Cavechat.org

I thought of a very simple idea today for how to make a cheap surveying compass.

All you have to do is fix a cheap laser pointer to an electronic compass in order to easily show that it is lined up with the next point. This method is already in use with some digital surveying equipment, but that equipment is very expensive and requires complicated calibration methods in some cases. I think this cheap method would work as long as your compass is accurate and the laser is lined up perfectly, which wouldn't be too hard to do. What I like about the digital aspect is that it would eliminate the need for lying in awkward positions and having to match up lights in your sighting, which can be very difficult some times. It could also be much more accurate if made correctly.

This is so simple that I'd be surprised if it hasn't already been tried before. Does anybody know if it has be tried? Any other comments on this? I would like to test this idea but I will need to find a suitable electronic compass first.

Most cells that comprise the battery in a laser pointer have a magnetic component. The laser pointer may also have magnetic material. Placing a pointer right next to a compass of any kind could have an influence on the readings. Locating the battery far enough away may be inconvenient. Maybe there are non-magnetic batteries?? Try it first before beginning a survey.

KeyserSoze wrote:I
This is so simple that I'd be surprised if it hasn't already been tried before. Does anybody know if it has be tried? Any other comments on this? I would like to test this idea but I will need to find a suitable electronic compass first.

http://www.cavediggers.com/MartinSlukaCL/index.html

the pointer is nonmagnetic, batteries are on quite long cable. Compass is standard.

m.

Good call on that link, thanks. I would have been more surprised to find out that this idea has NOT been tried before.

Do you know if that item is for sale or is it custom made? Or even if I just knew who owns one I could drop them an email with some questions.

KeyserSoze wrote:Good call on that link, thanks. I would have been more surprised to find out that this idea has NOT been tried before.

Do you know if that item is for sale or is it custom made? Or even if I just knew who owns one I could drop them an email with some questions.

Home made, compass is from French Topofil Vulcain. First model I used was +- from year 1988 (?)

Martin

sluka wrote:

KeyserSoze wrote:I
This is so simple that I'd be surprised if it hasn't already been tried before. Does anybody know if it has be tried? Any other comments on this? I would like to test this idea but I will need to find a suitable electronic compass first.

http://www.cavediggers.com/MartinSlukaCL/index.html

the pointer is nonmagnetic, batteries are on quite long cable. Compass is standard.

m.

Nice setup! I like the pivoting feature on the laser, which should significantly reduce errors on high angle shots. Silva had a new compass with a laser built into it, but it didn't have the pivoting feature. This was discussed on another thread:

http://forums.caves.org/viewtopic.php?f=26&t=9701&p=82350&hilit=laser+compass#p82350

The problem with digital compasses is that most of them only have a +/- 5 degree accuracy. (At least the ones that I have seen) It would be nice to aim your compass without having to sight through it, especially for those stations located in awkward locations.

Trogman