I have noticed when trying to stakeout accurately with rebar and cap if this situation occurs:
-Stake as accurately as possible
-begin to drive rebar
-soil is somewhat hard-packed
-by the time the rebar is driven it's off .03-.05'
-beat the rebar with the sledge
-drive the ground beside it to move it
-drive rocks down along side the rebar to finish "truing it up"
-set the cap
That the rebar will "walk" back to the original position. Maybe not all the way, but usually a measurable amount.
Because of this I have started using blank caps, and setting a tack on the cap.
I do some boundary work in areas where the unimproved land is worth roughly $1,000 an acre. Other areas I work in the land may be worth more than $1,000,000 an acre. I have been thinking of taking this same approach when staking boundary corners to eliminate that last little bit of error on the expensive projects.
The error ellipses are usually around 0.02'-0.05' on the corners, anyway, but why add more slop unintentionally? The tack on the cap method is also actually much faster.
I usually set a couple of concrete monuments if the site allows, but it's not always feasible because of fences, curbs, etc.
Does anyone else do this? I have heard ridiculous accounts (on here) of people finding that someone had "more accurately" placed a tack on their cap because they were a "better measurer". That's not what I'm referring to. If anything I am attempting to acknowledge that my measurements have error, and am looking for a quick/efficient way to control what error I can.
use aluminum caps with no center mark- punch your own mark when the cap is firmly set.
this will be your friend....flame on, Mighty! 😉
The plastic caps cheese away after 20 years of getting beat on by the sun, or after the first time the lawn mower clips it.
another thing to do is carry a 2 foot long piece of 1" od black iron pipe. Slip it over the top of your rebar and pull/bend your rebar past the point you want it- it should 'recoil" to a final position to about the true position you want.
Common practice around here is to bury them about a tenth, but I like Rankin's idea of punching aluminum caps.
Burying them helps keep them from getting molested (moved).
could you loan me a dimpler?
Well, Plumb Bill, I am a bit pedantic too, so I relate to your worrying about 0.04'!
I often BEND the rebar, so that in it's relaxed position, it sits where it is supposed to.
N
EVERY capped rebar gets buried?
of course not. That's my point, some solutions are not perfect for every instance.
i bought one to send you for Christmas, but i didn't have you address.
> The plastic caps cheese away after 20 years of getting beat on by the sun, or after the first time the lawn mower clips it.
And they melt away in a fire. I'm surprised people are still using them.
Let's be realistic
The typical bar used for a monument is subject to movement and to internal stresses. The center of the top of the bar will move some amount in some direction at some point after you have taken your shot. It will happen. It may only be 0.01' or it might be 0.06'. That will depend largely on the effort you made to ensure it is vertical and stress free. One helpful solution to cut down on the both problems is to use a drill to make a hole for the bar to go into. Shoot the hole again to assure yourself that the top is where it is supposed to be. Tap the bar into position. This should greatly reduce the potential for internal stresses to move the tip of the bar over time. It is not a fixall, just a simple way to improve the odds of the tip staying closer to where YOU THOUGHT IT WAS when you shot it.
Secondly, we are not designing miniature watch movements. We must live in the real world with things like frost heave and vandalism. We also must remember not to believe every number that appears on a screen to be infallible. I challenge anyone here to go back to bars set in normal ground conditions being more than 300 feet apart and get identical readings today as you did 20 years ago when you put them there. It COULD HAPPEN, but, those who will admit to the truth will confess that they find slightly different numbers, even between fixed points. It's called operator error, machine accuracy, adjustments, etc.
It pains us to admit that it is nearly impossible to achieve perfection in all that we do and when others at some later date report data inconsistent with ours that they may be correct.
You should look into Morasse brand caps available from Berntsen. UV (at an altitude of 7000') hasn't touched the first ones I set 29 years ago, and if you install them correctly a hammer never touches them.
given that rationale
I s'pose you don't wipe your rear end...after all, you can't get it perfectly clean, and even if you did- it's not going to stay that way long... lots of wasted effort for un achieveable results...better just put a christmas tree air freshener on your back belt loop
..er around your tail...and lord have mercy when you get fresh grass!!!! 😉
I laugh every time I see a punch mark in a cap...
I am very sad when I see 2 or 3 punch marks in a cap...
I've seen aluminum caps melt down in hot forest fire
> another thing to do is carry a 2 foot long piece of 1" od black iron pipe. Slip it over the top of your rebar and pull/bend your rebar past the point you want it- it should 'recoil" to a final position to about the true position you want.
3/4" black pipe works best for 5/8" rebar. I'm not sure if one could bend the top 4"~6" of 3/4" rebar, which would work with the 1" pipe. Another good thing to do is to purchase it as a nipple (threads on both ends) and then also purchase a union and split the union to protect the threads and make the entry both a little flared out and much stronger.
Carl
In some areas we work in aluminum turns into some type of papery-type substance after as little as 12 years due to some type of chemical reaction. Steel rebar erodes away after about 20 years.
Ultimately, the monument becomes the property corner, not the coordinate or bearing and distance from which it is set.
given that rationale
Sadly, as we go through life we must learn that perfection does not exist no matter how badly we want it to exist. I want things to be perfect, it just doesn't work that way.
To the old timers, a chain or a rod was a nice round number to use. Then someone decided we should do everything in feet. Eventually that became inches or tenths of feet....then hundredths....what's next--microns?
Sure, we all like to report angular readings to the second, but that is not a realistic thing through optics at any visible distance common to boundary surveying. We report a 20.00-foot dimension at a bearing to the nearest second. How thick is the crosshair? Pure foolishness. Sure looks nice on a report, though. And one should never believe numbers coming from a handheld pole and bullseye level.
