I like the versatility of the topcon combination optical plummet and the see-through ability to be able to use the guns optical plummet as well as a rotating optical plummet.?ÿ You can do a quick lower-precision traverse and/or get the more precision setups for higher-precision work.
Hi Conrad. Okay, what I should have written was that in my opinion you can't check a tribrach with optical plummet easily in the field. I've tried it by tracing round it and have never got on with it or felt it was very accurate.
I think using a carrier with a rotating optical plummet is easier and more accurate - in my opinion.
If you do it enough, and are good at it, you will find that it is very accurate, and you can do it quickly.?ÿ It's easy to scoff or write something off when you're not familiar with it.
"I like the versatility of the topcon combination optical plummet and the see-through ability to be able to use the guns optical plummet as well as a rotating optical plummet.?ÿ You can do a quick lower-precision traverse and/or get the more precision setups for higher-precision work."
I agree with Tom, the best of both worlds.
Loyal
I just received a new SX10, and got to use it last week. It has an optical plummet on the tribrach and can also use the on board video optical plummet which can be viewed on the data collector (and is, of course, rotatable). And it takes and stores an image of the view through the optical plummet as part of the station setup. I can check the level and centering from the remote end at any time.?ÿ
Now if it only had an EDM in the plummet for the HI....
?ÿ
LOL that one was a bad choice we weren't centered on the nail!!
I've seem many like that and the error was usually due to not having the eyepiece properly focused on the nail.
Also with the optical plummet in the tribrach, you can up on soft ground without the total station in place avoiding jolts to the instrument. Then once centred and level by the tribrach put on the total station and fine level.
Hi Conrad. Okay, what I should have written was that in my opinion you can't check a tribrach with optical plummet easily in the field. I've tried it by tracing round it and have never got on with it or felt it was very accurate.
I think using a carrier with a rotating optical plummet is easier and more accurate - in my opinion.
Hi fobos8,
How about the simple plumb bob (or plumb Barbara) method? It??s pretty easy.
My own method for checking goes straight to the prism and compares its position in space with the target on the ground, as best I can measure it. These two positions can be compared, made coincident, and the bubble and plummet are made to conform. This can be done (quickly enough) in the field and can be as accurate as you??d need. Granted it involves the total station, but I??ll involve it because it quantifies my adjustment.
Perhaps you can conjure up a novel method for checking fixed plummets if the pencil tracing method doesn??t agree with you.
I know I??m going off topic a little bit now fobos8, but the carrier that John H showed looks very much like the GeoDesy-made kit that is sold as leica kit as well. In leica colours it has a stated prism centring accuracy of 1mm, I??m guessing due to the tolerances the sliding parts can be machined and assembled to. add to that any play in screwing on a 5/8 mounted prism holder and it??s beyond where I am content. In my very humble opinion the rotating carriers, are not clearly the ducks-guts (though the leica precision ones are good). I??ll take a grt144 and tribrach mounted optical plummet myself.
John H, I mentioned your kit in my post but please don??t take any of that as a knock on your kit or methods
these Leica carriers rotate and look quiet good
these Leica carriers rotate and look quiet good
They are the ones I was referring to. Stated Prism centring accuracy of 1mm. I have not tested these despite owning one, and having a couple at work.?ÿ
they have the same accuracy as the GRT144 stubby carrier
I recently went through this upgrade, and ended up with GZR3 carriers for my personal use. Pricey, but it was worth it for me.
?ÿ
The GZR103 carriers that are linked above are indeed high quality, but it drives me nuts that the image is reversed when centering over a station...which is why I opted for the GZR3 carriers. I just can't live like that.
I was surprised to learn that the GZR3 is more expensive than the SNLL121 laser carrier.?ÿ The former does have a higher plummet accuracy specification, though -- 0.5 mm versus 1.0 mm.?ÿ
I keep an SNLL121 around for transferring below-grade marks to surface offsets.?ÿ The laser makes it an easy one-man operation.
I also have a GZR3 with a broken bubble that I've been meaning to fix for the last decade or so.?ÿ I had no idea it was that expensive!
The tripod for my base GPS looks just like that. It takes all of 20 seconds or so to check the optical plummet, I do it most days I'm in the field, we also mark the last time the plummet was in for adjustment, I think mine is marked as 2012 maybe, so five years without any issue.