OH DEAR…. Now you have me thinking. What bad things do you have to say about
the digital levels available in the big box stores? I am using one to check
the plumb of a Rohn 55 tower I am putting up. It is on a rotating joint and
the guys can be used to adjust the plumb. When I put it up the first time I
used a bubble level and it operated flawlessly for 28 years. So now do I have
to be worried about the new digital level I just bought?
Really, guys, aren’t we gilding the lily just a bit? Even on a self supporting
base, which has less adjustment that a rotating bearing, I would think that you
can get it “straight enough”. We have been putting these things up for years
and I haven’t seen any news reports of “leaning towers”.
Just a bit of tongue in cheek here — 73,
Dave, K4TO
ps— my Rohn 55 is already at 55 feet, including the rotating base. It is on
its way to 153 +/- feet and is looking “straight as an arrow”. The extra odd
footage is due to the short base section with the rotary joint and rotator on
it, plus the top section is only 7 or 8 feet. I forget which.. At my age
(75), the doctors (and my wife) would like me to quit climbing, so I
reconfigured my 200 ft Rohn 55 with the rotary joint at 50 to this
configuration with the rotary down where I can stand on the ground and service
it. I figure it will be easier to get volunteers to climb to 150 than it would
be to 200 feet. I still climb to 60 feet or so. I’m feeling great.
> On Jul 23, 2017, at 7:02 AM, Patrick Greenlee <patrick_g@windstream.net>
> wrote:
>
> Roger, What did you use to measure the error in the water level. My
> experience with water levels vs 4 ft and even 8 ft spirit levels shows the
> water level to be as close as I could read it, essentially zero instrument
> error.
>
> I second the disparaging comment posted here regarding cheap Chinese laser
> levels. I have a transit and find it no better than the water level.
>
> For a water level I use garden hoses with clear plastic extensions. The
> extensions are sold to use for filling RV water tanks. A small tipped
> marker pen can scribe a narrow line on each when the water is not disturbed.
> Some of the plastic extensions have 90 degree ball valves incorporated which
> makes it easier to move the hoses around without spilling water.
>
> Patrick NJ5G
>
>
> On 7/23/2017 1:25 AM, Roger (K8RI) on TT wrote:
>> I've never been able to successfully use a plumb bob for more than about 10
>> ft vertical outdoors. The repeat ability just isn't there for here, at
>> least not enough to trust it enough to make adjustments. It may be
>> absolutely still on the ground, but above 30 or 40 feet a breeze so light
>> you can hardly detect it can produce a substantial deflection of several
>> inches at ground level.
>>
>> Be careful with water levels. I've seen as much as an inch or more in 3 feet
>> and when the ends were paralled, there was still the same deflection. This
>> as in 1/4/, 3/8ths, and 1/2 inch Tygon. It was worse when antifreeze was
>> mixed in the water (used in some unheated garages and sheds). Water levels
>> are commonly used in building home built aircraft. The big box store laser
>> transits and levels for home construction were close enough for 18 to 20'
>> fuselage construction, but on an 18 to 24" tower base?
>>
>> 73, Roger (K8RI)
>>
>> On 7/23/2017 Sunday 1:40 AM, Clay Autery wrote:
>>> I'll use a combination of plumb bobs and water tubes.... gravity is
>>> remarkably more consistent than laser levels made in China. ;)
>>>
>>> ______________________
>>> Clay Autery, KY5G
>>> MONTAC Enterprises
>>> (318) 518-1389
>>>
>>> On 7/23/2017 12:00 AM, Roger (K8RI) on TT wrote:
>>>> When using laser levels there is a tolerance of +/- Something per ft,
>>>> yard, 10 feet, etc. It's often a lot more than acceptable for
>>>> leveling a tower base.
>>>>
>>>> I have two, a transit and a level. Setup and calibration are
>>>> critical. I have a plain old combination bubble and 3 digit, digital
>>>> level. Two digits to the right of the decimal is more than enough.
>>>> Calibration is easy. Find something close to level (level is not
>>>> necessary, but convenient) The two points should be about the same
>>>> distance apart as the bolts. You can even use those bolts, getting
>>>> them close with the bubble. Then you simply turn on the digital mode,
>>>> set the level on the nuts and push a button, swap ends with the level
>>>> and push a button. The digital level is now zeroed.
>>>>
>>>> NOTE: The calibration points must be STABLE! The nuts can not be
>>>> loose. The digital level properly zeroed is more accurate than the
>>>> laser transit or level you can purchase at the big box stores that
>>>> require much more care in calibrating. A surveying laser transit (A
>>>> lot more money) is accurate, but still takes care in calibrating.
>>>>
>>>> Were I to go that route, I'd rent a surveying transit, but being
>>>> frugal (some would say cheap) and a bit lazy, I'd use my digital
>>>> level. I have it, know how to use it, and with a fresh 9V battery in
>>>> it being the only cost.
>>>>
>>>> I've seen manufacturer's suggestions to use a plumb bob. Now depending
>>>> on where you live, dead calm days may be rare. We might have 3 or 4
>>>> days a year where it's dead calm long enough to use a plumb bob on a
>>>> 60 - 100 ft tower and a plumb bob is far more work than these other
>>>> methods
>>>>
>>> _______________________________________________
>>>
>>>
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>>
>>
>
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