That is brilliant John I will read that a couple more times to make sure I have it in my head then I will make an ammended video. Thank you for going to the trouble of explaining it so clearly.

@@SkillBuilder Thanks! I did forget one suggestion I should have made: Get the longest hallway in the building (or find a bigger building) and check the laser midway between two points that are 30 or 40 feet apart. Then, when you set up near one of your marks or tapes, you can really see the error at the distant mark and measure it well. Then, knowing the distance (15 to 20 feet each direction for the midway measurement) you can get the error at whatever distance (30' or 40' say?), and compare that to the XXmm spec per YY meters, to know exactly if it meets specifications.

Thank you John, I'm gunna read that ten times for it to sink in. 🙏👍

So if I understand it right you're in measuring pitch , rather than roll. Because the laser can be off in two axis. In your initial measurement, when you are half way, you are actually at the bottom of a T with ends of the horizontal bar being the tape/rods. When you set up next to one rod, you are setting up the instrument perpendicular to the first reading from there bottom of the T. But you might be in a situation where the pitch and roll are present in equal amounts, and you believe you have a clear reading, but the errors just cancelled each other. With a 360 later it's a lot simpler, but you could fix it by having a third tape/rod near the bottom of the T and checking all rods from every position. How I understood that right.

@@gallowsongs I don't completely understand everything you said, but I think I can answer your question because I do think I understand what you mean by "pitch" and "roll". "Pitch" in this case refers to raising or lowering the nose of an aircraft, whereas "Roll" refers to raising one wing and lowering the other. So, to understand completely what is going on, imagine that you have a perfectly plumb pole or pipe, and that you have attached to that a flashlight, and the beam of that flashlight points in an exactly horizontal direction. That is, the flashlight beam points towards the horizon, and relates to the plumb pole exactly 90 degrees angle. Now imagine that you replace the flashlight with a laser light that projects a tiny precise dot, but still exactly perpendicular to the pole, which still points towards the center of the earth's gravity (that is what "plumb" means). Now, you CAN think of that direction the light is pointing as "pitch". Pointing that laser beam "uphill" could be regarded as "changing the pitch". But, with a laser level, there are not an infinity of separate lasers pointing at 90 degrees. Instead, if you rotate the laser pointer and its laser beam around the plumb pole, 90 degrees to the right, you are now dealing with "roll" (if I understand correctly your use of terms). The key thing to understand here is this: If the pole or post or rod the laser is mounted on is perfectly plumb, and the laser is rotated very quickly, you will not see lots of laser dots, you will see a "line". If the pole is plumb and the laser is horizontal, the laser line will represent a "plane" (not an aircraft, but a geometric plane). If the pole is plumb, but the laser is pointing downhill or uphill, the laser line will represent a cone (actually, the part of the cone that intersects whatever wall you are looking at to see the laser line). In the first example, the rotation axis is plumb, and the laser is level, and the resulting figure is a level plane. In the second example, the rotation axis is plumb, but the laser IS NOT level. The resulting figure is a cone. I think the question you meant to ask is: "what happens if the level is 90 degrees (perpendicular) to the axis of rotation, but the axis of rotation is not plumb?". If that were the case, you would have a plane surface that might be "level" in the forward to back direction (what you call pitch) but off level in the side to side direction (your term "roll"). If that is a correct rendering of your question, you are also asking me "So John, how do you account for the possibility that the axis of rotation is not plumb, which would cause problems if everything else was good?". And, my answer would be "Wolfgang, you are correct, to find and correct that, we need to do the procedure twice". To account for this possibility (which is VERY rare) you would check the level exactly as I have described, but you would note the orientation of the physical laser device. This is hard to explain. If you have a car, or a camera, or a gun, or an arrow, there is an obvious "direction" that you can understand that the device "naturally points at". The barrel of a gun or the nose of an aircraft could be said to "point" in some direction. You could then call that arbitrary direction "Straight ahead" or "12 o'clock on a clock face". But your laser level has no "direction" that it "points at". So if your laser is shaped like a box, you would have to pick one face of the box and call that "straight ahead" or "12 o'clock. To check for the "roll" problem you mentioned, you would simply repeat the entire checking process, after turning the laser level so that it points "to the right 90 degrees" or "to 3:00 O'clock on the clock face". In other words, you perform my suggested checks/adjustments twice,, with laser pointed 90 degrees different the second time. Lets say you performed the level check as I explained it earlier, and you used the longest hallway you could find indoors to make it both easy and accurate. A long hallway makes for a very accurate measurement and correction of error, and inside makes the laser line easy to see. So, you would perform the check just as I had originally described, but you would note something about the laser that would allow you to define a "pointing direction". My laser is shaped like a tiny bus, with the two short sides of the bus being the "front and back" of the bus, and the two long sides being the "side" of the bus. So, if I was checking to make sure my level was good both in pitch and roll (to use your terms) I would first point the "front and back of the bus up and down the hallway, and do the whole check procedure. I would then repeat the entire procedure with the "sides" of the bus" pointing (oriented facing) the long hallway. Once your laser level tests level in both directions, you will have accounted for all possible sources of error. BUT, I must say, because of the way laser levels are designed, the "roll" error (rotation axis not plumb) is VERY unlikely to occur. On the other hand, the pitch error (laser not perpendicular to rotation axis) happens a lot. So, doing the check process I originally described is going to eliminate most possible error. Repeating the whole process with the laser level (the physical device itself) "pointing" 90 degrees right (or left) of where it pointed during your first check, that will eliminate all possible error sources. Why is this second type of error so rare? Gravity is used to make sure that the axis of rotation is perfectly plumb. Imagine that the axle (axis of rotation) is freely hanging from a support, and gravity makes it perfectly plumb. If I set up my level, and I tap it, I will see the laser lines on the walls around me "rock" up and down as the free hanging axle swings under its support. There are just not many ways this system can go wrong, its too simple and basic. But, rare is not impossible. If I left my laser outside for a couple of years, rain could get in, and rust the parts so that the axle could no longer hang freely straight down. In that case, I wouldn't need to do the above procedure to detect that. I would just turn the laser on, wait till the line stabilized, and gently tap the laser. If the laser line rocks gently up and down, it is working correctly. You are seeing the swinging pendulum that is the axle represented by the laser line moving on the wall. If it "shivers", then the axle no longer hangs straight down, but instead points "almost straight down" and does not want to move. At that point, you consign your laser level to the dustbin of history. I will finish by saying this: From my experience, the "roll" type error, which amounts to the axle not being able to "hang" exactly in line with the earth's gravity, is so rare I wouldn't bother to check twice with two different orientations 90 degrees apart. If your device did "freeze" this way, it would be immediately apparent in the odd behavior of the laser. When an axle does get stuck, it will usually give you a laser line on the wall that is so "off" you know it as soon as you see it.

Thanks Joe . Doing an American hook up next week

I will have to think about that. You may be right

andyhello Where have you been? We need you.

Ah yes my head hurts now. You are right, that would have been a better way.

That is assuming the 90-degree rotation doesn't have any discrepancy in the plate it is rotating on? A very slight change in the rotating plate would exaggerate the "change?" or am I way off with my own assumption? I have had to adjust my camera when doing this because the angle is slightly different. The laser would adjust for level but wouldn't there be a difference in height?

no, not necessarily - depending on what is the reason for the discrepancy your method may work or may not; Rogers method is better because it shows any error in any case!

@@filmevoncosima I like your channel. Nothing I enjoy more than being out on my bike. I have done the Etape a few times and countless other events. I love the mountains of Mallorca. I am going to binge watch them now.

@@SkillBuilder wow, you are a cyclist too, that's great! Sadly I did not ride my bike for some time due to an serious illness in my family which stole much of my time - and therefor no videos since than... but I hope to be back on the bike in 2020. Love the mountains of Mallorca too, and the Alps, it's wonderful to ride there. And I like working with wood and in my house as well (though it is not my profession as yours...). I love your channel too! Keep up the good work!!!

Yes you are right to trust your eye. I am still not trusting when I use a laser level so I still just check the line with my bubble.

i guess Im kinda off topic but does anyone know of a good website to watch newly released tv shows online ?

@@oakleybraylen7093 g t f out of here !

Good observations. The location was not ideal on this demonstration but outdoors it was a lost cause. I would tend to do it outdoors in the evening to have a better chance . Also I think I would mark out some lines and go back to the same spot for regular checking.

Most decent self leveling models will still perform up to about 4°

Big fan of the water level

@@SkillBuilder You should do a video! Had mine donkeys years. Man that taught me had it for years and gave it to me when he packed in. Actually made of brass and very niceley made. Few leaks in the hose and a bit of duct tape here and there but still works. Mind you, whats to go wrong! Cheers again.

@@tilerman We have a video coming out. That brass one was a Holland I believe. Very nice, I would buy one, mine is plastic.

If it is level it will be plumb because it all works on the same pendulum. Just mark on the end of the line then turn the level and mark the other point and see how it lines up. I think you need to try it to understand

It is self levelling and provided you line up on the mark it will be correct.

@@SkillBuilder yes but if the floor in another position is running up or down for any reason it will give you a false reading surely?

@@martin1977uk That is not the case. The laser self levels so lining it up with the second point should set it level with the first point. If it doesn't it has nothing to do with the floor, it is the level.

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@@SkillBuilder Thanks

Tim. Poles apart! That is great advice. As for Strictly, I have never watched it. Anything with a studio audience mindlessly clapping along to the music has to be placed in the same category as The Billy Cotton Band Show, The Black and White Minstrel Show and all those other naff productions that have blighted Saturday evening television for years.

@@SkillBuilder 😂😂 you do make me laugh - proper grumpy old man 😂😂, mind you do have more than a passing resemblance to James Cracknell 😂😂😂

@@timmargereson332 Good stuff Tim. Truth is that even when I was young I was grumpy. I ran a mile from all that middle of the road variety type stuff. In those days there were just two channels and the t.v companies thought their audience of 18 million was an approval rating whereas, in truth, it was a captive audience with nothing else to do. Now we have such a choice of viewing there is absolutely no excuse for watching Strictly. If I caught any of my family watching it I would pull the fuse. What we call in the trade a safe isolation intended to protect the occupants from harm.

I am going by the instruction issued by the laser manufacturer. They say top or bottom of the beam but it won't be that far out on a distance of 3 metres so either is fine.

I always go middle of the beam. I don't care if its against the manufacturers recommendations, manufacturers don't always understand how the tool gets used in the real world. Centre of the beam is always going to be the same line if your machine is reading level, no matter how wide the beam gets.

"Slight correction: a level that isn’t level is WORSE than useless, it’s a liability." Wrong, you should ALWAYS, ALWAYS, ALWAYS, check like you did when using any level. You can use a level that is out of level by knowing it not accurate and dividing/splitting the difference and checking again like you should do regardless.

and that sir is the correct way to work on a laser beam!

Hey, what do you mean by “with middle off beam”?

@@anas7hamed He meant middle of the beam (rather than the bottom edge, as done in this video.) His point was that lasers spread with distance, so the far end of the room will have a wider beam cast than the closer end. So if you place the black tape's top edge to coincide with the center of the beam, you avoid that effect.

According to SkillBuilder, the Bosch Laser HQ told him to work on the lasers edge. Go figure.

@@myshinobi1987 Manufacturers don't always understand how to use the tools they make.

I would never bother with a laser that needs the little bubble placing in the middle of the dot. It takes too long. That said there is less to go wrong and they are cheaper.

I am not sure how that would work but I will try it in our laser showdown.

@@SkillBuilder (in my head at least this makes sense so bear with...) fire the laser at the wall, tape one side of the horizontal beam (LHS for example), then rotate the laser on the tripod CCW so that RHS of the cross now sits on the tape (or above or below if it's not level!)...looking forward to the showdown, I've been looking at the Magnusson IM0301 from Screwfix, seems like a really good value laser for DIY'ers but not much in the way of reviews I can find.

Where do you get them done?

@@alexmassey4708 Hi Alex, we use a company called Zenith.

We have one of those coming up next week. Great kit, no batteries.

Best level in the world, 100% accurate and can go around corners. Use some food dye in the water to make it easier to use. 👍

@@MrJFoster1984 Food dye? Marmite?

@@SkillBuilder No the kind you use to change the colour of cake icing, Ask the missus she will know mate

Thanks this is just the kind of user comment we need. People can learn a lot from this experience.

Atmospheric pressure across the room may be different. ;)

Eddie Adventure Yes. And water density if temperature is different.

yeah

My dewalt level does NOT have a lock

some of them don't have a lock.

Pls doesn't

@@mighty_peach2760 not my native language....but thanks for help ;)

@@remus100776 you were correct, he wasn't.

No because it is taking the line from the other end you will see a discrepancy.

​@@SkillBuilderisyt1 is correct. This test does not verify that the laser is level, but that it is consistent. It only proves that the laser will give a consistent line independent of its position in the room, but does not prove that the line is level.

Good point well made. This tip was given to me when I visited the Bosch laser HQ. They said work to one side

Skill Builder can you explain this in a video please?

@@SkillBuilder it would be great to get a video explaining this point and why this is the case. I just bought one of these and I'd love to be able to use it the right way from the get go.

Yes you are missing something. This is how the manufacturers suggest you check your level to see if it needs to go back for callibration. If you watch the video on checking a spirit level you will see this is the same idea. Just turn the level around and ask the same question. The laser level is self levelling so, provided you have two marks on the wall you will be able to place the line on the marks to establish what the level says is level and then by moving it to the other mark and setting it up on the line at one end it should, if it is level, hit the other mark spot on. If it doesn't it shows the variation. You could go one step further and place the level midway lined up with a midway mark and that would show how much it is out at either end. In this case we would be talking about 1/4 mm at each end which is well within tolerance.

@@SkillBuilder Thanks for putting me right i now fully understand (maybe get a new presenter ;0)

I just picked a similar tripod up for mine at the local charity shop for £15, keep your eyes out, there's always loads at car boot sales and second hand markets for cheap

Yeah but my prob with most of them and the dewalt and bosch ones is there not really building site quality. That tripod he has there looks beefy lol

Well you just have to look after it then, some of the old camera tripods are pretty hefty to be fair

I tried to modify a tripod that hold a dump level but it never really worked lol ill find one soon i suppose. What laser have you got then iv got the 360 dewalt with the 3 beams

Yeah i were gonna say the same, my PLS doesn't have a locking device, wonder why?

@@Total-Solutions Thanks That's good info Might get me one of those Cheers

it is self levelling

@@SkillBuilder I don't understand. Does it have water inside that makes it self level?

@@ya00007 A bit late but I believe they use magnets at the ends inside. The pendulum arm for say to the horizontal line is running vertical inside the device and inside below the end of that pendulum are magnets attracting to help stabilize. They have a tolerance, most laser levels now are 3-4 degrees that you can be out of level. If the unit is beyond that the line will blink, it usually chirps an alarm to let you know the unit isn't level enough to self level. A slightly crooked floor, tripod or anything else won't matter. Once the unit stops setting off alarms it determines the self leveling can take control and it'll work to find level. In the demonstration here, level was marked with both ends using the tape to mark where the level said 'level' was. Then it was moved. Only sighted or adjusted to be 'level' at one tape mark. Now if the tool is in fact level (what's being diagnosed) then it should automatically be level at the other end, at the other tape mark. If it isn't then it's revealing some sort of deviation. Sort of like checking a square box for level across the diagonal corners, if it's level diagonally from one corner to the opposing corner, then level again from the other two corners like an imaginary X across the box, the entire thing should be level 360 degrees around. Whatever that 'box' may be, band joists, beams, deck, top plate of walls or whatever. A number of them can also be manually locked and in that case they can be tilted and the self level no longer tries to operate. Then it just gives a static line that can be tilted on a tripod for angles like stair railings. But then it's not trying to 'level' anything and it's only meant to be a straight edge.

If you want something really level over several metres use a water tube. Make sure there are no bubbles in it though! That sort of accuracy isn't necessary for most building projects though. With spirit levels, engineering levels are much more accurate than builders' levels

The degree of accuracy required depends on the job your doing. That’s why it’s is good knowledge to be aware of your tools limitations.

That is not the way that Bosch suggest in their handbook. They say to move the laser.

It shouldn't be the tripod. The line is re-set to tape so you get the story backwards.

@@SkillBuilder I would only assume if the tripod wound up smoothly and not in steps.

Tripods are neither in or out. It's just something to set the laser on. You could do the same test by setting the laser on a pile dog shit

It was level. It just got kicked. The good thing about self levelling lasers is that they recover.

I own a Bosch like that. It is blinking because the battery is low. It will blink and beep if its out of level, and the blinking pattern is more constant.

Right. Water level doesnt lie and cost $7.

​@@jovosedlar3395 water level can trick you also if you dont know how to use it

@@flaviokonti5522 of course. Person needs to know how to use it. I agree.

That is a good idea. Bosch say to use one edge of the line but the middle will do.

@@SkillBuilder Now that's interesting - Just checked to see where I got the information about marking the laser line & Dewalt's manual for my laser does state mark the middle of the line, I wonder if that instruction is model/manufacturer specific? Wrongly assumed it was for all. Live & learn!

@@DangleFilbert I don't suppose it matters that much, provided the marks are on the same bit,, but maybe the line thickens on the brighter setting.

ForzaRider what do you call a boomerang that won't come back? A Stick! Same as a level that isn't level?

Nicolai It makes no difference if the floor is out of level. You may need to think about this for a while but when you move it from say left to the right end you have to line it up on the mark you have made on the right. Then you can see if the level is running back to the left hand mark. The laser is self levelling or should be so if it is accurate you should see the laser hit that left hand pencil mark.

No. Read the comments below. The laser self levels so when it goes on a line it should meet the other one whichever way you do it. That is the whole idea of the laser level.

I would have to agree: a water level is the way to go if you really want to know. It may take a little longer to set up but it's worth it.

Makes no difference. You are lining up on the laser line from end to end and back again.

It is a self levelling level. Provided you put the laser line on your line it will find the level of the other mark. If it doesn't it is wrong. I think we need to do some basic instructions on these levels.

True.

Jeez Mathew over that distance it makes no difference at all. We are not building a piano. If we get withing 1 mm we are happy.

@@SkillBuilder it's very simple if the walls are not the exact same distance away the bottom of the line will be at different heights, meaning even if the level is dead on balls it could show that it is off. It's lasers 101 you go to the center of the line. It's simply not how you do it. Wrong. Imprecise. Not to mention you can just turn the laser to check.

Hi Paul You may say that it is flawed logic but if you just try and think a little more about this you will see why it is a method that most laser manufacturers recommend. The laser is self levelling and if you establish the two lines at either end of the wall and then move the laser to the second position you may then have to adjust the height of the laser so the laser is exactly on the pencil mark. This means that even if the floor were 300 mm higher or lower the laser would still start from the second position and run back to the first. If the laser is working properly the line from the second position will meet the first pencil mark. That is how you discover any discrepancy. The floor level is not a factor.

@@SkillBuilder I see what you mean however, given that the laser changes width over distance, the position of the laser device would need to be the same distance from each piece of tape vice-versa when the tripod is moved. Marking the centre of the laser with each piece of tape and then simply rotating the device on the tripod would give a more accurate reading.

Thanks Adam I am interested in your finding and will ammend the information with another video. It would help us if we can find somebody such as you to assist in the testing. All we are trying to do it establish a simple test that can show if a laser need calibrating.

I got lost in your explanation, can you simplify ?

I will add that you can use round posts or a wide opening where you can mark from both sides of the space .this method is essentially what you do with a mechanical level which is to test itself against the mirrors image ...

You don't need to. Just line up the beam on the tape.

We have a video on the water level. On the other point about the floor not being level that doesn't matter since the laser is self levelling. You just need the beam to be on the second mark you made when you move it. When someone says something is obvious it is often because they have limited their thought.

Yes listen to the music without all that talking

It is the way recommended by manufacturers and is good enough for the accuracy. Point me to your source material, I am interested to see the techiniques.

It is according to the instructions

The vertical line is far from useless. I wouldn’t use it as a plumb line but it’s an excellent replacement for a chalk/ink line. So long as you treat it as such, it’s fine.

Iggfer, quite right, that's what I do when I'm tiling a floor solo. Incidentally, the Bosch gsl range are great for tiling a floor, because the cradle they come with and the plumb bob dots make it easy to go mark to mark. My point was I would never use the plumb line of a laser for a plumb line on a wall, that's what my trusty four foot Stabila is for.