Until now, most digital straight edges are used to assess the finished weld after grinding, e.g. in conjunction with national normative like AS1085.20, EN14730-1 etc.

The purpose of steddi ONE and steddi MINI, however, is different from measuring a finished weld, and they’re not meant for it. The added value of steddi ONE and steddi MINI is that they facilitate the alignment process before the weld by providing an easy-to-operate device, higher accuracy in practice, and the possibility to record proof of alignment.

In our experience, due to the challenging and time-consuming manual measuring with a feeler gauge, along with time pressure and the level of training of the welders, mistakes are made during the alignment that could be avoided. Poorly aligned welds are then difficult to grind, and too often, the localised peaks or depressions remain on track.

To assess a weld after grinding, please use steddi GO.

No, as with a 1m straight edge, steddi ONE and steddi MINI don’t indicate the twist between the rails. We once considered this during the development but then discarded it due to the complexity and the low added value.

The welder can hardly correct a twist between the rails, at least not with normal means. And the reference for the alignment of the rails is always the rail head. Additionally, the alignment in the foot is only checked with a 300mm ruler or any other straight edge, as the 1m straight edge cannot be used here anyway.

With the aforementioned in mind and to keep both steddi ONE and steddi MINI simple, we have therefore decided not to measure the alignment in the foot.

Yes, they can both be used for all possible transitions, regardless of the grade of wear. This includes the combinations new-new, new-worn and worn-worn.

No. The gap between the rails is created or adjusted before the alignment works start. Measuring the gap would require a different kind of laser scanning technique and would add a level of complexity to steddi ONE and steddi MINI, which we tried to avoid.

Where heavy wear has caused the rail to form a considerable flange or burr at the running edge, steddi ONE can’t be used to measure the horizontal alignment. Similar to using the manual straight edge, steddi ONE requires a smooth surface to measure correctly. A too strong flange with its irregular and not-straight surface, however, can cause steddi ONE to indicate false values for the horizontal alignment.
Of course, as this is regarding the running edge only, steddi ONE could still be used for the running surface.

However, if you primarily work in rail maintenance where rails are heavily worn and can have large flanges and burrs, we recommend using steddi MINI instead. Since steddi MINI measures the running surface of the rail only, it works irrespective of any possible irregular geometry of the running edge.

The following figure illustrates the working principle. It’s a simple application of the rule of three where, in this instance, the ratio of a 1m straight edge 500/1.8 mm equals 166.6/0.6 of steddi ONE or steddi MINI. To keep it simple and consistent, the displayed values, however, are the same as those measured with a manual 1m straight edge.

From a metrological point of view, the big advantage over a 1 m straight edge is that the welder can align the ends of the rails to precisely the same height without needing a feeler gauge. This provides much better preparation for subsequent grinding and ultimately improves the grinding result.