Hi everyone,
I'm new to surveying (1year) and have had the opportunity to work with a couple of different surveyors. Recently, as I was setting up a total station, I was told that I was sinking the points of the tripod too deep. The way that my boss taught me, is to put all of my weight on the tripod foot brace and sink the tips of the tripod then repeat to ensure they are all secure. The guy I was helping told me that was wrong and that I should only sink the points of the tips. I should note that my boss has 25+ years in the field and that my setups have yielded tight closures.
So, any opinions? I've googled this and haven't found any information one way or another.
Many thanks in advance.
I, who only has 52 years of experience, always step the tripods into the ground firmly. This will provide for a stable setup and eliminate a few chances for error. There are still plenty of other ways to induce errors into your work. Why not eliminate the simple ones?
I weigh in at about 280 and I sink those puppies as far in as they'll go - flush with the ground if it's soft enough. Just apply even, steady pressure; don't stomp on it, I've seen them break.
Clint, you're sure to get plenty of opinions here. This is opinion central.
I personally have always put all my weight on the tripod foot, just as you describe. Can't think why that step would be there otherwise. If you only sink the tips, the gun might well settle under its own weight, depending on what the ground is like.
I was taught early on to set up on 1 x 2 hubs laid flat when setting on blacktop, with a nail driven through into the bituminous to keep the hub from sliding. And when setting up on frozen ground in winter, we always piled snow over the metal tripod foot to keep it from being warmed by the sun and melting its way into the ground. I've tried skipping those steps but the gun nearly always got out of level in a few minutes.
Too much pressure on the foot shoe causes the legs to bow out. Loosen the thumb screws to release the leg tension prior to fine leveling.
330 lbs of leg breaking fat.
DDSM
A hand at the top, loosen the clamps, set the foot as deep as possible. Don't forget to tighten the clamps before letting go.
It doesn't matter as long as you don't take any longer than 15 seconds to setup and level it.
Clint G., post: 360456, member: 11362 wrote: I should note that my boss has 25+ years in the field and that my setups have yielded tight closures
Both of those are pretty darn good arguments. There are other tricks when setting up in mud, or in snow on a sunny snow-melting day, etc. not to mention the concern of releasing bowing pressure on the legs. But it sounds like I'd go with the boss.
So welcome to the board.
Yeah, only he ain't the one running the gun.
When you are running the gun with good closures, nobody should have to tell you anything about how you are doing the job, especially to whine or complain about how deep the tripod feet go into the ground.
[sarcasm]Some people just have to b!@*h[/sarcasm]
Dan B. Robison, post: 360463, member: 34 wrote: Too much pressure on the foot shoe causes the legs to bow out. Loosen the thumb screws to release the leg tension prior to fine leveling.
330 lbs of leg breaking fat.
DDSM
Mash 'em in as far as possible - any tension created will be relieved when you adjusting the legs.
AND what RPlumb said...
Roadhand, post: 360467, member: 61 wrote: It doesn't matter as long as you don't take any longer than 15 seconds to setup and level it.
I'm screwed then, I take significantly longer than that.
I push along the direction of the leg as best I can, and sink it as far in as possible. Loosen the thumb screws prior to pushing it in.
One more tip: get the legs leveled and centered over the point with your tribrach, and THEN add the instrument.
It is easier that way and saves a lot of jostling and jolting of the delicate instrument.
Ken
Ken Salzmann, post: 360477, member: 398 wrote: One more tip: get the legs leveled and centered over the point with your tribrach, and THEN add the instrument.
Certainly, if you have that option. I posted last year about an archaeology project where I was very frustrated because their instrument had a self-contained tribrach and the professor wouldn't let them adjust the legs after mounting the instrument. I do it all the time, with a good grip to make sure the instrument won't get jarred.
I suppose everyone on here knows the procedure for rough positioning, which is so counter-intuitive until you think deeply about it. You use the leveling screws to point the optical plummet at the point, adjust the legs to level the tribrach, repeat if necessary, and then when you're close to positioned and leveled you switch to the intuitive method where you fine position by sliding the tribrach on the tripod head and leveling it with the tribrach screws.
I was amazed how much faster setup was after I figured out what the book sorta told me but I missed because it didn't highlight enough to make me think it through. When you change the length of the tripod legs, the head moves close enough to a circular arc centered near the point, and that makes the method work.
Bill93, post: 360479, member: 87 wrote: Certainly, if you have that option. I posted last year about an archaeology project where I was very frustrated because their instrument had a self-contained tribrach and the professor wouldn't let them adjust the legs after mounting the instrument. I do it all the time, with a good grip to make sure the instrument won't get jarred.
I suppose everyone on here knows the procedure for rough positioning, which is so counter-intuitive until you think deeply about it. You use the leveling screws to point the optical plummet at the point, adjust the legs to level the tribrach, repeat if necessary, and then when you're close to positioned and leveled you switch to the intuitive method where you fine position by sliding the tribrach on the tripod head and leveling it with the tribrach screws.
I was amazed how much faster setup was after I figured out what the book sorta told me but I missed because it didn't highlight enough to make me think it through. When you change the length of the tripod legs, the head moves close enough to a circular arc centered near the point, and that makes the method work.
Yep. The only thing I'd add to that is that I generally push in the leg farther from me, hold the two toward me, and look through the optical plummet and move the location of the legs I'm holding until I can see the point through the optical plummet before getting started with the rough leveling procedure described above.
That standing on the kleat is not a good practice. The applying your weight with the direction of travel of the leg is correct, standing on it doesn't add enough stability to justify that. You're going to need to depend on that tripod for your job, take care of it.
Here's a little trick shown to me a little too long ago. When you're setting up over a point, grip the tripod by two legs with the third resting on the ground about where you think it should be and put your foot up against the point you want to center on. Then sight through the optical plummet while swinging the setup around by the two legs until you find your foot (not too hard if you have giant clown feet like me 🙂 and once you find your foot, follow it down to your toe and on to the point. BAM! Carefully drop those two legs with the plummet on target. You can then loosen the legs and drive them in until they feel secure and level up by adjusting the legs with an eye on the bubble. Every setup is a little different, if it's solid, it's good. If it's all wobbly, it's not, so just trust your good judgment. All Most good surveyors learn to listen politely, and then turn around and do what they think is right. ;-):whistle:
I also put my weight on and put them in as far as they go. Not only flush if they go, but if it's soft I might even then put my toe on the pad and try to sink it even more than flush into the ground.
You have to get it firm. Especially if your standing by the instrument. Otherwise it will end up sinking and go off level which will in least be a pain and need to be reset. At worst you will have some wonky measurements
Thanks all for the replies.
I asked the guy I was helping what the logic behind setting just the points was and he said, "If you don't, the tripod will sink under the weight of the instrument." That doesn't make too much sense to me since sinking the tips will give more surface area and provide a more stable platform. At least in my mind. But hey, I'm no physicist so...
Anyway, glad to hear the old man knows something. kidding*
Thank you again for taking the time to answer.
Clint
Roadhand, post: 360467, member: 61 wrote: It doesn't matter as long as you don't take any longer than 15 seconds to setup and level it.
You're too slow.
Clint G., post: 360503, member: 11362 wrote: Thanks all for the replies.
I asked the guy I was helping what the logic behind setting just the points was and he said, "If you don't, the tripod will sink under the weight of the instrument." That doesn't make too much sense to me since sinking the tips will give more surface area and provide a more stable platform. At least in my mind. But hey, I'm no physicist so...Anyway, glad to hear the old man knows something. kidding*
Thank you again for taking the time to answer.
Clint
I use a tribrach to get the tripod setup, then remove the tribrach and put the instrument on there. No jarring the instrument.
Yes, sink the feet as far as they go.
Spend a little extra time fine tuning so the instrument is centered as nearly as possible on the tripod head. Definitely no cliff hangers allowed.
Never ever carry the instrument attached to the tripod.
