maybe i'm an idiot.. maybe i'm missing something. i have a drywall t square that is 48"... if i measure it it's about 47 5/8 ish... i went to the local menards today and looked at 3 different squares... all just short of 48" by 1/8-1/4"... is there a reason for this?
why are drywall squares not accurate????
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Dirtydan69
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Good luck at it actually being square
dirt_dobber
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wolf_from_wv
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That's what I thought the question was going to be...
claymont
Well-known member
Square is made to cut drywall which ends up getting mudded up, so you can't see where you cut anyway; how accurate does it have to be to do that job? It's a touch shorter so when the piece is laying against the wall, nothing will interfere with the blade.
JRC3
Well-known member
Maybe someone else knows of a video on cutting drywall longways/horizontally because I sure can't find one.
When drywall (usually multiple pieces) is stood up against a wall the square can be placed on top. A knife can be held against the square and the square can be slid across the top of the drywall to make the long cut. The square is a little short so it does not drag on the floor at the bottom.
Picture setting the square on top and sliding it back and forth. No imagine needing to take 3" off the 48" width of the drywall...The knife edge can be placed and held on the 3"/45" mark on the sqaure and slid with the square across the entire length. The short end of the square acts like a "fence" to keep the cut uniform. This is another reason why the numbers run both ways on the square.
A square is meant to make more than short cuts and it's all about speed.
When drywall (usually multiple pieces) is stood up against a wall the square can be placed on top. A knife can be held against the square and the square can be slid across the top of the drywall to make the long cut. The square is a little short so it does not drag on the floor at the bottom.
Picture setting the square on top and sliding it back and forth. No imagine needing to take 3" off the 48" width of the drywall...The knife edge can be placed and held on the 3"/45" mark on the sqaure and slid with the square across the entire length. The short end of the square acts like a "fence" to keep the cut uniform. This is another reason why the numbers run both ways on the square.
A square is meant to make more than short cuts and it's all about speed.
sierradmax
Well-known member
On the topic of drywall, how many guys here break their joints on studs or ferring? I break my joints between and build rock splicers out of some 1/2" & 1/4" plywood.
bmwpowere36m3
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Always break on studs... drywall isn't too bad. Cement board gets REAL brittle when driving that close to the edge.
Doug Arthurs
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I thought a drywall square would be well square. Found out different mine is out about a 1/16 over the 4' length.
guy48065
Well-known member
I know they can be adjusted but I don't remember if it's done by hammering the long bar near the intersection, on the acute side of the bar in order to "stretch" it towards center, or by using a punch.
Dirtydan69
Well-known member
Most are. You may get lucky and a brand new one is square but it's stay that way long. Measure 40" up aboth ends. Lay your square on the short side, on the mark and draw a line. Do this from both sides. Very rarely will those lines meet in the center of the sheet. But it's drywall and gets mud and finished.
You could use a chalk line but most Drywaller's just use their tape measure. Pull it too desired measurement say 10" for a 38" wide piece. Use your knuckle at that measurement on the edge of the sheet and your knife at the end of the tape. So the tape is stretched out and will be your guide for your "RIP" cut. Now run it down the length of the sheet. Now you'll have a 38"x96" piece of rock.
Similar to how that drywall knife from Canada is designed to cut.
Ps, if you do use a chalk line don't use red. It WILL show through your painted finish.
wolf_from_wv
Well-known member
I thought it would be "square" too, so I got one to use when thin paneling-type boards. The first cut I made was no where near square, so I measured both ends of the board, and it was about 1/4" over about 3 feet. Now, I just use it as a straight-edge or fence to clamp on the board.
LOL, sounds like an expensive experience. Similar to not using blue or black pen for marking stuff out..
sierradmax
Well-known member
Yes, use blue. Whenever I sand mud or plaster to a 3 coat finish, I then prime and mix a little mud with some blue chalk to hit anything that needs some touch-up. Then I know where I do so to sand/re-prime.
southalabama
Well-known member
Well this explains why when I used it to "square" a sheet of plywood up it wasn't square.
Also don't use red chalk on a metal roof. I ended up on one with soap and a rag after telling my help not to use red. I think they did it out of spite.
Also don't use red chalk on a metal roof. I ended up on one with soap and a rag after telling my help not to use red. I think they did it out of spite.