Ski Drill Bits

[Gunder]

There has been some discussion in gear swap, about ski drill bits, so I figured I would cross post that information here, as most are more likely to look for it in tech talk and not a no-longer current gear swap thread.

It is usually best to follow the guidelines that the ski mfg prints on their skis, but here is the general guidelines.

3.6x7.5 used for kids skis only. A 9mm bit will likely drill through kids skis. A 4.1x7.5 is used for kids race skis with metal laminates but that is very usual.

3.5 x 9 or 9.5 Mostly used on foam core skis, or skis with softer cores to help improve screw retention.

3.6x9 or 9.5 Mostly used on non metal laminate skis.

3.8x9 or 9.5 Not very common, but does have uses.

4.1x9 or 9.5 Used for metal laminate skis as the wider tip is needed for the alpine tap.

I actually use a 3.8 bit a fair mount. Mostly to pre drill metal skis before stepping up to the larger 4.1 bit as that can be a bit tough to punch through on some metal skis. You can also use a 3.6 bit for that as well, but that keeps the 3.6's in good shape.

Sharp bits do make a difference. However the thickness and type of the metal laminate makes a bigger difference.

The bigger issue with drilling metal skis is that ski bits are genrally ground with an approximate 90 degree tip. That’s fine for most soft materials but a machinist would never use a drill with that angle as it’s way too dull for most metals. Good quality all around drill bits tend to have a tip angle of 115 degrees. Good metal drill bits have the tip angles ground between 130 and 140 degrees.

Compare the tips of these two high quality bits.



The top bit is ground to 115 that’s great for starting a pilot hole in metal but is not great for removing a lot of metal. The lower gold bit is ground to 135. It’s broader tip won’t start a hole as well, but is way better at removing material and it won’t dull as quickly. Especially when drilling harder metals.

Here is my various non-ski drill bit selection:

That’s everything from fractional, letter, number, metric, Brad point, fostner and even left hand drills. FWIW all of my machinist bits are made in the USA by Triumph. They are the sweet spot for cost / quality when it comes to drills and will give you at least 10x the life of cheap hardware store drills.

Now let’s look at the new shipment of ski drills I just got. Truth be told I’ve never examined ski drills this close as I get new ones every year.

The 3.5mm x 9 SVST drill is on the top. The 3.5x9.5 Wintersteiger is on the bottom. Both are high quality drills and both are well regarded by most ski techs.



The shorter SVST clearly has a much broader tip. I’m guessing it’s around 130. So that’s better for metal but not good for starting the holes. The Wintersteiger has a tip around 90 degrees. That’s great for starting holes or drilling in soft materials but it’s not ideal for drilling lots of metal skis. Its going to wear out quicker in metal. When the mfg switches, but the depth of the bit stays the same, so does the tip geometry in my limited samples, so guessing its not a mfg thing, but actually a spec for the 9.0 vs 9.5 bits. Which would make sense, as the thiner pointier tip, are longer to get the same screw engagement as the shorter broader tips.

So based upon all of the 9.0 and 9.5 ski drills that I have on hand it’s fairly safe to say the 9.0 bits have broader tips for drilling metal and the 9.5 have tips better for piloting holes and drilling non-metal skis. The caveat to all of this is that I don't have a drill bit angle gauge that can accurately read drills with tips as small as ski drills....so thats all based upon my eye balls.

Hope that clears things up. If anyone has any actual data on the drill bit tip dimensions I would love to see it, but have never seen that much detail in all of my years around the ski industry. I hope that helps clear things up.

[BC.]

Awesome reference…..thank you.

[gregL]

Wow. I thought I was on top of it with 4 sliding drawers for my bits and a new 4.1 x 9.5 Wintersteiger each season . . .

[jacob_dbu]

Wait so how often should I be replacing bits? Every 5 skis? Every 10 skis?

[gregL]

Wait so how often should I be replacing bits? Every 5 skis? Every 10 skis?

Depending on how much Titanal you're drilling through, you'll probably notice a difference in bite after ~15-20 pairs. Not a problem if you're using a jig or something to prevent the bit wandering; I'm sure plenty of shops do hundreds with a single bit. I get a new one for myself and let my friends use last year's. 3.6mm lasts much longer, because no metal.

[nickwm21]

Dirtbag version.

9/64” bit for non-metal skis
5/32” bit for metal skis.

Both you already own from that drill bit combo pack.

Make a stop with duct tape.


Sent from my iPhone using TGR Forums

[Gunder]

Dirtbag version.

9/64” bit for non-metal skis
5/32” bit for metal skis.

Both you already own from that drill bit combo pack.

Make a stop with duct tape.


Sent from my iPhone using TGR Forums

Drill bit stop collars are dirt cheap and way more accurate than duck tape.

https://www.amazon.com/Depth-Drill-C...55832399&psc=1

[galibier_numero_un]

Great reference. Last year, I filled in my set to include all of the 1/64" increments. I'm a wanker in comparison with you ;-)

I have some dying bits, and will check out some high speed steel ones made by Triumph.

I love your photos, BTW (https://www.grantgunderson.com).

... Thom

[TAFKALVS]

Dirtbag version.

9/64” bit for non-metal skis
5/32” bit for metal skis.

Both you already own from that drill bit combo pack.

Make a stop with duct tape.


Sent from my iPhone using TGR Forums

The many skis on TGR gear swap with crooked, off-angle screw holes thank you for your service.

[XXX-er]

any 5/32nd drill bit and a bottle of wine

[Cocximus]

any 5/32nd drill bit and a bottle of wine

+1 5/32. The cork makes an excellent stopper. Small hoses also work really well.

[XXX-er]

Set screwed Drill collars slip SO drink the bottle of wine wait 1 day before drilling thru the cork,

use the cork as the drill stop by sliding the drill in the chuck to leave the amount of drillage you need

if you fack it up all that happens is you don't drill deep enough but you can try again

Don't forget to use a punch so the bit doesnt walk

a 3 1/2 inch drywall screw makes a good punch

[skimaxpower]

Don't forget to tap all holes.

I mean, definitely tap all holes for skis with a metal layer. But you'll have way fewer spinners if you you tap all holes regardless.

[NWFlow]

Does the 0.5mm difference between a 9.0 and 9.5 matter at all really? I.e. will i die if i use a 3.6 x 9.0 if a 3.6 9.5 is recommended?

[Gunder]

Does the 0.5mm difference between a 9.0 and 9.5 matter at all really? I.e. will i die if i use a 3.6 x 9.0 if a 3.6 9.5 is recommended?

No. Most binding screws only gave about 8mm of actual engagement in the ski. For example here is a shot of some very clapped out dukes and those give 8.5mm of engagement due to the mounting holes in the plastic of the bindings having deformed overtime.


Of note in Marker's tech manual the specify a 9.5 bit. Both Salomon and Tyrollia spec a 9.0. Only reason I can think of that Marker specs the 9.5 is that they also sell their own bits and they are as you might guys 9.5. The bigger difference is in the geometry of the two type of bits I explained above.

[Gunder]

Don't forget to tap all holes.

I mean, definitely tap all holes for skis with a metal layer. But you'll have way fewer spinners if you you tap all holes regardless.

I only tap metal skis. The threads on alpine screws are designed to be self tapping in wood. The actual spec for these according to the Salomon tech manual is 4.0NM. In the past I have seen a few spec up to 4.5nm. Most tech manuals do not specify an actual torque value anymore. I suspect this is due to the variation in the ski cores. Metal laminate skis and withstand a higher toque then say a foam core or soft wood core.

The best way to prevent a screw from spinning is using a torque limiting screw driver. Wiha , PB Swiss , Wera make very good ones, but I can’t justify the cost. Actually, after looking these up today, they have come down a ton in cost since the last time I looked them up, so I just ordered the WERA one. We will see how it works.

I personally use a Festool CXS. It’s electronic clutch in screw mode is designed to stop at the exact same torque every time. Set to #6 is perfect every time on my unit. I just use a hand driver after to confirm.

[NWFlow]

Thanks, super helpful information!

[XXX-er]

just run it in til she spins and back off a 1/4 turn

but seriously folks this is a wood screw going into what is probably

A piece of wood

[Jason4]

It's good to have friends like you. How much beer do I need to bring to mount some AT bindings on some Wundersticks?

[JayPowHound]

I mark my taps for depth with a sharpee...

Just wanted to add as I haven't seen that mentioned yet.

[galibier_numero_un]

I mark my taps for depth with a sharpee...

Just wanted to add as I haven't seen that mentioned yet.

Good point! 5 and a half tuns has always worked for me.

... Thom

[XXX-er]

I mark my taps for depth with a sharpee...

Just wanted to add as I haven't seen that mentioned yet.

Assuming one was lucid enough to use a tap

wouldn't the tap stop going in the hole

when it runs out of hole ?

[Conundrum]

a 3 1/2 inch drywall screw makes a good punch

What's that in liters or however y'all measure things?

[Conundrum]

Assuming one was lucid enough to use a tap

wouldn't the tap stop going in the hole

when it runs out of hole ?

Yes. Pretty easy to feel. But that's not to say a tap has never caused a problem.

[Gunder]

It's good to have friends like you. How much beer do I need to bring to mount some AT bindings on some Wundersticks?

12 pack of good ipa.