[TowerTalk] Be Careful With the Tolerance in Laser Levels (Tower base leveling.

[Grant Saviers]

IMO, straight is more important than plumb (assuming reasonable) for 
guyed towers.  Otherwise the tower is being bent and has stresses not in 
the load calcs.   Pro tower installers use a level-transit at each 
anchor (two is enough) for tall towers to insure the guys are keeping it 
plumb and straight when guys are being tensioned.  A decent one is 
better than +/- 3/16" at 150'.  Easy to rent.   Pretty hard to eyeball 
that or keep a plumb bob unaffected by wind or thermals.

I think a 6' carpenters level properly used is good enough to get the 
bottom section plumb and they are certainly cheap and easy to check, 
even if made in China.  (Stanley 6' spec 0.036" over 6', $43)  It's easy 
to see 0.1" error. At 100' that is 1.7".  I think I measured my R65 
bottom section 4 times all around before pouring and at least 2 times 
afterwards.  One trick is to use offsets at both ends of the level so 
interference from galvanizing imperfections can be minimized.  For 
towers <80' a level and eyeball check of straight are probably good 
enough.  Laser levels - nice for drop ceilings, setting forms, and 
grading.  (the coolest is the dozer blade that follows the laser).

For fun, one could use a 3D mems accelerometer to measure tilt, even 
cheap ones (new cars have lots of them) have sub 1 milliG resolution for 
+/- 1G range.  1 deg of tilt is 0.983G Z axis output, so dynamically 
measuring your tower's sway in strong winds is not so hard.  Use X & Y 
to measure direction of tilt.  1 deg tilt at 150' is 2.6'

Now that is REALLY gilding the lily.

..snip..

Grant KZ1W

https://www.digikey.com/en/articles/techzone/2011/may/using-an-accelerometer-for-inclination-sensing
http://www.analog.com/media/en/technical-documentation/data-sheets/ADXL313.pdf
lots of Arduino and other boards available
http://www.littlebird.systems/products/adxl313-breakout/?gclid=Cj0KCQjwktHLBRDsARIsAFBSb6zX0xmEobuQKJnIMuxZDAoiTp6pd487_6-cqYjKR3lBCu0Holh3ARoaAvROEALw_wcB