Optical targets are attached to a tribrach by an adapter that looks like a black hockey puck with three feet at bottom and central 5/8Û X 11 threads on top. But thereÛªs another type that has a built in optical (or nowadays laser) plummet and a level vial usually marked 60Û/2mm. Of course theyÛªll only work with non-optical plummet tribrachs or the Topcon brachs that allow seeing both ways. They can be had for $400+ or else $36+ from China.
My question: does anybody use these? If you are familiar with them, what do you know about the difference between spending $400 vs $36? I like the idea of being able to set up on a point with the same level precision as when the instrument occupies the point rather than being limited to the 8 minute circular vials on OP-tribrachs. The ability to verify by rotating the OP adapter is another plus.
I have both.
The ones from China will work and need more attention to keeping calibrated and are less durable than sokkia, wild or topcon original OEM equipment.
I started out with a lower budget and purchased the ones from China be cause I could get a complete tripod, tribrach, donut and prism for about $100.
They have since been replaced by quality equipment that I've placed more confidence in.
Being adept in using your equipment, no matter the quality, will be alloy the work to be acceptable no matter the cost.
A Harris, post: 345653, member: 81 wrote: I have both.
The ones from China will work and need more attention to keeping calibrated and are less durable than sokkia, wild or topcon original OEM equipment.
I started out with a lower budget and purchased the ones from China be cause I could get a complete tripod, tribrach, donut and prism for about $100.
They have since been replaced by quality equipment that I've placed more confidence in.
Being adept in using your equipment, no matter the quality, will be alloy the work to be acceptable no matter the cost.
Thank you for your reply. I see no differences in specifications that correlate with the price differences. How do you judge differences that lead you to expect better durability and calibration stability?
Any of the cheap gear from China that I have needs constant adjustment and are poorly made. For example poor clarity of optical plummet, difficult to eliminate parallax, horizontal bubble constantly going out of adjustment etc etc, all in all just not good quality. If your budget only allows for the cheap ones fair enough you can make them work, it's just the amount of time you spend adjusting them will add up in $ hours.
If you can stretch definitely try and get the better quality, Topcon, Seco, Leica etc.
Total survey is correct. The cheap tools last months to years and the good tools last careers.
The cheap tools lasted long enough for me to be able to be able to purchase the better equipment.
They are also more expendable to place on the line and in rough handling and/or dangerous conditions like alone and surrounded by cones near traffic.
Keep a eye on EBay, the good tools rarely make it to the auction block.
Surveyors keep them until they absolutely don't need them any more.
It depends on your instrument. If you're using an older instrument, or one that still uses locking tangent screws, then almost any tribrach will do. Since you'll be able to check the level and target with the adapter, turning multiple directions, you'll know if/when the tribrach needs adjusting.
Total stations with non-locking/friction screws seem to put more lateral force, and I've found that cheap tribrachs don't handle this well.
I had a good spectra tribrach for my robot. After 2.5 years the tribrach busted while carrying and my robot met it's doom on a flagstone patio.
Prolly had to do with me carrying over the shoulder more than anything else.
But this just does show that if it took 2.5 years for a $400 tribrach to bust, how long would had a $36 tribrach taken for my robot to meet its demise
Excuse me, but I have never heard of a tribrach breaking without extreme abuse.
Paul in PA
Ya it was the tribrachs faulto.O
Rich., post: 346388, member: 10450 wrote: I had a good spectra tribrach for my robot. After 2.5 years the tribrach busted while carrying and my robot met it's doom on a flagstone patio.
Prolly had to do with me carrying over the shoulder more than anything else.
But this just does show that if it took 2.5 years for a $400 tribrach to bust, how long would had a $36 tribrach taken for my robot to meet its demise
How did that happen? It actually broke off all the way and released the gun from the tripod? Never heard of that before and hope it never happens again....
Not over the shoulder with the instrument horizontal?
Yep. Half the tribrach still on the gun, half still on the tripod.
Was a sad day. But not the tribrach fault at all. It was showing signs of being loose
squowse, post: 346392, member: 7109 wrote: Not over the shoulder with the instrument horizontal?
Guilty. :-/
Paul in PA, post: 346389, member: 236 wrote: Excuse me, but I have never heard of a tribrach breaking without extreme abuse.
Paul in PA
You must be using the good ones then 🙂
I'll could send you a couple of ours that have failure through just plain regular (ab)use.
We find the current Trimble branded tribrachs to be poor quality - and we are now buying them from Leica - the only green in our otherwise yellow kit
guessing you won't be doing that again..
i hate seeing it, even with a level. drove past a couple of council surveyors doing it the other morning with a TCA1105
Once again...guilty! :'(
It's just so much faster and what I grew up on. What's the other option? Breaking down each setup and carrying in case? Sometimes I have 6 shot setups. I would be spending more time taking apart the gear each time. Maybe I should look into other ways to carry :-/
Once you start putting the instrument in the box between setups for carry, the change will become normal in no time.
Getting a topload Seco backpack changed things for the better.
Cutout a custom foam wrapper for a better fit.
I grew up on it as well. It was never a problem for my employer at the time really and was the culture there.
When I bought and paid for my own instrument that changed everything. Now it always comes off the tripod, 99% of time into the case sometimes carried in hand. Very, very rarely would it be carried on the tripod and that would only be if it was being moved a few metres. It's second nature to put in the case now and would feel like driving without a seat belt if I didn't.
Jim,
I have 2 Topcon tribrachs wih see though plumets, and a Zeiss with optical plummet that get used when jumping tribrachs on a traverse. I have several cheaper tribrachs with optical plummets that might get used when I have more GPS receivers out than my 4 fixed height rods with three legged bipods. I can and have adjusted the Topcons in the field when they get out of range, on the order of years apart. They probably get more abuse traveling around in the prism bags than in the field.
The few times I move my EDM on the tripod is plumb in a parking lot or yard and never more than 100' to a minor side traverse point. It makes no sense to not put it in the box, because that is where my data collector, spare batteries, field book, etc. are and I need them all at the next setup.
Rich,
"Yep. Half the tribrach still on the gun, half still on the tripod.
Was a sad day. But not the tribrach fault at all. It was showing signs of being loose"
Showing signs of being loose ... and you used it anyway?
Paul in PA
Maybe Ill give it a go. My focus came in a top loading case with backpack straps