Ski Builders Forum

Hey everyone, I've been trolling these forums for some time, and will be delving into making my first set of skis this month (we'll be making these in Michigan, and so far I haven't seen anyone else making skis here, let me know if you have). Hoping to start a trend...

First question of potentially many:

I've looked at the many different core profiling designs and had a question about the designs used by builders like Buuk and Endre (pre CNC days). I'm confused as to how this type of crib allows you to plane a core into the shape that you desire. I feel like adding enough pressure to hold the core in place along the profile of the core would be difficult, and the tension would release after profiling it, to create a strangely shaped core. What am I missing?

Mike

I wasn't convinced about using a planer to do core profiling either, until my ski-partner built the thing and showed me. Perfect profiles every time and extremely precise!

The rollers on the planer push the core down, so you are really planing a flat surface onto the core... except that the core is bent as its pushed down, so when it "un-bends" that flat surface ends up being your profiled shape... if that makes any sense.

We use hot glue to hold the core to the planer crib. When you first start profiling (you take off a little at a time, at least with our small planer) you will only be taking wood off of the tip and tail. It won't touch the middle of the core. As you cut down more and more, it'll be cutting longer sections on the tip and tail, until you end up cutting down the entire length. Then you just keep cutting VERY tiny amounts until you've got the right thickness.

So, are the knives actually cutting the "top" of the core, and the bottom of the core that adheres to the ski base is un-touched? My concern is that I'll be making bookmatched cores and I want them to be profiled so that the base of the skis cores are identical.

The knives are cutting the base side of the core.

Alright, I think I completely understand how this works now. I'll make our setup and test it out. Thanks for the insight.

Uh, I'm only on my first pair but for the ones I did last night I set it up so the knives cut the top of the core, not the base side.

My reasoning was thus:

1. I had routed a goove to accommodate the edges on the base side prior to profiling. Profiling the base side would have removed that work.

2. The cores started out flat on both sides (aside from my grooves of course). So, by running them through base down (knives on top) the bottom remains flat when it springs back out of the low spot you force it into temporarily. Seems to make sense to me and I believe that is what twizz describes.

Hot glue holds everything in place well and I don't think I needed the grip tape I put on the jig. At first I put glue dots on the base side but I found that running a thin bead of hot glue along the seam where the leading edge of the core blank meets the jig was easier to remove later (no jamming a small blade under the core and torquing, just scrape away with a screwdriver or whatever) and easier to apply.

I did not apply hot glue anywhere other than the leading edge (e.g. not on the tails). The planer blows chips under the core in the middle when it rebounds on the outgoing side. With the glue on the leading side I could lift up the core and blow the chips out before each pass and not mess up core placement. I think this helped alot.

In and out-feed rollers seem mandatory. The jig is big, bulky and heavy. make small adjustments as you get close to final thickness, my cores are pretty hard and I had some problems as they got thin but nothing that couldn't be salvaged.

Good luck. CR

Ours cuts the top of the core as well, but really it doesn't matter either way. The layup/press is what will create the camber in the ski, the taper in the core thickness is all that matters, you can flip it upside down and it shouldn't make much of any difference in the camber of the ski.

I suppose that makes sense. The first pair of cores that I saw being made was in Igneous's shop using a sweet planer setup that was on rails. I'd like to make a system like that, so the cores can lay flat and I can simply plane the tops of them, but the crib seems like a less labor intensive and more cost effective way to create the cores for the low volume I'll be making. If only I was made of money...

During lay up it is easier to have the unplaned side down. This allows more of the core to stay in contact with the lower layers before going in the press. It is also easier to rout out the flat unplaned side of the core to allow for the edge flanges.

edit: Hot glue is important. I lost a core (core 2 of a pair) on a final pass when the rollers pulled it in ahead of the crib. I was fine tuning to get it exactly the same as the other core. I thought I could get away without securing the core and I was wrong.

when you route out the core for the edges, are you accounting for the vds as well? I always wondered if the vds would impede quality layering (causing convex or concave bases). Or is it soft enough to press without much hassle?

The VDS isn't just soft enough, but its also thin enough that I wouldn't worry about it. You won't be able to get your router height set accurately enough for that to matter.

Awesome. I'm starting to make my crib this week. Looking to Press skis by the end of January.