Box Level question

[Greg Parrish]

Picked up a new level today and wondered if this makes any sense? It's a Stanley from HD and it has the machined edges on both sides. The packaging had the 0.0005 in./in. accuracy rating, which was the same claimed by Empire and Milwaukee models next to it. For how I'll use it, this one gave me the features I needed, but when reading comparison's on my phone while standing in the store, this spec from the Stanley website and also repeated on the HD website left me scratching my head. Do box levels have an accuracy measurement factor for both the surface accuracy and the vial accuracy? That doesn't make any sense to me and I'm trying to figure out what they are saying before I toss the package and call this one reliable. Any thoughts? Thank you.



"The STANLEY® 48 in. Box Beam Level features a center block vial for durability and precise measurement with 0.0005 in./in. surface accuracy. The durable box frame and shock absorbing end caps allow this level to stay accurate in the toughest of conditions. MaxEdge™ bridged center vial and mitered surfaces allows for a precise continuous marking surface. Combined with 0.001 in./in. 12mm easy to read tubular plumb vials, the STANLEY Box Beam Level is designed to stay reliable and accurate for any job."

[Dwayne Watt]

The surface accuracy is the flatness of the ground surfaces. 0.0005 in/in is a tolerance designating the surface profile. It's flat!
0.001 in/in on the vial is equivalent to 0.057 degree. This designates the accuracy of the level at worst condition. 0.001 in/in is 0.096 inches over 8 feet. There can easily be more operator error than that when using the level.
You should be good to go!

[Greg Parrish]

The surface accuracy is the flatness of the ground surfaces. 0.0005 in/in is a tolerance designating the surface profile. It's flat!
0.001 in/in on the vial is equivalent to 0.057 degree. This designates the accuracy of the level at worst condition. 0.001 in/in is 0.096 inches over 8 feet. There can easily be more operator error than that when using the level.
You should be good to go!

Okay, thanks Dwayne. So that is where Empire and Milwaukee are claiming 0.0005 in/in for flatness and .029 degree (not designated as to what, but guessing it's the vials they are talking about). Can't imagine that the difference between .029 and .057 vial accuracy on a construction grade box level is going to make that much actual daily usage difference considering the edge flatness is the same.

From Empire's site: "ALL POSITION ACCURACY
.0005”/in, .029⁰ ON BOTH WORKING EDGES"