Cycling UK Forum

This is a little OT, but the technically-minded might be able to help:

I've bought a couple of button compasses lately, intending to keep them on my keyring and use them for map orientation when out on tour. Unfortunately both of them have been well off north - around 90 degrees or so. I thought it was just the cheapness of the first (couple of quid on fleabay), so I spent a tenner on one from Silva - but similar story.

Is there anything I can do to fix this? My thought would be to sit it in a magnetic field for a couple of weeks and hope it realigns. No idea if that's likely to work though - maybe I should just send it back, and give up on button compasses altogether?

Thanks for any help!

Are you holding it/them near metal objects by any chance? Like for instance those keys?

Button compasses are never going to be much cop though anyway- look at them in a shop- they're usually all pointing in different directions in there!

If the pointer is being attracted by an extraneous object then the pointer would move round as you turn the compass or object.
Put the Silva on a flat surface away from any metal object and it should read correctly.

Where are you checking the compasses?
Is there a large electrical source nearby?

On a compass where the whole north/south thing rotates, there's a magnet underneath.....if the magnet is loose........

I've had a compass go wayward before, but by 180 degrees, not ninety. I cured it by stroking a strong magnet along the pointer. It has stayed true, but I still only dare use it for messing about with- I wouldn't trust it in the middle of nowhere. For yours to go off by 90 would appear to go against all laws of electromagnetism, so I suspect it's either interference, or a sticky needle.