DIY Magnetizer

[Malcolm T]

Has anyone successfully built a magnetizer to magnetize screws ?.

[Terry_VK5TM]

Just run them across a magnet several times in the same direction.

[Chrispy57]

Hi Malcolm,
I wonder what the background to your question might be? You are obviously sufficiently experienced/knowledgeable to be aware of how to magnetise a screw with a permanent mgnet, or to use a magnetised screwdriver when the occasion demands.

Cheers
Chris

[retailer]

Here's one I made a while back - very lo-tech - connects to any high current low voltage supply ie 24V truck battery - each central core is 38mm diam and about 115mm long - wire is ordinary pvc insulated domestic earth wire I happened to have on hand - a 3 ph contactor with all phases connected in parallel is used to switch the high current supply - an old laptop charger supplies the voltage for the contactor coil. Only used once to remagnetise a moped magneto which it did quite well.
I believe other forum members have made much more elaborate magnetisers.

[Valvepower]

Hello,

I made a magnetizer basically consisting of a whole pile of low ESR electrolytic capacitors amounting to quite a few thousand uF being charged up to 400-600V via a Variac to set the charge voltage and then discharging this lot through an EEV Ignitron into a workshop made magnetizing head wound on a shorth length of ‘stack’ pipe wound on the lathe in the workshop.

This magnetized quite a few speaker magnets before we made the Mk2 version…

The Mk2 used thyristor instead of an Ignitron and the magnetizing head was made by Redcliffe Magtronics in Bristol.

The current health and safety lot would have kittens now with these 'workshop' antics!

From memory I used an ancient dog eared Eclipse Magnetics application note book and some data provided by EEV.

Terry

[David G4EBT]

Small magnetiser/demagnetisers are cheaply and widely available to magnetise/demagnetise screwdrivers EG:

https://boxed2me.co.uk/product/durat...CABEgJ9hPD_BwE

Just a few strokes is all that’s needed, but a small magnet will do the trick just as well.

[jackrae]

I take it you do mean "Magnetiser" rather than 'De-Magnetiser'

[David G4EBT]

Originally Posted by jackrae

I take it you do mean "Magnetiser" rather than 'De-Magnetiser'

No I don't mean that - the gadget at the link I added as an example, (widely available from many suppliers on Amazon, eBay etc for about a fiver), performs both functions. So for example, if you have a screwdriver that has been magnetised, and for some reason you want to demagnetize it you can do. (Due to whichever North/South orientation is used I guess).

A magnetised screwdriver is essential when re-fixing a chassis in a cabinet such as an A22, where you have to lower the screws down into the cabinet to secure the brackets using a long-bladed screwdriver. I guess there are other makeshift solutions such as putting a blob of Blu-tack on the screw, but why struggle? When I tack the back off my watch to fit a new battery, the screws are very tiny and a magnetic watchmakers' driver is essential.

Only a small thing - see pic attached.

Hope that helps.

[jackrae]

Oops, my question was aimed at the originator - Malcolm - since magnetised screws are generally a pain in the butt

I have one of those little dual function gizmos

[David G4EBT]

Originally Posted by jackrae

Oops, my question was aimed at the originator - Malcolm - since magnetised screws are generally a pain in the butt. I have one of those little dual function gizmos

Sorry Jack - with your post coming after mine, I thought it referred to my post.

Maybe Malcolm will see your query and respond to it accordingly.

(The little dual-function jobby will demagnetise screws is they're pushed in and out of the demagnetize aperture a few times).

[Dennis M]

Here's one I made on a cut down spot welder core, not much use for small screws though.
2200uF charged up to 500VDC discharged through the coil giving 90000 amp turns.

[Malcolm T]

Thanks for replies , i do understand magnetism but never seen large scale magnetizing equipment other than a magnet to magnetize small screws etc.
I see some interesting builds there , thanks for the pieces , i don't think i will ever build projects that large though .
I will have a look at the small magnetizers ,

[Dennis M]

If you want an easy way to make a small capacitor discharge magnetiser I can send you the details.It uses the innards from a photography flash gun to power the coil.

[Cruisin Marine]

Those small de- magnetisers, how do they work, and how should one use them?
I had one many decades back from RS,and all both slots did was magnetise.

What is the purpose of the "staircase" on the de-mag side?

[Trigon.]

These demagnetisers are widely misunderstood, as evidenced by numerous Youtube videos...

The steps provide locations with a reducing field from the central magnet.

To demagnetise a screwdriver push it through holding it against the lowest step, move it to the next step and withdraw, move it to the next and push, and finally move it to the last step and withdraw.



Cheers

[Oldcodger]

Originally Posted by Malcolm T

Thanks for replies , i do understand magnetism but never seen large scale magnetizing equipment other than a magnet to magnetize small screws etc.
I see some interesting builds there , thanks for the pieces , i don't think i will ever build projects that large though .
I will have a look at the small magnetizers ,

Old trick used on screwdrivers with decent grade steel blades was to rub a permanent magnet along the shaft in the same direction. No need for fancy bits of kit.
I always had a small permanent magnet in my tool kit for putting in/getting out screws in awkward places.