Good morning everyone. As the topic title suggests I'm looking for tips on efficiently setting up a precision prism carrier/traverse kit with a level vial atop a tripod and plumb over a point. The carrier and tribrach are Leica and the tripod I'd be using is the SECO Tri-Max with the knobs for locking the legs. I know this is a elementary question. I can do this successfully, but not efficiently. I don't have much experience using the precision prism carrier/ traverse kit, so I'd like to practice, but if I'm going to practice a procedure I want to practice it correctly.?ÿ
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I'm looking to learn how to do it correctly from start to finish. From taking the collapsed and buckled legs to getting them plumb and over the point at the correct height and getting tribrach and carrier to follow suit. This would typically be on concrete sidewalk or slab, but could also be on asphalt or even dirt or another material that would have me steeping the feet in substantially. Or possibly a mix?ÿ of those. Any resources you could point me to or anecdotal advice you could give me would be greatly appreciated. Thank you?ÿ
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Answer:
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Just keep setting it up.?ÿ in all terrain and situations.?ÿ Learn the frozen ground tricks of the trade, not tricks at all but empirical data from tried and true usage. Similar for sand, or mud or slippery surfaces.
Are you taking a class in surveying looking for answers??ÿ?ÿ
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There is a counterintuitive technique that I use. After setting the tripod down over the point and stepping on the legs, use the leveling screws to point the optical plumb sight on the carrier at the point. The carrier won??t be level. Next adjust the leg lengths to level the carrier. Surprisingly it won??t move optical sight off the point much at all. Finally loosen the carrier and slide it to the point and then fine adjust the level. You always chase leveling and centering around each other, but I find that this reduces that chase.?ÿ
1. Practice
2. Practice
3. Practice
It's really all about being able to judge how to get the legs at the correct width with the tripod head close to level, and the center of the head reasonably close to over the mark. That's practice more than anything else. Once you are able to do that quickly, the rest comes pretty easily, but this is where technique is a bit more important.
Like Larry mentioned, one of the bigger mistakes I see is putting the tribrach on the tripod, then immediately trying to level it.
Don't. Look through the plummet or laser and first use the levelling screws to point the crosshairs/dot at the mark on the ground. (Make sure the screws are all at the neutral position to start.)
Then begin to level the tribrach with the tripod legs; because you are already pointed at the mark, as you adjust the legs, the head will "pivot around" the mark itself.
Once the tribrach is adjusted with the legs (bubble in center of circle), lock the legs and fine-tune the tribrach.
Thanks for asking about this because there??s nothing more aggravating than finding a cliff hanger on flat ground (tribrach hanging over the edge of the tripod head).
before beginning, center the tribrach screws and center it on the tripod head.
1. extend the legs so that the head is roughly level (adjusting for the slope of the ground).
2. Become a bombardier, with the head of the tripod against your chest guess is over the point, just roughly approximate.
3. look in the optical plummet and swing the target cross hair over the nail or pipe or rebar or whatever it is. Somewhere on the nail head is good.
4 at this point the tripod head shouldn??t be too far off level and it should be close.
5. Set the tripod feet but don??t tighten the screws yet (quick release levers down-engaged).
6. Look in plummet and turn the tribrach screws to bring the cross hair centered on the nail.
7. Level the bubble by sliding the legs up and down. You can tell which leg by looking at the bubble.
8. look in plummet, if more than a little off, I turn foot screws to recenter then relevel the legs. This is an iterative process. The goal is to minimize the need to move the tribrach.
9. finally, tighten the tripod screws, find tune the level, slide the tribrach over the point without turning or twisting it.
The surveying culture I grew in was everything has to be done in 5 milliseconds but I have learned over the decades that if you slow down and take time to do things correctly it will save a lot of trouble later.
take times to put things away, don??t throw the muddy shovel in the backseat on top of the chief??s briefcase because putting it away properly takes 15 seconds OMG. that sort of thing.
Study other chiefs setting up and determine what works for you. Ultimately, it takes practice and experience to become more efficient. Just don??t get in too much of a hurry and risk blowing a setup. I??ve always told my apprentice not to worry about how fast they can set up because we??re more concerned with accuracy than speed.?ÿ
Follow Dave Karoly method, but at item 2 if you want assurance, drop a small stone to check head is near enough plumb. If it isn't move ALL THREE legs by same amount for distance head needs to move (that way if the head was near enough level at the start it will stay level. The follow rest of Dave's procedure.
Oh! don't forget to measure target height while you are feeling pleased with yourself for setting up in record time.
here's my setup from the frozen melty frozen day....
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every setup is similar but very different. repetition and consistency is the key, and mistakes learned from propelling you forward.
if you're not making mistakes you're not doing anything....
you're going to be just fine
Once I am set up in the snow I cover the feet with snow, it keeps the sun from heating them up and melting out of level.?ÿ
One quick tip that always work for me was when first extending the legs out is to bring the plate up to your chin with the feet on the ground (tripod still folded in). This usually results in the eye piece of the instrument being close to the height of your eye when set up...this really made a difference back in the day with manual total stations when you knew you would be setup at one place for a couple hours.
I had an IM with a super power. He would spread the legs around the point. Horizon level the head over the point, stamp in the feet. Screw on the instrument, level it and do a slight adjustment to it.
He never had to swing any legs, never had to get over the point. He only had to place the tripod up and the head was centered and plumb over the point.?ÿ I never saw anyone else that could do it, I sure can't.?ÿ
Levelling up is always sort of a fidgity business, and doing it with ultra sensitive prism carrier just makes it more so. This is really never going to be a particularly efficient operation.?ÿ?ÿ
Once I am set up in the snow I cover the feet with snow, it keeps the sun from heating them up and melting out of level.?ÿ
I set up yesterday in an icy spot. There wasn't any snow near but there were lots of rocks so I piled them around the legs hoping it would help with the ice.
Nope!!
After a couple of hours I made my way back to the base and it had drifted. Not enough to ruin what I'd done (I estimate .02-.03'), but snow packed around the feet would have prevented it.?ÿ
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once had a whip antennae on a 15?? rod blow over and tug the base just enough to pick it up off the point and set it off to the side a foot or two. Luckily was far enough away to lose radio so didn??t get any bad shots. Also close to the truck too so just jumped in the truck and went to check on it.?ÿ
We have so easy with these new adjustable leg tripods. As late as early 1980??s I was setting up with a stiff leg tripod. On a stone wall it might take a half hour of piling rocks to make a place to put the legs.?ÿ
