Sestrel Compass and refuses to seal

[Refueler]

OK ... I've maintained liquid compasses as a hangover from my original career as a ships officer for years - but this one has me frustrated !

Sestrel traditional job ... all there except the nice wood box they used to have for storage.

Previous owner 'knocked' the prism frame and now it needs to be re-aligned as refraction causes offset reading. That's a mechanical job and not the issue.

The unit was passed to me with a bubble ... and the reference line (thin wire) was detached one end inside. Simple single thin strand of copper wire sorted the reference line. But the bubble proved harder to solve - in fact it steadfastly refuses to play ball !

I have cleaned all surfaces ... smoothed all gaskets etc. refilled it number of times ... made sure top fastened down evenly ... and still few days later - bubble appears. It grows larger over time - indicating the IsoProp is evaporating out slowly.

I have been reluctant to resort to the Baby Oil solution ... as it damps the card excessively. But I may have to ....

Thoughts from the 'panel' please ... apart from send in to Compass Repair shop ...

Would you replace the IsoP with Baby Oil ??

 

[VicS]

OK ... I've maintained liquid compasses as a hangover from my original career as a ships officer for years - but this one has me frustrated !

Sestrel traditional job ... all there except the nice wood box they used to have for storage.

Previous owner 'knocked' the prism frame and now it needs to be re-aligned as refraction causes offset reading. That's a mechanical job and not the issue.

The unit was passed to me with a bubble ... and the reference line (thin wire) was detached one end inside. Simple single thin strand of copper wire sorted the reference line. But the bubble proved harder to solve - in fact it steadfastly refuses to play ball !

I have cleaned all surfaces ... smoothed all gaskets etc. refilled it number of times ... made sure top fastened down evenly ... and still few days later - bubble appears. It grows larger over time - indicating the IsoProp is evaporating out slowly.

I have been reluctant to resort to the Baby Oil solution ... as it damps the card excessively. But I may have to ....

Thoughts from the 'panel' please ... apart from send in to Compass Repair shop ...

Would you replace the IsoP with Baby Oil ??

The agents are Sirs Navigation, perhaps they can help

The correct fluid is Bayol
Id guess its more viscous than 2-propanol but baby oil is probably too viscous.

Id have thought if was worth repairing it was worth repairing properly

 

[pvb]

If there's a bubble, it's leaking. The most common leaks are from the expansion bellows. It's worth fixing, but you need a proper compass repairer. VicS mentioned SIRS Navigation, I've used Seath in Lowestoft and can recommend them too.

Compass Adjuster UK | United Kingdom | Seath Instruments

 

[Refueler]

The agents are Sirs Navigation, perhaps they can help

The correct fluid is Bayol
Id guess its more viscous than 2-propanol but baby oil is probably too viscous.

Id have thought if was worth repairing it was worth repairing properly

The Compass is a Setrel Radiant from Henry Browne ... not the later 1648 SIRS copy and therefore is not Bayol fluid ...

HB ... the one being most used, pasted from Refill Info :

The Sestrel Radiant compass by Henry Hughes and older models by SIRS Ltd used 90% water with 10% alcohol added to act as
antifreeze.

Being that I live in a location that suffers colder winters than that combo can tolerate - I chose the second lesser used 100% alcohol variant.

One fluid that can be used as a universal substitute is Lamp Grade Kerosine. But it must be the clear purified version.

 

[Bilgediver]

OK ... I've maintained liquid compasses as a hangover from my original career as a ships officer for years - but this one has me frustrated !

Sestrel traditional job ... all there except the nice wood box they used to have for storage.

Previous owner 'knocked' the prism frame and now it needs to be re-aligned as refraction causes offset reading. That's a mechanical job and not the issue.

The unit was passed to me with a bubble ... and the reference line (thin wire) was detached one end inside. Simple single thin strand of copper wire sorted the reference line. But the bubble proved harder to solve - in fact it steadfastly refuses to play ball !

I have cleaned all surfaces ... smoothed all gaskets etc. refilled it number of times ... made sure top fastened down evenly ... and still few days later - bubble appears. It grows larger over time - indicating the IsoProp is evaporating out slowly.

I have been reluctant to resort to the Baby Oil solution ... as it damps the card excessively. But I may have to ....

Thoughts from the 'panel' please ... apart from send in to Compass Repair shop ...

Would you replace the IsoP with Baby Oil ??

I had the same problem and eventually got rid of the bubble which was trapped air from filling . I used a high volume hyperdermic needle to flush out the last of the air. However I had discovered like you that the bubble reappeared . These compasses live inside what is basically an aneroid cell and I suspect the adjusters have a means of subjecting the cell to low pressure until sealing is complete then the cell remains under positive atmospheric pressure
I couldn't be bothered to go to extremes but on a day of low pressure refilled it with cold oil . The compass has been bubble free for nearly a year unless subjected to low temperatures when a minute pinhead bubble appears.
My compass is a Sestrel Junior and the oil I used was lamp oil.
It is possible yours is not an aneriod cell construction however you may see the concentric rings of the diaphragm by inspecting throu bottom mounting holes

 

[Refueler]

I had the same problem and eventually got rid of the bubble which was trapped air from filling . I used a high volume hyperdermic needle to flush out the last air. However I had discovered like you that the bubble reappeared . These compasses live inside what is basically an android cell and I suspect the adjusters have a means of subjecting the cell to low pressure in till sealing is complete then the cell remains under positive atmospheric pressure
I couldn't be bothered to go to extremes but on a day of low pressure refilled it with cold oil . The compass has been bubble free for nearly a year unless subjected to low temperatures when a minute pinhead bubble appears.
My compass is a Sestrel Junior and the oil I used was lamp oil.
It is possible yours is not an aneriod cell construction however you may see the concentric rings of the diaphragm by inspecting throu bottom mounting holes

The Service Agents way of filling is to first subject the fluid to a vacuum to remove any air suspended in the fluid. Once its settled and been left in this vacuum state - it is then injected into the bowl in a vacuum chamber to prevent aeration. The temperature of filling is reduced to assist as you found yourself.

This is a more full text from Service Agents Sheet on refilling compass :

If your compass bowl is painted white inside then do not use isopropyl alcohol as it will almost certainly damage the paint. Also, if your compass has white paint inside the bowl, NEVER let the paint dry out, especially when working on it.
Remember that compasses are normally filled under vacuum. This is not possible for the home user, so it is good practice to fill your compass in cool conditions, and to let it stand for 12 hours to let bubbles form, then release the bubble(s) and do a final top-up before final reassembly.
De-gassing compass fluid. Whatever compass fluid you use, unless it is de-gassed bubbles will soon appear in your newly re-filled compass. All fluids contained dissolved air, which eventually works its way back out of solution, forming bubbles. To de-gas your fluid, whether it’s isopropyl alcohol, purified kerosene, water, or any other fluid, you need to place it in a vacuum chamber for a period of time until it stops bubbling, and then it is de-gassed and ready to use.
There are many other fluids that could be used, such as tap water if the compass is very old and not likely to be used in the cold. Water is a perfectly valid damping fluid, but freezes near zero Celsius, which is the only reason other fluids are used. In the past a certain amount of glycerine was added to the water to prevent freezing. The Sestrel Radiant compass by Henry Hughes and older models by SIRS Ltd used 90% water with 10% alcohol added to act as antifreeze.

 

[Refueler]

Well I decided in the end to go for it ... emptied out the IsoP and flushed the bowl and card.

Refilled with Lamp Kerosine - so far - no bubbles appeared ... lets see what happens over a few days ..

Tweaked the prism frame and that seems to be ok now.

 

[Refueler]

So far still good ... by now with IsoP it would have a small pin bubble ... but the Kero seems to have it sorted.

It might even get put back into service !!