I've been considering getting one of these for a while, but was confused by the different models and the lack of basic detail in the ads for them.
I finally splashed out on one and now I know what makes it tick, I'll try and describe it...
There were three types on offer, a £9.99 one with a tape measure and two different models types with the same makers name at £19.95. This was in Boyes at Whitby, if anyone I only looked at the latter two. Type 1 only seemed to produce an horizontal line and made no mention of 'pendulum'. Both boxes suggested better than 1mm per metre accuracy and a range of 100ft. So I grabbed type 2 which offered both for the same money, with not much idea of how they worked.
It came in a small yellow plastic suitcase style box, with laser head, tripod, a set of batteries and a small (very) instruction leaflet.. The tripod had single leveling bubble on it which was much further out than my own guess at level, other than that it was more than adequate to the job. Three lockable slide out legs for rough height adjustment, then a crank out top section for the final accurate height setting. Together they allow for around 18" to 65" of height setting.
The laser head screws on top with two more bubble levels and three micro level adjusters, to enable you to get the head level. I wasn't impressed with it at this stage with its potential or reproducable accuracy at all, though it seemed not too far out. Once the cells were in and the unit turned on, I found it had two laser beams produced from two diodes, producing a wide fan of vertical and horizontal line (both around 100 deg wide), about a 1mm wide.. Each separately switched so you could use H or V or H and V combined. The head once set for height, can be just rotated 360 deg, to place a H or V line anywhere on any of the four walls, calibrated around the base in degrees.
Then I glanced through the leaflet and found that a transit bolt had to be undone to enable the internal pendulum to swing free. The twin laser system is co-mounted on a pendulum - able to swing around 5 degrees, so all my efforts to get the head perfectly level using the bubbles had been a waste of time - my eyeball level would have been near enough. So far as I could tell, the beams spead is produced entirely by lenses, rather than any moving parts. So the line produced is quite dim and not much use out of doors in daylight.
Brilliant piece of DIY kit :-) I then checked the accuracy of the vertical and horizontal lines against my engineering level (accurate to .000 something mm per metre) and found it to be as near as I could tell spot on, on both axis.
The above level was one I used with various lengths of wood to get some dado level in place a few weeks ago, so I checked the dado with the laser. According to the laser level, I had drifted about 3mm during the long frustrating process of transferring levels around the hall, around doors and stairs etc..
Harry (M1BYT) (L)
Harry (M1BYT) (L)
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