Maurice Posted April 21, 2009 Share Posted April 21, 2009 Hi does anybody know what fluid should go in the M4,M3 , and DUKW compass ? I want to mount mine in my Firefly ,but there is only a little bit of fluid left in it . Thanks already Quote Link to comment Share on other sites More sharing options...
Topdog Posted April 21, 2009 Share Posted April 21, 2009 Medical alcohol is usually the fluid in compasses but not surgical spirit as that has an oil content as well. Quote Link to comment Share on other sites More sharing options...
Tony B Posted April 22, 2009 Share Posted April 22, 2009 Ask Catweazle. He might know of a compass swinger or someone who may be able to refill the thing. Quote Link to comment Share on other sites More sharing options...
rhj999 Posted April 22, 2009 Share Posted April 22, 2009 I know that this is a slightly different compass ie a Mk 8 RAF WW2 aircraft compass but the advice I have been given is as follows:- "If you don't have a spirit hydrometer with gauge 0-99 (a beer gauge is no good) to make up the required mix of 0.81 specific gravity, (as alcohol reduces the specific gravity of water to below 1), try the following recipe which is good enough for display purposes only. Pure alcohol is very difficult to acquire in small quantities so buy a bottle of surgical spirit (98% proof) from the chemist (the odour will not affect anything), together with a small quantity of distilled water as used to top up car batteries. A ratio by volume of 89% surgical spirit to 11% distilled water is about right. Pour both very slowly into a clean measured container. Mix thoroughly and notice the liquid will appear to be cloudy. Leave undisturbed with a cover over for a week. It will clear. Try not to move the liquid at all to avoid bubbles. Carefully fill the compass using a syringe and tubing ensuring there are no bubbles but occassionally tapping the compass to dislodge any small air pockets in the compass." Hope this helps. Quote Link to comment Share on other sites More sharing options...
Maurice Posted April 22, 2009 Author Share Posted April 22, 2009 Thanks , I will start mixing tonight . Now I understand wy all these compasses slowly empty themselves , evaporation. Some people told me that there is lamp oil in them , so they are not right then . About acuracy , I was reading the little booklet wich belongs to it , and you will be busy for 2 hours to adjust it , compensators and the sort to get it right with all the armour around it , and then drive the vehicle off road to check and adjust it right. Quote Link to comment Share on other sites More sharing options...
Tony B Posted April 22, 2009 Share Posted April 22, 2009 Don't forget Deviation on the compass will change at night when the lights are on. Or any other electrical equipment. Quote Link to comment Share on other sites More sharing options...
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