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06-16-2012, 08:30 AM #1Gu-powered Tech bindings
- Join Date
- Dec 2004
- Amherst, Mass.
Tolerances for ISO 6004:1991 Alpine Ski Binding Screws?
I suppose we could pony up the $ to buy the pdf, but speculating is more fun, right?
Based on measuring a couple dozen alpine screws of all sorts of sizes and vintages, I'm finding a very consistent ~5.4mm major diameter ... except for Dynafit Speed heel screws at ~5.7mm. Any other exceptions like that?
Pitch is very consistent at ~1.8mm (measured at 9mm across six crests).
Minor diameter I can't measure accurately.
Thread form, hard to say -- some seem "sharper" than others, but could just be the color, etc.?
Nordic screws are definitely different, but they have their own ISO 7794:2011, so that makes sense.
06-16-2012, 11:49 AM #2
That seems right. In my box of 28 different alpine binding screws, including screws for Salomon, Marker, Look, Tyrolia and Geze, the major diameter ranges from 5.34 to 5.49 depending on the individual screw and the precise cross section you are measuring. Average is around 5.4 even though they are all nominally 5.5.
06-17-2012, 01:46 AM #3not awesome
- Join Date
- Mar 2011
I bet if you buy some #12 sheet metal screws (NOT wood screws) at the hardware store, they will measure very similar and have a thread depth that looks similar. The Nordic screws I looked at seemed to have a deeper thread but same pitch.
#12 sheet metal screws are easy to get, but harder in stainless, and pretty impossible with a Pozidriv head. Lengths may or may not be ideal. Occasionally useful for spares/projects.
06-17-2012, 08:36 AM #4
A ski binding screw thread is a ST5.5x1.8 were:
The ST prefix = self-tapping.
The 5.5 = 5.5mm outside thread diameter
The 1.8 = 1.8mm pitch
The nearest imperial thread size is a 12AB which in metric is a M5.3x1.81. Because it's so close to the binding screw spec & is more readily available it's the 12AB taps that are used to tap the metal top sheets for skis.
Don't have any info re the thread size tolerances.