Montucky Skis

[MontuckyMadman]

The temperature must be ramped up from room temperature to 175F over about 10 min, then held within +/- 5 degrees of that for one hour, and finally cooled before the board is removed from the mold.

http://www.happymonkeysnowboards.com/MonkeyBlog/?p=340

[doughboyshredder]

sometimes even head monkey is wrong

[Head Monkey]

What?! I’m never wrong. Ever!!!



Actually, I’m wrong on a daily, if not hourly basis… and I should update that post Montucky links to. I do ramp up from room temp to 175 over about 10 min or so, and I do hold it there for a one hour cure. But I’ve never let it cool all the way before removing the board. I always think I should, which is why I wrote that, but it never happens in reality. I do let it cool some, though, by having the controller ramp the temp down, but honestly I don’t think I’ve ever been patient enough wait for it to actually cool all the way. IIRC, I usually end up taking the board out, with gloves, when it’s around the 145-ish mark, usually no more than 45min after the one hour cure.

So, the reason I ramp up over about 10 min is so I can control the temp differential between the top and bottom. If I just turn my blankets on and let them go on full then I see the bottom temp rise significantly faster than the top temp. My supposition is that the cat track makes an excellent heat sink. So while I’m bringing it up from room temp I actually unplug the bottom blanket once the bottom temp exceeds the top temp by 5F. I plug it back in when the top catches up or even exceeds the bottom a bit (and it is a “catching up” effect… the bottom tends to remain stable and not drop while waiting for the top.) Once they’re at 175F I leave them alone and while the top is cooler, it’s never more than 5F off.

Why do I leave it in to cool down some? I don’t honestly remember why I started doing that… someone probably suggested it to me, and it sounded reasonable. I haven’t every had any problems with a warped board like’s been described above, though… maybe that’s because I’m taking it out while it’s still at 145F? Maybe there’s some other reason, who knows.

I’ll throw out two more bits of food for thought:

1. Doughboy’s info on what they do in a big production shop is excellent, but I will suggest that their processes were likely optimized primarily for throughput.
2. Have you ever taken a true-bar in your backpack and checked your base after an hour on the hill? A board that is flat in the shop is not flat out on the snow

I’ll go update that post now… hmm… if it was on a wiki then Montucky could do it… or at least mark that part as “currently controversial” and link right back here…

Enjoy,

Mike

[MontuckyMadman]

I do everything just like that described in most instances without my recent foray into carbon.
We did them independently before, some pulled hot and some left to cool under pressure. We were sure the ones pulled hot were the cupped ones, maybe not.
But for sure that damn thing was flat as fuick after 5 days at room temp and a nice grind.

4 days and freezing temps later and the base is cupped, I swear, its really hard to see but it wasn't there before.

The other denting and warping maybe from a less than stellar "new" mold and exacerbated by the carbon layup maybe and the pressure cool.

Strangely enough we did notice a depression in the bottom of the press across the 1/2 inch plate, from where they keyhole welded it and had some warping. Its minute.
Could it translate through all that mdf 5"+ and the blanket and al sheets, 4 of them? I don't have a 1/4 inch slab of aL maybe we will get some 3/16 steel to span and smooth the mold or retool the mold or both.

We also may fill the bottom of the press with something. Its so nominal its insane that this could cause an issue. Talking .3 mm over a 4-5 inch area kinda cupped in the middle, prolly from heat warp.

[falls]

Hey Montucky
Interested in your layup and how well it all bonded.
Standard ptex and edges, VDS over edges, then carbon, then core, then carbon?
Or did you use more VDS?
Have I read that carbon doesn't like to bond to wood that much? and VDS use is really important?
Sounds also like the carbon is more difficult to wet out?
I am thinking of doing a uni carbon and biax carbon layup to make triax. The stuff I can get is:
UNI: 200 or 315gsm (5.8oz, 9.3oz)
BIAX: 200, 410, 450 (5.8oz, 12oz, 13.3oz)

OK looked back and you used 12oz biax and 4.5oz uni.
So for this carbon did you adjust your core profile to get what you said was a pretty good flex. Basically do you think your carbon (total 16.5oz) mimicked triax fibreglass 22oz?

Thanks.
I just had a very long weekend at work, which has the upside of a small fortune to blow on carbon experimentation.

[MontuckyMadman]

I used the same amount of vds just above edges and in the tip and tail.
I used a totally new core profile.
Most of the skis I made were profiled on center. This left the forebody of the ski feeling very unforgiving but gave the ski a nice round flex.
Some I went with a flat spot and some with a thicker tail behind center.
All worked fine but this one was totally different.
I used ash which I had not worked with.

I put the thick point 10cm behind center I think and left a swollen, not flat spot 40cm to a standard 2mm tail.
This left the tip with a longer angle and consequentially softer.
The ash feels pretty sweet. Its different than the other woods for sure.

Yes the composite was light and slightly soft in the tip but still really nice overall I think.

I am making the exact same ski in vectroply triax to compare.

I did not prebend the tips as I have done previously and 2 skis at a time one edge had some edge fall and a bit of delam there.
Pretty critical when you have the two skis together to have the cores exactly the same in the tip area.

[Brazen]

MM, was this the pair that gave you base issues? Because, if so, you just named your problem...it's mold compliance in the tip section. You'll get such a crazy base from that. The answer, if that's the case is to more closely follow the bottom tip rise curve with the top mold and everything else will fall into line. The slight offset on the bottom of your press strikes me as inconsequential if you have a "balancing" layer between it and your cassette. I've had a couple and might have missed something though, but hey...free beer

[falls]

fair to say then that this new core had just as much wood (if not more) than your previous ones?

[Brazen]

^Hey! Zip it! One question at a time

[MontuckyMadman]

Prolly more wood than previously. But I reduced the core profile dims.
The tip mold is an exact copy and we get great visually compression in that area.
When we prebent, those problems went away.
Of course no one can see them but us as skibuilders the average person doesn't know what to look for.

I feel like 60psi just isn't enough some times.

[Brazen]

Prolly more wood than previously. But I reduced the core profile dims.
The tip mold is an exact copy and we get great visually compression in that area.
When we prebent, those problems went away.
Of course no one can see them but us as skibuilders the average person doesn't know what to look for.

I feel like 60psi just isn't enough some times.

If, when you prebent these problems weren't present "res ipsa loquitur"

I will sometimes press in at a higher psi then back off a little.

[MontuckyMadman]

[MontuckyMadman]

[falls]

that's one fat ski
looking good

[COsurfer]

Nice!!!!!! how did you do the graphic?