Anyone out there have any experience using nomex honeycomb? I was thinking it would make an interesting core material. I see Burton's new Vapor board is using a honeycomb core which supposedly saves a full pound. I'd sure love to take a pound off my backcountry boards...
paul
I got a 20x20cm piece of honeycomb and I laminated both sides with carbon. First I impregnated the two carbon sheets, then I glued them to the nomex with epoxy.
The only problem if you want to make skis is the tapering. Nomex is not the easiest thing to cut. Then you should put some reinforcement in the binding area, so the screw will not be pulled out.
Im pretty sure the kids who build skis out of the U of U tried some honeycomb...
How about using a tapered wood piece above a flat honeycomb piece for a sortof composite core?
something like this:
that wouldn't be too tough, i'd think, easier than tapering honeycomb. probably back to wood for the tip and tail if the honeycomb couldn't handle a bend there also.
my dream ski:
105 mm underfoot, moderate sidecut, moderately stiff...
but only 4 - 5 pounds per pair.
my current powder plus's weigh in at 10 pounds total. sooo heavy.
I saw those jib skis the U of U guys built. Pretty cool ideas there. I wanted to ask them about the honeycomb, but the contact info I've got isn't working (jib_ski@yahoo.com). Anyone know how to get a message to those guys?
thanks,
paul
We milled out a section of the core in both the tips and tails and replaced it with honeycomb. The honeycomb was then pre-bonded to the top of the core using a sheet of 16 ounce biaxial fiberglass. This was necessary so that the cells did not fill with resin during the wet lay process which would have inherently negated the benefit of the weight saved by using the honeycomb in the first place. After the resin cured, the honeycomb was sanded to match the core profile.
If you've got any more questions just post them on the forum here. I'm working up in AK now and cannot access yahoo mail from my work computer.
cheers
Right, don't want the cells full of resin. Did you mill the core all the way through? Just partway? And would you say honeycomb has strength/stiffness properties that make it a good core material for skis?
Thanks for the info, this is helping.
paul
First we cut the honecomb into thin sheets using a bansaw, just barely thicker than the thickest pat of the core where we were implementing it. Next we milled the core all the way through (actually I think we were getting too much vibration when milling so we went with the bansaw and chisel method) and fitted the honecomb in the milled out slot. Unfortunately this relieves all the internal stresses, and the free ends of the core want to branch outward when you do this so we had to epoxy the outside walls of the honeycomb to the insides of the milled out section of core, put it in compression using tape, rubberbands, or a vice, and let it set before pressing. You'll want to do this on all 3 sides of the honecomb that contact the core, we had some delam issues at the transverse wood/honeycomb convergence point. We then took it to the belt sander to profile the honecomb to the exact shape of the wood.
I'd say the diameter of each honeycomb cell was less than 1/8", and if you held a ski core machined out of this in the middle there would be noticeable deflection at tip and tail due to its own weight. We used ploycarbonate honeycomb, aluminum honeycomb may be more suitable here. The weight of the fiberglass implemented above and below the core definitely contribute substantially to the flex of the finished product. On our skis there was a noticeable difference from the 17.5 to 20 oz glass.
If you were to use honeycomb for the entire core you'd end up with and extremely light ski but I think the flex would suffer some. Wood just feels more solid underfoot for me...
hope this helps
Rory
to broskier: can't you add pop(stiffness) maybe using carbon stringers or a full carbon sheet on top or bottom???
carbon definitely helps add some pop, we used several stringer in the tails of both of our skis
be careful how much you use, a little bit goes a long way
also, carbon has a negative coefficient of thermal expansion so it reacts differently than all your other layers to the changing temps, both during pressing and up in the snow, we didn't experinence any delams due to this but if you used a full sheet this might be more of a problem
Hi! Im trying to get all the material I need to build my first skis but I dont know which resin is the best one for this purpose.
I have asked a construction trader and he recommended me poliuretane resin but Im not really sure. You guys use epoxy but Ive used epoxy stick stones to build my rockwall and its very rigid so I think it wont work.
In other places they tell me that what i need is poliester resin or vinilester resin. I think Im getting crazy. Which one do u use and which is better for building skis??
Thx 4 all!!
I think pretty much everyone uses epoxy resins, most of the poly and vinyl ester resins do not work really well with the different materials in a ski. You need to glue the core with epoxy since polyesters will not bond well enough. Polyester resins can not be used over epoxy resins because they will not cure. Epoxy resin for boatbuilding should be available somewhere near you. Some brands that I know are MAS, SP-Systems,
West and Epiglass from International paints. There are others who use other epoxy resins so I hope they'll chime in and tell you some other types.
I just noticed that the boat show is in Madrid this weekend, someone there could lead you to some good epoxies
I also think that pretty much everyone is using epoxy resin for ski lamination. I have done a lot of testing on the epoxy that I use (from QCM... see the links page on this site) and have been amazed at how strong and flexible it is... if mixed and processed properly. I use the heat cure hardener and I learned the hard way that if it is not heated to at least 160 C, the epoxy will harden okay but will be very brittle and will crumble to powder when flexed only slightly... a real bummer when your ski falls apart in your hands when its removed from the press. Anyway, QCM also has a number of other systems that cure at room temp... they just report that the heat cure system is a bit stronger. I happened to think last night about what might happen if my press heating system failed for some reason before reaching 160 C. I guess that I'd just have to let the epoxy cure until it was hard (takes about 6 hours at room temp), then remove the ski and throw it away... something to think about when one is trying to decide whether or not to use a heat cure or room tempcure resin. Anyway, Mutombo, sure there are lots of epoxy products that are formulated to cure to a rigid state, but there are a lot of others that are formulated to be very strong and flexible. Since you are located in Europe, have you checked out the links page on the Graf snowboard site? They list a lot of material suppliers in Europe as well as some in the U.S. that they have used to order their stuff from.
Good luck to you and don't let it get you too crazy. The stuff is out there, it just takes some looking around to find it. I think I would never have managed to get it all together without all of the help and 'teamwork' from the folks on this site.
type L at www.r-g.de
i am using West systems 105 resin and 206 hardener at a ratio of 5 parts resin 1 part hardener.
works pretty good so far and here in Aus its pretty cheap.. so i would imagine its cheap in the US as well
I use the same epoxy as you, schuss.
$110CAD for a gallon of resin, and $40 for the hardener.
Works out to about $0.35/sqft
Thank you guys! I have already found a dealer in my country that suplyes epoxy resin. Now Im going on looking for the base and edges.
Thx again!
P.D.: the resin is EC131LV and the hardener is W342
One question? How many kg do you use to make a pair? I would lie to know in order to buy the proper amount
this site has a very good section on "how to" including how much epoxy you need and how important mixing it in a few batches for one layup is so the exothermic reaction of the large mass doesn't make the whole volume "kick" too quickly. This technique gives you time to get the whole lamination together and into the press and compress it into form before the assembly can begin to stiffen. I learned this the hard way repairing carbon epoxy surfboards.
Mutombo, for bases and edges i buy from www.snowboardmaterials.com.
They have a convenient online store where you can select quantities and such. Delivery is quick too, it took one week to diliver to AUS. so if your in the states it would be faster again.
prices are around $2.20US for an endge and under $21 for a base sheet. (30cmx170cm)
have a look around tho. im sure they cover this in some other topics.
