Framing and Sub-Flooring - Are those laser squares suitable to serve as basis for new wall?

I'm going to frame my basement and have read about the 3X4X5 rule. However, on the way out of Home Depot today I saw some very snazzy looking laser squares. The nicest was $400, the cheapest under $40 (though accurate only to 1/2" at 30 feet, which isn't great). Are these suitable for acting as the chalk line for a new wall and if so what's the minimum accuracy I need? I assume it's easier to use one of these than playing around walking back and forth with a real chalk line and measuring tape.

Also these have built in a laser plum in some cases. Is there a minimum accuracy I need from these? I guess the only 100% accurate way to plumb a wall is with a plumb bob, but these could make it a lot quicker.

Not that I'm old school, but understanding the basic tools is cheaper and far more reliable. Had a friend years ago that was reading his compass backwards. That compass was very accurate, but he was still going in the wrong direction.

The 3x4x5 is nice, but measure the biggest triangle you can and just use a calculator. (a) squared + (b) squared = (c) squared. If you are doing a square room, just make sure the two corner to corner measurements match. All kinds of simple tricks to do a better job than a $50 or $100 laser. I have lasers, but for bigger and more frequent jobs.

Example, snap a chalk line and it is THERE. Set up a laser and it is gone as soon as something blocks it. Then try marking the floor with a laser line before you start AARGH.


Bud

I have 3 or 4 lasers that people have gifted me over the years. All of them are inexpensive and all of them are less accurate and more difficult to use than the old fashioned tape and chalk line. All of them reside in a junk drawer in my shop.

I have rented the more expensive contractor grade lasers and they are a real time saver. IMO the stuff marketed for the homeowner isn't worth it.

The 3x4x5 is nice, but measure the biggest triangle you can and just use a calculator. (a) squared + (b) squared = (c) squared. If you are doing a square room, just make sure the two corner to corner measurements match. All kinds of simple tricks to do a better job than a $50 or $100 laser.

I knew the Pythagorean Theorem I learned in my 10th grade geometry class would come in handy one day. I use it all the time when establishing a right angle. :D

Some home building stores sells a square for setting your walls that is collapsible. It is several feet long each direction and has what looks like a rivet on one end and a lock on the other and you put it together and it is square.

You can just set it in a corner and then move the wall until it is square. When you are done, you take it apart and put it back in the truck.

Measuring works well but a transit works even better.

1/2" in 30' is not acceptable in any aspect. It isn't square. The Pythagorean theorem or 3-4-5 is the best method and fool proof.