Fluid for Compass?

Try this link

John H

Take care, any dust or debris you get out of it is likely to be radioactive and possibly harmful to health, especially if inhaled.

Russell

I topped mine up about ten years ago with white spirit, and it's been fine ever since. Shame it's calibrated in military 'grads' rather than degrees though !!!

AWEM

Whiskey or vodka wood be a place to start.

Isopropyl Alcohol is the fluid of choice, used in many compass damping systems. 'Maplin' sell it by the litre. Or maybe your local chemist will supply lesser amounts. Its been in my mark III for years.

Ray

Don't you mean "mils"? 6400 to the circle. That is the norm for the military.

A "mil" is the angle subtended by 1m and 1km. It is a very easy unit to work with when "gun laying" etc. It is close the true milli-radian (2Pi/1000, about 6280 to the circle).

(I used to work in military navigation systems.)

The Grads is 1/400 of a circle and is (or perhaps was) used in surveying.

OK on the White spirit, probably the most "available" liquid. Thank you.

Regards

Brian

Thank you for all the replies.

I've now several ideas to explore.

Every time I "visit" I seem to get a positive response here, it is most refreshing.

Regards

Brian

I'd be cautious using white spirit - in fact I wouldn't use it at all. The "proper" fluid is alcohol, either ethyl alcohol or isopropyl alcohol

- I'd be worried that white spirit might dissolve the paint/ink on the markings etc.

Isopropyl alcohol (IPA) is both cheap and widely available - many chemists stock it, as do some of the better electronics and computer shops: or you can get IPA from eBay for a few pounds delivered, eg

Also, you can probably use rubbing alcohol (which is about 70% IPA and

-- Peter Fairbrother

this chap seems to know what he's talking about:

-- Peter Fairbrother

In addition to the problems of chemical compatability with paints, glues, and seals that others have pointed, it is worth considering the viscosity of the fluid. Low viscosity liquids such as the various alcohols will give little damping; while higher viscosities such as oil or glycerol will damp the motion more. I imagine that a hand held compass for use on the move would need more damping than one for static use.

Cliff Coggin.

I second that.

My prismatic compass still has its original alcohol - and that's been there approaching seventy years.

Mmmmmm! Should be mellow!

But that may not apply to the damping fluid...

I would think he reverse is true, especially as all the good quality hand-held (and costly) instruments I know contain alcohol.