Section8 2012-2013

skidesmond · Post by **skidesmond** » Tue Jul 31, 2012 9:03 am

Figured I get started on this seasons journal even though skiing is still about 5 months away. Haven't done much since last season... Mentored a fellow ski builder from Virginia in june, that was a good time, and now he's hooked too.

A proper cat track is in the works. In the past I've used MDF and/or plywood. MDF/plywood worked but occasionally a rib work crack and made it frustrating. I solved part of the problem by using a 4 foot piece of Plywood in the middle of the cat track and used a ribbed cat track on each end. That worked great for the middle but still got some breakage on the ribs.

So I spent couple hours today cutting AL square tubing, 3/4 x 3/4 inch with a 1/8in wall. I think a 1/16in wall would be adequate but the supplier only had 1/8. I'll spend the next few days cleaning burrs off and drilling holes to wire it up.

Also did some sample layups using carbon fiber last night. I will do some testing on it. I'll post the testing info in my other post in the next couple days: http://www.skibuilders.com/phpBB2/viewtopic.php?t=3868

skidesmond · Post by **skidesmond** » Mon Sep 24, 2012 3:27 pm

Hybrid sidewall -
That's what I'm calling it. It's really my quest to still have a wood sidewall with some benefit of UHMW sidewall also. The purpose of this experiment is to protect the wood sidewall from the file while planing the sidewall when sharpening the ski. And to perhaps appease some folks who are leery of an all wood sidewall.

I layed up a simple sample as follow:
p-tex base
metal edge
vds,
ptex/UHMW sidewall - 2 strips about 1/2" wide *** (this is what makes it a hybrid sidewall)
Triaxial FG
2 layers poplar veneer (1/16in thick each to simulating wood core )
Triaxial FG
Sapele veneer for posterity

I did 2 experiments in 1 sample. Part of the layup used 1 layer ptex sidewall and the other half I used 2 layers.

After pressing I cleaned up the sidewall and then put a 20 degree bevel on it.

Took out my ski hand file/planer tool and ran it over the sidewall. The file just barely cleared the 1 layer of ptex on the sidewall. The section that has 2 layers of p-tex sidewall had plenty of clearance and the wood sidewall was not touch by the file/planer.

So is it worth doing for real? One thing I didn't do in this simple sample is use a real wood core. If I were to use a real core I'd have to route a groove in the core at least 3.5-4mm deep in the core to account for the 2 layers of ptex, the step of the metal edge, vds and FG. That's a good chunk of the wood core. By the time I get near the tip and tail the sidewall would be all p-tex/UHMW. Not sure how that wood look from an aesthetic point of view.

Anyone pouring urethane sidewalls could do the same. Route the groove about 4mm, pour the urethane and then profile the core.

I'll post some pics later.

falls · Post by **falls** » Mon Sep 24, 2012 4:01 pm

Seems like a lot of work desmond with all the negatives of bonding uhmwpe and not all the positives of a uhmwpe sidewall.
I like wood sidewalls. I have found them to be durable, but my biggest trouble is that everything I have painted on to seal them seems to be abraded off by skiing. Maybe just haven't found the right sealant yet?

skidesmond · Post by **skidesmond** » Mon Sep 24, 2012 5:13 pm

I like the wood sidewalls and prefer them because of the simplicity and looks. But I'm thinking of the masses, the folks who only know of plastic sidewalls who may be turned off from wood thinking that it's not durable.

My thought was to route the channel in the core then lay 2 strips of p-tex base (or if you can get 2mm ptex, that would work ok) in the groove, glue in place (epoxy or poly-u glue) and then use spring clamps told hold the p-tex in place until the glue sets. Keeping excess glue out off the core and out of the groove could be problematic.

Yea does seem like a lot of work. :-) But pouring a partial sidewall wouldn't seem too bad.

Falls - Try System Three LPU. I've had good success with it.

http://www.systemthree.com/store/pc/WR- ... at-c29.htm

sammer · Post by **sammer** » Mon Sep 24, 2012 9:13 pm

falls wrote:Seems like a lot of work desmond with all the negatives of bonding uhmwpe and not all the positives of a uhmwpe sidewall.
I like wood sidewalls. I have found them to be durable, but my biggest trouble is that everything I have painted on to seal them seems to be abraded off by skiing. Maybe just haven't found the right sealant yet?

I still stand by the boiled linseed oil.
120+ days and still like new on the original everydayfatties.
I've never reapplied, its so easy I dont know why I haven't 'cept I haven't needed to.
Takes a couple days to dry (soak in) then your good to go :-)
I'll be sticking with wood sidewalls until something (drastic) changes my mind.

sam

falls · Post by **falls** » Mon Sep 24, 2012 10:47 pm

Yeah. I'm not sure if it is the bamboo, but I have tried the boiled lindseed oil and it didn't seem to penetrate very well and after a day skiing the sidewall looked bare again. I think the bamboo is pretty water resistant just by itself but this means that finishes don't pentrate it and stick that well.

Richuk · Post by **Richuk** » Tue Sep 25, 2012 2:21 am

SD,

I think I had a bash at this approach, but using ABS. It works fine and connects the tips and tailspacers. The drawback is the increase the number of layers that can delaminate.

Have you thought about using urethane (chrismp). Instead of routing out say 12mm. Just route as you intend and fill them up. It means your core needs to be a little wider, but the material will be bonded to the wood. It's a direction I would like to travel, but just don't have the time at the moment.

skidesmond · Post by **skidesmond** » Tue Sep 25, 2012 3:25 am

Rich - I think poured urethane like Chrismp does is the way to go, if you don't want wood sidewalls. I'll continue to make wood sidewalls for myself.

I'm looking for a good alternative for those who are turned off by wood sidewalls, whatever their reason. And I want to make it easy on myself too.

Here's what the sample looks like:

Richuk · Post by **Richuk** » Tue Sep 25, 2012 6:26 am

I understand: viewtopic.php?t=2405&postdays=0&postorder=asc&start=75

I'm just suggesting Chrismp method, but to a different depth. It avoids using UHMWPITA plastic. I thought something around 3 or 4mm - tapering to 1mm if required. Creating the channel requires is no great shakes, you just need slightly wider cores.

Great use of excess material BTW! I would be conscious of the step you are creating in the FG layer (two layer to one layer boundary of the base material). Square corners when flexed are going to crack over time?

skidesmond · Post by **skidesmond** » Fri Nov 16, 2012 4:21 am

Got the day off from work today. Going to pick up some wood for core making this weekend. Hopefully they have ash. Locally there is a bug (came from china, thanks china) eating the ash trees and the state may impose a band on transporting ash wood of any kind, whether it's for lumber, fire wood, etc. Also will pickup some IPE if available for sidewalls.

Will try making cores the traditional way this time using stringers of ash/fir or ash/poplar mix with IPE sidewalls. I'll see if the skis perform any differently from my other core making method.

Rich -btw in the above pic where I showed 2 layers of p-tex and stepped down to 1 layer, that was for demonstration purposes only, to see how it would look and to see how much wood/ptex the sidewall planer would remove.

Richuk · Post by **Richuk** » Fri Nov 16, 2012 1:17 pm

You're an inspiration!

skidesmond · Post by **skidesmond** » Fri Nov 16, 2012 7:46 pm

Richuk wrote:You're an inspiration!

Ah shucks.

skidesmond · Post by **skidesmond** » Sat Nov 17, 2012 5:47 pm

The lumber yard did have Ash and Ipe. I knew from my research that Ipe is hard and heavy but had no idea exactly how much until I picked up a board. Bought 8 - 1"x4"x8' for sidewalls. So how wide are folks making the finished sidewall? Since the total width of an edge is 8mm I was going have them 8mm finished, but a little concern about weight.

Glued up an all poplar core. Think this ski will be all mountain:
178cm
125-82-108
3-10+-3.
IPE sidewall
9.4oz uni CF
19oz Traix FG
Topsheet undecided (Teak?)

Will shape the core attach sidewalls during the week.

vinman · Post by **vinman** » Sat Nov 17, 2012 5:57 pm

I start with a 13 mm sidewall, knowing that there is ~3mm of waste in the flash. This is give me 10mm total to cover and support the edge. And enough to put a decent bevel on without cutting though to the core. I figure I get about 6-7mm at the top of the ski with 10 directly over the edge.

skidesmond · Post by **skidesmond** » Sun Nov 18, 2012 9:02 am

The thought process is slightly different making cores with sidewalls. But I finally got started shaping the core to the dimensions when the polar core split. And it wasn't at a glue seam. I think it's because I tried to take to big of a bite w/ the router, combined with vibration.... Anyway it wasn't a loss, just a PITA. On the second core I did a rough cut with the jig saw and then finished with the ski template and router. Next I'll go back and finish the other core that split, then glue the sidewalls on and finally shape the core. This is a lot more work and time consuming than my other method. I hope the Ipe sidewalls is worth it.

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Section8 2012-2013

Section8 2012-2013