Tap guide is a block of steel or plastic, with holes that hold your tap perpendicular to the work surface.
I’ve you’ve got steady hands and a courage, perhaps thread tapping ski screw holes without a tap guide is ok. I do it myself quite often, but in general do not recommend it.
Tap guides are simple. They’re a block of steel or plastic, with a hole that holds the tap somewhat perpendicular to the ski topskin. They’re inexpensive and easy to find. No reason not to get one and use it.
(Back to basics, what exactly is a “tap?” Just a tool with sharp “cutting” threads that makes grooves inside a hole you drill, so a screw can follow the groves. Why is this necessary? Ski screws are just glorified wood screws. They cut their own threads if asked to, and sometimes can damage the drill hole if the threads don’t catch and pull the screw downwards. More, the specified diameters for ski binding mounting screw holes are tight, and without tapping the insertion of a screw can inordinately bulge the ski’s structure.)
We have lots of content here at WildSnow dot com regarding ski binding mounting, drilling screw holes and tapping. For example, check out this post. And be sure not to miss our series listing recommended tools for ski work.
(A previous post in this position was written by Jonathan Shefftz. As part of our ongoing effort to currat our existing content, the original post required updating and general rework, as a result Lou entirely rewrote the post so we changed the authorship.)
27 comments
I have a small flat piece of maple that I carefully put a drill press guided hole through. Cheap, though I don’t mount too many bindings these days.
Of more interest to me is :
1- tapping in general. In the metal top sheet days we tapped everything. I remember a plastic Solomon mini brace & tap. It wobbled a lot. I couldn’t find anything on the BD web site recommending tapping. The skis do have have a 3.5 x 9.5 mm bit suggestion on the ski. Who’s call is this? Shop or ski manufacturer?
2- my pet peeve (mostly w/ Dynafit toe pieces) is plastic base plates that grip the screws. In my experience it is impossible for the 5 tapped thread holes in the ski to match exactly the threads of the screws coming out of the base plate. The binding won’t tighten hard to the ski until one set of threads (in the ski or in the base plate) strip. My solution is to drill out the base plate so the screw spins freely.
3-Glue. I have an allergy to epoxy, even small doses. I’ve been using some new clear, runny Gorilla glue. No problem so far. Any thoughts out there?
John, good points. In our mounting instructions for Dynafit we mention drilling out those holes. It’s always been weird to me that they’re made that way. Insiders told me it’s so shop employees don’t get the screws mixed up. Not much faith in shop employees, I guess…
As for glue, whatever works so long as it’s waterproof and you don’t pull bindings off skis. I like epoxy because it’s strong, waterproof, and easily releasable with a soldering iron held for a few seconds on each screw.
John W, my thoughts on your three points:
1. I tap all my holes, but truly definitely necessary usually only for skis that have metal, which would always (I think) be indicated by a 4.1mm rec.
2. I haven’t had the courage to do this yet, but that would explain why I’ve had some puzzling spinners in the past. Plus Lou says to do so, which means I should, right?
3. I just use Titebond III wood glue to lubricate and seal up the hole. I know Lou says to use epoxy, and that I should do everything that Lou tells me to, but seems both unnecessary as well as causing potential complications for removing bindings. Gorilla Glue though, doesn’t that expand significantly? Seems like it could create problems?
For not doing everything I say Jonathan is hereby sentenced to ski on nothing but Duke bindings for the next two weeks. 😀
Thanks guys, I confess I’ve not read Lou’s Dynafit mounting rap because I have access to a jig. Once you commit to the modification don’t go half way, drill out the base plates so the screws will spin. Thanks Lou for all the DIY tips, it is an amazing library of knowledge. I suggest investing in the ski / jig specific drill bits (3.5 x 9.5 mm seems to do most these days). It cuts like butter, stays sharp because you don’t use it for other drilling, works in a jig if you have one and you can not possibly drill through your wife’s new skis. Titebond 3 work fine, I wish it was a tad runnier. The clear Gorilla glue dries white and expands a bit which I like (use less). No comment on the Duke’s. They scare me.
Interesting stuff. I am thinking that for my next mount on a set of Goode skis; I will shorten the mounting screws by grinding the points off the screws, and, then tap the holes. Anybody see any problems?
Bar, I’ve mounted Goode several times. Yes, be super careful of screw length, tap holes, use epoxy. When you grind the screws shorter, grind a point on them rather than making them blunt, that works better for getting the threads to bite as you screw it in. Lou
Having never mounted bindings (yet, as reading how it’s done seems easy enough), take with a grain of salt. However, i can’t imagine how filing the screw point would be good unless your drill bit were to bore a flat bottom hole. Last i checked most bits have points. And even then the screw tap is tapered at the tip too so more space to fill and griping surfaces for the glue.
Neon, all we’re talking about is making the screws shorter for a thinner ski, and I was suggesting that when doing so, keep the screw pointed rather than making it blunt.
…ok. Your reply posted while i was typing. At any rate i learned allot and plan to give it a go, will any off the shelf two part epoxy from HomeDepot/Lowes do or have you found some better then others wrt releasing via soldering iron if need be?
If the ski profile is very thin, might help to buy shorter bits specific to junior skis. (I had to do this for some Icelantic Scout skis that were surprisingly thin in the heel mount area.)
Okay, now time to rest my weary bones from all that skinning in my plug boots and Diamir setup (figured that was close enough to meet Lou’s sentencing guidelines).
Jonathan, Titebond III is great, but I found out something interesting a couple seasons ago. I unscrewed a ski binding screw from a hole filled with Titebond II or III. The glue had cured at the top, but not below; there it was still liquid after several days. What is curing dependent upon? Temperature? Contact with air? Contact with certain materials like wood, fiberglass, rubber, metal? I mention this as I haven’t seen similar uncured epoxy deep in screw holes on skis.
SVST sells an ingenious screw cutting tool. I ordered one. Grinding or filing screws likely isn’t as precise. I’ll let you know how it works when I get it.
Mark, one reason I gave up on water based glues for ski binding screws is that they indeed introduced moisture into the screw hole. As proof, I was finding plenty of screws that were corroded after a year or two, as well as simply not locked in the hole the way I’d want them to be. Never looked after a day or two, but now that I think about it, am wondering if that corrosion was caused by moisture that lingered in the screw hole for some time.
It’s funny how ski shop culture persists myths like using wood glue for steel screws in everything from foam to plastic (sorry Jonathan), I mean, skis were once 100% wood so it made sense, but can we just move along here?
Now, to not get too extreme or opinionated, when I mount demos that I’ll be pulling the bindings from in a few days, I sometimes do so with no adhesive. I also experiment with Gorilla glue, but have found that unless I use just a tiny amount of Gorilla to seal the hole, it tends to lock the screw in almost as good as epoxy, but doesn’t release as easily with a soldering iron touch like epoxy does, so I’m pretty leery of the stuff, but I might use a dab for skis that I’m planning on leaving the bindings on for a few weeks, just to keep moisture out. Also, the expansion of Gorilla glue is weird, and concerns me, as well as I wonder how well it cures in an airtight situation.
What I want when I mount bindings for the long haul is a 100% maintenance free screw attachment. No water corrosion or entry, no loosening, extra strength in comparison to a “dry” mount, and in the end, easy release when it’s time to pull bindings. Epoxy gives me all of the above. 5-minute version from big-box discount store preferred for most applications, but one hour ok as well.
Thanks for the info. I’ve been buying XC gear here and there for use at neighborhood parks, i’m not in the snow belt so no hurry. Now i feel confident to mount the bindings. Besides less to lose than AT gear if it doesn’t go as planed although i’m sure it’ll be a breeze and i’ll get the DIY satisfaction.
I “tap” my Dynafit front holes by making 4-6 turns in each hole with the Dynafit rear screws.
Summit, I don’t understand. Why would you use the rear screws instead of just any screw?
I’ve also seen mount screws that, when unscrewed after perhaps multiple years of use, show significant corrosion. Lou’s point that water-based glues might be the culprit is noteworthy. I like using Titebond III Ultimate Wood Glue, but wonder if it might be unwittingly contributing to moisture ingress into screw mount holes. Upon trying to unearth safety data sheets with some indication of what this glue is really made of, I hit dead ends. Does anyone know how to find out what is in this glue? I realize this may be more than difficult as the maker of Titebond probably isn’t legally compelled to disclose all or much of what makes up it’s wood glues.
Titanal mount plates seem almost impenetrable. I sometimes use an Armada step drill bit that steps from 3.5mm to 4.1; the 3.5mm is easy as the bit is sharp, but then getting the bigger 4.1mm to breech the metal is arduous. Any thoughts on how to make this go smoother? I’m using a DeWalt 18 volt XRP cordless drill. Seems to take way too much force to get through some Titanal mount plates.
Tried newer 18 volt cordless drill in hammer mode; drilled through the Titanal plate faster, but the noise and vibration were problematic–one end of mount jig came loose.
Try a new bit? I’ve drilled Fischer Hannibals (which have a pretty strong plate according to Lou https://www.wildsnow.com/14924/g3-ion-review-mount-weight-ski-touring/) without a problem. I was using a drill press, however.
I must be bored with work as I just spent 40 minutes researching drilling Titinal.
Titanal is ~7% zinc and very similar to 7075-T6 Aluminum. Amateur machinist sites
encouraged drilling at the highest speed available with standard twist drill bits.
At thickness less than 5 diameters, dry drilling is fine. Speeds up to 15,000 rpm
were mentioned (not likely with any hand tool). Do you have a friend with a mill/drill in the basement? Maybe a drill press that will go to 3600 rpm?
I have considered a drill press and corded drill. Thoughts? I have 16 pairs of skis to mount with Titanal. That’s a lot of hard drilling.
Mark, a sharp bit works well with Titanal but it dulls way too fast. I’ve never liked using a drill press with a binding jig, it always seems slow, weird, and awkward with much potential for damage. It actually would not be too tough to sharpen ski bits… Lou
Mark you might want to look into how to sharpen drill bits. Just hand mounting inserts, with a drill guide, into my Findr’s (which have a titanal mounting plate) has definitely put some dullness into my bits. I noticed the amount of time/ pressure needed increased towards the last few holes even with taking the bit out a few times to let it and the material cool.
Kinda bummed that bits that are meant to put holes in metal, 4.1mm bits, don’t have a different tip angle than say a 3.9mm that isn’t made for mounting metal laminated skis. At least Wintersteiger step bits don’t.
Any normal drill bits that aren’t bargin basement/ home depot grade have different tip angles for metal/wood/plastic. The ones I got in school when I took a machining class were hardly more expensive than a standard dewalt set per bit but had different angles.
I am very interested in sharpening the bits, as some of them dull REALLY quickly. The Armada step drill in about $24 bucks, and I won’t plunk down for a bunch of them. My sharpest bits go through the material much quicker, but they dull rapidly.
Mark
I just experimented last night with using a diamond stone that you’d use to sharpen a knife with to do a small sharpening of my Wintersteiger bits and even just a tiny amount of work can really help with making it easy to get through those metal mounting plates.
If you look up AvE’s youtube video on how to sharpen drill bits that gives you just enough info to touch up to tip of your bits by hand. He uses a angle grinder in a vice, but just taking a drill bit to a stone by hand works on the same principles.
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