Model Boat Mayhem

Technical, Techniques, Hints, and Tips => Other Technical Questions... => Topic started by: BarryM on March 11, 2011, 08:33:19 pm

Title: Demagnetising
Post by: BarryM on March 11, 2011, 08:33:19 pm

My digital vernier calipers have become magnetised. Before I try demagnetising them with another magnet, will somebody confirm that this will not affect the digital read-out display? Magnets, I understand. Digital read-outs are voodoo.

Thanks,

Barry M

Title: Re: Demagnetising
Post by: xjohn66 on February 14, 2012, 12:32:28 am

Hi Barry, I am new here so forgive me for jumping straight in.
The usual way to demagnetise is to introduce the magnetised object into an AC magnetic field and slowly withdraw it until out of range of the field.
As far as I am aware you won't damage the calipers with an ordinary magnet but it won't be easy to neutralise the magnetism of the calipers using this method.
Best regards.
John.

Title: Re: Demagnetising
Post by: derekwarner on February 14, 2012, 06:00:00 am

Barry M.....  may sound {-)...but you need to ask a few questions

1. is it only one jaw of your vernier calliper that attracts metallic swarf? ...remember a magnetic field is polarized with a north & a south pole
2. or is it the field set up between both jaws that attracts the swarf?
3. degaussing  {:-{ is the term for removing permanent magnetism...[ships, aircraft, electronic components .........the list is endless]
4. magnetism created & generated in metals is usually by friction ....it is difficult to understand how this would occur in a pair of vernier callipers  %%
5. one thing is that the function of the linear transducer in the calipers will not be affected by the magnetic field

I would do nothing apart from keeping them away from swarf............& continue to use them..........Derek

Title: Re: Demagnetising
Post by: cliff2903 on February 14, 2012, 05:23:50 pm

or pop into a local grinding firm and ask for a 'go' on the demagnetiser ;)

Title: Re: Demagnetising
Post by: dodgy geezer on February 14, 2012, 05:40:33 pm

I wonder if holding them close to a big transformer (while working!) and drawing them away would help....?

Title: Re: Demagnetising
Post by: dave301bounty on February 14, 2012, 06:00:27 pm

I use a tool that de mags ,its for watch repair ,cant have any magnetic near a watch for obvious reasons ,you can buy one from a firm in the Midlands  quite a reasonable price for a very handy tool .Just swich on ,put the tool /whatever in centre and take it out slowly ,you can feel the force working ,.clever stuff.