Section8- GS Comp ski

skidesmond · Post by **skidesmond** » Fri Dec 31, 2010 11:46 am

This is my attempt at making a ski suitable for GS racing as well skiing. Our first race is 1/5. Nothing too unusual for this build.

Ski Length 180cm
Ski Dimensions - 114-68-100
Maple Core - 2-12-3
Top Sheet - Sapele veneer from www.certainlywood.com
Fiberglass w/ Carbon Fiber - 20 oz from www.snowboardmaterials.com. I thought the carbon fiber was weaved through out the FG but it's only about 3 inch wide strip down the middle. Obviously it's for snowboards, DUH! More on this later.
VDS - From www.skibuilders.com
Edges - From www.skibuilders.com
Epoxy - QCM

The ski is modeled after one of the Fischer GS racing skis. Whether it will perform like one is another story.

The ski is a full wood core, no tip fill and a 3/4 edge wrap. This is the first ski I made using my new aluminum cassette, 1mm thick. Hopefully it will fix the edge fall problems.

Last night I marked out the cassette for proper alignment for the bases, then fastened the bases to the cassette. Today I did the lay up and realized I forgot cover the bases w/ masking tape. I had already started laying down the epoxy, DOH!

The FG has carbon fiber stringers weaved down the center of the FG, about 3 in wide or so. I assumed the CF was weaved through out the FG. Luckily I was able to cut the CF center out and the left over FG was still wide enough to make skis.

I used 4 - 24in pieces of CF in the binding area. One below the wood core and one above the wood core as well as the typical FG lay up. I hope the ski is not too stiff.... Time will tell.

The skis are in the press. Had a heck of a time getting the layup in the press because of the length of the cassette. Hopefully nothing shifted... fingers are crossed.

Will update the out come in the next day or 2.

HAPPY NEW YEAR!

OAC · Post by **OAC** » Sat Jan 01, 2011 11:43 pm

How is the progress?
Fun with race. Have you been doing any dry-land training this season?

Release Wax your casette instead of taping the base. Much more convenient IMO. But you have to remember to do that aswell...

skidesmond · Post by **skidesmond** » Sun Jan 02, 2011 4:59 pm

Overall they came out good. The camber is 14mm! I guess adding the middle support to the press is making all the difference in retaining camber. But I'm still getting edge fall. It's really annoying me now. One ski was almost perfect the other ski had one side that looked like the epoxy didn't hold. Maybe I didn't wet it out good. But I thought I did. It's fixable but it's a hassle to have to fix it all the time.

I didn't pre-bend because I used a full wood core. Maybe the answer is to use tip fill and pre-bend??? IDK, getting discouraged...

Almost no epoxy on the bases. YEAH! I used wax paper under the skis at the last minute to catch any epoxy squeeze out because I didn't put release wax down.

The skis have a firm flex but not overly stiff. I'll post pics when they are done.

I should have the skis ready for the first race.

(* why is it before I'm done w/ this ski I'm already thinking about the next one

Thinking about going back to the roots/basics of ski building. All wood ski w/ edges, perhaps P-Tex base... The idea is still baking...... *)

OAC - No dry land training, unless you count 16oz curls. Biked until it got too cold if that counts.

Brazen · Post by **Brazen** » Sun Jan 02, 2011 5:31 pm

are you giving everything an extra cleaning with mek or acetone prior to layup? I'm just askin'.

skidesmond · Post by **skidesmond** » Sun Jan 02, 2011 5:50 pm

I used to use acetone on the edges. But not on the bases. Previous posts recommended only use water and a clean cloth as acetone can ruin the flame treatment from the factory (Crown).

I wipe down the work area and materials before lay up.

The degree of edge fall has been inconsistent too. Sometimes not that bad. It's always been fixable... just a big pain in the a$$.

One thing I should of kept track of is which ski (left or right) out of the press has the worse edge fall and if it the inside or outside edge. Maybe that will be a clue. I checked that the hose had good compression all the way around, as far as I could see.... looked good.

Thanks

Brazen · Post by **Brazen** » Sun Jan 02, 2011 6:06 pm

Weird. I mek everything before I flame treat the ptex just prior to layup. I have to ask though...how do you fix an edge? Do you inject epoxy and re-press? I've never done it and it seems like something I'd love to know if you're willing to share.

BTW, where in west mass? peebuddy? lol

skidesmond · Post by **skidesmond** » Mon Jan 03, 2011 10:25 am

Here's some pics:

Look pretty good at first out of the press:

Minor epoxy on base. Not bad considering I did not protect the base with tape of any kind.

Here's where I get bummed out! The edge fall on the other ski was worst but was too pissed off to take a pic. I was able to fix both problems with epoxy and C-clamps. What a royal pain.

Tips repaired. If I could only get them to come out of the press like this:

They were still a bit wet in the pics. I'll do some minor clean up and mount bindings on them tonight. And hope they ski good enough for a season of racing.

skidesmond · Post by **skidesmond** » Mon Jan 03, 2011 10:30 am

Brazen wrote:Weird. I mek everything before I flame treat the ptex just prior to layup. I have to ask though...how do you fix an edge? Do you inject epoxy and re-press? I've never done it and it seems like something I'd love to know if you're willing to share. BTW, where in west mass? peebuddy? lol

Yup I jam in as much quick setting epoxy (50 min) as possible and use C-clamps. I wrap the area w/ wax paper and clamp over the wax paper so the clamps don't become permanent. Then cleanup the excess.

Peebuddy is eastern mass. I'm Southampton, 30 min outside Springfield.

Richuk · Post by **Richuk** » Mon Jan 03, 2011 12:39 pm

SD - what are your AL sheets saying about the problem? Any imprint? If not, does it begins to looks like a pressure issue ...

skidesmond · Post by **skidesmond** » Mon Jan 03, 2011 1:15 pm

No imprint. I wish I took note on which ski it was when it came out of the of the press. I made 2 other skis prior to this one and they had minor edge fall.

This time one edge looked like epoxy didn't take hold or maybe didn't have enough. The hose had good contact, fully engaged, all through out the tip block... Pressing at 35-40psi, not using heat.... Frustrating!

I'm sure pre-bending would fix the issue, but seems it would be difficult w/ a full wood core. The full wood core is what makes the skis unique. I guess I could try adjusting my layup to pre-bend the tips, and then fasten the base, core and aluminum cassette using zip ties to keep pieces from sliding around.... Just thinking out loud.....

The kicker - A buddy of mine mentioned to a local ski shop that I'm making skis and they're willing to take a look at selling them if they like what they see. I really need to get this nailed down before I even think about selling anything. Hate to let an opportunity like that go by. Well, one step at a time. Still just a hobby....

Richuk · Post by **Richuk** » Mon Jan 03, 2011 2:34 pm

Mentioned 'pressure' because the topsheet looks as though it came a drift too. You could use a couple of teflon sheets to ensure consistent pressure. If its not pressure, then how do you mix your epoxy - paint mixer? Or do
you transfer your mixed epoxy out into a new container before use after mixing by hand?

I've taken to storing my edges near the radiator before use, the coating goes from dark to light grey, as it dries out.

Pre-bending ... there was that guy who offered edge benders for $35 recently, does he have any left? If not, you'll be looking down the barrel of a sandblaster. Can't think of anything else ... hope this is helpful. Shout if you need more

MadRussian · Post by **MadRussian** » Mon Jan 03, 2011 3:47 pm

you have full wood core where tips will be subject to a lot of pressure from wood trying to get flat, and if epoxy not fully cured separation is possible. Before trying to change anything in your setup try increase pressure in the hose and/or increased time for epoxy to cure before taking ski out of the press

skidesmond · Post by **skidesmond** » Mon Jan 03, 2011 4:54 pm

Richuk - Teflon sheets, thanks for the reminder. I went back through the forum/post and saw the bit about the Teflon sheets. I'm adding that to my lay up process next time.

I mix the epoxy by hand. Funny you mentioned transferring the mixture. This time I measured out the 8 oz resin and 2oz hardener. Then poured each into another container and mixed for about 2 minutes. Usually I measure the resin, measure the hardener and add the hardener to the resin and mix. Not that different. I just used a bigger container to mix in this time.

MadRussian- I pressed under pressure for 10hrs at 35psi or so and then left them over night, total time about 18hrs.

Thanks guys.

MadRussian · Post by **MadRussian** » Mon Jan 03, 2011 5:36 pm

skidesmond wrote:
MadRussian- I pressed under pressure for 10hrs at 35psi or so and then left them over night, total time about 18hrs.

Thanks guys.

what is FULL care time for your epoxy? You can always experiment to see if longer time needed.

skidesmond · Post by **skidesmond** » Tue Jan 04, 2011 2:26 am

Not sure of the cure time, I'll have to check the QCM website. The rest of the ski comes out fine.

When I lay down the base I fasten the tip AND tail to the cassette w/ tape. Then lay down the VDS, FG, core. The core also gets taped to the cassette. Then lay down FG, top sheet. I'm wondering if the taping of the tip and tail is restricting the layup to bend and slide properly under pressure.

Other folks use teflon to allow for some sliding to occur. I'm going to run some tests over the next couple weeks.

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Section8- GS Comp ski

Section8- GS Comp ski