Limb walk station alarm

Tom Dunlap

Tom Dunlap

Here from the beginning
Administrator
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Retired in Minneapolis
This year I got around to building a sturdy alarm for the limb walk station. The alarm is made from 2" pvc and a 12v car horn. the horn is powered by my cordless tool batteries.

The legs slip into a PVC Y. I drilled a clearance hole for the vertical tube. The tube is capped on both ends. A 1/4" diameter threaded rod goes through the PVC tube. A nut on both ends keeps the caps on. The tube is filled with beach sand to dampen the wind swaying.

The easiest way to describe the circuit is from the switch. The rod is wired to the battery, which connects to the horn which connects to a plate that I got at the junk store for a buck.

The whole works, excluding the batteries, would only cost about $25 to make. The legs aren't glued in so the whole works compacts for storage. The caps on the tube keeps it from coming apart.

If there is interest, I'll take some time and make up a DIY plan.


There is just a bit more work to be done on it for next year.
 

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Looks like a rocket launch pad.
I guess I will have to ask, what is the purpose and how does it work?
T - 10 and counting /forum/images/graemlins/jpshakehead.gif
 
Are you familiar with the Limb Walk station in the TCC? The climber needs to go to a station that is on the end of a small limb, ring the bell and return without putting too much of a load on the limb. If the climber has a heavy foot and stomps out to the bell, they will deflect the limb. With this alarm the deflection can be measured and set the same for all of the climbers.

The horn that I got is a little bit lame. It bleats, what I would like to get is an air horn :) Even with this horn there is no question when the alarm goes off.

Mahk worked with it the whole day so he would have a better idea if it worked like it should.

One change that I need to add is an adjuster on the plumb bob end. A simple friction hitch or traditional climbing hitch setup would allow adjustments.
 
Last week I went to the flea market and bought one of these reels for $10

http://www.gopaddleacanoe.com/Reels/source/f022004.html

I loaded it with the thin Spectra throwline that Sherrill used to sell. It's like thick dental floss. This is used for my in-tree throwline. I can spool out as much line as I need. When I'm done, I hit the trigger that pokes up out of the top and the line zings back in like a measuring tape. Way cool!
 
I have in my hand (well, on the desk just left of the keyboard now) a "Shakespeare Automatic No. 1821" very similar to that. It was my grandfather's, and would have to be no newer than 1949 when he died (I also have the accompanying Montague split bamboo fly rod in it's original tube and case -- 4 3' sections for a 9' rod, with two differing-action tip sections; but I digress). I've not taken any of it into a tree yet that I know of, though I don't doubt I've gotten a fly caught in some limbs while using it...

The gammon reel is not merely for stowage of the line, but is an integral part of the plumb bob system length adjustment as well.
 
After buying the reel I wanted to find out something about how it worked. I found that the real that I have was made in about '46 or '47, older than me :) I think that a reel like this could work the same as the Gammon. Someday if I need to do a lot of plum bob work I'll probably check it out.

What a treasure to have that rod and reel.
 
Always thinking huh Tom? Looks like a clean set up. Cant really see how the three legs are connected to the straight tube, looks like maybe vinyl tape holding the 4 tubes in place. I like the light weight, easily portable set up (and economical)
Frans
 
Hey Wolter,

It's said that if a sufficiently-large underground mass were present not directly below it, but to one side a little, a bob would hang not plumb to the horizon (same reaction with a spirit level, so if a structure were built on the site it would correctly be built "vertical" against the resultant gravitational pull even if that's not exactly the center of the earth). Seems by your photo this would be true. Look how the bob, building, and people are all leaning slightly from the true vertical!

Tom,

Within finite limits acceptable to typical usage, the mass of the Gammon reel itself is insufficient to materially alter the "trajectory" of the bob. I somehow tend to think that would not be the case with the fly-line reel unless a bob weight were proportionately scaled as well. (though that's not really a concern of your specific purpose, is it?)

Here's a thought: set a "disqualifying" limit for your event, but using a system based in part on what I'm seeing in Wolter's attachment, one could make use of a "tattle-tale" mechanism to award the biggest prize to the climber who'd deflected the limb the least! (assuming on my part that's not done already)

Glen
 
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Hey Wolter,

It's said that if a sufficiently-large underground mass were present not directly below it, but to one side a little, a bob would hang not plumb to the horizon (same reaction with a spirit level, so if a structure were built on the site it would correctly be built "vertical" against the resultant gravitational pull even if that's not exactly the center of the earth). Seems by your photo this would be true. Look how the bob, building, and people are all leaning slightly from the true vertical!


[/ QUOTE ]

/forum/images/graemlins/rotflmao.gif

Man, Glen, this can't be true.

I specially modified the posted picture to set the curve of the earth in the right way to be viewed in Britain. I bet the Germans can see it straight. Here is one for you and maybe this is in a better angle.
 

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Glen,

I like your idea! It would be a fun challenge to see who could make the station with the least deflection. It would be a prize totally seperate from the other prizes. Maybe a "lite"__________, you fill in the blank.
 
I think the limb walk station should be sponsered seperatly, maybe by a fast food chain.

The person who sets off the buzzer while furthest away from it wins his/her weight in pies/hamburgers!!
 
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I would be Twinkletoes, that horn would never blow.

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Hey I'm looking for a room mate, you should go.
 
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[ QUOTE ]
Hey Wolter,

It's said that if a sufficiently-large underground mass were present not directly below it, but to one side a little, a bob would hang not plumb to the horizon (same reaction with a spirit level, so if a structure were built on the site it would correctly be built "vertical" against the resultant gravitational pull even if that's not exactly the center of the earth). Seems by your photo this would be true. Look how the bob, building, and people are all leaning slightly from the true vertical!


[/ QUOTE ]

/forum/images/graemlins/rotflmao.gif

Man, Glen, this can't be true.

I specially modified the posted picture to set the curve of the earth in the right way to be viewed in Britain. I bet the Germans can see it straight. Here is one for you and maybe this is in a better angle.

[/ QUOTE ]
Wolter,

I see you have a good sense of humor, and that you "get" mine too.

The nearby mass thing is in fact real, though a quick google search primarily turns up mountains as the main cause. http://www.physics.ox.ac.uk/history.asp?page=BigGHis http://pangea.stanford.edu/courses/gp025/webbook/08_tectonics.html
 
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Hey I'm looking for a room mate, you should go.

[/ QUOTE ]

That would be awesome, my brother! /forum/images/graemlins/cool.gif
 
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