View Full Version : military lensatic compass
Devildoc
4 July 2007, 18:09
I was dusting off my old compass, thinking about heading back to the bush as I have lost many of my skills. I noticed the rotation dial frequently gets stuck and requires me to tap the side or shake it to get it loose. Any ideas to solve this? Time to trash the compass? Any way to refurbish? Thanks.
Carl Spackler
4 July 2007, 18:11
Silva Ragnar
The old mil lensatic beats a Silva any day. But in your case, time for a new one.
Try some penetrant solution to loosen the dial.
The old mil lensatic beats a Silva any day...
Yep.
Carl Spackler
4 July 2007, 20:49
Not an issue...anymore anyway:cool:
NightLandNav
4 July 2007, 23:15
1:50k Tritium Ill. Lensatic M Compass is worth every penny. I've always carried a Silva as a secondary (for possible comparison of floating/liquid dial readings) in a pocket, which is where two of them broke. Still, I kept buying Silvas for the above reason...even though I used them only a few times.
Then GPS came out and everyone thought they were Daniel F. Boone...until they couldn't get SATCOM, or the back-light wore down the batts at O'Dark30...
"I ain't never been lost, but I've been a might confused for a day or two." - Brian Keith, (Bill Frapp); The Mountain Men.
Devildoc
5 July 2007, 10:28
Yeah, I was thinking I was going to have to retire the compass. It is circa early 80s anyway. I do have a Silva, not sure of what model, it is not nearly as good in regard to having to go 5,000 meters on a bearing and find an ammo can with my next coordinates, but it will get me within a few hundred meters of where I need to be, and that's just as good. As far as GPS goes, when I started diving they did not have dive computers. I still do not use a dive computer. Just cannot get comfortable trusting my life to a dive computer, or GPS, but have no problem with either being a backup.
Invisible J
5 July 2007, 18:36
The military issue compass has a service life of 10 years from date of manufacture.
Just a fun fact for your useless knowledge file :D
BrooklynBen
5 July 2007, 22:37
the British "Francis Baker" model 88 (OD) or model (73 black) is the single finest compass I've ever come across. I'm still banging one around that I originally bought back in 1980 (when they were the only ones that offered tritium night dials). They're a little heavy by comparison to the US plastic models and they're $400 to $500, but if I were to lose mine, I'd spend the money again to get another. I suspect mine will last at least past my lifetime.
Just one of their benefits in the way they're made is that they don't seem to be influenced very much by all the metal hardware one sometimes is humping around by day or night ;)
If anyone is interested, here is one site to find them but there may be cheaper venues available which will drop the British VAT in shipping outside the UK.
http://www.pyser-sgi.com/product.asp?ParentID=8
NightLandNav
6 July 2007, 01:14
...They're a little heavy by comparison to the US plastic models...
Cheap plastic models exist, but the US issue MIL-C-10436L are Aluminum.
The military issue compass has a service life of 10 years from date of manufacture.
Just a fun fact for your useless knowledge file :D
Is that the tritium model? or both?
Invisible J
6 July 2007, 07:28
Is that the tritium model? or both?
I'll look it up when I get to the shop, today is going to be a slow day :D
Devildoc
6 July 2007, 08:07
10 year shelf life?? Holy cow...'they' don't seem to care about shelf life on the food they put in our bellies...do they really care about the shelf life on a compass? Still...it was a great compass and I kinda hate the idea of parting with it.
AngryBob
6 July 2007, 16:24
Damm, thanks Guys! You got me digging for mine. I have not seen it for 3 or 4 moves.
Invisible J
6 July 2007, 18:09
Is that the tritium model? or both?
Today was busier than expected so I didn't get a chance to look it up, but I don't recall any distinction between illumination types in the T.O.
Really though, as long as it glows, points north and rotates freely, it's good to go.
do they really care about the shelf life on a compass?
The Air Force does - I'm pretty sure some of the compasses I used in the Corps were "expired" though :D
...I'm pretty sure some of the compasses I used in the Corps were "expired" though :D
Along with the MREs...
:D
Look closely at the side of the "bezel." (That's navigator talk for the rotating part). You will see that it is held on the compass body with an expanding ring. You can use pin-point needle nose pliers, or even two toothpicks, to push the ends of the split ring together and pull the bezel off the top of the compass. Clean it out the raceway with a toothbrush, lightly lube it with oil (LSA is best, but 3-in-one oil will work). Clean the glass (bottom of the bezel, top of the compass body) and snap the bezel back on the body.
The arrow points to the split ring gap:http://members.aol.com/cbjpegs/Compass.jpg
The "10 year shelf life" is for the tritium models. Tritium has a half life of 12 1/3 years, so 12 years from the manufacture of the tube illumination will be one half of the value when new, after 24 years it will be one fourth, and so on.
Olive Drab
7 July 2007, 00:52
maybe a watch maker can relume
Devildoc
7 July 2007, 08:16
As far as the age of the compasses the Corps issued, AND the MREs, spot on. Got me wondering...I wonder just how many are floating around the mesas of Pendleton and swamps of Lejeune? I have been at both, and many a Marine and corpsman lost their compass (to their pockets??). I will disassemble and lube up. Also, any reason the floating dial (the part that moves and points north...you know, the important part) would occasionally stick as well?
The "important part" is called the "compass card" even if it is (now) made of plastic.
When the lens assembly is folded down, it presses on a lever that lifts the compass card up and off the pivot point. That way, there is almost no wear on the needle sharp point of the pivot or the cup shaped bearing on the underside of the compass card.
One of the tests a navigator should make is to watch as the lens is folded down over the bezel to insure that the lever lifts the compass card, which will totally cease moving. And also check that the lever is totally released when the lens assembly is unfolded. If the lens assembly is not unfolded enough, the lever will not totally disengage from the bearing, and the compass card will not rotate freely.
A little WD-40 in the gap end of the case (near the hinge of the lens assembly/thumb loop) might assist in making sure the lever is pressing and releasing.
If there is damage to the top of the pin or the bearing, it's time to buy a new compass. They are available at $35 ~ $65, cheaper for no tritium, expensive for tritium. The PX sells them at Clothing Sales, and you can find them at Brigade Quartermaster, the Cavalry Store, etc.
Devildoc
7 July 2007, 13:48
Thanks for the gouge. Although I would like to 'tinker' with it to see if I can get to work, I have no particular emotional attachment which prohibits me buying a new one...just a cheap a--. A buddy at work and his wife went into Nantahala National Park and had asked me to teach him some land nav...made me miss it, which is why I broke it out of storage and now wanting to polish my rusty skills. If I gots to buy a new one, I gots to buy a new one!
I'm sorry Devildoc, no gouge intended. I'm a tactless SOB on occasion when I am writing in a hurry and don't think through how the words look. I've been a college instructor on navigation (GPS) issues and I tend to be precise.
I hope you enjoy Nantahala, I did training ops there with 7th and 11th SF group. Beautiful country, easy to navigate because of the well compartmented terrain.
Invisible J
7 July 2007, 20:41
I'm sorry Devildoc, no gouge intended. I'm a tactless SOB on occasion when I am writing in a hurry and don't think through how the words look. I've been a college instructor on navigation (GPS) issues and I tend to be precise.
I hope you enjoy Nantahala, I did training ops there with 7th and 11th SF group. Beautiful country, easy to navigate because of the well compartmented terrain.
:D I think by "gouge" he meant "information" :D
Devildoc
8 July 2007, 15:52
Hey, CB, no offense taken...my wife would frequently say my communications get fouled up! See Invisible J's post above...I really do appreciate all of the info. Back in the day I did a fair bit of land nav in Nantahala, Pisgah, all around...I am a coast man through and through, but I do love the mountains. Now the only land nav I do is to the fridge and sofa.
yojinbukai
8 July 2007, 17:54
A little bit off-topic.... I'm a die hard fan of the lensatic as it's all we ever had. The Ops-Chief over at MWTC was in my office not long ago and showed me a new Brunton that he's spec'ed out with assistance from the folks at Brunton. Tons of features, mineral oil filled so it doesn't freeze, thermometer in the lid, all sorts of things. I want to say it's the S-90 M or something like that. I'll try to get the name again from Mitch when I get back to work.
Is that the tritium model? or both?
Tritium last 10 years, hence the cutoff.
The91Bravo
8 July 2007, 18:23
Devildoc,
if you want to unload the compass, I will be happy to buy it. I am the leader of the 1st through 6th grade boys at my church, and we have been teaching them mapreading and camping/survival skills. And we need compasses. (even ones that dont work perfectly) Let me know. thanks in advance
Steve
Poppadelta
8 July 2007, 21:31
spend a little time rotating it while in the flat position and it seems to loosen up the pivot a bit and stop the lag in the dial.
i have one that is easy 25 years old and still works great.
best,
pd
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