That sinking feeling

[IanF]

Set up a string.. put them on one at a time.. bin any that don’t agree

[duncs500]

I'm officially in a Schrodinger's cat paradox. You're not meant to hang more than one string line from a string, so I can't test them to a sufficiently accurate degree all together. The levels are both accurate and inaccurate at the same time, and I can't handle this

Could've just taken my advice and solved all your problems. They're not the right tool for the job.

[Jobbo]

If you hang a level on a string line, no matter how taut the line it will have a slight curve to it. So even if the spirit levels were accurate you wouldn't be able to measure accurately. Use the right tool for the job, as Duncs said.

[duncs500]

I don't know what level of accuracy you need or if you have another pair of hands to help. A rotating laser level will probably be fine if you're on your own. It seems like it's all people use on site nowadays anyway, in my day we used to do it properly with an optical level.

Can hire it for not much money I'd have thought.

[mik]

I don't know what level of accuracy you need or if you have another pair of hands to help. A rotating laser level will probably be fine if you're on your own. It seems like it's all people use on site nowadays anyway, in my day we used to do it properly with an optical level.

Can hire it for not much money I'd have thought.

Less than £100 for a little self-leveling DeWalt job non?

edit: Yes. Accurate to +/- 0.3mm at 10m

https://www.toolstation.com/dewalt-dw08 ... vel/p98428

[Mito Man]

I don't know what level of accuracy you need or if you have another pair of hands to help. A rotating laser level will probably be fine if you're on your own. It seems like it's all people use on site nowadays anyway, in my day we used to do it properly with an optical level.

Can hire it for not much money I'd have thought.

Less than £100 for a little self-leveling DeWalt job non?

edit: Yes. Accurate to +/- 0.3mm at 10m

https://www.toolstation.com/dewalt-dw08 ... vel/p98428

How would that work in my original application? In the video it’s being used to project on a pre-existing wall. In my case it would be projecting a laser in the air which wouldn’t be visible.

[Sundayjumper]

If you hang a level on a string line, no matter how taut the line it will have a slight curve to it. So even if the spirit levels were accurate you wouldn't be able to measure accurately.

But we're talking here about two points that are more-or-less level to begin with, so as long as you attach the level more-or-less in the middle of the string, the deviation from the true level will be miniscule. Easily good enough for this project.

An important differentiation though, is that bubble levels give a fairly rough indication of the angle compared to horizontal, while the clear hosepipe will give an absolute height difference. Distance between the measuring points being the factor that links them.

The laser level is just a posh version of the hosepipe. It's not as if nobody ever built anything straight before lasers were invented

[duncs500]

I'm talking about something like this:



So you set the receiver so that it beeps with the staff length you want for the level you want to transfer. Then you can just go round and transfer that level wherever you want.

I'd not suggest buying it, but you can hire for about £30 from HSS or someone I reckon.

[duncs500]

The laser level is just a posh version of the hosepipe. It's not as if nobody ever built anything straight before lasers were invented

Hey, I'm not denying that's how it was done throughout most of history. We have better tech now though, why not use it?

[Mito Man]

I'm talking about something like this:



So you set the receiver so that it beeps with the staff length you want for the level you want to transfer. Then you can just go round and transfer that level wherever you want.

I'd not suggest buying it, but you can hire for about £30 from HSS or someone I reckon.

That does not look like something I would be able to use!

The better tech thing reminds me. At first I thought I should use Sketchup to design the building and make sure everything fits. About 15 mins after downloading it I got out a pencil, ruler and some graph paper

[duncs500]

I'm talking about something like this:



So you set the receiver so that it beeps with the staff length you want for the level you want to transfer. Then you can just go round and transfer that level wherever you want.

I'd not suggest buying it, but you can hire for about £30 from HSS or someone I reckon.

That does not look like something I would be able to use!

Trust me, you easily could.

The lasers self level, so you set up the legs and screw it on top. Switch it on. Loosely clamp the receiver on to the staff, locate the staff on the level you want to transfer and move the receiver up and down until it hits the spot (it'll beep faster as you get closer, the go to a continuous noise when you hit the spot), tighten up the clamps. Then take it to wherever else you want to transfer the level and move the staff up and down in the same way you did to locate the receiver. Might look intimidating, but it couldn't be easier and is used by labourers the world over.

[Jobbo]

If you hang a level on a string line, no matter how taut the line it will have a slight curve to it. So even if the spirit levels were accurate you wouldn't be able to measure accurately.

But we're talking here about two points that are more-or-less level to begin with, so as long as you attach the level more-or-less in the middle of the string, the deviation from the true level will be miniscule. Easily good enough for this project.

Not convinced. Ignoring the fact that over a long span even the smallest deviation from level will mean a noticeable difference in height at the ends, consider a slack string. Hang the spirit level approximately in the middle between two relatively close height posts and it will always indicate pretty much horizontal. Making the string tauter doesn't alter this, it just makes it look like you're measuring the right thing when you're not.

[duncs500]

Jobbo is correct, if the spirit level is in the middle of the line and reading level the line could (and probably is) sagging by a fair bit depending on length and how tight you're able to pull it.

Even one of those cheap laser string line things would be better than a normal string line IMO. Set it up say 50mm above the first base facing along the line and then go and dip a tape measure on each base seeing where the laser is shining on the tape (or dip stick). As long as they all match, you should be good (assuming you can get those things leveled to a good degree of accuracy).

[DeskJockey]

I'm talking about something like this:



So you set the receiver so that it beeps with the staff length you want for the level you want to transfer. Then you can just go round and transfer that level wherever you want.

I'd not suggest buying it, but you can hire for about £30 from HSS or someone I reckon.

That does not look like something I would be able to use!

Trust me, you easily could.

The lasers self level, so you set up the legs and screw it on top. Switch it on. Loosely clamp the receiver on to the staff, locate the staff on the level you want to transfer and move the receiver up and down until it hits the spot (it'll beep faster as you get closer, the go to a continuous noise when you hit the spot), tighten up the clamps. Then take it to wherever else you want to transfer the level and move the staff up and down in the same way you did to locate the receiver. Might look intimidating, but it couldn't be easier and is used by labourers the world over.

So. Much. Innuendo...

[duncs500]

I don't know why I didn't just link a YT video, there's one for everything. There you go @Mito Man



He gets you there in about 2mins 30secs (#innuendo), that's how easy it is.

[Sundayjumper]

...consider a slack string.

But we're not talking about a slack string. And we're not talking about hanging a significant weight on it either. It's easily good enough here.

I'll also offer some empirical evidence - string levels are a thing. If they didn't work they wouldn't be.

[duncs500]

Nobody is denying they are a thing, but they are used for line not level.

[duncs500]

Might not matter, but worth adding that I got paid to survey/set out for a few years (as many engineering grads do). I'm not just making it up as I go along.

[duncs500]

All that said, I'm just telling you the right and professional way. Is it necessary in this application? I don't know what tolerances Mito has in the structure that's going to sit on it... might not matter if it's a bit out of plumb (or you might be able to use packing and a spirit level if the bases are out).

[Jobbo]

...consider a slack string.

But we're not talking about a slack string. And we're not talking about hanging a significant weight on it either. It's easily good enough here.

I'll also offer some empirical evidence - string levels are a thing. If they didn't work they wouldn't be.

They aren't for this job.

If you consider a heavy mass and a slack string, then make the string tauter and the mass smaller, you have the same shaped curve, just flatter. Might be adequate for bricklaying, but not for levelling the two ends which will be some way apart.