After calibrating my total station and storing the error in the instrument, I still notice that when I check the instrument for error I have 17" error on the vertical reading. That is when i sum the FL and FR readings. Is this proper? I though after calibration the instrument automatically applies these corrections to subsequent observations?
Its good to note that 17" was the vertical error during calibration that was saved in the instrument.
I am curious how often, if at all, members of this group have their TS and Tribrachs adjusted.
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Yearly at a minimum.?ÿ The calibration baseline is a nice idea, but a number of agencies (mostly mass transit related) I've worked with want to see current calibration certificates from a manufacturers service & testing center as a requirement to submit work plans for projects on their facilities?ÿ
I find and check into old traverse hubs and repeat setups so often to check that my equipment is producing the same results on a?ÿ regular basis.
When my instrument shows any sign of needing a new lube it gets sent in for a checkup and that depends upon how many times it is used each year, kinda like thread depth on your tires as to when they need replaced or wheel bearings need to be cleaned and packed.
I correct for temp/pressure 3 times a year.?ÿ
I run columnation checks at the same time.
Tribrachs are checked annually by tracing outlines and rotating..... and I inherited some beat to crap sokkia tribrachs, Which came tumbled together in cardboard box. Now in new padded bags, and require very little, if any adjustment.
Robot is sent in every 3 years.
Caveat: my checks are based upon usage, rather than intervals, as well as the level of work I perform. The robot is probably only used once a week on average, typically for topo work.
I double angles routinely and the "splits" tell me when I need to collimate. Which turns out to be much more than once a year. More like monthly. When I used Trimble that was plenty. With the Topcon I use now daily wouldn't be too much.
I correct for temp and pressure at every site, every day.?ÿ
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I like to have it done yearly; part of the reason for that is to be able to certify to clients that it was done within the previous year. If you calibrate your own tribrachs and field calibrate the instrument, there really isn't that much need to have them serviced unless you notice something is amiss. Unless the firm you're sending it to is an authorized and trained service center for the brand of equipment you own, they're not doing a whole lot more than you can easily do yourself. You have to have training and a lot of specialized testing equipment to do much more than a field calibration. As far as I know, there's still nowhere in the US that can service an SX-10, although I know that Trimble was working on getting Dayton up to speed on it.
To date, have a Leica robot that has not been to the shop in 4 years. My Sokkia went back two months ago, all was well, went to the local baseline and the Leica was within 0.003' on average, had some shots that were flat, others as much as .005' difference than the Sokkia. I've been adjusting my own tribrachs since the mid 1980's, is why God invented the hockey puck. Rods get checked about once a month, or if one gets dropped or blows over in the wind. I keep 3 rods I trust in the rotation, all carbon fiber. One still has dried concrete stuck to it from the construction layout days.?ÿ
I use Wild rotating optical plummets and only use tribrach that have an see thru bases.?ÿ
Essentially the tribrach is checked every setup. And adjusting a tribrack is easily done in the office, or in field.?ÿ
A very high accuracy baseline isn??t too hard to establish. No reason to not check every reflector and edm every 60 days.?ÿ
I take the MS50 in every couple of years, which I think is Leica's recommendation.?ÿ I have the instrument set to remind me every two weeks to run a field calibration.?ÿ I use a Leica tribrach without plummets combined with laser or optical plummet carriers that can be checked by simply rotating them.?ÿ I check the tribrach and carrier bubbles against the instruments digital bubble when I do the calibration.?ÿ Rods are checked monthly at least.?ÿ Atmospheric corrections are entered at each setup.?ÿ If conditions change change dramatically then I adjust the corrections.?ÿ These are simple and quick procedures that minimize the chance for systematic errors.?ÿ For my work product I prefer to fill my error budget with random errors.
By law, we have to go to a baseline once a year and keep records of the measurements on hand. Sending the instrument in to be calibrated does not satisfy the requirements based on how the law in NJ is written.
Massachusetts General Laws Chapter 97, Section 2 requires us to "...at least once in every year, adjust and verify his compass by the meridian line so established in the county in which his surveys are to be made..."
and Section 7 provides "A surveyor who violates the provisions of section two, if he has used his compass to measure an angle in surveying within the year preceding, shall be punished by a fine of ten dollars, to be divided between the complainant and the county. "
Section 3 is a little more up to date with technology.
do the bi-weekly calibration (several times) when reminded by the robot.
Set up two tripods. Put the instrument on one and a tribrach on the other. Then take all your prisms and put them on the tribrach one at a time, measuring the distance. Sometimes there is quite a bit of variation between identical prisms.
