heated ski press

[Biggie]

So do you only need one heat blanket for the bottom side?

[bigKam]

yes, that's sufficient. take a look at this:

http://www.skibuilders.com/articles/heatedpress.shtml

[hose-man]

Another great article! I am impressed by the time and money you invest in doing things right. The solid state relay is a great example of this. Kudos to you guys for showing us how to do it the right way, the first time.

When my heated press is done I expect everyone will be impressed with what a little duct tape & bailing wire can accomplish.

One question from the article though. The auto tuning PID controller..... What does PID stand for? Thanks -J

[bigKam]

Another great article! I am impressed by the time and money you invest in doing things right. The solid state relay is a great example of this. Kudos to you guys for showing us how to do it the right way, the first time.

When my heated press is done I expect everyone will be impressed with what a little duct tape & bailing wire can accomplish.

One question from the article though. The auto tuning PID controller..... What does PID stand for? Thanks -J

PID stands for Proportional-Integral-Derivative. basically, it's a somewhat fancy feedback controller that helps achieve the setpoint temperature value. here's a link for more info: http://www.expertune.com/tutor.html

feedback control design can get really technical...

[melvs]

how expensive was the whole setup?

and the most important question.. where could you go cheaper?

[bigKam]

Does the camber in the mold still have to be exagerated in the heated press? I remember reading that previously you were loosing about 10mm of camber.
Thanks,
Ben

here's another follow-up to this question:


Kelvin is holding up one pair of our new skis: Daddy's Little Girl. notice the amount of camber -- it's ridiculous. an eyball inspection will give 2-inches gap as shown. our mold has 28mm of camber, and the heated press works like a charm, but it doesn't seem to leave much in the way of camber relaxation. whatever camber is designed into the mold of a heated press, that's the camber your skis will end up with.

[Ben]

Thats Awesome!!
Im really intrerested in how they ski, they look like a lot of fun. A comparison between the "stiff upper lips" and those should be interesting.

[Guest]

When my heated press is done I expect everyone will be impressed with what a little duct tape & bailing wire can accomplish.

Okay, you caught my interest at least. Care to elaborate?

[kelvin]

The whole setup cost about $400. $300 of which was for the blanket. The controller ($35), ssr($20), definite purpose contactor($20), and the enclosure($18) were all from ebay. All of the stuff I got from ebay were new and a whole lot cheaper. Just the controller would cost about $175-$200 from a retail place.

To cut cost you could get a smaller blanket for 1 ski instead of a pair. The DP contactor is also not crucial. Going to a smaller blanket also helps in that the components you choose won't have to handle as much current and therefore are usually a little cheaper. However, on ebay, it doesn't seem to matter much.

There are ways to go dirt cheap on the controller, but if you are going to spend the money on a blanket, you might as well build a decent controller for it.

-kelvin

[melvs]

ya, so the blanket is the expensive part.

would a couple space heaters positioned near the press make much of a difference? it's not going to be direct heat, but it might very well heat up the stuff a bit.

[kelvin]

would a couple space heaters positioned near the press make much of a difference?

it'll keep you warm while you work, that's about it.

[melvs]

what if I put the whole press in a big oven?

haha, I'm off to get some stuff so I can hopefully finish up the molds this weekend/the next week or two. Then I can start playing with the whole process.

[Guest]

My question is for Kam
I wonder at what temp did you heat your press?
And wich pressure and topsheet material you use?

I own a heated snowboard press and got some trouble with bump on the topsheet even if only the bottom mold is heated, and your finish look great on your ski the topsheet seem to stay pretty flat?

By the way I use ICP 1145 topsheet material.

Thanks Guy's

*Its a totaly great site

[hose-man]

When my heated press is done I expect everyone will be impressed with what a little duct tape & bailing wire can accomplish.

Okay, you caught my interest at least. Care to elaborate?

I was basically saying that my approach to things is slightly more ghetto then these guys. I'm using salvaged I-beams and elements reclaimed from a radiant heat unit to heat the press. My set up is more garage than lab & these guys do a great job in their ski labratory.

[bigKam]

what if I put the whole press in a big oven?

i dunno. i'm no expert, but let's consider the mass of your press and mold, and the time constant for a first-order thermal system. basically, it will take a significant amount of time for the entire system to heat up uniformly. talk about requiring a lot of power! it's not worth heating everything up. all you want to do is bring the ski materials and epoxy up to temp, then hold it for a sufficient amount of time and finally turn off the heat. so far i think the best solution is what Kelvin has come up with. it's simple, but i do agree that it can be expensive. again, remember that this garage-based ski building thing isn't about making money or mass production. it's about tinkering, doing things yourself, creating, having fun, and, of course, the spirit of skiing....

My question is for Kam
I wonder at what temp did you heat your press?
And wich pressure and topsheet material you use?

Kelvin's the expert on the heated press and i'm sure he'll chime in with his comments. but what i can say is the temp we pressed at was 190-degrees F. i cranked the compressor to deliver 45 psi of pressure, and the topsheet material is Dura-surf P-tex, from Crown Plastics.

we didn't notice any bubbling effects on the topsheet.