It actually gives you a line, which may (or more usually) may not be
level. A few weeks ago I was measuring across a large room using the
high tech measure (hose pipe with bits of clear tube stuck in either
end and filled with water) when a "consultant" came in (his card said
"BA (design for buildins)" (sic) Luton" - which I think is the modern
day version of "BSc (Calcutta) (failed)" for those that remember the
proper version of "1066 and all that" before it was sanitised)).
He wore a shiny grey suit and white socks with black plastic shoes.
Producing his laser level and balancing it on a remarkably shoddy
tripod he proceeded to mark off "levels" which were a good 5" out
from my water level.
When questioned he questioned whether or not my hosepipe had a
calibration certificate and if not how did I know it was accurate.
When asked if he knew about gravity he wanted to know if they were
Investors in People certified (which his organisation apparently was)
and if not his levels were more level than gravities, no matter who
they were, because his were certified.
For his next trick he has to make water flow uphill, but I haven't
mentioned that to him yet.
Suited idiot aside, I've had a hose level be off... I'd checked it
against itself, and it was off by half an inch. Turned out I'd missed
a bubble in the non-transparent bit.
If I had to use one frequently and wanted a "permanent" one rather
than putting one together from bits when I wanted one, I'd use clear
tubing throughout. (Then algae would probably grow in it...)
The real problem with water levels is 'stiction'. I made a level using 1/4"
bore clear plastic tube which I had lying around, and found it virtually
useless as I could get the water to settle anywhere in about a +/- 30mm band.
This seems to be due to the stiction of the water to the inner surface of the
Peter should have somewhat better luck with a wider bore, such as a hose pipe,
but it will have some residual uncertainty. I would be interested to know if
there are any tables (or calcs) that relate length and bore to uncertainty.
Well, obviously there are - what I mean is where are they.
The uk.d-i-y FAQ is at http://www.diyfaq.org.uk /
Remove NOSPAM from address to reply
On Fri, 02 Jan 2004 18:52:40 GMT, Phil Addison wrote:
Drop of washing up liquid added to the water would probably cure that
by destroying (or at least much reducing) the surface tension.
Untested mind but that is what I would try but agree 1/4" tube does
seem a bit narrow to be particulary successfull.
Dave. pam is missing e-mail
On Sun, 14 Dec 2003 16:40:22 +0000, Paul Mc Cann
Many thanks for all the suggestions.
As I rather suspected its back to paper and string.
Using a stick or staff to transfer the datum to a point higher up is a
possible error inducing step.
Having then to join two such transferred marks allows more errors to
Methinks I'll stick with a 1200mm spirit level,string level or water
in transparent hose. ( As someone said, they once had an error in
using a water level device. I had a similiar problem which I didn't
spot in time. I assumed I made an error in setting the two level
markss but I suspect his suggestion that a bubble was trapped in the
pipe was the most likely. I'll be more confident trying that method
the next time. I suppose a little food coloring in the water would
allow any potential bubble trouble makers be spotted .
Paul Mc Cann
All levelling operations can induce errors. You are more likely to introduce
a considerable error in setting up the level, than you ever would by
transferring a mark with a staff
For the majority of domestic or other non structural purposes, these normal
errors can be ignored
I can't agree. The possibility of not getting the staff vertical (
which probably necessitates using a plumb line) is the first
opportunity for errors to creep in . And this has to be repeated for
each positioning mark
Then one is left trying to transfer a mark up to and beyond arms
reach. Step ladders may have to be used.
The staff may have to be affixed to the wall with accuracy.
Two sightings would have to be made for every mark
Sod law will dictate that there will be many times when the use of the
staff would be obstructed by existing fittings.
All in all, I think if the laser level could be made do the job, I'm
going to get a damn sight more accuracy with that than faffing about
I'm well able to set up a level having used dumpy levels many years
ago. Anyway its only a matter of centreing a bubble, not exactly
Big assumptions you are making there. Who said we were restricting
ourselves to domestic or even non structural purposes.
The reason I was toying with getting a laser level is the regular
requirement we have to fix runs of storage cupboards at varying
heights. The runs can be up to 60 feet long and include
circumnavigating alcoves etc.
Paul Mc Cann
I was using non-transparent hosepipe, with bits of clear tube bodged
on the ends. If I needed such a level more often, I'd use some clear
tubing. Maybe even add valves at the end so it can be left filled, and
then also moved without emptying...
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