Hi guys
Have been out today with a Trimble S7?ÿ3 second and Leica GPR121 prisms to setup some control stations.
The horizontal face left and face rights readings are out by between 5 to 12 seconds. The verticals are out by 6 to 8 seconds.
The traverse accuracy meets the specification fine and I expect the readings to be out by a few seconds?ÿbut I'd like to know how much of a difference between face left and face right readings is acceptable? The machine is a 3 second.
The S7 was set to autolock and I noticed that on a few readings it was a couple of mm of the centre of the prism. I guess I could improve things by taking the autolock off.
Best regards, John
?ÿ
How well does a Trimble S7 and a Leica prism play together? Is the Total station set to the same offset as the prism? How do the distance measure vs recorded?
they should work fine together. I set the offset in the S7 to -34.4mm as advised by Leica for this prism.?ÿ
John G.?ÿ?ÿ your spread between face left and face right of 5 to 12 sec. for horiz. and 6 to 8 sec. for vert. are good
as long as they remain near constant. They can change with different weather conditions (overcast or sunny) but should
be about the same. Now to answer your real question; using the old optical instruments the book used to say you could
go to 1 minute (Wild T2). If it is kept small then it is easy to mean your D & R if you do it by hand and your brain as opposed
to a data collector.
?ÿ
JOHN NOLTON
?ÿ
... using the old optical instruments the book used to say you could
go to 1 minute (Wild T2). If it is kept small then it is easy to mean your D & R if you do it by hand and your brain as opposed
to a data collector.
?ÿ
JOHN NOLTON
?ÿ
1 minute??ÿ That seems awfully high, unless I am misunderstanding your post.?ÿ It should be within seconds on the Wild T-2's.?ÿ I don't remember my differences, but it was never out a minute.
My T2 rolled down a mountain (in the bullet case) and hit a tree. I had to finish some work that day (hours away from the office), and the splits were out by 4 minutes if I remember, I think it was the vertical. All of the data was OK, we were turning 8 sets, it means out D+R. Took it in to the shop and there was nothing wrong with it other than it needed an adjustment. That was about 35 years ago. I am imagine if I rolled an electronic instrument down a mountain and against a tree that would be the end of that.?ÿ?ÿ
?ÿ
There are calibration routines you can run on the S7 to adjust out (electronically) the differences and also get it to point directly at the center of the prism. That is important if you are mixing autolock and manual pointings. However, if it appears to be not autolocking on the center it is probably OK because it will be consistent.?ÿ
"The horizontal face left and face rights readings are out by between 5 to 12 seconds. The verticals are out by 6 to 8 seconds."
?ÿ
This is that traverse you set out the other day with 45 M legs ? ?ÿ5"/2 @ that distance looks like you are doing good work
Tom Adams, the manual for the Wild T2 stated that you could let the Collimation Error (H&V) get as large as 1 minute
before adjustment was needed. As I said above it is always nice to keep them small so you can mean them quick and easy.
?ÿ
JOHN NOLTON
?ÿ
PS?ÿ none of my T2 were out more than 5 to 7 seconds if that.
Tom Adams, the manual for the Wild T2 stated that you could let the Collimation Error (H&V) get as large as 1 minute
before adjustment was needed. As I said above it is always nice to keep them small so you can mean them quick and easy.
?ÿ
JOHN NOLTON
?ÿ
PS?ÿ none of my T2 were out more than 5 to 7 seconds if that.
John:
?ÿ
I remember checking my T2 collimation several years ago and found it had a slight eror. But according to the manual, it stated to leave it alone and not to do any adjusting as it was in the tolerance of the the instrument and would do more harm than good than making an adjustment to eliminate the error. So did any line projecting by the old "double centering" method.
?ÿ?ÿ
So John based on the data I put in the opening post should I run the calibration routine or not. I did notice that its a couple of mm of the centre of the prism
Regards, John G
Old rule of thumb was twice the direct read.?ÿ +- 3" gun I would want 12" or better, anything greater I would turn another angle or more until I get that. I also still do exterior angles if applicable.
The nice thing about the electronic instruments is that a lot of these "errors" can be corrected electronically, often no mechanical adjustment is needed. Same with a digital level, you can run a collimation check and have the results automatically applied to all of the readings. Still, I prefer to do everything face left and face right (i.e. direct/reverse). Everything except most topo shots, they usually do not warrant the extra observation. But on dam deformations EVERYTHING is observed in both faces, and we vary the number of sets depending on what is being shot. Setup points of course get more rounds than an observed station.?ÿ
Tom Adams, the manual for the Wild T2 stated that you could let the Collimation Error (H&V) get as large as 1 minute
before adjustment was needed. As I said above it is always nice to keep them small so you can mean them quick and easy.
?ÿ
JOHN NOLTON
?ÿ
PS?ÿ none of my T2 were out more than 5 to 7 seconds if that.
?ÿ
Thanks John, I did misunderstand your post earlier.
Charles L. Dowdell?ÿ?ÿ?ÿ Your memory is still good and what you posted is right on. For what John Gaddass is doing
NO adjustment (calibration) of his instrument is required.
Hope all is well with you and have a great Xmas.
?ÿ
JOHN NOLTON
John:
?ÿ
Everything is is about the same as when we last visited. Bev is still hanging in there. Have wondered if you are still getting along okay since we haven't had?ÿ any contact for a while. I have so many "roundtoit" things to do and can't seem to pick which one to start on first. :>) A Merry Christmas and Happy New Year to your house.
?ÿ
Charles L.
thanks for the replies guys.
To summerize is the acceptable difference 4 times the accuracy of your machine? Mine's a 3 second so a difference between face left and right of 12 or less is okay. Anything more than that means do a field calibration.
Cheers, John