Laser Level Calibration Check

An Eccentric Anomaly: Ed Davies's Blog

This evening I went up to the site for the first calm dry evening for a while to use my laser level to mark up the position of the centre stud for the east gable. While there I did a check of the level's idea of horizontal.

To use the laser level over any distance outside it needs to be a bit dark so I went up just about as the sun was setting. Sometime in the middle of the proceedings I took this photo showing the street lights in Lybster and the ships out at the wind farm to give an idea of the sort of light the camera was compensating for.

Last time I played with the laser like this I made marks on the end south main posts at nominally the same height according to the laser which was then shining eastwards from the porch/greenhouse through the house. Tonight I shone it in the opposite direction, westward through the (not yet existing) gable on the main bedroom. The post with the mark is the one on the left of the picture.

Tweaking the height of the tripod put the laser line on the mark from last time. (Yeah, that post will need a sand, I did the tie beam above it and the top of that post and its friend to the north a couple of weeks ago.)

Up at the west end of the house it was a bit darker with the gable up so it was quite awkward to photograph the laser and the old mark. It was too dark for the camera to autofocus; this is the best of my attempts at manual focus:

The beam is noticably fatter at this distance but nicely centred around the marks so I'm happy that the level is, indeed, level.

That's over a distance of just over 16 metres (16.2 plus a bit for the thicknesses of the gable walls which I can't remember off the top of my head and has been fiddled with anyway). For scale, that's a 145mm square post sandwiched between 20 mm EPS and 18 mm ply.

Then on to the main act of the evening: taking a line down from the ridge beam to the east gable tie beam and edge beam. Laser on tripod on some OSB offcuts stored in the kitchen:

Laser line on the ridge beam (two runs of 18 mm ply sheets alternately bolted together):

Shining on tie beam and scaffold tower ready for marking. The aluminium handrail of the scaffold tower might have been helpful to pick up the beam but actually it was dark enough by then that it was easy to see.

Forgot, though, while it was calm and the scaffold tower was up to poke a bit of batten up to the ridge beam to get the exact measurement to the tie beam. Doh!