Optical plummet vs. laser plummet

Optical plummet

Optical plummet all the way.

I haven't used the laser plummet very much, but I just can't get the hang of it. I can also adjust the OP should need be. I'm not sure if that's possible with the LP.

Just my $0.02.

Carl

laser plummet all the time. I hate when I have to use an optical one!

A laser plummet reduces tribrach error, too. Well on my instrument it's built into the instrument not the tribrach..

For a 5600 you shouldn't cut corners on the tribrach; I'd get the best O/P tribrach Seco makes at minimum, and would probably even consider going with a high end Leica.

> Aloha,
> I am wondering which one do you prefer and why?
>
> I have Trimble 5603 TS. About to buy a replacement tribrach, thought ask here first for few thoughts. I used the $169 Laser tribrach--I purchase couple years ago (Made in China;-) I could not get the laser to be plum after fiddling around with it for more than 3 hours yesterday!
>
> There are so many options to pick from...
>
>> http://www.amazon.com/dp/B0098TLIY6/ref=wl_it_dp_o_pC_S_ttl?_encoding=UTF8&colid=DDIT353CAMVY&coliid=I3IL6OE1NCRQVH
>
>> http://www.ebay.com/itm/260330106675?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2649
>
> Of course there are whole bunch that below $50! Not sure if I should look even look into them?
>
> Btw, where would one use the tribrach without plummet?
>
> Thank you!

Check eBay for a Wild Heebrugg GDF6 Tribrach.

DDSM

The laser is tough to see in the sunlight, but is a dead ringer over the optical. When they don't coincide, it's the quickest and easiest way to figure out that the gun needs colminating.

I have always used optical.

I am very satisfied with the black tribrac that came with the Trimble 5600.

Our remaining tribracs are Wild brand. In fact just today, I had to do a minor repair to the eyepiece - tighten the set screws. It wouldn't focus. I like those kind of repairs.

Some of the older transits had the optical plummet built into the instrument, thus no need for one in the tribrac. I'm thinking Nikon..?

I think some of the total stations may even have a laser built in that shines through a hole in the tribrac.

I have a Leica TCRA1102 with a laser plummet. For most applications I'd prefer an optical, as I find it hard to tell if the laser dot is centered on a dimple -- which reflects the laser light around, diffusing the visible pattern -- without getting down and holding a white card on the mark. (I hold the white card down, mentally record the dot position, then slide the card out of the way to reveal the dimple and compare with my retained image. It sounds more complicated than it is.)

For marks down in a hole the laser is generally better.

> For marks down in a hole the laser is generally better.

That is what the mirror on your compass is for.

I work with a guy that also uses the lid to his chew can.

The last time I purchased Tribrachs, I managed to get some Wild GDF22 Optical Plumb Tribrachs for $72.37. These are the best Tribrachs I have used except for the Wild GDF6 that DDSM recomends. These have better optics than the old GDF6. You have a high percision instrument, don't put it on a cheap tribarch or Tripod. That defeats the perpose of the high percision total station.

> I am very satisfied with the black tribrac that came with the Trimble 5600.

I find the black Trimble tribrach's to be very light weight and flimsy.

Also the coasting on them doesnt stand the weather well, they oxydize very quickly.

I much prefer those from Leica - and they cost about the same.

I see no advantage to a laser plummet - optical does not need batteries

Or a put a tic-tac (white candy) on the mark

Carry a stick of chalk in your gear for brightening up the end of a rod in a hole.

> Carry a stick of chalk in your gear for brightening up the end of a rod in a hole.

Yes, that's exactly what I do. I add punchmarks to iron rods and spikes to use as reproducible centers for the markers. A swipe with a piece of chalk will whiten the dimple made by the punch to make the punchmark stand out quite well for an optical plummet. Chalk is a useful thing one would want to have on his or her person in the field for a number of other purposes.

Aloha, THANK YOU SO MUCH for all the input. Now I have a better sense of what to buy. DDSM I am watching the one on ebay!:-)

If you want to run "tall stakes" you have to have a laser plummet. That is tall sticks, driven into ground, with a small finish nail on top, and reflector tape, and survey flagging behind it.

You cannot focus an optical plumet on something 2" below the Bell Housing. The Bell Housing is the part of the tripod, that you rotate, to screw the 5/8"x11 threads into the bottom of the survey inst.

Nate

> If you want to run "tall stakes" you have to have a laser plummet. That is tall sticks, driven into ground, with a small finish nail on top, and reflector tape, and survey flagging behind it.
>
> You cannot focus an optical plumet on something 2" below the Bell Housing. The Bell Housing is the part of the tripod, that you rotate, to screw the 5/8"x11 threads into the bottom of the survey inst.
>
> Nate

Aloha, Nate:
Thank you for the additional thoughts! I assume the "tall stakes" are set when you are staking for cut and fill right?
I always appreciate yours and few others here always take few extra minutes to explain some of the terms used. I only know what "bell housing" because you explained it!

It must be a struggle in the early days of surveying before the laser plummet to set these tall stakes!

I hope you are fully recovered from the tick fever and its ongoing related health issues. Have a great weekend Nate (all everyone else too)

Tall Stakes

Are where you go out with 4' Tomato Stakes, or homemade wood stakes, and drive them in the ground. Tie flagging tightly around the top. Set an 8d or 12d finish nail in the top, with an accordion wrinkle of flagging on it, with a bit of DOT tape, that will give a return to the reflectorless Total station. PRESTO! It is a backsite, Setup point, and Foresite, all in one. You can run solo traverse all over with it. If you have a 2 man crew, you can have one out front setting up traverse, and one running it. You can eat up miles with it.

Cut off small trees, in the woods, and do the same thing.

N

Quality laser plummet only way to go

Saves old phart like me bending over!

That red dot minimises chances of incorrectly setting up over a pebble or some other object that appears like a mark in a dimly lit hole.

Can also see when a problem and observing a circle as you rotate the laser plummet through 360 degrees/

Do not mess with cheap equipment ! Purchase Leica or equivalent quality. The beauty with Leica is that the target Height is the same at the instrument height when interchanged.

RADU

If I were looking to save money I would look for quality used tribrachs instead of cheap Chinese ones. The machining in the old ones is better, if you can find a quality one that was not abused and has been professionally cleaned and adjusted you will find a better product than what is offered new.

I prefer optical for most applications, if the gun does not have a laser plummet built in I suppose I would want one laser tribrach for the occasional special purpose.