This is my first post on the board but have been reading for years. I have an issue that is absolutely driving me crazy and was wondering if anyone else has had this problem or maybe knows something I don't know about identifying what the problem might be.
My average traverse closure using a new S6 has consistently been in the 1:20,000 to 1:30,000 range. The best closure I got was 1:50000 and have done about a dozen traverse loops with it. The instrument is less than a year old and I collimate and run through the adjustment routines before each traverse loop. Each time I check and calibrate my tribrachs and use professional grade prisms on a -30mm offset. I turn 3 sets of rounds using autolock at each station and the residuals are consistently negligible.
Before buying the S6 I used a different instrument (a cheap Sokkia 3" gun) and was routinely getting between 1:50000 to 1:100000 closures depending on terrain and weather conditions.
Has anyone else had issues with the S6? Is there a possible setting I need to fix? Do I need to send this thing back to Trimble and get a new one? Thanks in advance, any help will be greatly appreciated.
-Mike
What sort of condition are your tribrachs and tripods in? The tribrachs can be in good adjustment but if the contact points are worn and the instrument isn't seating on them well it can blow up your precision. And the S6 is a rather heavy instrument, if the tripod isn't tight it can wobble.
If you have a small loop with short legs in your traverse then you will not be able to achieve greater closures, the math precludes it as a possibility. I am assuming there is not other problem.
0.1':200'=2,000
0.1':2000'=20,000o 200,000
The tribrachs are fairly new and seem to be seated firmly. But you do bring up a good point about the weight of the S6. I am generally setting up on asphalt and rarely in the dirt so I cant stomp the legs in the ground. Is it possible that the robotics of the instrument are torqueing the tripod and causing some error?
As far as lengths most were between 2000 - 5000 feet. Frontsite and backsite distances were as balanced as possible considering site conditions.
on hot days the lege will settle on warm days the legs will settle on payment the legs will settle
Tripod type with a robot is very important. Not sure if you were using a robot before, but if you are now using a robot on a standard tripod you may very well run into the kind of errors you are seeing.
My thought as well. Maybe check it against a base line. Rule that out.
I'm using new Crane Tri-Max tripods that the Trimble rep sold me with the S6. There doesn't appear to be any movement or vibrations and the guns is staying in level. Not saying that there couldn't be some movement but I would not think it is substantial. That is kind of what is blowing my mind. The tripods, tribrachs and glass are all in great working order from what I can tell. Nothing we are using is more that 1 year old.
Try some wood under the legs on the asphalt; as stated above, the legs sink, and it does not have to be too hot for this to happen. I use a 6 inch section of hardwood lath. Set the legs hard in the wood, it pushes onto the pavement and your set-up should hold pretty well.
The baseline suggestion is a good one too; something could be out of whack.
Good luck.
Ken
Check the range on the autolock. You may be stretching it too far if you are going 5000'.
do your angles close reasonably well?
Just a few things off the top of my head:
- When you do the collimation adjustments, do you do them all? (HA/VA, trunnion, autolock)
- Are you sure you have the correct prism setup in your collector?
- Are you carefully aiming the prism toward the gun for each sighting?
> As far as lengths most were between 2000 - 5000 feet. Frontsite and backsite distances were as balanced as possible considering site conditions.
Those are some long shots for the S6 - I'm told. I got a couple of shots over 1000 feet and got a little scolding for stretching it out. They weren't traverse legs so it wasn't a big deal.
You didn't mention what prism you are using. I think that would make a difference as well. We had a 360 prism used for everything and it was suggested to me [from here on the board] to not use that for traverses.
However, I was only involved with a couple traverses using that gun. Usually, the boss would run the loop/loops over the/a weekend and send me and my partner out in the following week so all we had to do was occupy the points. We did have to re-turn a couple of legs on one job though. He never said how bad the closure was nor did he mention how much better we made it.
Are you collecting sets on your legs? My first experience on a robot turning sets left me with the impression that I don't trust robots to turn angles. They know how to do it mathematically (yeah, I can cheat and dial in a "better" angle as well). I was being given a lesson one morning on a Trimble robot turning sets and I stayed with the gun to see how it aimed. I watched front sight and back sight shots - ok, good.
Then it flopped for reverse shots. I jumped on the radio for them to hold so I could look and see what it was "seeing". Back sight shot - fine, keep going. It turned to the front sight and took a shot and they reported all good. I said to let me look at what it's looking at. At only a couple hundred feet it was easily looking 5 or so feet off horizontal. Vertical was pretty good best I could tell but it was obviously not even looking at the prism or anything reflective.
Thanks for the input. Just to be clear I meant a total traverse length of 4000 - 5000', most legs of the traverse were between 500-700'. I am using standard sokkia prisms with a target on -30mm offset. I ran the gun myself on most of these traverses and used Autolock. which looking through the gun, never is aimed at the center of the prism, and according to the S6 Manual, it shouldn't. I was very anal about looking through the scope to make sure I was locked on the prism and not something else each time. Also, when I was done turning sets, I checked the residuals and they were very low. I would think that an aiming error would show up here but I could be wrong.
As far as the adjustments, I do them in this order:
Compensator, horizontal collimation, trunnion collimation and then tracker collimation.
I'm using autolock on the entire traverse loop and all sets turned return very very low residuals (usually around 1")
I am confident with the prism setup at -30. Trimble access keeps it listed on the side of the screen and I have checked distances to my -30 offsets and my 360 prism and they match.
Another thing I forgot to mention, which adds to my confusion lol, is that each time I set a new point and move up, the backsite checks are almost flat each time. Which was making me think that the error was in the angles and not the distances... How can I check the horizontal circle of the gun??? I have never done that before.
What type of angular error do you get when you use N-2 x 180?
A Robot On It's Own Centers The Prism...
...because it has no other choice. It cannot find an optical target, precise or otherwise, so it accepts the strongest signal as the target point. In light of that you have to go out of your way to align the prism to the gun. It would be a good idea to get prisms that have the optical center actually on center. Most likely it will change your offset so you have to replace them all.
Some robots doing sets have the habit of always aiming where the first shot was and not recentering on the prism. What you get is a very tight looking set when in reality an honest spread of observations would have meaned out closer to the truth.
Technology is not always your friend.
You may be totally shocked if you look through the scope on a flopped shot.
Paul in PA
If I recall correctly, it was almost a minute on at least one occasion. Not very good at all. I will check a few of the others when I get back in the office tomorrow and get back to you with more specifics.
Generally with care, using a 3" gun, I expect an angular closure equal to the number of stations multiplied by 1.3 This is just a method I developed based on my experience/methods.
I would suggest running a practice traverse two different ways. First the way you have been doing it, then manually sighting and recording in a field book. This will help you isolate issues with software/firmware.
I would look at my angles first separately from my distance measurements. That is step 1. I like to skip the software and simply add up the interior angles.
> I'm using new Crane Tri-Max tripods...
Those should be good, as long as the legs are well seated, clamped, and properly tightened at the head. By that I mean that when you lift a leg so that it is suspended outward horizontally and you let it drop there is some resistance. It shouldn't just free fall. Not too tight either!
>.. There doesn't appear to be any movement or vibrations and the guns is staying in level. Not saying that there couldn't be some movement but I would not think it is substantial.
You wouldn't see it. Remember, you are taking a baseline that is, at most, a few inches long and projecting it out hundreds of feet. Microns matter.
