:: View topic - heated ski press

Hey all,

First off, this site is incredible. It is the best resource I have come across.

I am trying to see if anyone has found a way to add heat to their press. I know the big ski/snowboard makers use metal heat platens which are built into their presses, but that is too expensive.

I am thinking of using ceramic infrared emitters. I know these are used to cure paint and other things.

I talked to a guy at BriskHeat about silicone heat blankets but I don't think they are going to work.

If anyyone has found a solution that isn't too much $$$, let me know.

Thanks,

Jordan

BTW the snow's comming........

I know that some professional ski press use hot water pipes (I suppose copper) to heat up the mold.

I think I was wrong about the silicone heat blankets. I think they might work.

I don't know if anyone else is/has tried to use them, but I think I'm going to give them a try. If anyone has used them with bad results let me know.

-jordan

my question is why would you think they wouldn't work?

To: Guest.

That's one of the things this forum is for. To post ideas for other to critique. If someone has already tried a silicone heat blanket but (for example) had issues with mantaining consistant heat at 170* F then D*MINION wouldn't have to discover that the hard way, or he could plan for the expected problem.

I for one have some electric heating elements which I plan to use to heat a small enclosure which I will roll my press into once the ski is layed up. The only obsticle I have yet to overcome is that of the proper thermostat for 170-180*F. I am going to go visit with an appliance repair shop to see if a regular oven thermostat may be used successfully in my ski press oven. Then hopefully he will let me scrounge a used one for cheap, or free.

I see no reason that this shouldn't work (Guest) but if anyone has sees any contraindications to using this big oven method, by all means, speak up. Thanks. -Jed

Hose-man -

I appreciate your comments, and I am FULLY aware as to what this forum is about.

I think you took my question out of context ...but that was most likely my fault.....I took his (Dminion) statement as ..he spoke to a manufacturer..and after doing so thought the silicone blankets wouldnt work..... I wanted to know what the manufacturer said ...if that was the case.... that changed his mind. Was it cost ..volatge requirements ...etc etc..

..sorry if I wasnt clear.

no worries Guest. Looks like I read you wrong.

I contacted a manufacturer (the first on a google search of silicone heat blankets) if they would work between 50 and 100 psi. He says that as long as the pressure is even it would work and they seem to have a well thought out temperature control setup. Hope this helps.

Ben

I dont believe the site was the first result from the google search so here it is http://www.briskheat.com/ I hope this can make the process easier, let me know how it works out if you try to go this route.

Ben

here are some more:

http://www.benchmarkthermal.com/flex.htm

http://www.watlow.com/products/heaters/

Hey all,

The reason I'm flip flopping with the heat blankets was that I assumed after intially talking with the manufacturer that the blankets could not withstand the pressure of my press (80-100psi). Then I asked them directly if it could withstand up to 100psi and they said yes, but only if the pressure was evenly distributed. So I'm thinking it can work b/c if I put it between the bladder and the top pressing sheet in my press the pressure would be even.

However, I just got off the phone today with the manufacturer and by "evenly distributed" he also meant the heat blanket must lay flat and not kink at all or bend (this is a problem for the tips and tails and possibly even the slight arc of the camber. They are getting back to me if they think it can handle the arc of the camber) . Sooooo.........I'm still figuring it out if I can use it and it be safe.

So all this is to say that I 'm still talking with the manufacturer to work out the details of using a heat blanket. They have been real nice and are trying to see if they have anything that can work.

Hose-man: I thought of making an "oven" as well. You're going to have to let me know how that works. I was thinking of using infrared heaters in it (like a sauna, b/c they make accurate digital temp. control units for them), but I wanted to explore the heat blanket idea first.

Also, I am real new to this. I haven't even pressed a ski yet. But I cannot wait.....I 'm getting close.

snow is comming.......

-jordan

What about simply laying sheet metal down the length of the mold having some stick out. Then heating the metal from outside the press? We all know metal is conductive.

I've been working on this and just received my heat blanket the other day. I have the control box wired and running and the heater seems to work really well. I haven't put the blanket in our mold yet and pressed a ski, but will do so in the next week or so. There should also be an article soon about building the controller.

The blanket is very flexible and will withstand pretty much any pressure that you can apply. However, you can still puncture it with sharp corners or points.

Kelvin:

Cool, I really am curious about how the heat blanket will work. I actually never ended up ordering one b/c the manufactuer seemed very hesitant about using it in the press (he was worried about it pinching, or crimping around the top of the ski). I think it was hard to describe to him exactly how I was going to use it. I was going to put it on top of the pressing sheet not directly on the ski. I felt like that could work b/c it would keep the pressure from pinching or contorting the balnket too much. Where are you going to put the blanket in your mold?

You guys are great. Thanks for all the info.

-jordan

My heat blanket is in the bottom mold under a sheet of thin aluminum. Looking from top to bottom: Aluminum, blanket, 2 sheets of 1/8" hardboard, mdf ribs. I made sure to smooth out any edges and elminated any pressure points.

I got my blanket through: http://www.michaelsenterprises.com

They are very good to work with.

we will be pressing some skis this weekend with the new heated mold. Stay tuned!

kelvin

Let us know how it works out Kelvin. I am very intrigued

We were able to test out the heated press and it is AWESOME! We were able to press 2 pairs in a few hours. Each pair took 40 mins. Pictures and writeup are coming soon.

kelvin

yes, the heated press was a success! i'll have some photos to share at the end of the day. must work now...

Great. Glad to hear it went well.

Its amazing how you just need to talk to the right people. The guys I talked to about the heat blanket were nice but did not think it would work. I was also working on putting the blanket in the top part of the mold as well, which probably was the main problem.

So, did the blanket you use extend the full length of the ski? i.e. up the tip and tail curves? Sorry....I'll wait for the full report.

I'm axious to know how this worked. I was starting to move on to a more expensive solution of having electric heating elements built into a sheet of aluminum. Basicly a heated platen design.

Glad you were able to make it work!

-jordan

Awesome BigKam! Can't wait to hear the particulars...

for now, drool over the intro photo.. . http://www.skibuilders.com/

Kelvin did a fantastic job building and designing the heated addition to our press. it works like a charm, and it only takes about 40-minutes for a pair of skis to cure. i personally think that heat is the way to go!

Kelvin is in the process of writing up an article about the heated press. we'll post it soon along with comments about our two new pairs of skis: Daddy's Little Girl and Kaffeine.

couple questions about pressing..... I'm getting ready to make the base contour of the mold portion of the press. I plan on using MDF. I will alternate camber pieces with tip/tail radius pieces. I read (somewhere on here) that with this layout there is some wavy-ness in the ski base that has to be tuned out. I still need to purchase the sheeting for the base & top release layers. What are you using as your release layers and is is effective in minimising this wavy effect? I'm getting ready to order the last few things I need from Durasurf & I need to know if you're using any plasics in the over/under layering of the press. I remember that someone was using 1/8" MDF layers to smooth the wavy-ness but with marginal success.

Thanks as always.

PS- I've checked the site a dozen times this evening waiting for the details on the new skis & hot press

hose-man: one of the causes for the wavy-ness is our mold design. to minimize cost and make the building process easier, we decided to space the ribs as shown in http://www.skibuilders.com/howto/equip/mold01.jpg. notice how there's a gap between each rib. the width of the gap is the thickness of an MDF rib. we covered the mold with a couple sheets of 1/8 - 1/4" hardboard. we thought it would be enough to provide for a smooth surface, but during pressing the pressurized hose can exert quite a bit of force, therefore causing the ski's base to be wavy. in our skis we noticed that the wave pattern matched the rib-spacing pattern in our mold, which suggested that our rib design was a potential cause. so, one way to avoid such wavy-ness is to make the base mold solid, i.e., do not space the ribs as we have done. doing that will cost a lot of $$ and time, obviously. but that avenue is probably not necessary. for example, in our heated press Kelvin added a sheet of aluminum (i think 1/16") on top of the two layers of hardboard and heater element. the alumium made the mold surface more resistance to "bending" over the gaps in the mold. so, if you can make the mold surface "stiffer", then you can probably avoid the wavy-ness effect. and interestingly, we didn't notice any wavy-ness with the two new skis we pressed using Kelvin's modification. the only thing we noticed was the base was slightly concave. this most likely is caused by the edges, because we did not recess the core material to account for the fact that the edges stick up above the base material. anyway, both the concave and wavy-ness isn't much of a problem as long as it's not severe. they can be removed by grinding..

be patient, we'll have photos soon !

I indend to use the same alternating rib assembly for my press base in order to allow me to vary the length of the ski. I suppose that the heat cure might also hasten the curing process enough that the ski doesn't have time to deform into the spaces between the ribs. Since my cure will be heated as well, I may not need to even worry about this.

Has anyone else got a way to vary the length of the ski press base without the gaps of the alternating tip/tail and camber ribs?

BTW the above link to image is a dead-end

What are you currently using as a release layer above the topsheet to keep excess epoxy from gluing the ski to the press. Below the ski I 'm guessing would just be the painter's plastic to contain the glue.

oops, remove the "." from the end of the link. anyway, it's the second photo on this page: http://www.skibuilders.com/howto/equip/mold.shtml

for release paper, Dan Graf suggested for the heated press to use baking sheets. you know, the wax-like paper that you use to cover a tray to keep cookies and what not from sticking during the baking process. i forget the brand name, but Kelvin knows and i'm sure he'll chime in at some point. i'm on the east coast right now and it's 3 hours earlier than Seattle. Kelvin is probably still in bed dreaming about skis....

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

NO!! in fact, we didn't notice much relaxation. our mold has 28mm of camber, and previous to using heat, we experienced significant loss in camber. but the heated press seems to produce skis with camber that matches the camber in the mold. for example, the two pairs of skis we just made using the heated press has like 25mm of camber! it's ridiculous. anyway, we'll show some photos and talk more about this.

We are using parchment paper (from the baking section) as the release. It works great and doesn't melt like plastic would. (thanks dan for that tip)

The aluminum sheet seemed to have taken care of the waviness. It is a little (<.5mm) concave, but is less than it was before the aluminum addition. On the 'daddie's', I put a rabbet in the cores to allow for edge tabs. It seems flatter, but I can't really tell for sure until I clean up the skis and pass them through our belt sander.

I was quite surprised that the camber didn't relax. We'll have to modify our mold to fix that. They are like springboards now.

Kelvin

My mold actually is able to adjust length and I don't use ribs. I am set up to press one ski at a time. For the ends, I just cut several pieces out of 2x4's, (similar to the MDF ones the Kams use) and used straight brackets to mount them to the mold. My "mold" for my first pair of skis consisted of a 1x8 piece of utility grade lumber. It didn't have any camber, but I wanted to make it as simple as possible for my first round. The ends didn't really see a lot of force pushing them back because the bladder continues past them and pretty much pins them in place.

I also have a mold made of several 2x4's that I cut to shape and glued together. I haven't tried using this mold yet, but I think it should work pretty well with the end pieces screwed to it.

Greg. do you end up with a kink, ledge or flat spot where the tip block terminates?

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

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

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

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...

how expensive was the whole setup?

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

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.

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.

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

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

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.

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

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.

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

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.

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....

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.

Has anyone else got a way to vary the length of the ski press base without the gaps of the alternating tip/tail and camber ribs?

Hose-man:

Check out http://www.grafsnowboards.com they built a system so they could slide the tip and tail blocks. They use several sheets of MDF and Aluminum to smooth out the transition. The information is far down on the home page on the right near the Nov 5th entry.

I'm planning on using something similar to this.

Hose-man...

You said you were taking the heating element out of an old heater for your press, which seems like a good idea to me. How are you mounting it? I had a kinda crazy idea about making your own silicone blanket. You could lay out the wire in some regular pattern and than cast silicone around it. Doing a little googleing it seems that ordinary silicone caulk is rated to 400 deg F and you should be able to thin it with xylene [nasty stuff, but at any hardware store]. I was thinking: lay out the wire in a shallow mold; cast a layer of silicone as thin as possible and let cure; flip it and lay a very thin layer on what was the bottom. Holding a vibrating back massager to the bottom of the mold should make it level out pretty well. It seems silicone doesn't like to bond to silicone that's allready cured so that might be a problem if you're not gentle with it.

That last post, about casting silicone, was me in case anybody wants to throw questions/criticisms my way.

Hi Guys , I was wondering how much did cost to build your heat blanket setup???

thanks for the incredible site.

Greetings,

I was wondering if anyone has establised an ideal temperaturs for curing the skis? My thoughts on the cheapest way to provide the heat varies with the end temperature required. If a temperaturs of say 150 F is good, I think enclosing the press and supplying heat externally using a propane or electric heat source might be all that is needed. However if the ideal cure temperaure is 300 F the silicone strip heater sounds optimal.

I have been spending a lot of my spare time working my way through this great site and am really excited about getting set up so I may be making my own ski creations shortly as well. Thanks for all the hard work and dedication required to make this site work so well and bringing together people from all over to share some pretty clever ideas. My learning curve has been shortened by many years as a result.

My epoxy from QCP specifies a press temperature of 170-190 degrees F.

Haven't tested it yet, for lack of time, so I cant tell you what result varying the temp had on the product.

I just put a ski in the press yesterday and got around to putting a thermometer on it as well. My department store modified heat blanket heats the ski up to about 105 degrees F, or about 40 degrees C. This is certainly not extremely hot, but with the epoxy and hardener I am using (QCM ECA-315 and EHV-0050) I was able to press a ski in about 3.5 hours. It probably could have come out in 3 hours, but I wanted to make sure.

greg, how exactly did you modify your heat blanket? i was digging around in one my closest last week and found an old heat blanket. i want to try your method since it fits into my non-existant ski building budget.

I bought a heated blanket from a second hand store a couple weeks ago. I ripped the whole thing apart to get the heating coils out. I hooked it all up to my top cassette and it seemed to heat the cassette up nicely. I did a test run with pressure and something happened. The heated "wires" got super hot for some reason, and some even started to melt together.

I was in a bit of a rush to get the press working so I abandoned the heating project. I am very interested in getting this heating aspect of the press working now that I have a little more time on my hands.

Any details that you have on your set up would be awesome.

Class5:

One possibilty is that your wires are shorting out. My other thought is that the heating blanket is designed to be used open to air and when you encase it in your press, the wires may be overheating due to the lack of air cooling.

-kelvin

To make my heat blanket, I bought a heating blanket at Macy's (formerly the bon marche) because Target didn't have any. The first time I used it, I just folded it up and layed it on top of the ski. This worked okay, but not phenomenally. After the first trial, I ripped apart the blanket, and layed all of the coils into a loop. Then, I cut a strip from the ripped apart blanket, and used the material and my sewing machine to sew one heat blanket about 7' long and 8" wide. The only issue that I have been having with it is that when I lay it between the ski and the bladder, it can form perforations in the topsheet of the ski where the pressure from the bladder pushes on the individual wires. My next idea with it though is to use some metal flashing between the blanket and the ski, and hopefully that will solve the perforation issue.

For reference, I used a twin sized heat blanket, but with a king sized heat blanket you might not need to do all the sewing because it would be long enough to fit in the press. Also, when I run the press, I set the blanket to the highest setting.

Greg, thanks for the info.

Kelvin, I think that the wires must have been shorting out. The wires melting together were actually outside of the press and lightly touching each other.

In the next few weeks I'll see what I can get working. I also have a great resource as I consider my brother to be an electrical genius. There is something cool about having a heating system that costs under $10!