiring access hole where the dust was getting in, belt braces and the appropriate gesture to the need to sort it.

 

[Digit]

I've had this apart Chas and it is of course the mechanical type. I'm surprised about the dust on your machine, this one is sealed tight, not a speck of dust. I've dismantled it and the problem is a welded up contact.

Roy.

 

[9fingers]

I've fitted a number of the toolstation DOL starters and had no complaints.
Including the overload relay, they work out at about £30 and free delivery.
With any starter there is a possibility of failing on if the contacts weld but that is pretty unlikely.

HTH

Bob

 

[Digit]

What's got me puzzled at the moment Bob is that it's only one contact, till I examine it closer I can't see if that would have held 'tother set in or not.

Roy.

 

[9fingers]

If it is one of the mechanically operated, magnetically latched the the welded contact would have been enough to defeat the mechanical off button.
I've had a a number fail - usually open circuit coils but I hate the things.
They are £17.30 from axi and yet offer no overload protection. I'd replace with a full DOL for peace of mind.

Bob

 

[Digit]

Can't at the moment till I've worked out the reason for the 5th wire. Gonna have a look tomorrow when the temp gets above the current 3 degrees. I know, I'm a wimp!
I suspect its the brake.

Roy.

 

[CHJ]

I've had this apart Chas and it is of course the mechanical type. I'm surprised about the dust on your machine, this one is sealed tight, not a speck of dust. I've dismantled it and the problem is a welded up contact.

Roy.

The spade terminals pass through oversize holes in the 'clip on' clear plastic enclosure. Fortunately turning the switch body 180 does not stop the Emergency Stop/lock off cover working.

 

[Digit]

It's back to the subject of the SIP planer that a poster mentioned, I stated then that if it was useless it wasn't cheap! Same with these damn NVRs, mine is sealed as I said, but I have known saw dust get in.
I read an account of a case in America. The guy had a basement workshop and his wife woke him one night with the usual, 'I can hear something!'
To him it sounded like his TS, so he crept down to look and sure enough, the saw was running. Thoughts of ghost etc, but in the morning a strip revealed wet sawdust. He reckoned that it had caused the coil to be energised and so switch the power on. Sounds doubtful to me but sawdust in NVRs isn't generally a good idea.

Roy.