QC LAB: Remounting previously drilled skis
Before any piece of Black Diamond gear makes it on to the shelves, it spends months, sometimes years getting put through the wringer by our Director of Global Quality, Kolin Powick, and his team of Quality Assurance engineers. Through extensive and meticulous testing, both in the lab and in the field, KP and his team help ensure that you can count on your BD gear to be as durable, reliable and as strong as possible every time you head into the mountains or out to the crags. Our QC Lab posts aim to answer some of climbing's most common gear-related questions. This month, KP and the crew tackle the issue of mounting a pair of skis that have been previously drilled one or more times.
[Photo: Grant Gunderson}
We get two main questions when it comes to mounting bindings on skis:
- Which method should I use—glue, epoxy, no glue?
- Can I re-use holes in skis to re-mount and/or how close to previous holes in my skis is it ok to drill?
We decided to tackle number 2 today, and we'll leave the first for another day (for the record, BD recommends using a slow-set 2 part epoxy to mount your bindings).
A lot of seasoned ski techs have their own rules of thumb when it comes to re-using pre-existing holes (not recommended) or how close to drill. So we had our tele-charging, QA Engineering wizard, Andy Rosenberg, perform our standard, not-overly-scientific-limited-data-point study to see what kind of differences we got when drilling holes and mounting screws varying distances from pre-existing holes.
Once again, this is not comprehensive, just some info—do with it what you will.
- 3.6x9.0 drill
- Standard penetration depth
- Pre-existing holes had a screw run in and out (no actual binding mounted)
- BD O3 screws
- No glue or epoxy used
- All tests performed on one BD ski
- Distances measured center to center
- Each distance had its own baseline data point taken
Comments and Conclusions
As usual, this is super limited data - there is much more that could be done to get a more conclusive look at the situation:
- Use pre-existing holes that have actually had bindings mounted and have been skied hard
- Use many different types of skis (wood only, with metal, sidewalls, etc) Note: the BD ski we used is known as being particularly burly
- Try different type of screws; different screw pitch in pre-existing holes
- Do the tests with wood glue, or epoxy in the pre-existing, or new, or both holes
However, given this test, it looks like you may want to stay 7mm away or greater in order to attain maximum strength when drilling next to pre-existing holes.
There you have it. Pray for snow.