I'm either dumb, or I'm out of this line of logic.
I'll drink to that
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I can only see the substantial increase in cost over inbuilt plummet tribrachs as off-putting otherwise better to level and to plumb.
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Same reason total stations come with a plate bubble (and the electric bubbles on more modern instruments) and some way to plum and rotate (optical or laser)
For years I've used Leica's TPS height meter (GHM007 w/GHT196) which clips onto the tribrach and give a direct measure-up the the center of the instrument/prism.?ÿ Apparently Leica's new instruments are coming out with the holly grail of laser plummets.?ÿ It will do the measure-up as well as center.?ÿ About time.?ÿ?ÿ
Eh, as my old man used to say, just one more thing to break down.
I never thought setting up an instrument or prism target and measuring up was all that difficult or time consuming that I'd need a better way to do it.?ÿ
One of the main advantages I see in having the plummet in the adaptor instead of the tribrach, especially a rotating one, and with a real level vial instead of only the bullseye level common to tribrachs, is that you should be able to have the tribrach well within tilt range of the instrument when you move the total station to the forward tribrach.?ÿ If you are relying on the tribrach bullseye level, you almost certainly will have to adjust the leveling of the tribrach, meaning you are no longer over the occupied point as precisely as you thought, meaning to level the instrument and re-center you are unavoidably introducing a bit of error into your traverse leg.
Incidentally, I just looked at Topcon's price sheet and they no longer list that adapter (S2 w/ OP and 40" vial) so I suppose they didn't sell many of them.?ÿ Price was about $660 for the adapter.?ÿ Plus another $350 or so for the standard tribrach, and another $$ for a prism.?ÿ Pretty soon, you're spending some real money.
Also, the Sokkia version of that adapter is better because the height is adjustable and the price is better, by a considerable margin.?ÿ The Sokkia version is still available and lists for $440.
When using forced centering, each time the TS moves up, if the tribrachs are not relevelled and recentered, ....
Stop right there. If you are recentering you are not forced centering. Period.
The End.
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Yep, I screwed that up. Meant to say, "when traversing". Didn't catch that until after the edit period was up.
On the subject of forced centering traverses - forced centering removes centering error from the overall traverse, but not from the individual stations.?ÿ So if the purpose of your traverse is to establish a string of control points for future use there is little to be gained by employing that strategy. But if your purpose is to, for example, traverse through the woods between 2 section corners, without having any ongoing use for intermediate traverse points, then forced centering is very appropriate. In theory, you wouldn't have to set hubs at any of the intermediate traverse points at all. Just traverse from tribrach to tribrach.?ÿ ?ÿ?ÿ
I always put something temporary down, just in case. A cross-head screw will do. Don't do that and you'll kick the leg and yourself!
i did say ??in theory?. To illustrate the point. In practice one would be foolish to not drop a nail or some such.