3.6 vs 4.1 drill bit

[Woodserson]

I have usually been mounting my skis with a 3.6 drillbit but I have a pair of skis with 4.1 written on the topsheet next to the drill icon. 3.6 works well with the Voile bindings I use, but I think I should defer to the ski manufacturer? There is not metal in the ski. Thoughts? I don't have a 4.1 I'd have to buy one.

[fisheater]

I use SAE sized drill bits, and make the metric conversion. I have a set that has a lot of 64th and 32nd sizes. I've been doing it since the 80's, alpine and Telemark. Not saying it's the correct thing to do, but I will stay with it. I think that I am really being professional when I use electric tape to make a shoulder stop. I started in the tool shops before I went into the construction industry. I held a lot of +/- .0001" tolerances, I don't see the need to be that precise with skis. Btw I didn't make a mistake with the decimal point

[Woodserson]

So just go with what I have in the 3.6? I didn't know if there was a technical reason when the ski doesn't have metal. I hear a titanal layer wants the 4.1 for some reason (according to Tognar) but if the 3.6 has been working for me in all my skis I couldn't puzzle out a solution.

I'm a pretty big hack too, I have/had electrical tape stops too (until I bought a jig and a bit) and it was always good enough.

Anyway, thanks for the confidence

[fisheater]

The titanal layer can bubble up if the pilot hole is too small. I have planed those little bubbles with a sharp wood chisel to keep the mounting surface flat. The bubble I planed has always been top sheet.
If I was running a shop, I would be by the book. It would be a PITA, to start over. However, you could turn the first screw in and pull it to check results. I would just use a little bit of Titebond for lubrication for the first time in.
Good luck, waiting for the first Chuck Flannel video of the winter of 18/19!
Btw. I did the math, the difference between 3.6 mm and 4.1 mm is .021". 1/64" is .0156". I don't believe it is significant.

[Rodbelan]

Usually, if you have a metal plate reinforcement, the recommendations will go for 4.1... If the ski is solid wood, it will be 3,6... as simple as that...

[Woodserson]

Usually, if you have a metal plate reinforcement, the recommendations will go for 4.1... If the ski is solid wood, it will be 3,6... as simple as that...

Well, yes, as I mentioned. My question was more why would a non-metal ski ask for 4.1?

[dnt_upton]

Well, yes, as I mentioned. My question was more why would a non-metal ski ask for 4.1?

What skis you got? Could you be wrong about the metal? Is there metal just in the binding plate? Or perhaps carbon fiber in the topsheet? Using 4.1 for a non-metal ski seems unicorn rare to me.

Softer materials such as wood or plastic will compress when driving a screw into a 3.5mm hole. You should use the 4.1mm bit for non-compressible materials like metal and carbon so the shank does not compress and damage the material while being driven into the ski.

[Rodbelan]

Agree with DNT... What is the ski? Sometimes, you need to drill to find out about the metal retaining plate under the binding location... The makers aren't so specific about it, specially if you take the touring skis; I had once to talk to several different techs from Rossi to figure what was that plate in the new and lightweight Seek 7...

[Woodserson]

It's an Atomic Bent Chetler 100. As far as I know, no metal.

But then there's also a Black Crow Camox Freebird lurking around the basement with a titanal re-enforced binding area and they say to use a 3.6.

[dnt_upton]

Maybe then it's due to what Atomic calls the "ultra-lightweight carbon insert that runs the length of the ski like a stabilizing backbone." In any event, I see no harm in using the 4.1 bit.