Ski Builders Forum

So I've been reading a lot of the everyone's posts hereon the site and I've noticed that many of you have built your adjustable bottom molds like this example from Head Monkey's site. So in essence you have a piece of MDF laying flat along the running length and meeting the tip and tail molds which butt up against it.


I'm just curious why so many people use this method and it is making me wonder if I'm missing something. With this style, wouldn't you have to have a different length piece of MDF to swap out for every length ski or board you want to make?

I was thinking I would make my tip and tail molds sit directly onto my bottom (Cambered) mold. The thin portion of the tip mold would get thin right at the transition point between the bottom mold and the tip mold. Do you see anything wrong with this style? It would eliminate having to buy a bunch more MDF. Thanks for any tips.

For the center section you don't necessarily have to use one continuous piece of mdf. You can add or remove pieces to accommodate different length skis or boards.

I think if you wanted to taper your tip and tail molds down to nothing at the transition they would be way too thin and fragile.

Most of the time I use one continuous piece between the tip molds but I have used several on occasion as well. I just make sure that it is a real tight fit and screw them down.

Depending on temp and the quality of the MDF available in your area, you may want to use ply for the centre section. 80oC/50psi appears to be around the critical values.

WhitePine- That will work also. You want to be sure at the transition point it blends into the bottom mold. You don't want much of a gap there that might transfer any irregularity into the base of the ski. A good AL cassette will help prevent that also. Wood might make a better tip/tail mold in this case because the thinness at the transition point will be a little more durable than MDF.

Perfect. Thanks for the responses guys. This is exactly the information I was looking for. Would you use 1/2" or 3/4" for the center section?

I'm using 3/4.

WhitePine wrote:The thin portion of the tip mold would get thin right at the transition point between the bottom mold and the tip mold. Do you see anything wrong with this style?

Have you ever tried to cut MDF to a point that thin? It will chip/break. By having the center board, the tip/tail molds don't have any thin/sharp corners.

I had an idea of doing what you're describing, but having the MDF go down to a thickness of like 1/4" or 1/8", and then put a piece of thin sheet metal or formica on the mold surface. There would still be a small lip at the end of the metal or formica, but it wouldn't chip over time.

I was using 12mm.

twizzstyle wrote:

WhitePine wrote:The thin portion of the tip mold would get thin right at the transition point between the bottom mold and the tip mold. Do you see anything wrong with this style?

Have you ever tried to cut MDF to a point that thin? It will chip/break. By having the center board, the tip/tail molds don't have any thin/sharp corners.

I had an idea of doing what you're describing, but having the MDF go down to a thickness of like 1/4" or 1/8", and then put a piece of thin sheet metal or formica on the mold surface. There would still be a small lip at the end of the metal or formica, but it wouldn't chip over time.

Yep, on my first couple molds I did this. Used pine and had to sand it down to the point.
My latest mold I used MDF there was no way I could get it to the point.
Just kept breaking out.

WhitePine wrote: I'm just curious why so many people use this method and it is making me wonder if I'm missing something. With this style, wouldn't you have to have a different length piece of MDF to swap out for every length ski or board you want to make?

You just might be missing something here. Swapping out this middle piece of MDF is probably the easiest part in making a different length ski/board. You will need a different length cassette, adjusting the top mold is usually awkward to say the least, the cattrack may or may not need to be extended, the metal protecting the heat pad will need to be changed, and then of course all the ski ingredients need changed. FWIW my mold uses a 3/4" sheet of MDF for the flat section just like Head Monkey's. It might be a good idea to design it for a 1/4" piece of hardboard or something. Then you could use a thicker board (1/2" or 3/4" thick) for your camber that will taper down to the 1/4" height. Or just leave a flat piece in there. Camber is way overrated.

Powderho - I totally understand what you mean. I had the pleasure of riding my friend's Bluehouse Maestro's the other day. They have zero camber underfoot. They were awesome in the powder and can turn on a dime in the trees but I noticed they get a little squirrely at speed. Not unmanageable, but noticeably different. It was a really fun shape and ill probably model my first ski after it. First though, I'll be building a snowboard that can handle pow. My Burton malolo struggled at Snowbird last week.

I think camber has its place though. I plan on putting about 3 mm of camber into a 170cm board. The problem is that the camber gets huge on the 185cm skis I want to build later. And from what I've seen an adjustable camber mold is a bit too cumbersome. I guess I could always plane down the camber on the mold later.

Anyway, I'm glad I posted this question. You guys saved me some money by avoiding a costly mistake. I've never worked with MDF so its a learning experience. Thanks.

Are you going to use heat for your pressing?

I use a flat mold and control my camber with top and bottom heat. It takes a little experimentation but this way I don't have to make new molds.

Initially no, I plan to use the natural heat of my garage. In the summer it easily gets to 110°F. Mainly I'm shooting for at least room temperature though. Eventually I'll add heat blankets if I can justify the value of them. For now this is a bare bones operation.