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Jeff
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Jeff
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PostFri Jan 01, 2016 9:12 pm 

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moonspots
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PostFri Jan 01, 2016 9:17 pm 
Jeff wrote:
I know air bubbles can happen in a compass, but I have never had one this large/ The needle takes a long time to settle and even then it will easily shift 20 degrees or so. This one is only 6 years old, but it's been on a lot of trips. Time for a new one or am I just being picky?
That's a 1/2 inch bubble!
For as cheap as these type are, I'd just get another one. Especially when you mention +/- 20 degree shift.

"Out, OUT you demons of Stupidity"! - St Dogbert, patron Saint of Technology
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Bernardo
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PostFri Jan 01, 2016 9:26 pm 
I wonder I performance would be affected if you drill drill whole in the bottom and drained the liquid? If you choose to attempt this experiment, let us know the results!

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cdestroyer
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PostSat Jan 02, 2016 8:56 pm 
I was brought up on maps and compasses back in the 50's. here in montana the trails are marked with a yellow metal plate divided into grids with a hole in the location. these match the montana forestry maps. you get lost here you should have stayed home....I have always carried a lensatic compass and map of the area I was hiking, and long before anyone ever heard of gps....

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spamfoote
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PostSat Jan 02, 2016 11:46 pm 
Bernardo wrote:
I wonder I performance would be affected if you drill drill whole in the bottom and drained the liquid? If you choose to attempt this experiment, let us know the results!
Bearing sticks. The liquid holds the "hands" up and therefore it floats. Therefore the force required to move the hands is low compared to the bearing friction and therefore you get accurate readings. Yes, it will work with just air. Not as accurately and it will also be very susceptible to shock or even just normal walking causing the the bearing surface to the hand to be destroyed. Old surveyors compasses had a bleed hole you injected mineral oil to get rid of big air bubbles.

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spamfoote
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PostSat Jan 02, 2016 11:48 pm 
Jeff wrote:
I know air bubbles can happen in a compass, but I have never had one this large/ The needle takes a long time to settle and even then it will easily shift 20 degrees or so. This one is only 6 years old, but it's been on a lot of trips. Time for a new one or am I just being picky?
That's a 1/2 inch bubble!
That is probably acrylic plastic. You could drill a small hole, fill with mineral oil, and then fill the hole with acrylic glue.... Or just buy one for $20.

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mbtigger
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PostMon Jan 04, 2016 8:24 am 
I get bubbles lie this after several years of use and I just buy a new one.

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Navy salad
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PostTue Jan 05, 2016 4:43 pm 
spamfoote wrote:
You could drill a small hole, fill with mineral oil, and then fill the hole with acrylic glue.... Or just buy one for $20
I once had an expensive sea kayaking deck compass that developed this problem. I had the same thought about drilling a hole and filling it to eliminate the bubble. I called the manufacturer who said they used some special fluid (I don't recall what it was, but I know it wasn't a kind of oil) that wasn't supposed to have any dissolved air -- specifically to avoid the bubble problem. Fortunately, they offered to send me a brand new one free of charge! You might call them and if they won't send a replacement, I'd shell out the $20 and buy a new one.

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Malachai Constant
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Malachai Constant
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PostTue Jan 05, 2016 6:08 pm 
The fluid damps the needle, without it the needle will oscillate for some time before coming to rest like an old school analytical ballence.

"You do not laugh when you look at the mountains, or when you look at the sea." Lafcadio Hearn
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Bernardo
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PostWed Jan 06, 2016 12:06 am 
So we have one view that the the fluid damps the needle and another that without it the needle will stick. I've had some old compasses that didn't have fluid and based on them I'd say the fluid is more important for damping. But in any case, it's not a big deal. The compass will still work well enough without fluid for most purposes. On the other hand, the price of a new compass is low.

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spamfoote
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PostWed Jan 06, 2016 1:26 am 
Navy salad wrote:
I called the manufacturer who said they used some special fluid (I don't recall what it was, but I know it wasn't a kind of oil) that wasn't supposed to have any dissolved air -- specifically to avoid the bubble problem
As I said in my previous post. Mineral oil. It is clear. Used to be able to buy it at a hardware store. Who knows now. Could just as well use clear thin tapping fluid oil or lamp oil(refined Kerosene). Makes no difference to the compass. Just that pesky air bubble. Water is not used due to its polar nature and its high surface tension. Otherwise water could be used.

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texasbb
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PostWed Jan 06, 2016 9:27 am 
spamfoote wrote:
Water is not used due to its polar nature and its high surface tension. Otherwise water could be used.
And water provides "too much damping" below 32F. smile.gif

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Windstorm
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PostWed Jan 06, 2016 12:40 pm 
Jeff wrote:
Do compasses with mirrors help at all when setting and following a bearing? I know the mirrors are nice when TAKING a bearing on a landmark, but I rarely do that.
Yes, the mirror will be helpful if you're following a bearing. The motions of following a bearing are very similar to taking a bearing except that you rotate your body until the north arrow lines up instead of rotating the compass bezel. In both cases, the mirror helps you see when the north arrow is lined up while the compass is at arm's length.

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Malachai Constant
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Malachai Constant
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PostWed Jan 06, 2016 1:57 pm 
Compasses with mirrors are also useful for signaling and contact lens insertion and removal.

"You do not laugh when you look at the mountains, or when you look at the sea." Lafcadio Hearn
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mike
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PostWed Jan 06, 2016 2:37 pm 
If you get one w/ a mirror (recommended) make sure that the declination is adjustable.

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