I'm rounding out a recently acquired Trimble robot (a current model sps930 - S6-S8 equivalent - 1" - running access on tsc3) with accompanying traverse kits.
Trimble has little available information about their kit (#slsu-s2009) prism, carrier, tribrach); at first I didn't think they even offered one. My Trimble dealer and others that I've contacted don't seem to have been supplied with more info than one could scrap up on the internet, or that can be found on one page in the total station manuals. On the other hand, Leica has an abundance of information on their components, across price point/spec model lines. You can choose what you want and know what you're getting down to nitty details.
Pricing the Trimble kit with Leica's high quality line is pretty much the same. When used in "leapfrogging" [sic] traverses (leaving tripods and tribrachs on controls, and shifting the total station and prisms), and knowing the correct horizontal prism offsets, I think this leaves matching vertical offsets as the open-ended question.
There are a few diagrams that illustrate what can be found on the Trimble end, that I'd attach once I have a few more posts and the forum lets me. In the meantime, does any one have any more information on the Trimble traverse kits? Or alternately, does anyone have insight into running a Trimble station on Leica tribrachs and accompanying traverse setups?
-Mike
I was told a while back that the verticle offsets are the same (96mm?). Never verified it, though. I went through this exact same saga a couple of years ago. The sad truth is that it seems Trimble isn't interested in trying to satisfy the little bit of need for certified accuracy components.
There is a Seco trav kit that should work, but it's quality is suspect. If you go with Leica be sure to study their absolute prism constant information that will be included.
We eventually bought a Trimble traverse kit to use with our S6 and VX, but it just didn't compare in quality vs. the old Leica set I had.
In casual conversation someone mentioned that their new Trimble gear does not fit in Leica tribrachs, not something I have verified.
party chef, post: 363246, member: 98 wrote: In casual conversation someone mentioned that their new Trimble gear does not fit in Leica tribrachs,
They work fine for us (S6 and S8).
The Leica tribrachs are much better quality than the junk Trimble supply
Thanks for the comments -
Plumb Bill - what you wrote mirrors my thoughts. And it seems a shame to effectively handicap an instrument with lesser quality kits, especially when the Trimble and Leica versions are the same $. Interesting about your experience w/ each product.
Party Chef - I was worried I'd be dead in the water from the gate if they just don't fit, so this is definitely important. I wonder if there have been changes in Trimble's station bases/mounting pegs over the years or across models that complicates it further.
Jim, do you know what year your S6 and S8's are manufactured? The dealers should know if Trimble ever changed the station bases, and that could help this part of the problem.
Do you run the Leica tribrachs across the station, foresight, and backsight, and what are you using on top of the tribrachs for the reflector setup?
Mike J., post: 363255, member: 11452 wrote: Jim, do you know what year your S6 and S8's are manufactured? The dealers should know if Trimble ever changed the station bases, and that could help this part of the problem.
Do you run the Leica tribrachs across the station, foresight, and backsight, and what are you using on top of the tribrachs for the reflector setup?
Our gear is all pretty new - within the last 3 or 4 years.
We still have some Trimble tribrachs - mostly those that came with the instruments - we no longer purchase them. Most of the traversing will be done with a mix of them.
On the tribrachs we have an adapter then use a trimble target - they look like this but are Trimble branded.
Thanks, Jim.
This is a tangent of my own question - I understand the utility of having an instrument and its targets at the same vertical offset, but more so as it relates to simpler instruments, like levels, that don't have software and can't account for so many things. And that weren't as capable as more modern and sophisticated equipment, nor with respect to my earlier equipment, as accurate.
In practice, when traversing with these low second transits, and removing stations/targets from their tribrachs and shifting them down the line, how much can you count that the optical heights will be consistent, anyway? Do you re-measure height at each control as a check, or as a necessity to re-enter your station height?
We measure HI and HT(forward) at each setup
Another user of Trimble equipment with Leica tribrachs here. Can verify that the newest Trimble equipment still fits in the Lecia tribrachs.
The instrument/target heights are the same Leica/trimble. 196mm seems to be the measurement quoted but I am not sure where this is measured from.
In practice I have found 2-3mm discrepancies on the traverse kits of both instruments. The only way I know to get it exactly right is to make your own prism stems. these can be fettled to the exact right height by making reverse observations, swapping instrument and prism. have got it down to 0.1mm (see attached).
Still pondering a way to check the centring with a similar method not relying on the optical plummets
A little insight on the 196...
196 mm was the height of the Wild T-2. Then they made Wild glass targets at the same height. Zeiss made the S10 the same, and then Trimble with the S series. We purchased an adapter for our 100 mm scanner sphere targets that also make them 196 mm (all of this is above the tribrach plate). Most of our prisms are seco mini prisms, which, with a hockey puck adapter, are 0.083 m above the plate. So, that is the only difference in our work, but it is a constant difference. The only prisms that are different are a few larger ones that we use for longer shots, but there aren't that many long shots anymore.
We have a rotatable optical plummet that has a height mark that is the same as the bottom mark on the S6. And, none of our tribrachs have optical plummets (at least not the ones we usually use). So, we always setup the tripod with either the S6 (which has a built in rotatable optical plummet) or the separate rotatable optical plummet. The measured HI will be the same. It is not necessary to measure any of the prism HT's (which are not able to be measured exactly) nor the scanner sphere HT's. I know that if I add 0.042 m to the measured HI's above, I will get the HT of the prism (for any normal height between 0.75 and 2.1 meters, not likely to have any setups outside of that range).
I think our old scanner (Trimble GX) was also 0.196, but the current scanner we use, Trimble TX8, is not, it is 265 mm.
The whole point of all of the above is to measure as few HI's as possible to avoid errors and the slight uncertainty in measuring to prisms. This really makes trig elevations quite good carried through a traverse. Knowing all of these relationships I can make sure in the office that all is correct.
Also, I take issue with the statement that the trimble tribrachs (Hungarian) are junk. That is all we use (without optical plummets), and I have been very happy with them. Although I will say that is the only thing that broke when the tripod with tribrach and prism was picked up in a sudden storm and hurled off of a wall and across a lock chamber to slam in to the opposite wall and then fall 30 feet down to the bottom of the lock chamber (rocks). The trimax tripod was fine, as was the seco prism.
squowse wrote
"In practice I have found 2-3mm discrepancies on the traverse kits of both instruments. The only way I know to get it exactly right is to make your own prism stems. these can be fettled to the exact right height by making reverse observations, swapping instrument and prism. have got it down to 0.1mm (see attached)."
You can adjust the prism height on that adapter by loosening the screws on either side of the small window with numbers on the side of the adapter.
There is about a 18 mm adjustment range.
Thank you everyone for the help and input. I'll call around during the week to put together an order and try it out. Honestly, I think finding someone informed at a bigger internet dealer (that sells both leica and seco branded trimble kits) might verify all this more easily than a Trimble dealer.
Here's what I've found in ways of manuals & illustrations:
Leica's pretty clear, 196mm from center trunnion axis to top plate of tribrach.
Trimble has their (arbitrary?) measurement from trunnion axis to a "special" reference point. No info I could find to top plate of tribrach.
And it seems both offer their own ways of measuring instrument/prism height; Leica with their special measuring tape and add-on tape holders, and Trimble with their "bottom mark" on the total station and a flip-out reference on their own branded prism carrier. Seems Leica's tape version would factor in their vertical offset and then work for use on any software platform. Trimble's "bottom mark" would only work with Trimble's software, without an added correction.
Also attached info on breaking down Leica's prism constants for use on non-Leica software.
However, I'd add... Eyeballing it with a ruler and my sps930, the center of optics to top plate of tribrach looks very close to 196mm.
Is there a type of adopted standard for instrument/carrier mounts and tribrachs? Seems there needs to be considering that mixing brands has worked for others, and it appears the tribrach's notch for the comm ports seem to be in the same place on various brands.
I use Leica prisms with an S6. Leica zero offset prism I use -34.4mm offset in Access. Leica 360 prism I use -11.3mm.
Those intent on clicking on Mike J.'s 3 pictures probably should get the small children out of the room first.
Mike J., post: 363347, member: 11452 wrote: 196mm from center trunnion axis to top plate of tribrach.
I don't have a tribrach handy, but if memory serves the measurement is actually to the 3 contact points that protrude above the top plate, rather than to the top plate itself. The difference is probably only a mm or so.
Target height will actually vary a little depending where on their threads the footscrews are currently sitting
jim.cox, post: 363388, member: 93 wrote: Target height will actually vary a little depending where on their threads the footscrews are currently sitting
Not so, unless you're measuring to the wrong place. The 196 mm is constant.
Jim Frame, post: 363389, member: 10 wrote: Not so, unless you're measuring to the wrong place. The 196 mm is constant.
I disagree - there is about a 7mm range of movement on the Tribrach I just measured.
Your 196 might be constant relative to the top of the tribrach - but height above the top of the tripod, or to the ground mark, can vary (just a little)
