Just had a Client call and ask about using GPS to locate anchor bolts and send the pattern to the steel manufacturer and they would bore the base plates to match. I told him I did not think we were there yet and would not take the liability.
Does anyone use GPS/GNSS to stake or locate anchor bolts?
With the equipment most of us have I would say no. Talk with one of the bridge guys about millimeter GPS. Even if you can my question would relate more to 'should'. One of those Jurassic Park deals..
hpalmer, post: 432908, member: 336 wrote: Just had a Client call and ask about using GPS to locate anchor bolts and send the pattern to the steel manufacturer and they would bore the base plates to match. I told him I did not think we were there yet and would not take the liability.
Does anyone use GPS/GNSS to stake or locate anchor bolts?
GPS for bolt pattern to bore base plates? I would use a square, a pencil, and 2 pieces of cardboard. Measure the bolts on the pieces of cardboard. Then drill one out to match the bolt pattern. Send that to the manufacturer.
thebionicman, post: 432911, member: 8136 wrote: With the equipment most of us have I would say no. Talk with one of the bridge guys about millimeter GPS. Even if you can my question would relate more to 'should'. One of those Jurassic Park deals..
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"Millimeter GPS," if you're referring to Topcon's proprietary setup, only improves elevations (by incorporating a laser level).
To the OP, I'd definitely say don't do it. This is auto-tracking/robotic total station work all the way, in my opinion. I'm not aware of anyone who does this kind of work who would use GPS. I imagine you're shooting for no worse than 0.01' precision. No GPS equipment manufacturer claims that kind of real-time precision, even in ideal conditions.
Just plain NO.
Jules J., post: 432913, member: 444 wrote: GPS for bolt pattern to bore base plates? I would use a square, a pencil, and 2 pieces of cardboard. Measure the bolts on the pieces of cardboard. Then drill one out to match the bolt pattern. Send that to the manufacturer.
Make sure to report bolt pattern skew in relation to column lines, as well as any bolts out of plumb. Hopefully your contractor was savvy enough to pour the column bases with bolts held in a template, but I've seen lots of foundation pours that weren't done this way.
I'd do it in a heartbeat.... if the base plates were a 1/2 mile across!
Otherwise, 1/2" piece of plywood on top of the bolts, whack it with a hammer - send it in - Done.
hpalmer, post: 432908, member: 336 wrote: Just had a Client call and ask about using GPS to locate anchor bolts and send the pattern to the steel manufacturer and they would bore the base plates to match. I told him I did not think we were there yet and would not take the liability.
Does anyone use GPS/GNSS to stake or locate anchor bolts?
No.
toivo1037, post: 432920, member: 973 wrote: Otherwise, 1/2" piece of plywood on top of the bolts, whack it with a hammer - send it in - Done.
Some of the bolts I've encountered over the years were sticking out of the concrete a long way, and not vertical.
They came out of the concrete at proper spacing but above that were "all over the place"
Makes interesting survey to obtain their position and orientation.
I do agree with that concept though, with obvious caveat.
I'd never entertain a GPS for the task.
LOL hell no
The client must be a do-it-yourselfer. I hope. There is something to be said for a feller with a lot try and a little ignorance. He'll figure it out. If its a builder or contractor he will be outta bidniss in a few weeks.
One of the biggest cluserf@&#s I ever had to deal with was to come in behind another firm that laid out 250+/- anchor bolt for three material silos at a quarry/concrete plant with RTK. It was the survey equivalent of being the guy with the shovel behind the elephants in the circus parade.
Clients today often confuse a Robotic TS for a GPS. I here this at least once a month.
That said I do see a lot of licensed surveyors doing layout for building offsets with GPS. Then the contractor will use those hubs to layout footers, walls and anchor bolts.
[SARCASM]This would only work if the machine shop setout the holes on the plate with GPS of the same manufacturer using the same coordinate system and geoid.[/SARCASM]
toivo1037, post: 432920, member: 973 wrote: I'd do it in a heartbeat.... if the base plates were a 1/2 mile across!
Otherwise, 1/2" piece of plywood on top of the bolts, whack it with a hammer - send it in - Done.
I like it. What about carbon paper?
Let it ride. Will make for some interesting results!! "Well my GPS said so," conversation will eventually unfold.
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Jules J., post: 432913, member: 444 wrote: I would use a square, a pencil, and 2 pieces of cardboard. Measure the bolts on the pieces of cardboard. Then drill one out to match the bolt pattern. Send that to the manufacturer.
toivo1037, post: 432920, member: 973 wrote: 1/2" piece of plywood on top of the bolts, whack it with a hammer - send it in - Done.
Chances are 50-50 which side is up when they transfer from the board to the steel.
hpalmer, post: 432908, member: 336 wrote: Just had a Client call and ask about using GPS to locate anchor bolts and send the pattern to the steel manufacturer and they would bore the base plates to match. I told him I did not think we were there yet and would not take the liability.
Does anyone use GPS/GNSS to stake or locate anchor bolts?
Good God No!
leegreen, post: 432955, member: 2332 wrote: Clients today often confuse a Robotic TS for a GPS. I here this at least once a month.
That said I do see a lot of licensed surveyors doing layout for building offsets with GPS. Then the contractor will use those hubs to layout footers, walls and anchor bolts.
I don't use GPS to layout anything with a tack or dimple in it.
At least in the building offset scenario the maximum error is outside of the building and would get smaller for the interior columns. (If the contractor did the rest of the layout by some other means). Back to the OP - Locating all those bolts with GPS would result in a total disaster I think....I have not tried it, and I don't think I will any time soon...
Since when is it appropriate to allow the client to dictate which measurement tool you are going to use?