Ski Builders Forum

Hello everyone, this site is a great rescource, thanks for sharing all of your knowledge.

Im all fired up to build my own snowboards and have some questions.
I'm trying to build with as much salvage/recycled product as possible, for the cost and I just like to reuse.

Has anyone used plywood to construct their mold blocks. Is there a reason to use MDF vs plywood, the reason I ask is I have an almost unlimited supply of plywood scraps near me,(nice scraps)

I also have an almost unlimited supply of low density polyethelene(sp) plastic sheet scraps, about 1.5 millimeter thick, could this be used for tip spacer, does anyone want some? does it have some uses I'm not thinking of? Could this be used to line my mold with? From my exp. resin doesnt usually stick to LDPE, so maybe a tip spacer is out but maybe i could uses somewhere else.

Also is there a primer anywhere on board design. For example x amount of camber equals this type of performance, x amount of sidecut means this type of turn, this much nose rocker is goood for this type of ride style.

Thanks.

I'm not the most experienced opinion here, but I think the biggest advantage of MDF is its stability (dimensional and resistance to warping). Even plywood can be susceptible to changes in the humidity. If your plywood stash is marine ply though, you probably don't have to worry about that. MDf is also cheap. Its disadvantages are that it's heavy and, though easy to work, a bitch when it comes to dust. You'll want a respirator and goggles, and unless you have a full on ventilation/dust collection system in your shop, everything (I mean EVERYTHING....) is going to be coated with MDF dust by the time you're done making a mold. It's also very fragile to any kind of impact and you definitely don't want to get it wet.

I would say go for it with the plywood. I don't see why it won't work.

Where are you based? Stateside or elsewhere? Material availability and cost can change more than ten fold depending where in the ski building world you are located.

As for a design Primer, if it's Boards (Skis) hunt around this forum. If its A Board then there is more to be found at Graffsnowboards. Although the rest of the building process is the same as skis - I think there is more construction knowledge to be found here (but that is me being biased).

I think MDF is used because it machines easily and gives a smooth finish. But as agiocochook mentioned everything will be covered in dust. It goes everywhere. You'll need to have some sort of dust pick up/vacuum on your power tools or do it outside. But in either case wear a good dust mask. It's nasty and hazardous.

But plywood will work also.

For a primer go to www.skibuilders.com. On the top there categories, ABOUT, HOW TO and ARTICLES. Lots of good info. After reading those site try using the search function. There's a ton of info already in the forum. I'll send you a spreadsheet that one of the contributors developed. I don't totally understand all the info it provides. But it's a good start and will have more meaning after you've built a ski or 2.

thanks, for the responses.

As for the plywood it is cheap(free) but not very stable, I live in the wet pacific north west, so humidity is an issue.

Desmond, thanks, i took your advice and read all the articles and how to's on ski builders. The COMPARISON OF SKI DIMENSIONS by Jed Simpson, didnt really answer my question but gives me a pretty good idea that some useful dimension primer doesnt really exist.

So i have a couple more questions.

For a mold has anyone used dimensional lumber, profiled and then either clamped/bolted/glued together? Along with plywood scraps, there is an almost unlimited suppply of lumber scraps, hardwoods, softwoods, etc.

Which leads to my next question about cores. I tried looking for this answer on the forum but I may have missed it.(i'll try not to waste peoples time by asking that which can easily be answered by searching the forum, which i have been lurking on for awhile, and have read a large part of.

Core Questions.

For a basic core recipe what is a good width for my strips of vertical endgrain to laminate together. And what is a good height/depth of my strips, before i plane my laminated core?

Does any one have a rule of thumb for the deconstruction of a board/ski? Lets say there is a board i like the flex of, if i took a measurement of depth/thickness at equal spaces down the center line, I would get an idea of the overall taper of the board. Does any one know how much thickness to subtract for the various laminate layers(base,glass,resin,topsheet etc) to arrive at an approximate thickness of the core?

we start with 1 3/4" strip for the laminate and then bookmatch the cores to get 2 skis at about 15mm thick and plane to 13mm to start the profile process.

what is the ski you like?

I have skis that were 12mm core on center at thickest point and with 2.2mm base, 2 layers 22oz triax and rubber and a 1/42" thick venner with entropy bio resin at 50psi and they are 16mm thick after a quick base grind flatten.

So that may tell you something about extrapolating thickness profile but the wood material has very different mechanical/stiffness properties.

madman

It's a snowboard, not a ski i'm gonna build. i grew up surfing, so i never could learn to face forward on two planks and ride, whether water, or snow skis

The board i like the flex of is the Amplid Paradigma. Its kinda like a burton custom(peter Bauer who used to do r&d for burton now has his own company called Amplid, and they do skis and boards) The board is pretty stiff compared comprable models to what else is out there, and i know its made with , biax top and bottom, poplar core.

Thanks for your measurements, that helps and i'm gonna study them and hopefully others will post similiar results.

i realize that the properties of different woods wil offer different characteristics. However if the core thickness profile is the same shouldnt the base flex pattern be similiar. I'm not referring to the stiffness or pop. I want a stiffer board than what i'm riding I just want a similiar feel when i curve/flex the board/ Does that make sense?

my first core will be maple stringers for the inserts, and sidewalls, with spruce imbetween, mainly cause it is salvaged wood, and i'm looking for a stiff ride,

You're asking all the right questions, but there really is no 1 answer. Depends on the type of ski you want to build. A lot of guys build skis for powder. I build for North East skiing. Totally different designs. Some really cool designs here, you'll never see elsewhere.

But as for molds, I used MDF on the bottom and dimensional lumber for the top mold (2x6's). I used 2x6 only because it was lighter to work with, but I think you can use MDF for top/bottom molds, plywood or dimensional lumber. No matter what you use the main goal it to get as perfect mold as possible, smooth and consistent. btw- I bolted everything together, no glue.

As for glueing up vertical laminates there's no rule. I've use solid ash, no glue ups or plastic sidewalls. Other guys use plastic sidewalls. I've also used poplar and maple strips, 1 poplar strip down the center with maple on the side to make a 5 inch wide board. Others mix different types of wood to get a desire flex, stiffness or to make it light weight. It all depends.

Generally I would a say most ski thicknesses run from 2-3mm in the tips and tails to 8-12 mm in the middle. May not sound like a big range but it is. It's surprising to see how much diiference a mm makes, but it does.

There are pics of skis that have been deconstructed and you'll see the big manufactures use very thin strips, maybe 2-4 mm? But you don't have too.

There are so many factors it's hard to say "This is how to do it...". But a good starting point is to copy a shape you like already. Measure everything about. But unless you know what went into the ski you're trying to copy, you can get a totally different ski in the end. It may look the same dimensionally, but perform differently... hopefully better!

I use SnoCad-x for designing skis. It can be used for snowboards too. You can also use any other CAD type programs too.

So back to general rule of thumb..... It depends... As for a typical layup, I use:

P-tex base
metal edges
VDS rubber
22 oz Fiberglass
wood core of your choosing
22 oz fiber glass
top sheet of your choosing

For deconstruction.... If your current ski is say, 80mm wide in the middle, subtract 5mm and that will get you pretty close to width of the ski w/o edges. So when you design a ski, keep that in mind. As for thickness, that is really hard to pin down because unless you know exactly how the ski was made and the materials used it's nothing but a guess. My first ski I made I copied from a ski I was using. The thickness at mid ski was about 13-14 mm. I made a wood core of about 12mm.

After the layup the ski was super stiff. A lot stiffer than the ski I copied. I'm guessing if I went with a 10mm thickness it would have been better.

This is what makes ski/board building so much fun (maybe frustrating too at times) you can break the rules, make the rules.

But I would go simple at first. And take it from there... You can't just build 1 set of skis . So, that's my 2 cents. Good luck!

Also just as a side note. i know there is alot of curiousity on fiberglass vs carbon fiber, The Amplid Paradigma comes in an all carbon version called the Unweight. it's the same mold, profile, runninglenght etc just a different core and layups.

i prefer the glass version, it's actually slightly stiffer longitudnally(sp),

they also have two sets of skis, one glass and one carbon but otherwise the same. i dont know the model name but you can see it at amplid.com. this isnt an ad, just a real world comparison of one layup vs the other.

If anyone lives near mt. hood oregon, i can put you in touch with the guy and you can demo both and see what the difference between glass and carbon layups but otherwise the same are. i dont know of any other companies that offer the same model in different layups.