Digital-free accuracy

In the modern workshop, indeed in many walks of life, digital is the new sliced bread (you know: “The best thing since sliced bread”).  Digital this, laser guided that, and that isn’t necessarily a bad thing.  Sometimes it goes too far (laser guided jigsaws – give me strength, and worse, the laser-fitted handsaw!) but as a general rule they are very convenient, and accurate enough for the task.

However, there is also a tendency to use this very cheap, accurate technology to offset a decreasing quality in manufacture.

Now I’m not knocking digital accuracy systems in themselves- there is too much of it in my workshop that I’d be a right hypocrite if I did.

Digital is a pretty new inclusion though, and we’ve been managing high degrees of precision well before LCD readouts, self-leveling lasers etc became a common feature.

Take the humble level – a device used in one form or another for centuries, even millennia.  In ancient Egypt, over 4000 years ago they knew about using water as a reference to determine whether a platform was level or not.  There are modern devices, self-leveling , or at least can be zeroed off from a reference point.  Pity many of these are not checked back against a known level surface (such as one set using a flexible water tube-level)

The primary tool before the digital age kicked into high gear (and a tool still very much in common use even so) is the bubble level, or spirit level.  A sealed tube with a fluorescing-yellow/green liquid, and a bubble of air that moves off-centre as the level is tilted.

It is a very functional tool, low-tech and gives a quick reference if something isn’t as flat as it could be.  The tube itself has a radius to the wall sides (they are curved) otherwise the air bubble would spread over the whole surface when level, and would drift to one end immediately that the level was lifted.  Instead the air bubble works its way along the curve of the tube side as the level increased in angle.  The radius of the wall sides is typically 200mm.  But what happened if you decreased the curvature closer to flat, and had instead a radius of say 1000mm?  The accuracy and responsiveness of the bubble-tube would jump dramatically.

Enter stage left, the BMI SuperRobust R1000.  It is 1200mm long (there is also a 600mm version), and instead of being a basic box-section, has a 4-chamber cross section with 2mm wall thickness for very high levels of torsion resistance.  (These can be seen by removing the rubber end-caps, which are designed to be removed easily when required).

Torsion resisting cross-section

The level vial is a reflexion-free horizontal vial with a magnifying effect.

Simulated example of Reflexion-free horizontal vial

It prevents the creation of the optical illusion of 2 bubbles from some angles, and the magnification makes it even more accurate, and as the name suggests (R1000), the vial has a radius of 1000mm giving a claimed 5x more accurate response when determining whether a surface is level.

Typical level vs BMI SuperRobust accuracy

Simulated example of accuracy

The bottom edge of the SuperRobust is milled,  and overall the accuracy of the level is quoted at 0.3mm/m

There is one off-centre handle, that I find is actually very well placed – not too far off-centre that it is uncomfortable, and it feels nicely balanced in the hand (the overhang presses against the underside of the arm, giving the impression that the level is an extension of the arm itself).  Even the inside of the handle has a soft rubber surface – attention to detail.

There is a short video available at www.bmi.de (yes, this at least is still a German product, German engineering), and are imported to Australia by Promac.  These levels are brand-new to the marketplace.  Digital-free accuracy.  Decent engineering – it is a beautiful thing.

Guess my old level will be used only for non-critical operations- it can be used for such tasks as spreading and leveling sand and stones (and occasionally wet cement) (damhikt!)

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