DIY Guide: Mounting Tech Bindings

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Despite widespread paranoia, mounting your own ski bindings is easy if you have the maturity not to rush the job. The tools, skills and knowledge are all elementary. I mounted my first pair in 2006 after buying $80 skis from a big box store and not wanting to pay as much for mounting as the skis cost. Since then I’ve mounted about 10 pairs and made the full gamut of mistakes, which I try to advise against here.

This guide is written with tech bindings in mind, but can be used for other AT or alpine bindings. Alpine bindings are typically easier to mount as they don’t require a heel gap and are often one piece instead of two which reduces sources of error, however some alpine bindings obscure the bolt holes which makes using the binding as the template hard – in which case finding a paper template online is advised. Otherwise you don’t need one. Any ski binding can be mounted with the general principals contained here.

The quality of a DIY ski mount can easily match or exceed that of a shop mount. Shop mounts use a jig that rapidly centers the mounting template onto the ski and leaves little room for error. A DIY mount will never be as fast and at best will equal this precision. However, where a DIY mount wins is in attention to quality which is often compromised in a high volume shop. I’ve seen many shop mounts where the screws were incorrectly tightened, the tops of drill holes were left mushroomed so the binding didn’t sit flush, or the holes weren’t epoxied. If nothing else, a DIY mount is cheaper and gives you a deeper understanding of the gear you rely on.

This guide provides instructions on mounting with either traditional wood screws or metal inserts + machine screws. I prefer using inserts, as they allow for a more robust mount, a nicer aesthetic and rapid swapping of bindings between skis. However they do add cost and a little weight. Inserts and machine screws are available from Binding Freedom or Quiver Killer. The Quiver Killer inserts looks a little nicer, but I buy from Binding Freedom as they are removable via a flat bladed screwdriver and they’re cheaper.

Everything you need for a DIY mount
Everything you need for a DIY mount

Before starting you need the following:
– One free evening
– Ski, boot and bindings
– Binding screws or inserts with appropriate bolts
– Drill & bit (usually 3.5mm but 4.1mm for skis with metal layers or 1/4″ if using inserts)
– Measuring device (ruler is tolerable, digital caliper is best)
– Hammer and small nail or screw
– Epoxy or a good glue (use >15 min epoxy or Gorilla glue)
– Tape of any sort
– Appropriate screwdriver for binding screws (Usually Pozi or Phillips)
– Something to bevel the holes (Dremel, knife, large drill bit etc.)
– Inserts also require thread locker (blue) and a 5/16-18 tap

Step 1 is drawing a center line down your skis in the areas where the bindings will go. Measure the width of the ski, mark the midpoint with a dot and repeat until you have enough dots to draw a perfect line down the center. Do a good job here as the accuracy will pay off later. This should take 20-30 minutes for heel and toe center lines on both skis if you’re being paranoid enough. I use a fine point Sharpie and remove it later with alcohol, but any drawing tool will do.

Perfectly drawn ski center line
Perfectly drawn ski center line

Next determine the fore/aft location of the toe piece. Clip the boot into the toe piece and align the center mark on the boot sole with the mounting mark on the ski (or elsewhere if desired – I mounted these skis at +1.5). With the boot roughly fore/aft aligned (don’t sweat 1-2mm for this), mark the front and/or back of the toe piece location so you can remove the boot and replicate the spot. In the above picture I’ve marked the back of the toe piece.

Now remove the boot and put the toe piece back in the right spot. Put a dot on the center of the front and back sides of the toe piece and use these to line it up on the ski center line. The toe piece should be perfectly centered and parallel to the ski. Parallel is especially crucial for bindings with separate toe and heel pieces, such as tech bindings, as you need the heel of the boot to land precisely in the center of the heel piece for proper function. With the toe piece at the proper fore/aft location, hold it carefully in place while you use the binding as a drill hole template. I like to trace the perimeter of the holes to achieve a circle, then remove the toe piece and make a dot perfectly in the center of the circle where I’ll actually drill. Attention to detail here has a large impact on the final quality, so take your time and recheck fanatically. Replace the toe piece and ensure your dots are perfectly centered.

To drill the toe holes, take your hammer and nail and make a small dent where you want the hole. This will guide your drill bit. Now take a small drill bit (i.e. 1/16″) and drill a perfectly centered hole on the dot you’ve drawn. It’s easier to be accurate to the center with a small bit and you can still fix things later if it’s a bit off. Starting with the full size bit is a good way to introduce error. Before you drill, wrap the bit with tape at 9.5mm up the shaft (the standard hole depth) so you know when to stop drilling. Drill slowly and carefully and make sure you aren’t pushing the tape up the shaft. The bit will make much faster progress through the wood core than the plastic top sheet, so the biggest danger is blasting right through the ski when you penetrate the top sheet. With the pilot hole drilled, take the proper size bit, again wrapped with tape and drill the final hole. This bit is 3.5mm for normal screws or 1/4″ if you’re mounting inserts, although skis with metal layers require a larger 4.1mm hole for normal screws. If you’re using inserts, drill 10mm deep as the inserts are 9.3mm long and you want them to sit slightly recessed from the ski surface. Skis can typically handle about 12mm before you start drilling into the base.

Your drilled holes will likely have some mushrooming at the top where the top sheet bulges up. You need to remove this so the binding will sit flat on the ski. Many shop mounts fail to do this, which is lazy and poor technique. I use a large grinding stone in a Dremel to bevel the hole, but you can use a variety of tools to achieve this including a sharp knife or an oversized drill bit. If you use a large drill bit proceed very cautiously as the bit can bite and drill deeper than intended. Slow drill bit rotation can yield an ugly result, so spin the bit at a high RPM but with very low pressure.

Notice the lightly beveled holes with all mushrooming removed.
Notice the lightly beveled holes with all mushrooming removed.
Beautifully tapped holes
Beautifully tapped holes

If you’re using wood screws, you can now gently screw the toe piece into place. Don’t use epoxy or much torque yet, as you’re just mocking up the toe to align the heel unit. If you’re mounting with inserts you’ll need to tap the holes first with a 5/16″-18 tap. Taps can be purchased individually for ~$5 dollars at any good hardware store or at the same places that sell inserts. Hold your tap against the insert to verify the threads are a match, and then carefully screw the tap into the hole to create threads. Again, use tape on the tap (shown below) so you don’t bottom it out and strip the holes trying to tap deeper. Gently and without epoxy, screw the inserts into place and gently mount the toe piece (This is why Binding Freedom inserts are good, as they can be easily removed and re-inserted later with epoxy). Prior to using epoxy, tapped threads in wood are fragile so avoid substantial torque.

Tapping the holes
Tap taped at 10mm

The heel piece is essentially the same process, but you need the toe in place to nail the fore/aft mounting position. If you are mounting a one piece alpine binding you can usually drill all the holes at once. With any tech binding, you need a 4-6mm gap between the boot and the binding heel piece (refer to your binding literature for the precise specification). Clip the boot into the toe piece, insert the binding heel pins into the boot heel fitting and then slide the heel piece fore/aft to achieve the desired gap. Dynafit bindings typically come with a spacer to make setting the gap easier. Now mark the heel piece location on the ski, remove the boot and re-align the heel piece on the center line after drawing dots on the front and back centers of the heel. Repeat the mounting steps used for toe piece (draw circles, dot centers, make indent, pilot drill, main drill, tap if applicable, bevel). If your heel piece has an adjustable boot sole length you can be more hasty here as you can adjust the heel piece post hoc to dial in the gap, but make sure the heel piece is in the center of its adjustment range when you do the mounting unless you want the adjustability biased in a certain direction.

Notice the mark for the back of the heel piece
Notice the mark for the back of the heel piece

With all the holes ready to go, you can remove all the lines and marks you’ve drawn on the ski. Alcohol, WD40 and most solvents will remove Sharpie, while pen or pencil can often be rubbed off. Double check that your holes are deep enough by screwing everything into place and ensuring the binding sits flat to the ski, or if using inserts, that the inserts can be screwed in enough so they don’t protrude above the surface of the ski.

Now mix up your non-rapid setting epoxy or glue, apply about 2 drops into each hole and rub it around onto the sides. Don’t apply it to the screws/inserts or it’ll get all over the top sheet. Mount up your bindings or inserts and torque the screws solidly into place. If you’re using inserts just torque them lightly to avoid stripping the wood. They’ll be solid later when the adhesive hardens. If you’ve done a sloppy epoxy job, thread bolts into the inserts to prevent epoxy from dripping in. Make sure the screws or inserts are inserted such that the binding sits / will sit flat on the ski.

Now you’re almost done. Let the epoxy cure and then insert the boot and adjust the binding settings if applicable (DIN, boot sole length). If you’re using inserts, now you can actually mount up the bindings. Use blue threadlocker on the bolts for security and moderate torque. Try to buy Pozi bolts, as they are much harder to strip than Philips.

All set to go skiing
All set to go skiing

Common Problems
The most common problem is drilling sloppy holes that aren’t in the right location. You can be pretty far off and the binding will still mount, but still you want to minimize this. The provided process should minimize this (circle with a center dot, hammer/nail indent, pilot hole, real hole) but careful work and constant rechecking are important as well. My holes used to be worse when I didn’t use a pilot bit. Good results, as shown below, aren’t hard to achieve with care.

Hole locations should be darn good like this. The camera angle makes some holes look a little off.
Hole locations should be darn good like this. The camera angle makes some holes look a little off.

Less initially obvious problems occur with improper hole depth. If you drill the holes too shallow, the screws won’t fully insert and you won’t be able to get the binding flat on the ski. As a result, you’ll try to crank the screws down harder which can lead to stripping the holes or damaging the base of the ski. The screw/insert will push on the bottom of the hole which can create a bump on the base of the ski (yes I’ve done it). The opposite problem – too deep of a hole – is only an issue if you go way too deep and into the base. It’s a bit frightening to drill right through the ski (again, I’ve been there), but it’s actually easy to fix with Ptex and about 5 minutes of your time. It’s best to put tape over the hole, finish the mount, then carve out the epoxy as needed and drip in Ptex to repair the base. If you Ptex it first, the air pressure from screwing in the screw/insert will push the Ptex out or seep epoxy through the seam. You can avoid this problem with due diligence, or by using a professional ski mounting drill bit which is stepped so it’s impossible to drill deeper (~$15 online).

Other issues include using rapid set epoxy, which hardens before you can get everything screwed in place. This is a major problem but can be easily avoided with the right adhesive. If this happens to you, heat will often soften the epoxy so you can remove the screws, clean the holes and re-do it the epoxy. Worse case scenario, abandon the holes and re-mount +1 cm.

Advanced Techniques
If you want to take your mounting to the next level, you can buy jigs for drill bits that help you drill perfectly perpendicular holes. In combination with a stepped drill bit that makes it impossible to drill too deep, you can take a lot of variance out of your hole drilling.

Another trick is to use masking tape on the ski to avoid drawing directly on the ski. I typically draw on the ski as it’s easy to remove, but if you’re mounting expensive new skis and worried about aesthetics then masking tape provides peace of mind.

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