Degaussing small tools

[andyf]

If I'm the last to find out about this, apologies for wasting bandwidth.

Small tools sometimes manage to get themselves magnetised and turn into furry little swarf monsters, but can be cured with a Weller soldering gun.

Here are a screwdriver and toolbit deliberately magnetised, then dipped in the swarf on the left:



Here's the treatment - dip the offending item slowly in and out of the loop-type soldering bit two or three times. I've bent this old loop a little to take larger items. It will be hot, so mind your fingers, but it doesn't matter if the tool makes contact. You can feel the tool vibrate at 50 (or 60) Hz:



And here's the result - tools dipped in the swarf again, but no hairy coats 



Andy

[sbwhart]

Hi Andy

Thats a neat tip thanks for passing on.

Stew

[mklotz]

Also, look for bulk tape erasers at electronic swap meets, etc..  They'll do well for larger tools that won't fit through the soldering gun loop.

With all these things, the trick is to withdraw the tool far from the demagnetizer before turning the latter off.   If you turn it off with the tool close by, you may catch the mains sine wave at a peak and the tool will still be magnetized.

Aside:  Most of us wouldn't be caught dead using a pair of all plastic calipers.  Nevertheless, if you happen on to a pair, stick them in the tool box.  The next time you want to measure a super magnet without magnetizing your good calipers, you'll be glad to have them.

[John Hill]

This is excellent news!  I always thought a Weller soldering gun had no practical purpose but you have shown me wrong!

[andyf]

Marv wrote: the trick is to withdraw the tool far from the demagnetizer before turning the latter off.   If you turn it off with the tool close by, you may catch the mains sine wave at a peak and the tool will still be magnetized.

Good point, Marv. Thanks for making it.

John Hill wrote: This is excellent news!  I always thought a Weller soldering gun had no practical purpose but you have shown me wrong!

Oh, I don't know about that, John. I use mine for medium size soft soldering, but I did once get into serious trouble over some accidental pyrography on the kitchen table which I'd omitted to protect   

Andy

[CrewCab]

I always thought a Weller soldering gun had no practical purpose! 

Your not into modifying automotive electrics then John 

CC

[Mike K]

Nice tip, thanks Andy.  I have a tape head demagnetizer (little wand that plugs into the mains) that I've tried with no luck.

Mike

[John Hill]

Electrically competant people could take the armature out of an regular induction motor to make a demagnetizer just like an electric motor growler.  As always, safety first.

[Darren]

Heat de-magnetises, I wonder if that is contributing as well?

[andyf]

John Hill wrote: Electrically competant people could take the armature out of an regular induction motor...

John, I write as one who is reasonably competant with electrics (famous last words... ). Rather than sacrificing a motor, do you reckon removing the core from a (biggish) transformer and passing the tool through the hole in the bobbin would work? Scrap transformers are easily found.  Careful insulation, obviously - or would a mains transformer fed with low voltage AC to its primary winding do the trick?

Andy

[Darren]

have you ever tried to remove a core from a transformer without destroying it?

[Darren]

You have a lathe, just wind a bobbin and away you go.....

[andyf]

Darren wrote: Heat de-magnetises, I wonder if that is contributing as well?

No, Darren. Putting it simply, when steel is magnetised, its molecules get lined up, forming N and S poles. Putting a magnetised bit of steel through an alternating magnetic field created with alternating current jiggles them around and confuses them so much that the magnetism is lost.

Though the process is bound to heat the steel up a tiny bit, the effect is so small that you can't feel it getting any warmer.

Andy

[John Hill]

John, I write as one who is reasonably competant with electrics (famous last words... ). Rather than sacrificing a motor, do you reckon removing the core from a (biggish) transformer and passing the tool through the hole in the bobbin would work? Scrap transformers are easily found.  Careful insulation, obviously - or would a mains transformer fed with low voltage AC to its primary winding do the trick?

Andy

 

I assume that would work OK Andy but the current must be kept under control, one way to do that would be to wire a mains light bulb in series, or you could use a lower voltage.

If you can get the core of your biggish transformer apart I assume the core is made of the famous 'I's and 'E's?  If so, just take the core apart and reassemble with one side of the core open, that is how the couple of bulk tape erasers I have seem to have been made, but you still might need the light bulb in series to control the current.    If you have a power hacksaw or metal cutting bandsaw you might be able to cut the core off one end?

If you do use a transformer dont forget that any stray un-used ends of wire are most likely live!

Safety first with electricity!

[John Hill]

have you ever tried to remove a core from a transformer without destroying it?

Not easy is it?

[bogstandard]

This is getting very close to telling people to stick the tool into a live wall socket.

Bogs

[CrewCab]

This is getting very close to telling people to stick the tool into a live wall socket.

 

    Which is not a "Good Thing" chaps, ............  let's just get back to discussing soldering irons shall we 

Thank you John (BS) ........... good call 

CC

[andyf]

Discussion closed, then, for reasons of H&S.
 
Andy

[Darren]

No it's not, you say E's & I's but getting the buggers apart if they have no air gap is nigh on impossible.

I have tried to salvage vintage iron, cos it was iron and not steel, to wind new output transformers for valve amps. Single ended transformers are easy cos they have an air gap and a nice bit of paper to stop them rust welding together....

[Darren]

This is getting very close to telling people to stick the tool into a live wall socket.

Bogs

Not really, winding wire is insulated. But if you break through that then you may be in trouble. What you need to do is wind a bobbin with say 1000 turns around a plastic tube and then cover that with a bigger tube. Perhaps expoying it all together.

No more dangerous that switching your lathe on and tripping over that screwdriver you forgot you just dropped.

It's all relative, crossing the road is dangerous and more people die from that alone than our workshops or playing with electrickery.

We have RCD's, MCB's RCBO's and guad knows what else these days....

[John Hill]

No it's not, you say E's & I's but getting the buggers apart if they have no air gap is nigh on impossible.

I have tried to salvage vintage iron, cos it was iron and not steel, to wind new output transformers for valve amps. Single ended transformers are easy cos they have an air gap and a nice bit of paper to stop them rust welding together....

If you are only salvaging the materials then you can stand the tranny on the hotplate (when you are home alone ) with the edge of the laminations touching the plate.  Heat it up a bit to melt the varnish they used to seal the core pieces and stop them rattling.  Pick a few 'I's out first then get to work on one of the outer 'E's.  Once you have the first one out you can use a blade, kitchen knife maybe, to poke down between some of the others until the whole pack is loose.

I think the metal they used was 'Mu' metal which is some highly magnetic permiable alloy of iron.

[John Hill]

This is getting very close to telling people to stick the tool into a live wall socket.

Bogs

Yes it is Bogs, safety with electricity requires eternal vigilance against carelessness, so always, safety first!

[spuddevans]

have you ever tried to remove a core from a transformer without destroying it?

Not easy is it?

For a real challenge try removing the core from a toridal transformer without distroying it     

Tim

[dsquire]

For a real challenge try removing the core from a toridal transformer without distroying it     

Tim
[/quote]

Are you going to show us how its done Tim? 

Cheers 

Don

[Andy]

Didn't know about the soldering iron method. I got one of these - http://magnetking.thomasnet.com/item/finished-magnetic-tools/precision-magnetizer-demagnetizer/pn-1194?&forward=1

Got it from somewhere in UK, not this firm, but just the same.

It works well at both functions.