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Jeff Member
Joined: 18 Aug 2008 Posts: 202 | TRs | Pics
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Jeff
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Fri Jan 01, 2016 9:12 pm
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moonspots Happy Curmudgeon
Joined: 03 Feb 2007 Posts: 2456 | TRs | Pics Location: North Dakota |
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moonspots
Happy Curmudgeon
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Fri Jan 01, 2016 9:17 pm
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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
"Out, OUT you demons of Stupidity"! - St Dogbert, patron Saint of Technology
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Bernardo Member
Joined: 08 Feb 2010 Posts: 2174 | TRs | Pics Location: out and about in the world |
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Bernardo
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Fri Jan 01, 2016 9:26 pm
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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 Member
Joined: 14 Sep 2015 Posts: 1249 | TRs | Pics Location: montana |
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 Member
Joined: 26 Oct 2014 Posts: 860 | TRs | Pics
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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 Member
Joined: 26 Oct 2014 Posts: 860 | TRs | Pics
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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 Sherpa Da
Joined: 14 Apr 2011 Posts: 697 | TRs | Pics Location: Sucking the dry air |
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mbtigger
Sherpa Da
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Mon Jan 04, 2016 8:24 am
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I get bubbles lie this after several years of use and I just buy a new one.
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Navy salad Member
Joined: 09 Sep 2008 Posts: 1864 | TRs | Pics Location: Woodinville |
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 Member
Joined: 13 Jan 2002 Posts: 16088 | TRs | Pics Location: Back Again Like A Bad Penny |
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
"You do not laugh when you look at the mountains, or when you look at the sea." Lafcadio Hearn
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Bernardo Member
Joined: 08 Feb 2010 Posts: 2174 | TRs | Pics Location: out and about in the world |
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Bernardo
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Wed Jan 06, 2016 12:06 am
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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 Member
Joined: 26 Oct 2014 Posts: 860 | TRs | Pics
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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 Misplaced Texan
Joined: 30 Mar 2009 Posts: 1153 | TRs | Pics Location: Tri-Cities, WA |
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texasbb
Misplaced Texan
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Wed Jan 06, 2016 9:27 am
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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.
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Windstorm Member
Joined: 16 Dec 2014 Posts: 288 | TRs | Pics
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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 Member
Joined: 13 Jan 2002 Posts: 16088 | TRs | Pics Location: Back Again Like A Bad Penny |
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
"You do not laugh when you look at the mountains, or when you look at the sea." Lafcadio Hearn
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mike Member
Joined: 09 Jul 2004 Posts: 6389 | TRs | Pics Location: SJIsl |
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mike
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Wed Jan 06, 2016 2:37 pm
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If you get one w/ a mirror (recommended) make sure that the declination is adjustable.
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