Hi guys
I need to set out a radius tomorrow for a curved concrete beam. The deck for the shuttering is all there and covered in plywood which is what the foreman wants me to mark the beam out on.
Is this a suitable base to put my tripod on? This is the best place for it to see all the required points.
Kind regards, Andrew
How well supported is the plywood? Does it give when you walk on it? What is your position tolerance?
Hi Bill
I'll see tomorrow when I got to the site how stable it is. The foreman (as they always do) says they want the setting out perfect, I said 6mm (2/8 inch) is reasonable.
Will the tilt compensator take care of any wobble on the deck? I know from previous jobs that if the surface is wobbly my S7 gets the shakes and refuses to work.
regards, Andrew
?ÿ
I strongly doubt it will be stable enough for anything tight.?ÿ Set up on a roof top (with a gentle pitch) one time years ago.?ÿ Every time I shifted my weight, even a little, the instrument was not happy.?ÿ Now, if you weigh under a hundred pounds, you might get by.
It will be impossible to get better than 1/4"; impossible...
You and the foreman will be much happier setting up on 2 or 3 points, on stable ground.
We used to set grid/columns on the decking for concrete building construction. I never knew how we set it so tight, because we were using an S7 and even a 5600, up to 8 or nine floors. The whole building moved, but the decking was stable because they were planning to pour on top so all of the supports were in place and ready.?ÿ I'm sure other conc layout and construction surveyors have a bit to offer in here as anecdotal advice, but yeah, if its moving enough to throw off the compensator, i think i wouldn't want to be set up on it anyway.?ÿ JMHO
Thanks guys, I'll find somewhere else to do it or agree looser tolerances
Playwood Decking is NOT suitable for tripod setup for accurate layout.
Options: Top of exposed concrete columns, beams, shear walls, that you can set up on.
Have the contractor pour you a concrete pad to set up on. The weight of the concrete will help stabilize your setup.
Set up exterior to the building being constructed. I've had good luck with adjacent parking garage structures.
Column clamp. My opinion, for a surveyor, this is last resort.
The type and purpose of the decking is important. You may be able to drill some holes and set up on the underlying structure. Resect in and get it done. Of course you might buy some really expensive stuff if you don't ask first...
@thebionicman I agree.
Don't tell anyone, but for q-deck buildings, I've drilled a 1/2 inch hole through the q-deck, then a small divot in an underlying beam to get a stable step. Intersecting beam points allow this for all three tripod legs.
Thanks guys, awesome advice as usual.
I might be able to put the legs on the corners of some local blockwork walls.
i recommend that you lay out your radius from a chord/offset table. do some reading and make a spreadsheet or calculator program
chord/offset
That lets you stand somewhere past an end of the curve to set the chord line, which gives you more setup choices.?ÿ And you can probably do it more accurately this way than radially.