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UK diy (uk.d-i-y) For the discussion of all topics related to diy (do-it-yourself) in the UK. All levels of experience and proficency are welcome to join in to ask questions or offer solutions. |
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#1
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spirit level bubbles - calibration marks/meanings?
Hello
Every spirit level I have owned (you know, the standard Stanley thigs a yard long, with a vial filled with green liqwuid) has got two marks at each end of the vial - two thin lines close together at one end, and the same at the other. Clearly when the bubble is centred the level is flat, but what's the graduation of these two lines at eaither end? If the bubble touches the inner line and then moves to touch the outer line, is it standard to be able to say that the inner line is so many degrees away from horizontal, and the second line is thus so many extra degrees? DDS |
#2
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spirit level bubbles - calibration marks/meanings?
Duncan Di Saudelli wrote:
Hello Every spirit level I have owned (you know, the standard Stanley thigs a yard long, with a vial filled with green liqwuid) has got two marks at each end of the vial - two thin lines close together at one end, and the same at the other. Clearly when the bubble is centred the level is flat, but what's the graduation of these two lines at eaither end? If the bubble touches the inner line and then moves to touch the outer line, is it standard to be able to say that the inner line is so many degrees away from horizontal, and the second line is thus so many extra degrees? It's down to drainage angles for gutters and other things. Dave |
#3
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spirit level bubbles - calibration marks/meanings?
"Dave" wrote in message ... Duncan Di Saudelli wrote: Hello Every spirit level I have owned (you know, the standard Stanley thigs a yard long, with a vial filled with green liqwuid) has got two marks at each end of the vial - two thin lines close together at one end, and the same at the other. Clearly when the bubble is centred the level is flat, but what's the graduation of these two lines at eaither end? If the bubble touches the inner line and then moves to touch the outer line, is it standard to be able to say that the inner line is so many degrees away from horizontal, and the second line is thus so many extra degrees? It's down to drainage angles for gutters and other things. Dave Please expand - I'll be putting some guttering onto the summerhouse fairly soon, and this sounds like useful knowledge. Cheers JW |
#4
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spirit level bubbles - calibration marks/meanings?
Duncan Di Saudelli wrote:
Hello Every spirit level I have owned (you know, the standard Stanley thigs a yard long, with a vial filled with green liqwuid) has got two marks at each end of the vial - two thin lines close together at one end, and the same at the other. Clearly when the bubble is centred the level is flat, but what's the graduation of these two lines at eaither end? If the bubble touches the inner line and then moves to touch the outer line, is it standard to be able to say that the inner line is so many degrees away from horizontal, and the second line is thus so many extra degrees? I have always believed that the idea was that, when looking at the bubble, you place your eye so that the four lines appear to be symmetrical. This ensures that you are looking perpendicular to the phial centreline, and thus minimise parallax error. Chris -- Chris J Dixon Nottingham UK Have dancing shoes, will ceilidh. |
#5
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spirit level bubbles - calibration marks/meanings?
On Sun, 18 Apr 2010 21:30:00 +0100, "Duncan Di Saudelli"
wrote: Hello Every spirit level I have owned (you know, the standard Stanley thigs a yard long, with a vial filled with green liqwuid) has got two marks at each end of the vial - two thin lines close together at one end, and the same at the other. Clearly when the bubble is centred the level is flat, but what's the graduation of these two lines at eaither end? If the bubble touches the inner line and then moves to touch the outer line, is it standard to be able to say that the inner line is so many degrees away from horizontal, and the second line is thus so many extra degrees? The angle to move from the centre to the end of a vial is dependent on the curvature of the vial, think of a vial as a segment chopped out of a large clear tubular ring. The bubble in a small diameter ring say 1ft diameter will be much more sensitive and move more with a small angle change than a bubble in a large diameter ring of 10ft diameter -- |
#6
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spirit level bubbles - calibration marks/meanings?
...think of a vial as a segment chopped out of a large clear tubular ring... Modern ones seems to be straight bi-conical tube, rather than a parallel-sided curved tube. Mine will show a true level regardless of whether the level is sat on its narrow face or wide face - now and again quite a useful thing. |
#7
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spirit level bubbles - calibration marks/meanings?
John Whitworth wrote:
"Dave" wrote in message ... Duncan Di Saudelli wrote: Hello Every spirit level I have owned (you know, the standard Stanley thigs a yard long, with a vial filled with green liqwuid) has got two marks at each end of the vial - two thin lines close together at one end, and the same at the other. Clearly when the bubble is centred the level is flat, but what's the graduation of these two lines at eaither end? If the bubble touches the inner line and then moves to touch the outer line, is it standard to be able to say that the inner line is so many degrees away from horizontal, and the second line is thus so many extra degrees? It's down to drainage angles for gutters and other things. Dave Please expand - I'll be putting some guttering onto the summerhouse fairly soon, and this sounds like useful knowledge. Cheers Will do when I get it confirmed tonight. Dave |
#8
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spirit level bubbles - calibration marks/meanings?
On 19 Apr, 12:28, The Other Mike
wrote: The angle to move from the centre to the end of a vial is dependent on the curvature of the vial, think of a vial as a segment chopped out of a large clear tubular ring. * The bubble in a small diameter ring say 1ft diameter *will be much more sensitive and move more with a small angle change than a bubble in a large diameter ring of 10ft diameter Are you sure you have that the right way around? For a given angular displacement the bubble in a large diameter tube will move further than the bubble in the small diameter tube, giving finer granularity when observing a small change. At the extreme, a straight tube would be most accurate as any deviation from level would send the bubble straight to the end of the vial. |
#9
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spirit level bubbles - calibration marks/meanings?
The Other Mike brought next idea :
The bubble in a small diameter ring say 1ft diameter will be much more sensitive and move more with a small angle change than a bubble in a large diameter ring of 10ft diameter T'other way round I think 8-o -- Regards, Harry (M1BYT) (L) http://www.ukradioamateur.co.uk |
#10
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spirit level bubbles - calibration marks/meanings?
Dave wrote:
John Whitworth wrote: "Dave" wrote in message ... Duncan Di Saudelli wrote: Hello Every spirit level I have owned (you know, the standard Stanley thigs a yard long, with a vial filled with green liqwuid) has got two marks at each end of the vial - two thin lines close together at one end, and the same at the other. Clearly when the bubble is centred the level is flat, but what's the graduation of these two lines at eaither end? If the bubble touches the inner line and then moves to touch the outer line, is it standard to be able to say that the inner line is so many degrees away from horizontal, and the second line is thus so many extra degrees? It's down to drainage angles for gutters and other things. Dave Please expand - I'll be putting some guttering onto the summerhouse fairly soon, and this sounds like useful knowledge. Cheers Will do when I get it confirmed tonight. Phoned my b.i.l. up an hour ago, he has been in the building trade since he left school and has only ever seen levels with 2 lines and not 4, So my original answer could be wrong. I'll keep asking and if I find anything out I will post again. Dave |
#11
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spirit level bubbles - calibration marks/meanings?
On Mon, 19 Apr 2010 19:20:10 +0100, Harry Bloomfield
wrote: The Other Mike brought next idea : The bubble in a small diameter ring say 1ft diameter will be much more sensitive and move more with a small angle change than a bubble in a large diameter ring of 10ft diameter T'other way round I think 8-o I knew what I meant, even though my fingers didn't -- |
#12
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spirit level bubbles - calibration marks/meanings?
"Dave" wrote in message ... Phoned my b.i.l. up an hour ago, he has been in the building trade since he left school and has only ever seen levels with 2 lines and not 4, So my original answer could be wrong. I'll keep asking and if I find anything out I will post again. Dave OK - cheers Dave. JW |
#13
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spirit level bubbles - calibration marks/meanings?
On Monday, 19 April 2010 17:39:42 UTC+1, pcb1962 wrote:
On 19 Apr, 12:28, The Other Mike wrote: The angle to move from the centre to the end of a vial is dependent on the curvature of the vial, think of a vial as a segment chopped out of a large clear tubular ring. Â* The bubble in a small diameter ring say 1ft diameter Â*will be much more sensitive and move more with a small angle change than a bubble in a large diameter ring of 10ft diameter Are you sure you have that the right way around? For a given angular displacement the bubble in a large diameter tube will move further than the bubble in the small diameter tube, giving finer granularity when observing a small change. At the extreme, a straight tube would be most accurate as any deviation from level would send the bubble straight to the end of the vial. yes I think you are right. |
#14
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spirit level bubbles - calibration marks/meanings?
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#16
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spirit level bubbles - calibration marks/meanings?
newshound was thinking very hard :
Not sure about the parallel with Chilcot but the description of vial geometry is completely wrong, (proper) vial interiors are barrel shaped. I agree with the barrel interior shape, but the net result is that the curvature of the 'up side' will still form a segment of a circle. |
#17
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spirit level bubbles - calibration marks/meanings?
On 26/04/2017 21:27, newshound wrote:
the description of vial geometry is completely wrong, (proper) vial interiors are barrel shaped. I just checked. Both my levels have curved tubes. If you are about to say "Then they aren't proper" I refer you to the No True Scotsman fallacy. Andy |
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