I thought I would do a comparison between the Heuer Bund and the Sinn 156 because a lot of accepted wisdom is that the two use the same case, and I wasn't so sure. I hadn't seen a direct comparison between them anywhere, so I thought I would do my own for general interest. This may seem a little boring, but I think it is worth it, so bear with me.
There is no doubt that the two are connected. Helmut Sinn's company had the maintenance contract for the Bund chronographs in service, and I have seen printed material showing that it was the Sinn company that sold many of the refurbished Heuer Bunds when they were de-commissioned from active service.
It is clear that the 156 was developed by Sinn in order to land a later generation of Bund supply contract, but it never came to pass, and the Bund chronos were procured from Porsche Design, Arctos, Tengler and Tutima. To my knowledge the 156 never saw issued service.
The 156 has had three main variations, most notably the first with two sub-dials (the 24-hr sub-dial at 12 was missing, much as if it were powered by the Lemania 5012, not 5100), the main variation (pictured here), and the later B variant which did away with the screw-retained movement barrel in favour of a conventional case design with screwed back.
Anyway, on with the comparison.
The first thing to note is the clear similarities. Case diameter, bezel, crystal size and format and lugs are near, if not exactly similar.
At the same time some differences are clear. The size of crown is different. However, this merely denotes that my 156 is a little later than some, as the Sinns originally started with the same crown as the Bund. The next is the pushers, with the diameter the same, but the Bund's pushers spaced further apart (around the case diameter) and also seeming to be longer, as the barrel underneath the cap can be seen outside the bezel, even though the camera is to the left, which would usually serve to disguise them to a greater degree than the Sinn.
How about the back?
This serves to exaggerate the difference between the pushers. A further detail emerges, with the outer case holes for the Sinn's pushers going the full thickness at full diameter, whereas the Bund has stepped holes.
As an aside, this design of case is intended to facilitate crystal replacement. The inner case is retained by the four scrrews shown here, and if they are undone, the movement can be removed through the back of the outer case, much as the the Omega 176.0012 does. The difference is that with these, the screws press the inner case to the front of the watch, which sandwiches the crystal (and gasket) between it and a lip at the front of the case.
Continuing with the comparison, the above also shows the crown is positioned also slightly further towards the caseback on the Sinn.
It also becomes clear that the retaining screws (for the inner case module) are slightly differently positioned. On the Sinn, the threaded holes overlap onto the base of the lugs, whereas on the Bund they are clearly inside the edge of the main case and do not protrude over the furrow at the beginning of the lugs.
However, all of these changes can be effected onto an identical case, as they represent post-manufacture machining. So, is the case the same?
No.
The first clue is above. Note the flattened area around the bubbleback. On the Sinn it is larger, and more noticeable. I reckon at 39.7mm as opposed to 38.8 on the Bund
Moving on, this side view clearly shows that the Sinn (top) has a significantly deeper barrel to the case (I measure it as 5.0mm as opposed to 3.8).
The crown/pusher side shows the same.
This difference shouldn't really come as a huge surprise. The 5100 is automatic, and the case must therefore accommodate a rotor. Clearly a taller movement needs a deeper case. I measure the total watch depths as 14.0 and 15.9mm for the Bund and Sinn respectively. 1.2 of these 1.9mm difference is in the barrel, the rest is in the bubbleback.
Lastly, here is another view of the pushers, from an oblique side
This shows the stepped holes for the pushers (on the Bund, on top), but also shows that the bubbleback on the Sinn is also not only deeper, but also the curve of the bubble extends further into the centre of the watch leaving a smaller flat area in the centre.
My conclusion of this is that the 156 is a total hommage to its illustrious forebear. The differences in barrel, pusher length, crown size and bubble back mean that although the company that manufactured it had access to the original watch, they used none of the original case parts whatsoever, and only retained the bezel and crystal.
This is not to detract from it. It is still a great watch (I would say that, the Sinn is mine and the Bund is Al's).
Hope this was of interest. It was fun, in a geeky stylee, to do, and I hope it furthers knowledge of this bizarre world we play in.
Cheers
DaveS |