The surface I use is 3mm thick.

I use TR Mold Release wax but I've heard Partall Paste #2 wax also works well.

What thickness is recommended? Also when using lexan as a surface should a mold release agent (like vaseline) be used on the surface?

It's Lexan (aka Polycarbonate). Plexiglass is too brittle to work as a mold surface.

Dante, could you tell me what the clear mold surface material is that you are using? Is it plexiglass, Lexan or another type?

Thanks,
Nathan

I think it depends on how the software blends the radii. It looked like the tip and tail radius were effecting the region of the profile from the contact point to the tip or tail respectively, and not effecting the profile between these two points. In this case, by increasing the tip and tail radii by the offset from the mold, you only effect these regions.

I am starting to think that since the contact points are offset perpendicularly (straight up) from the horizontal plain the board sits on, you are shaving off the change in the center radius, however you've essentially flattened it.

If you draw a curvy W in Autocad, and then use the offset function a few times to make parallel curves, you can kind of see it happening.

If the center of the profile was dictated by a radius, as is the tip and tail, you could just decrease this center radius by the offset distance, while increasing the radii of the tip and tail by this offset distance, and you should come out with what you are looking for exactly. But, because the center profile is dictated by effective edge and camber, it's a little trickier.

It's virtually negligible. I think when I calculated the changes to these dimensions, it was less than .4 mm on the effective edge, and .6 mm on the camber. Not much you can do with that.

Shadly,

I think you are on to something with this but I don’t think I fully get it yet. In the proof you say “any offset to the base will increase the distance between the contact points. But, because the tip and tail radii (r2, r3) are lessened, the overall change in length is not effected”

My main question is if you have both r2 and r3 offsets biting into EE wouldn’t EE be decreased because you basically have 2 offsets going against 1?

One slight correction. My geometry is off for the part where you correct the Camber after offseting the distance between contact points. The equation should be:

New Camber = Camber - (Camber * change in EE / (2 * EE))

The way I drew it, the camber was being increased to correct it, this is wrong.

Yeah! Great success! You can delete all those failed attempts. Sorry about that.

Proof:

Attached Proof:

Try this again:

I think I figured it out. When I was saying Effective Edge, I meant the distance between the rear contact point and the front one. When you have a camber on your board, you are creating a curve in the middle of the board which is being accentuated. Because the tip and tail radii are being lessened, this cancels out, although you have reproportioned the regions of the board. The center part, between the points where the board contacts the snow is widened, while the tip and tail are shortened.

Hope this confusing proof helps.

I think you might be right about 2x being too much. Attached is an image that lead to that line of thinking but it's only valid for the points indicated.


I think the real difference is in running length. The nose and tail would still be the same length but they would begin elevating before they are supposed to. The overall board length will remain the same because we are not stretching or shrinking it (the base material is cut and the edges are attached).

As for measuring... it's not a clean measurement to take because it's tough to identify the exact point where the curves begin and end.

I've got a free pack of inserts for the first person to definitively solve this conundrum with a replicable, verifiable calculation

I dusted off the trigonometry a little, but didn't come up with much. So basically the only parameters that would be offset would be the tip and tail length correct? Wouldn't the overall board length be effected, not the effective length because you are actually increasing the radius of the curve between your feet? I think if anything the effective edge would increase by less than two times the surface thickness.

Have you found any difference in camber height and effective edge from what your plans predict?

It should all be proportional though. You might want to just measure one of your boards versus what it's supposed to be, and come up with a ratio per parameter.

You bring up a really good point and it's an issue I haven't quite figured out yet. The challenge is calculating how to compensate. The curves are essentially offset by the thickness of whatever you put on top of the mold ribs so they are hardly impacted. However, the running length of the snowboard will shrink because we are effectively closing in on the center of the board from the tip and tail. It's hard to determine exactly how much running length shrinks because it depends a lot on the radius of the nose and tail. I think the steeper the nose and tail climb the more significant the impact will be on running length.

Right now I just extend my running length by 2x my surface thickness but this is overly simplistic and I'd like to get more exact.

If anyone out there comes up with a more accurate method for calculating this please let me know. I'd be happy to make it a calculator that everyone can use.

I built my mold rib slats out of a lot of 1/4 x 1/4 in. MDF. Should I be worried about the thickness of these throwing off the curve of the mold ribs? I believe, because the shape of the ribs is a "W" essentially, the curve would be exaggerated at the ends. When you built yours, did you offset the curve 1/4 in. first to compensate for this, or is it not too much of a big deal?

This thread discusses the Content article: Snowboard Mold Setup - Part 5

Discussions on the Snowboard Mold Setup video should go here.