Ski Builders Forum

I was aiming for 2mm in the tail there, but ended up with something near 1mm

Sorry, it's scrap. You could feasibly try to patch it by adding 1mm of wood, but that's a lot of effort and the final product won't be any good. Even ignoring the deepest "trough", the rest of it looks super ratty.

Save the base/edge/fiberglass/resin for a good core, you're only out the cost of the wood and sidewalls for this one. Chalk it up as a big lesson-learned (before I had my CNC router, profiling cores was the single most difficult part of the process for me... I started with a router and did a few pairs, moved to a planer and did a few pairs, and trashed MANY cores along the way). This lesson is worth way more than one ruined core

It's a few more bucks and a bit more time waiting for materials (assuming you don't have extra wood/sidewalls on hand), but you will be glad you took the time to do it right.

Gotta agree with twizz mate, not trying to sound harsh but that core looks pretty horrible. Even a roughing cut shouldn't look like any part of that.
If your next core was heaps better then that's cool. A lot of us on here have a lot of success with router profiling so if you want to post some pics of your set up you might be able to get a lot of pointers on how to improve it.
A good router profile table doesn't need to cost a lot but it should take you a fair bit of timeaand effort so you have something that can make quality cores over and over. You got to remember, this is one area making skis is more critical than snowboards because you're making two and they both need to be exactly the same.

May I suggest the planer/planer crib method...
Of course it requires a planer and some decent cribs, but it's much quicker and accurate. IMHO. :-)
After that, CNC...

cut lengthwise, in one direction only, if you can

build a vac table, a shop-vac should hold it, tape all around it to seal the edges of core material and it will hold down even better.

use a bit that is straight or "down-cut". If it's an up-cut bit, it will pull on the material.


And step down the router in small increments... maybe 1/16" of an inch at a time? I wouldnt cut much more than that in a pass, even if it takes forever the result will be much smoother. Even with a CNC, my profile job takes 1.5hrs running at near max speed. I need a much bigger bit.

Climb milling will also reduce the likelihood of ripping the sidewalls (or any of the wood grain) off. Even on my CNC I make doubly sure I am always climb milling. (google it)

I made a small repair on it with some veneer and it flexes great and all i need to do now is belt sand it.

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I know you feel you have a ton of work into that core that your probably pretty proud of even with the oops but your better off just trashing that guy and moving on. You could use it but you will not be happy. Besides the base, edges, top sheet, tip fill, vds, epoxy are all the expensive part of the ski so why waste all the hard work to come on that core....

I kinda agree with Cornice on this. I know it sucks. I practiced a few times on some shitty timber and then had a crack at the real thing and the results from the first test to the first proper core was huge. I also spent a little bit of time strengthening my bridge and adjusting my technique so the bridge doesn't flex. Do you think that could be why your depth is variable?

DO NOT TAKE ANY MORE CLOSE UP PHOTOS OF THAT CORE!!

It hurts my eyes to look at that.

Dude, slow down, take a step back and think about what you want to build. This is your third set of skis. I would prefer one good rideable set than three pairs that are worse than a cheap second hand old hire set off ebay.
If you have some sort of belt sander set up that will make that look anything like a core then you should use that from the start and burn your router bridge. Have a look at your own photos of this core before you glued the edges to it. See how nice and even it was then, now look at it. The sanding after router profiling should be about 3 minutes worth of a light clean up.
You don't want a shed full of shit skis do you? Start again, and not just start this core again, I would suggest going back and starting your whole process again. You said yourself, materials aren't cheap, so stop wasting money buying materials to make skis that don't work.
Post some more photos of your equipment and I think you will be surprised how much help the people here could offer you. But please don't post more pictures of that core.

Maybe keep it up on your wall so you can look at it in the future of what to never do again.

Remind me not to piss off Gav wa!

I am no expert by any stretch of the imagination. I am a hack compared to most of these fine folks.
Two things that might help you out.
1. I always read that you should profile from tip - tail rather than left to right as you will get steps if you don't do it right. You don't need to do the whole length. I have done it in sections before and it worked ok.
2. It sucks but lots of small passes are king. If you try and router bridge a full cm off in one go you will end up with a shitty looking profile. I know, I tried it the first time. I do a few mil a pass. Does it take a while? Shit yeah, What else am I going to be doing though? Watching so you think you can dance?

Thicken that bridge up and have another go with it set to a couple of mm per pass and it will come out as smooth as butter.

Ya my first core was one pass and my next core witch is much better was done in three passes with an updated bridge.

DUDE!! that second core looks like it was done on a totally different setup. That is exactly what you want.

You definitely have to scrap that first one now, you cant ruin the good work you did on that second one by having one good ski and one that performs differently.

Props for sorting out the issues after the first core.

I dont have a bridge, but if i did, i'd try to do the following:

1), put some kind of lock and "Steps" on the bridge or y axis. Cut only in the x or lengthwise direction, and try to lock the position of the y for each pass.. this would be more time consuming, maybe something you ocan hold with a trigger hand?

2), only cut in small depths, my cnc only steps down 1/16th for each pass. And I overlap 50% for each pass.

3) use a downcut bit, at the very least a straight bit, do not use an upcut bit if your clamp/vacuum setup isn't that strong.

If you did all this, i bet you wouldnt even have to sand afterwards, maybe just the sidewalls.

the.quass wrote:Shit yeah, What else am I going to be doing though? Watching so you think you can dance?

This is going to be my new canned-response anytime someone questions why I'm doing one of my weird projects.