Stanley Covington
10-13-2017, 10:40 PM
This is a continuation of my series of posts about ancient tools, and the second of four posts about plumblines. If you have not read Scroll 1, the previous post, this one should still be interesting, but it will be more informative if you read it first.
“Twice cut and still too short.” (Anon)
Transferring Layout Lines Overhead
In typical building construction, one builds a flat wooden deck or concrete slab, and lays out walls, stairways, ductwork, pipe risers, and a hundred other things by drawing lines and arcs directly on the floor using stringlines, chalklines, inklines, trammels, straightedges, and squares.
Let’s look at the construction of a typical stud/gypboard wall. It has a bottom plate of wood or light-gauge steel fastened to the floor, and a similar top plate fastened to the underside of the slab or floor joist above. Vertical studs go between these two plates. The bottom plate’s position is already drawn on the deck, but locating the top plate’s proper position above is a bit more difficult.
The classical method is for one man with a plumbline to climb a ladder while his partner directs him to move the plumbline left or right, forward or back until the plumb bob’s point is centered on the corresponding point marked on the floor. The guy on the ladder marks this point overhead. He transfers two points this way, then snaps a line to mark the location of a straight top plate. There are laser widgets available nowadays that make it possible for a single man to perform this operation, but they are not necessarily more accurate.
https://lh5.googleusercontent.com/NqVbQJPMMO4hMVpP_-EVoTVDrLTv2qeDNXlkEdKRXbTmxoB8__1fuJ1xoHTZ75gujS6L vyrdpg7UwsldDAKCfCcNHfWkT_4lPr43r_M37YVYbrr5GknRBE bmcBTH9XGL9yltv7w
Laying a Vertical Line on a Wall
Part of building a wall includes laying-out the precise location of door and window openings and intersecting walls. After locating the opening’s sides, mark out its vertical sides with a plumbline. An offset block equal in thickness to the bob’s radius minus ½ the plumbline’s thickness is attached just above the opening location and right on the mark for the intended opening. The plumbline passes over this block, and the bob is lowered as far as necessary. Set one leg of a square against the wall’s face with the other leg just kissing the plumbline, and mark the wall near the header and base. Connect these two points with a chalkline or inkline, and voila.
If you are in a situation where don’t have a precisely-dimensioned offset block, use whatever is at hand. A 2x4 or LGS cutoff (deburr it well) is usually available. Get two of these the same thickness and attach one above to run the plumbline over. Use the other below between line and wall. A metal square placed on the floor against the wall works well too, but checking a plumb bob’s point against an engraved line on a square on the floor deck is slow and tedious.
This post and the previous one were about techniques. The final two posts will be about two tools that employ the plumbline as a component.
“Twice cut and still too short.” (Anon)
Transferring Layout Lines Overhead
In typical building construction, one builds a flat wooden deck or concrete slab, and lays out walls, stairways, ductwork, pipe risers, and a hundred other things by drawing lines and arcs directly on the floor using stringlines, chalklines, inklines, trammels, straightedges, and squares.
Let’s look at the construction of a typical stud/gypboard wall. It has a bottom plate of wood or light-gauge steel fastened to the floor, and a similar top plate fastened to the underside of the slab or floor joist above. Vertical studs go between these two plates. The bottom plate’s position is already drawn on the deck, but locating the top plate’s proper position above is a bit more difficult.
The classical method is for one man with a plumbline to climb a ladder while his partner directs him to move the plumbline left or right, forward or back until the plumb bob’s point is centered on the corresponding point marked on the floor. The guy on the ladder marks this point overhead. He transfers two points this way, then snaps a line to mark the location of a straight top plate. There are laser widgets available nowadays that make it possible for a single man to perform this operation, but they are not necessarily more accurate.
https://lh5.googleusercontent.com/NqVbQJPMMO4hMVpP_-EVoTVDrLTv2qeDNXlkEdKRXbTmxoB8__1fuJ1xoHTZ75gujS6L vyrdpg7UwsldDAKCfCcNHfWkT_4lPr43r_M37YVYbrr5GknRBE bmcBTH9XGL9yltv7w
Laying a Vertical Line on a Wall
Part of building a wall includes laying-out the precise location of door and window openings and intersecting walls. After locating the opening’s sides, mark out its vertical sides with a plumbline. An offset block equal in thickness to the bob’s radius minus ½ the plumbline’s thickness is attached just above the opening location and right on the mark for the intended opening. The plumbline passes over this block, and the bob is lowered as far as necessary. Set one leg of a square against the wall’s face with the other leg just kissing the plumbline, and mark the wall near the header and base. Connect these two points with a chalkline or inkline, and voila.
If you are in a situation where don’t have a precisely-dimensioned offset block, use whatever is at hand. A 2x4 or LGS cutoff (deburr it well) is usually available. Get two of these the same thickness and attach one above to run the plumbline over. Use the other below between line and wall. A metal square placed on the floor against the wall works well too, but checking a plumb bob’s point against an engraved line on a square on the floor deck is slow and tedious.
This post and the previous one were about techniques. The final two posts will be about two tools that employ the plumbline as a component.