I took these pictures last fall, but ski season kept me from putting this thread together. I figured now was a good time, as ski season winds down and before I get busy with yardwork and summer activities.
My procedure has been refined over a few years and dozens of binding mounts. It's based on an engineer's / carpenter's background with the practical limitations of DIY capabilities mixed in. If you have feedback, comments, tips, suggestions, etc, please post them below.
And of course no DIY thread would be complete without a disclaimer: make sure you know what you're doing before mounting your own bindings. You should be capable with tools and have a full understanding of the risks involved. I assume no responsibility for your work, and these directions are here for information only. If in doubt, let a trusted ski shop handle the work. They have the proper tools, jigs, and expertise, and can assume the risks.
The first thing I like to do is evaluate the manufacturer's mounting point. In this shot, the leftmost pencil mark is the ski's center of running surface (CRS). I place my boot on the ski with my approximate ball of foot (BOF) location over the CRS mark. The next pencil mark (over the middle zero in the serial number) is where the boot center lies. The last two marks are 1cm and 2cm aft of that point. You can see that the manufacturer's mark is approximately 2cm behind a true BOF mount. For all-mountain with powder considerations, I like being about 1-2cm behind BOF, so the manufacturer's mark is just about right in this case (325mm boot on 183cm Head iM82).
Once the mounting position is determined, the next step is to establish the ski's centerline (CL) relative to the edges. I start by laying down some masking tape along the approximate CL of the ski to provide a marking surface. Next procede on to the actual measurement. It's important to NOT mark the CL relative to the topsheet or topsheet graphics, as they are not necessarily going to be centered on the ski edges.
I use a little carpenter's square with two angle blocks mounted on the ruler to find the center. Just set the angle blocks to some ticks that are symmetric about a convenient mark on the scale, then slide the measuring jig along the edges until it stops, angling as needed to line up with the edges. You'll see that there is a position where the jig is perfectly wedged against the edges symmetrically, such that the ruler scale is also perpendicular to the centerline. When that happens, you can mark the ski centerline with a pencil. Place one mark up front, another towards the back.
Then, using a ruler, carefully scribe a line between the two marks to establish the centerline. You want a sharp pencil and careful positioning of the lead for all marks you make on the ski, by the way. Accuracy is important!
Next, transfer the boot center mark from the sidewall to the centerline. I use a protractor or drafting triangle for this.
With centerline and boot center established, it's time to lay down the templates. I create these templates by first scanning the underside of bindings to get the screw hole positions. Then, graphics software is used to turn this into a blueprint of sorts.
During this process, spacing of the toe and heel pieces is determined, taking into account displacement for forward pressure, etc. This takes some prior knowledge, or an existing set of mounted bindings you can eyeball for specs. If in doubt, place heel and toe pieces around your boot and allow for about 3-5mm of heelpiece movement for forward pressure (meaning the heel piece should be mounted 3-5mm forward of where it would be with no tension on the forward pressure springs). You can also make practice mounts on a piece of 1x3" wood to get the template dialed in perfectly before moving onto skis.
Once you have everything worked out, the template can be printed. This entire process requires a computer that is properly calibrated to preserve scale from scanning all the way through printing. If you have a Mac, it's probably already set up to do this with no extra tweaking, but always double check the printed result and adjust (likely scaling) if needed. Here are some shots of the work in progress:
One good trick is to scan a ruler with the bindings, and keep that in your work all the way through the printing. Double check the scale when you print out the final template.
I used to print the templates in two pieces on 8.5x11" paper, but now I get them onto a single 11x17" sheet of paper diagonally.
Once everything is printed up, cut the templates to ski width and get them ready for mounting.
I cut a small window in the center of the template near the intersection of the midsole mark and centerline. Then I lay the templates on the ski using double-stick tape, carefully lining up the centerline at front and back, and the centerline / boot center in the middle. If the ski topsheets are textured, you may want to use masking tape to hold the templates down. Whatever the case, make sure the templates are taut and perfectly flat when they go onto the ski.
Be sure to double check the fit every step of the way. Here, I am laying the toe piece lifter over the hole marks to verify the pattern is correct.
Also double check the heel piece fit, the spacing of the toe and heel, and the overall position on the ski. Make sure the bindings are going to point in the right direction, toe in front and heel in back (don't laugh -- shops screw that up all the time). Do as many sanity checks as you need to confirm the binding position will be correct and the same on both skis *before* proceeding to the next step.
At this point, you should be 100% confident in the mount template, so it's time to mark the holes with an awl. Make sure the awl is sharpened to a fine point. Carefully position it over the hole centers and give it a rap with a hammer.
When all holes are marked, peel up the template, leaving just the awl marks on the ski.
Now it's time to drill. Most skis will have the required bit diameter marked somewhere on the sidewall or topsheet (see first picture up above). The general rule of thumb is to use a 3.5mm bit for skis with no metal layers, or a 4.1mm bit (and tap) for skis with metal layers. These sizes are closely approximated by 9/64" and 5/32" drill bits, respectively.
True binding bits will have the depth fixed by a shoulder or collar, but you can also do it with tape (I've done dozens of mounts this way with no problem, just measure and check the tape before each mount, and don't whale on the drill).
The depth is usually 7mm or 9mm -- check to see how far screws protrude through your bindings, and also make sure the skis are thick enough in the binding area! Almost all of the bindings and skis I have mounted use a 9mm hole depth for the screws.
Of course it goes without saying that you should carefully position the bit, centering it on your awl marks. Make sure the drill is straight and perpendicular to the ski topsheet. Then drill in with medium speed and gentle pressure on the bit. Skis have layers, and the bit will cut slowly through some (metal) and fly through others (wood core), so be gentle. When done, shake or vaccuum debris out of the holes, and clean off your workbench.
Since the iM82 has metal layers, tapping is required (this prevents the screws from separating the metal layers from the laminate construction when going in). I have actually taken to tapping all skis --metal layer or not -- because I think it makes for a cleaner mount, but it's really only needed for skis with metal layers. Anyhow, here's what my tap looks like.
Line up the tap straight over each hole, and start twisting it in. I like to give 1-2 twists, then a quick reverse, then another 1-2 twists, then a reverse, and so on, until the tap just touches the bottom of the hole. In case you're wondering, the reverse twists help clear debris out of the tap so it cuts cleaner -- an old machinist's trick.
When done tapping, you'll likely be left with a burr or raised edge around the hole opening. I like to trim this off with a sharp chisel. If you used a true binding bit when drilling holes, it probably created a slight countersink that offsets the burr.
Once again, shake or vaccum out the holes. You want them perfectly clean at this point. Now it's time to screw in the bindings. Back off all the binding screws so that they barely poke through the bottoms of the bindings -- just enough to help locate the holes.
Place a drop of glue in each hole in the ski. It can be wood glue, white glue, etc., whatever is compatible with the materials in the ski. Don't use a foaming/expanding glue like Gorilla Glue, or a glue that would permanently hold the screws in. The glue is merely needed to lube the screw as it goes in and to help seal the holes and prevent water from getting in the ski core later on. I have recently switched to "Roo Glue Clear" for binding mounts, and like it a lot. One benefit is that it remains flexible and seems to hold up better over time than other glues. I got this recommendation from a shop.
After putting glue in the holes, I like to use a toothpick to stir it around and break any air bubbles. You just want enough glue to coat the inner surfaces of the holes.
Now screw in the bindings with a Pozi-drive #3 screwdriver. Tighten each screw a bit, going around in an alternating pattern, to draw the binding down evenly. With tapped holes, the screws should go in pretty easily. With untapped holes, be prepared to apply some grunt as the screws go in (part of the reason I like tapping -- you get better control when driving the screws in). Keep cranking until the bindings sit flat to the ski and you feel the screws begin to snug up. At that point, finish snugging up the screws no more than another 1/16 or 1/8 of a turn, again going around the screws in an alternating pattern. I tweak them little by little until the voice in my head says "good". You'll know when the screws are tight enough. Resist the urge to overtighten, as you will only mangle the threads and possibly strip out the holes.
That's pretty much it! At this point, it's not a bad idea to store the skis bindings-down at room temperature for a few hours to let the glue dry. And don't forget to set forward pressure, adjust DIN, etc. before heading out to ski!
With careful measurement, marking, and drilling, this mounting procedure should be accurate to within ±0.5mm or a ± 1 pencil lead thickness, whichever is greater. This is as good or better than most shop mounts using a jig.
Edited by skier219 - 4/19/2009 at 02:52 am GMT