Plastimo Compass repairs

Discussion in 'OnBoard Electronics & Controls' started by buzzman, Sep 28, 2012.

  1. buzzman
    Joined: May 2011
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    buzzman Senior Member

    Does anyone know if it is possible to refurbish Plastimo compasses? I can't seem to get onto their website for some reason.

    I recently scored an older bulkhead-mount, two-way-view which is labelled Contest Classe B No. 346 SN.

    The outer convex lens is badly UV affected, and there is a large air-bubble, which I assume means a seal has leaked somewhere...

    Can they be DIY repaired or only by 'authorised agents' at great expense?
     
  2. gonzo
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    gonzo Senior Member

    You will need a new lens, seals, etc. The company won't refurbish them since a new one would be cheaper.
     
  3. hoytedow
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    hoytedow Wood Butcher

    The lens can probably be improved with the same stuff they sell at the auto parts store for restoring headlight lenses. I believe you wet sand it then apply a clear liquid coating of some sort. Seal might be a large o-ring, possibly available at a plumbing supply house. Not sure.
     
  4. Frosty

    Frosty Previous Member

    Yes ive stripped them down and cleaned them out I have ground the needle to a point because mine was sticking. I then refilled with the clearest oil you can get--it does'nt matter what oil but thin . I used baby oil lotion.

    Its surprising how dirty it is. The card may be dirty but if its UV affected I dont know what you can do.

    I dont know if mine was Plastimo . They are generally too cheap to mess a round with. But when it was done it worked fine. The seal is a rubber O ring.

    If the plastic is faded dump it.

    I use GPS for compass readings.
     
  5. hoytedow
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    hoytedow Wood Butcher

    I keep a compass because GPS could be compromised.
     
  6. buzzman
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    buzzman Senior Member

    Well, I strpped it down to see if it was worth attempting reapirs, but the outer lens, apart from being badly yellowed and slightly crazed from sunlight, was also badly stained and had several cracks, so I have decided to buy a new one after all.

    I then pulled it apart to ensure myself that this was not a good idea, and I was right. The Contest is two convex lenses joined by a rubber/plastic bellows/seal whic appears to be glued to the two halves with something like super-glue - it produced that same crystallization on the plastic lenses. Unfortunately I also broke the post that holds the gyro mechanism, so the inner lens is also buggered - doh - but if anyone wants the card, gyro, inner lens or an intact seal to replace a damaged one, let me know via PM.

    Having said that, I suspect you'll never get it to seal again properly, so it will probably be a waste of time and effort. Plastimo is correct when they respond that these units are not designed to be repaired. But as they leave a screw for re-filling, presumably that is a 'service' that is allowable.

    However, in order to do so, you need to know what fluid is in the compass. In the course of my research I discovered that a light mineral oil product named Varsol made by Exxon was once used widely to fill compasses.

    Exxons website states that this has been superceded by Exxsol, but when I inquired for a supplier via their website form, the 'translated from chinese' reply was 'so sorry, no longer imported to Asia-Pacific region'....

    So any of you Yanks or Canuks out there want to try and chase Exxon on home turf and see what you can come up with?

    I'm sure their are loads of wannabe DIY compass repairers who would be fascinated by the results, as the topic of 'what to fill a compass with' is one widely discussed in other forums.

    Some suggestions include, solvents, baby oil, isopropyl alcohol, vodka, gin and a mixture of water and alcohol.

    But far and away the most sensible answer is that pre-war compasses often used alcohol, but more recently either mineral oil (eg: Varsol, kerosene or similar) and more recently still, a neutral silicone-based fluid seem to be the most correct responses.

    So if anyone can find out anything about supplies of Exxsol...???
     
  7. sdowney717
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    sdowney717 Senior Member

    I have found that oil is too thick, especially when its cold. The card in the compass can not turn.
    The fluid that works is odorless mineral spirits.
    The rubber bellows in the compass bottom allows the fluid to expand and contract keeping the pressure from cracking the plastic dome.
    However with the wrong fluid and wrong rubber, you will find compass fluids either dry out the rubber bellows or leach color out of black rubber parts into the fluid.

    A Ritchie compass is rebuildable. I had to repair mine and was able to order new rubber seals. That place also sells compass fluid.
    That richie has turned out well for years.
    Another make I repaired, the fluid has turned slightly yellow-green. I used odorless mineral spirits in both.

    A trick to remove dissolved air in the compass when you refill is put them in the freezer. Fluid will shrink and the dissolved air is forced out.

    My Ritchie source for parts was

    Island Marine Instrument Co INC.
    2214 Broadway
    Everett, WA 98201-2322

    888-539-2757

    My total cost to rebuild the Richie was $20
     
  8. gonzo
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    gonzo Senior Member

    Varsol is a trade name for mineral spirits/paint thinner.
     
  9. sdowney717
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    sdowney717 Senior Member

    Can you buy clear untinted ethylene glycol?

    http://www.sbioinformatics.com/design_thesis/Ethylene_Glycol/Ethyleneglycol_Properties&uses.pdf

    I think it would work great as a compass fluid.
     
  10. gonzo
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    gonzo Senior Member

    Yes you can. Most compasses are built for either alcohol or mineral spirits and their dampers calibrated for those densities. What advantages would glycol have?
     
  11. sdowney717
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    sdowney717 Senior Member

    Where can you buy it?
    With Ethylene Glycol you can dilute it with water if it was too thick.
    Advantage might be price and likely that one compass that discolored the fluid would have stayed clear using glycol.
     
  12. gonzo
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    gonzo Senior Member

    You can buy mineral spirits at any hardware store. Many supermarkets have it too.
     
  13. buzzman
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    buzzman Senior Member

    Yeah, the stuff that came out of my Plastimo was definitely mineral spirits of some kind, but it was far from 'neutral' in odour - rather pungent in fact.

    Kinda cross between kerosene and thinners.....

    Anyone in USA willing to suss out the supply situation on Exxsol?
     
  14. sdowney717
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    sdowney717 Senior Member

    Odorless mineral spirits has less volatile components so this means when it heats and cools, there will be less pressure inside the compass. It also is expensive maybe $10 per gallon. Still lot cheaper than something branded genuine compass fluid.

    Where could you buy Ethylene glycol without the pigments or the bitterant added?
     

  15. Duane P Wetick
    Joined: May 2013
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    Duane P Wetick Junior Member

    The compass card does not turn...the card stays stationary...the part that moves is the lubber line.

    DPW
     
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