Most crews meet the Shields Dead Center Jig as an as-built tool — a way to find true dead center on an anchor bolt that's already in the ground. That's where it earns its keep. But the same jig runs the other direction too. The moment you're laying out and setting points, it's just as useful. One tool, two jobs.
As-built: verifying what's already there
This is the job most people picture. The concrete is poured, the bolts are set, and the survey crew comes through to record where everything actually landed. The trouble is that anchor bolts rarely come out of a pour perfectly plumb — they lean, they get bumped stripping forms, they take a hit from equipment.
Set a rod and prism on a bolt like that and you're not measuring dead center; you're measuring your best guess at it. The jig removes the guess. It slides over the bolt and locates the true dead center regardless of how the bolt is sitting, and your standard mini-prism mounts right on top. Every crew member reads the same point — not their own interpretation of it — so the as-built you hand off is a measurement, not an opinion.
Layout: establishing what comes next
Here's the part crews tend to overlook. The same jig that verifies a bolt can help you set one.
When you're laying out new work — staking embeds, marking bolt locations, establishing control before the pour — you need a precise, repeatable point to work from. The jig gives you exactly that: a definitive center you can occupy again and again and get the same answer every time. Whether you're checking reality or creating it, you're working off the same kind of point, captured the same way.
That consistency is the quiet advantage. A crew that uses one method to lay out and the same method to verify isn't reconciling two different ways of finding center. The point they set from and the point they check against speak the same language.
Why working from one definitive point matters
The value of a repeatable center isn't just accuracy on any single bolt. It's that everyone on the job — and every stage of the job — is anchored to the same reference.
On a small footing, a little variation in how you find center is easy to absorb. On a prefabricated structure with hundreds or thousands of bolts, small inconsistencies stack into a pattern that won't accept steel. When layout and as-built both run off the same definitive center, those inconsistencies never get a chance to accumulate — you verify against the same standard you built to.
The takeaway from the dirt
It's easy to file a locating jig under "as-builts" and leave it there. But the tool doesn't care which direction you're working. Locating dead center is locating dead center — whether the bolt is already in the ground and you're confirming it, or you're setting the point that everything else will be built around.
One definitive center. Two jobs. That's the whole idea.
The Shields Dead Center Jig finds dead center on bolts from ½" to 2" in diameter — even bent or leaning ones — verifies plumb with an included laser plummet, and mounts a standard mini-prism for any major total station. Built around a 6061-T6 aluminum body and made in the USA, serialized with its own Certificate of Accuracy. See the specs →
See the full Shields survey tools lineup.