Bosch GLM80

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Re: Bosch GLM80

Postby trogman » Feb 17, 2014 3:30 pm

I got a reply from Bosch today concerning the aforementioned shortcomings with the unit. Here is what they said:

"Apparently they never thought anyone would want this feature. They said they’d keep this in mind for future models, but they would not be reprogramming any current models."

So it looks like I'm stuck with what I've got. I thought maybe I could somehow attach a laser pointer to the outside of the unit. How crazy is that- attaching a laser to a laser? :doh: That would be the only way to make it fully functional the way I need it to be.

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Re: Bosch GLM80

Postby driggs » Feb 20, 2014 12:31 am

Extremeophile wrote:But mostly it is better.


I did a poor job of getting my point across, so let me try again...

There are a class of users who I envision considering this Bosch GLM80 laser distance meter. Those users are already equipped to do a cave survey the "old fashioned way", with a compass and clino (or a compass+clino) and fiberglass tape. They are looking to add laser distance capability to their arsenal, because - as you point out - in many situations, a laser is better than a tape. The cost to buy a cave-worthy laser distance meter is, arguably, in the $75 - $150 range. If those users can get a unit with built-in digital inclinometer for free in that price range or for just a bit more, then this device could be quite attractive.

For this class of user, the DistoX isn't necessarily "better".... it's a different tool than they want or need. They have either decided that the cost is too prohibitive, or they've decided that it doesn't meet their requirements for one of the reasons I outlined above.

There's another class of users who may consider the Bosch GLM80... sketchers. I always user a laser when sketching, whether for LRUDS or for anonymous splay shots. Using a laser with built-in clino means I could shoot ceiling heights without standing directly underneath the spot of interest. I wouldn't buy a second DistoX for this purpose, but I'd pay $50 more for that capability when my current laser dies.

Extremeophile wrote:I've heard it argued that the cost is nearly the same as a Disto + Tandem.


Sure, if you purchase a Leica Disto E7400X and a brand new Suunto Tandem at full retail price, the cost is comparable.

However there's no need to buy a Leica Disto unless you're building a DistoX; the posts above show that cave-worthy laser distance meters can be purchased new for 1/2 to 1/3 the price of the Leica. Further, the Suunto Tandem's "street price" is 1/3 the retail price. So the actual cost of a laser + Tandem is very significantly less than that of the DistoX 2.

So I'm calling BS on that argument.


Extremeophile wrote:
The DistoX2 is considerably more influenced by magnetic interference than a traditional compass.

Is this a fact?


Yes. Beet Heeb alludes to this fact on the "Hints" page of the DistoX 2 User Manual.

My not-a-physicist guessplanation is that the compass card in a Suunto must fight the rotational resistance of its mass suspended in fluid, while an electronic sensor has no such impediment. Thus the Suunto requires a stronger magnetic influence to skew it.

Try it!


Extremeophile wrote:Since it sounds like the clinometer in the Bosch may have limitations, it's worth considering an unmodified Leica 7400x. It has a tilt (vertical angle) sensor that goes all the way from +90 to -90. The rangefinder will measure distances over 300', and the unit has a better dust/waterproof rating. You can also decide later if you want to spend the additional $250-300 to modify it to a DistoX.


To play devil's advocate, I'll argue that if the user is merely adding a laser with bonus inclinometer to their existing traditional cave survey setup, they're unlikely to choose any high-angle shot greater than 60° anyway, as that makes sighting a compass quite difficult. I probably wouldn't want to survey a cave without the option for extremely high-angle shots, however, even if I try for plumbs when possible. So the limited clino on the GLM80 does make it less appealing.
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Re: Bosch GLM80

Postby Martin Sluka » Feb 20, 2014 2:59 am

driggs wrote:But I did a poor job of getting my point across, so let me try again...

Hmm, and try imagine, that with DistoX you are able to survey and sketch alone. I tested it and there is no any obstacle. Nor for F/B measurements. No any nervous, frozen caver around. So one caver could be one surveying group. Three cavers each one with DistoX three surveying groups.

I apologize myself, but this discussion is something as to try to make an automobil with legs, because the horse has the legs.
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Re: Bosch GLM80

Postby GroundquestMSA » Feb 25, 2014 4:19 pm

I apologize for blurting out about the GLM80 when I didn't know what I was talking about. We were all comparing lasers in the cave, and I thought I clearly remembered the disto/clino being a Bosch. It was not. It was the Leica Disto E7400X. The owner paid $230 for it at a lumber yard.

driggs wrote:However there's no need to buy a Leica Disto unless you're building a DistoX; the posts above show that cave-worthy laser distance meters can be purchased new for 1/2 to 1/3 the price of the Leica.


It appears the Bosch doesn't have a useful inclinometer, so there may be good reason for, "Those users are already equipped to do a cave survey the "old fashioned way", with a compass and clino (or a compass+clino) and fiberglass tape" to consider the Leica, even if they aren't interested in a DistoX. I don't know how valuable the clino feature would be though, since it would make instrument reading faster and possibly put more pressure on the sketcher. For my own "works of fiction" I would like to have a Leica, since we often have a 2-person team, and there is room for quicker data collection. Maybe I'll look for a used one.
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Re: Bosch GLM80

Postby Extremeophile » Feb 25, 2014 5:15 pm

GroundquestMSA wrote:I don't know how valuable the clino feature would be though, since it would make instrument reading faster and possibly put more pressure on the sketcher.

This has been a long-used argument against the need for digital survey techniques, i.e. the rate limiting step is the sketcher, so speeding up data collection won't speed up the survey. This of course is not universally true, and the more experience anyone gets sketching naturally the better and faster they get, often to the point where they may be waiting on the instrument reading crew. With experience you will find many other uses for Distos during a survey. You can shoot the distance down alcoves or to intermediate objects such as breakdown, formations, or ledges. You can shoot to the top of canyons or up domes. You can shoot through holes or across delicate areas where a tape cannot or should not go. All of these uses help to make the sketch more accurate, and help speed up sketching. I personally prefer the Leica brand. They are well made and reliable, some models are dust and water proof, they often have better distance range than cheaper models, and most models display the last 4 measurements so LRUDs can be captured efficiently. There certainly are less expensive brands, but I haven't seen any with the same functionality at 1/3 to 1/2 the price.
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Re: Bosch GLM80

Postby GroundquestMSA » Feb 25, 2014 9:02 pm

I wish I could keep up with the instrument reader(s). I don't have an artists eye and need lots and lots of practice.
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Re: Bosch GLM80

Postby trogman » Feb 26, 2014 8:13 am

Groundquest- From my research the DISTO E7400x is the cheapest Disto model that has the 360 degree tilt sensor.

One aspect of a laser clino that I haven't seen a lot of discussion on is accuracy. With traditional clino instruments, alignment with both the from and to stations is approximate at best. With a laser it is about as exact as you can get. The same goes for a laser compass such as has been discussed on this forum. The only problem is, I (and probably many of my fellow surveyors) can't ever see spending that kind of money for such a tool. But the DISTO E7400x, which retails for about $279, might be attainable some day. If I hadn't spent that $140 on the Bosch, I'd be that much closer. :down: Oh, well, live and learn, I suppose. Hopefully my experience has helped some of you avoid making the same mistake.

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Re: Bosch GLM80

Postby GroundquestMSA » Feb 26, 2014 8:54 am

The disto certainly gives easier accuracy. The survey crew that was using the laser clino was using a Suunto for backsights, and got good results. I find that I sometimes tend to drift off of the from station when shooting inclinations, but if you're careful it seems that a Suunto is very accurate.
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Re: Bosch GLM80

Postby driggs » Feb 26, 2014 8:45 pm

GroundquestMSA wrote:It appears the Bosch doesn't have a useful inclinometer...


OK, the Bosch GLM80 functions as a digital inclinometer between 0 - 60°. I remarked previously that high-angle shots are generally avoided when using traditional cave survey instruments, and I didn't really give this fact a second thought. Sure, the digital clino on this device is limited; but to say that it's not useful is silly. Let's just see how badly our cave surveys would be crippled if we couldn't shoot high-angle clino shots...

I wrote a quick script to extract an inclination histogram and checked some decent-sized local cave survey data. Here's what it shows:

Memorial Day Cave (23.5 mi):

Code: Select all
INC   COUNT   PERCENT   HISTOGRAM
00   2434    35.8%   ###########################################################################################################
05   1099    16.1%   ################################################
10    705    10.4%   ###############################
15    504     7.4%   ######################
20    401     5.9%   ##################
25    350     5.1%   ###############
30    308     4.5%   ##############
35    223     3.3%   ##########
40    125     1.8%   ######
45     81     1.2%   ####
50     51     0.7%   ##
55     29     0.4%   #
60     11     0.2%
65     17     0.2%   #
70     13     0.2%   #
75      5     0.1%
80      4     0.1%
85      1     0.0%
90    444     6.5%   ####################
     6805   100.0%
Summary: 51 (0.7%) shots are high-angle 60-deg or greater


Hellhole (41.7 mi):

Code: Select all
INC   COUNT   PERCENT   HISTOGRAM
00   3352    30.7%   ############################################################################################
05   1943    17.8%   #####################################################
10   1257    11.5%   ###################################
15    861     7.9%   ########################
20    785     7.2%   ######################
25    532     4.9%   ###############
30    454     4.2%   ############
35    337     3.1%   #########
40    278     2.5%   ########
45    178     1.6%   #####
50    124     1.1%   ###
55     68     0.6%   ##
60     47     0.4%   #
65     31     0.3%   #
70     24     0.2%   #
75     14     0.1%
80      8     0.1%
85      3     0.0%
90    623     5.7%   #################
   10919   100.0%
Summary: 127 (1.2%) shots are high-angle 60-deg or greater


So, at least in our West Virginia caves, one out of every 100 survey shots have an inclination of 60° or greater (not including vertical "plumb" shots). That's because it becomes nearly impossible to accurately shoot a compass for high inclination shots; once it gets steep enough, you're much better off doing a plumb up/down shot.

One could make the argument that using a DistoX (or other combination digital compass and clino) means that you can now take high angle shots that couldn't be done with traditional instruments... and I agree! In fact, it's entirely likely that the few high angle shots in the above dataset were done with a DistoX. But that argument doesn't apply to the use case of traditional compass with combination laser + digital clino, such as the GLM80.

In other words, despite its limitations, the digital clino in the GLM80 is far from "useless"; the above data shows that it is suitable for literally 99% of the shots you would take in conjunction with a traditional compass.

Edit: To be clear, this data shows that approximately 1% of inclination shots from a large West Virginia survey project have "high-angle" inclination between 60° - 89°. These shots could not be done with the Bosch GLM80's built-in digital clino. The other 99% of survey shots could be done with the GLM80 (and no clino is necessary at all for the 6% plumb vertical shots).
Last edited by driggs on Feb 27, 2014 10:15 am, edited 1 time in total.
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Re: Bosch GLM80

Postby GroundquestMSA » Feb 26, 2014 11:17 pm

quote="driggs"]In other words, despite its limitations, the digital clino in the GLM80 is far from "useless"; the above data shows that it is suitable for literally 99% of the shots you would take in conjunction with a traditional compass.[/quote]

The above data is nice, quite spiffy. I especially like the green letters.

I missed some of the details of Steve Brewer's summary. I thought that the inclination function would not work at all when the laser is on. That would make it useless. However, trogman did say that he, "soon discovered that the angle does measure and display dynamically when taking a distance measurement, but the only way to lock it in is to use one of the triangle functions." I'm not sure what that means, but if it's possible to use the GLM80 for shots of under 60 degrees without much hassle, then you are right, it would certainly be suitable for most shots.

I'm sorry, I seem to be missing a lot lately. I've two strikes on this thread alone.
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Re: Bosch GLM80

Postby Extremeophile » Feb 27, 2014 12:11 am

Dear Dave,
You really need to spend more time underground ... or find a girlfriend.

Sincerely,
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Re: Bosch GLM80

Postby trogman » Feb 27, 2014 8:53 am

GroundquestMSA wrote:quote="driggs"]In other words, despite its limitations, the digital clino in the GLM80 is far from "useless"; the above data shows that it is suitable for literally 99% of the shots you would take in conjunction with a traditional compass.

The above data is nice, quite spiffy. I especially like the green letters.

I missed some of the details of Steve Brewer's summary. I thought that the inclination function would not work at all when the laser is on. That would make it useless. However, trogman did say that he, "soon discovered that the angle does measure and display dynamically when taking a distance measurement, but the only way to lock it in is to use one of the triangle functions." I'm not sure what that means, but if it's possible to use the GLM80 for shots of under 60 degrees without much hassle, then you are right, it would certainly be suitable for most shots.

I'm sorry, I seem to be missing a lot lately. I've two strikes on this thread alone.


Jonah- It was probably more my fault for not clearly describing the operation of the tool.

Yes, the clino does function with the laser on, but only up to 60 or -60 degrees. (How the heck do you insert a degree symbol in here?) When you shoot a distance, the angle (again, limited to 60 deg.), displays as you are measuring, but the angle value is not locked in when you take a measurement. In other words, the distance you just measured is shown, but the angle keeps updating according to the current angle of the unit.

When you use either the indirect length or indirect height measurement modes, the length and angle are displayed after a measurement, but the function must be reset after each shot.
In order to obtain an angle > 60, you have to use the dedicated angle function. Then you must press the angle button again to make it read with the instrument on its side.

Image

In this mode, the laser is turned off. I am considering using a separate pointer laser mounted on the side of the unit for steep angles. The mount would allow me to easily attach or remove the pointer laser. As I said, it seems strange mounting a laser to a laser, but it might be a usable workaround.

driggs- I agree that the majority of shots will be <60 degrees, rendering the GLM80 somewhat useful. But it also means that you'd probably need to carry a traditional clino for those shots. Either that, or you'd have to use some straight up or down shots coupled with horizontal shots. It could turn a survey of a steeply-sloping passage into a stair-step lineplot, and perhaps require a lot more shots than would otherwise be necessary. But you are correct in saying that it is a very small percentage, at least in the examples you cited. It might be a little different here in TAG; I'd have to pull up my numbers to see.

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Re: Bosch GLM80

Postby Hunabku » Feb 27, 2014 3:05 pm

I really appreciate all of the great info and opinion this discussion has brought.

I think I am going to go ahead and get a GLM80. I think it will be a useful tool for most of what I will likely run into in Florida. Besides, mounting a high power green laser to it might not be a bad idea anyways.
Why not go out on a limb, thats where all of the fruit is.
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Re: Bosch GLM80

Postby snoboy » Feb 27, 2014 7:10 pm

trogman wrote:(How the heck do you insert a degree symbol in here?).

Trogman :helmet:


press and hold the ALT key while you type 0176

:grin:
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Re: Bosch GLM80

Postby trogman » Feb 27, 2014 10:38 pm

snoboy wrote:
trogman wrote:(How the heck do you insert a degree symbol in here?).

Trogman :helmet:


press and hold the ALT key while you type 0176

:grin:

°
Thanks!

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