|Neil Wyatt||31/10/2014 21:16:03|
16585 forum posts
I've just got one of these simple things with two holes. It works 100%, magnetising and demagnetising a screwdriver every time.
Inside, two magnets. easy to see how two magnets that reinforce each other magnetise the screwdriver, but how does the demagnetiser hole work?
I have a large pile of iron filings nearby, which shows the magnets are aligned, so the magnetised hole puts the screwdriver through two strong fields. Demag makes it run along the field. Demag also works best if you use it quickly.
|Danny M2Z||01/11/2014 06:03:12|
745 forum posts
Maybe opposing magnets in the de-magnetiser hole cancel any residual magnetism in the screwdriver?
I actually use a cassette head de-magnetiser, left over from my early computing days (when all home brewed software came on cassette tapes). It looks a bit like an 'adult toy' but it sure is effective. Works on the principle of an alternating field (current) reducing in intensity as one slowly moves it away from the tape heads.
I mention this because I just 'resurrected' my first computer, a Z-80 based Aussie 'Microbee' that was hand soldered together in 1983...even the CRT green screen still works! Some of the old cassette tapes were dodgy but the de-magnetiser soon fixed the data recorder. Now back to re-learning Z-80 assembly language and teaching the old girl to talk to an Arduino via a serial shield (horrible name btw, why just not call it an I/O interface).........work in progress.
I am not ashamed to be called a 'Hacker' btw, because way back 'then' it earned a lot more respect than the term does nowadays.
I hope you do not mind me bending your thread a little Neil
Regards from Oz
* Danny M *
Edited By Danny M2Z on 01/11/2014 06:05:11
|Neil Wyatt||01/11/2014 09:09:51|
16585 forum posts
No, the demag side just passes it across the side of one magnet.
|Russell Eberhardt||01/11/2014 10:00:39|
2484 forum posts
This is what I use:
It works fine and is big enough to demagnetise my chuck jaws. I got fed up with swarf sticking to the work!
|Andrew Johnston||01/11/2014 10:40:13|
4855 forum posts
It will be interesting to hear how the darn thing works! I was under the impression that demagnatisers used an AC field which was gradually decreased to zero, or the item moved slowly away. I don't see how it works with just a magnet. Somebody must know, and will spill the beans!
|Michael Gilligan||01/11/2014 10:56:25|
14024 forum posts
There was some interesting discussion on a previous thread.
|jason udall||01/11/2014 17:24:20|
|2011 forum posts|
|Having remembered and now reread that previous discussion. ..|
Let us suppose that a tool is held in one hand and magdemag gizmo in other. ..
A few strokes of the tool through the magnetise hole.makes ( say) the tool tip north.
Now you want a tool demagnetised. ..again A stroke in the demag hole...
Oh bum..not demaged...
Try this..First magnetise then demag with one or more strokes in demag slot..
Why this might work.
The orientation of the poles in mag hole combined with how its held ..leaves a permanent "set" one way or the other.. ( hold tool and gizmo differently and you might get south at tool tip)..now we have a known state in the tool...now without changing grip , take a stroke in the demag slot..which attempt to magnetise the other way..net result nil
If you went at the tool with an unluckily alligned field..you might just magnetise it some more.....
You could use what UTM..or UTH.. did when they needed non magnetic tools.....bronze..screwdrivers..spanners..socket sets....even wire snips
Edited By jason udall on 01/11/2014 17:28:26
|32 forum posts|
My demagnetiser is the stator from a domestic washing machine pump. The impeller had failed and the pump was replaced.
In use the coil is energised by the mains supply with the item to be demagnetised held in the magnetic field; the item is then slowly withdrawn from the field before the electricity supply is switched off.
Of course precautions must be taken to prevent contact with the live coil windings whilst carrying out this operation. Enclosing the stator in a nonconductive box with a hole to allow the item to be operated on would seem sensible.
|Ian S C||02/11/2014 09:52:47|
7447 forum posts
|Oompa Lumpa||02/11/2014 09:58:44|
|888 forum posts|
How many channels does that radio get Ian?
|The Merry Miller||02/11/2014 13:11:15|
484 forum posts
You may be interested to know that CPC (Farnell) sell small a small version suitable for screwdrivers etc for,
wait for it, wait for it, 98 pence, yes 98 pence.
Now the sting in the tail is that V.A.T. will be added at 20%, oooh! I hear you say.
The CPC code number is TL1406805, don't all rush!
|Robert Dodds||02/11/2014 15:02:11|
|264 forum posts|
Not as cheap as Len P's but at 4.37 ex Toolstation the Wera magnetiser/demagnetiser does the job for me on screwdrivers etc
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