Surveying: Plumb Bob Mounted Prisms

[@pippensculps]

These videos are priceless. I truly hope you don't stop uploading. THANK YOU.

[@leansurvey8212]

Thanks for the encouragement, new video just posted!

[@luisramos2521]

I’m a old timer student, been practicing surveying for over 27 years your videos are awesome, God bless you and your business. Thank you.

[@MGoBlue789]

These are fundamentals that used to be passed on from party chief to I-man, I-man to rodman...sadly w/more outfits moving towards 1 man crews that mentoring is unfortunately fading. I'm glad to see someone is still keeping this information alive for future professionals. Bravo!

[@leansurvey8212]

It's difficult to reproduce the accuracy of simple line of sight observations with robotic equipment and one person. Much agreed, I also appreciate the mentor/learner relationship created through these two person tasks. Difficult if not impossible to replace!

[@tambaurorastation756]

Another slick tool I need to add to my collection. Peanut prism string bracket. Thanks for the video!

[@leansurvey8212]

That is SECO part number 6030-00, they are only about $12!

[@tambaurorastation756]

@@leansurvey8212 Thanks for the part number. I was searching the Seco Catalog last night for it, but I could only find it in a kit.

[@wsyler9922]

@@leansurvey8212 AdirPro also makes a (slightly) cheaper version...I would assume more or less similar quality.

[@leansurvey8212]

@@tambaurorastation756 Seco hasn’t added them to the catalog, but vendors and distributors can order them directly. Search “seco plumb bob bracket” and you the vendor AllTerra Central has them in stock.

[@tommydavis2696]

Love your videos - would love to see your technique on layout out anchor bolts and embeds in a vertical surface

[@Arif_PAK]

Could you please elaborate the use of prism centre or prism plate when the point on the ground can not be directly sighted due to obstruction. Thanks!

[@jddrafts]

I remember learning how to do this as a kid working for my dad. I haven’t done it in 15 years though.

[@mattymattareeno4326]

Wow man great great videos, I make sure all my employees watch these!!!! I do have a question tho….why is the -30mm a standard?

[@leansurvey8212]

@@mattymattareeno4326 a prism sits in a small canister, right.. there is the flat face of the glass, and then the facets of the prism converge further back in the canister. The prism is always intended to be tilted toward the equipment when operating but when you are aiming across a site, it’s easy for that rotation to be a little off. You get more viewing angle (allowing your rotation to be less perfect) when your prism is mounted recessed at 30mm. At zero, you really have to aim near perfect or else the canister housing blocks the facet convergence point much more easily and you are unable to get a prism reading. It definitely happened for a reason, that’s why 360 prisms are taking over, no more rotational worries.

[@armorvestrus4119]

It seems to me that a plumb bob mounted on a thin steel rod with a prism at the top being supported by a tripod system would be much better than a bubble mounted system. It would self plumb the prism if made correctly. It would always be plumb. One might not even notice it the bubble plumb moved out of plumb. What do you think of this idea?

[@geekonomist]

why hang a plumb bob 12 inches? What does that give you? what is the use of the plumb? what are you trying to plumb?

[@leansurvey8212]

In this example it is being used to give line at your back sight while also providing a target for distance. It’s plumb over the back sight or foresight point. This would be in cases where you need to get off the ground a small distance but would like to keep your rod as short as possible. For tight tolerance work, a 6.5’ rod that has not been recently calibrated OR is not being held perfectly plumb (which we are just eyeballing anyway) can introduce a small measure inaccuracy into measurement. I’d rather see the prism sitting right on the back sight as in other related videos, but this video is empathizing sticking with a ‘close to the ground’ alternative.

[@geekonomist]

Thank you for the explanation.@@leansurvey8212