Hot Box

nate · Post by **nate** » Fri Dec 23, 2011 10:38 am

So I'm home from college on Christmas Break. Want to make a new pair of skis.

Context aside, everyone says heat is a must, and my last pair were pressed in my basement at what was probably 60-65 F with Entropy expoy. This time I want to do it one better and get some heat in there, but I have limited time and money that I want to put into this. I ordered Resin Research epoxy http://www.resinresearch.net/id2.html (2000 and 2100 S on their recommendation).

Buying a heating blanket is too expensive. Making one a bit too time consuming and still spendy. So, despite never having seen anything like this on the forum I'm making a big insulated box for my whole press and I'm blowing hot air into it using a couple little space heaters.

So after a test run, a few modifications, and another test run here are my results:

Temperatures taken with a turkey probe:
After about an hr:
In Cat track: 85 F
At the top of the box: 190 F

I'm considering pressing for several hours, then taking the skis out of the press and putting them on top of the press, still in the box, where they'll bake at 180 for a post cure?

Opinions?
Maybe I could fit some sort of circulation fan in to get the temperature more uniform.

Richuk · Post by **Richuk** » Fri Dec 23, 2011 11:30 am

Madrussian is the heating engineer ... maybe he's lurcking?

What about using an extractor fan, plug and go: http://www.google.co.uk/products/catalo ... KEBEPICMAE

A bit of hose borrowed from the back of the tumble dryer?

MontuckyMadman · Post by **MontuckyMadman** » Fri Dec 23, 2011 1:25 pm

pretty amazing a couple space heaters can get it to 190F.

skidesmond · Post by **skidesmond** » Fri Dec 23, 2011 1:51 pm

190f with space heaters, pretty good. If you have extra material try a test. I'm sure after 3hrs of pressing w/ some heat the epoxy would have kicked.

I still press at room temp too. But I have thought about putting the skis in a hot box after wards in hopes it will speed the curing process instead of waiting 4-5 days (or longer) before cutting the flashing and flexing.

Well, let us know how it works :-)

nate · Post by **nate** » Fri Dec 23, 2011 7:04 pm

MontuckyMadman wrote:pretty amazing a couple space heaters can get it to 190F.

Yea, I was very surprised. Just need to spread the heat around now.

MadRussian · Post by **MadRussian** » Sat Dec 24, 2011 3:59 pm

I have not got this far on my project. I can only advise from experience doing other thing with insulation.

My press located in the corner and Hot box will be more like small room 5'w x9' l x 6' h. I am thinking to use fiberglass board with foil face 1" thick or yellow foam insulation board with foil you can buy in Home Depot... cheaper per Square feet and higher R value than tape all seems with foil tape to make it airtight.
For even air circulation=heat distribution I thinking to put Cat tracks on top and bottom. For now as a heat source I'm thinking to use torpedo heater hooked to thermostat inside the box this way circulator may not needed. Possible problem increase air pressure inside the box. Another option small space heater inside the box and air circulator but at 180° household fan will probably get shots off by termo protection. most likely blower with external motor with ductwork will work or maybe attic fan.
IMO torpedo heater is most simple way to heat hotbox.

nate can you post more details on your hotbox? and of cause picture worth 1000 words

nate · Post by **nate** » Sat Dec 24, 2011 5:21 pm

Here's my press, the bag holds everthing together. Also prevents good air flow. The whole thing is far from ideal for this sort of heating. The box is made of 1" foam board, with duck taped seams. It has about 4" clearance on all sides, and just slides over the whole thing.

My time is so limited for this build that I'm going to be content with whatever I can get, but I think there is potential for doing this well.

I'll get a picture of it in action sometime in the next week.

MadRussian · Post by **MadRussian** » Sat Dec 24, 2011 5:57 pm

nate wrote:
Here's my press, the bag holds everthing together. Also prevents good air flow. The whole thing is far from ideal for this sort of heating. The box is made of 1" foam board, with duck taped seams. It has about 4" clearance on all sides, and just slides over the whole thing.

My time is so limited for this build that I'm going to be content with whatever I can get, but I think there is potential for doing this well.

I'll get a picture of it in action sometime in the next week.

yours set up definitely not the best for air heating but because it single ski press heat get to laminate faster. What kind heaters do you use? If you are using one with a fan you should circulate around the press and have exit on another side so air circulate around the press also you can take 4" hose used for laundry dryer and connect back around so air making full circle.
Also you can put something to make corner of insulation box arounded for better airflow.

I will have to heat substantially bigger space and my press double wide not sure how heat distribution will work for me

nate · Post by **nate** » Sat Dec 24, 2011 6:05 pm

I've got two heaters, on opposite sides of the box. They're something like this:

MadRussian · Post by **MadRussian** » Sat Dec 24, 2011 6:22 pm

nate wrote:I've got two heaters, on opposite sides of the box. They're something like this:

you should have one at the tips one at the tale of the ski located diagonally so air circulate around the press.

nate · Post by **nate** » Sat Dec 24, 2011 6:30 pm

Yea, that's how they're set up. They're not entirely in the box, they're in cutout and draw outside air into the box.

MadRussian · Post by **MadRussian** » Sat Dec 24, 2011 6:38 pm

nate wrote:Yea, that's how they're set up. They're not entirely in the box, they're in cutout and draw outside air into the box.

I don't think you can do any better… Probably thermostat [/list]

nate · Post by **nate** » Sat Dec 24, 2011 6:46 pm

Yea, I'm pretty satisfied. My plan is to press first ski for 4-5 hrs at 80-90F, then pull it, put the next ski in, and put the completed ski on top of the press where it can post-cure at 180F while the second ski is pressing. I think I should be pretty successful. 20x better than 12hr at 60F.

MadRussian · Post by **MadRussian** » Sat Dec 24, 2011 8:12 pm

nate wrote:Yea, I'm pretty satisfied. My plan is to press first ski for 4-5 hrs at 80-90F, then pull it, put the next ski in, and put the completed ski on top of the press where it can post-cure at 180F while the second ski is pressing. I think I should be pretty successful. 20x better than 12hr at 60F.

I'm not that far into my build so don't know to tell you. Keep us posted because is this hotbox work for you it should work for me as well.

BTW put something underneath of skis for post-cure so air can circulate around freely.

barnboy · Post by **barnboy** » Sun Dec 25, 2011 6:50 am

Hey Nate -
We pressed 3-4 pairs doing exactly what you're doing, only using heat guns instead of space heaters. We placed one gun "aimed" at the tip, on the long side of the box, and the other at the tail on the opposite side.

With the guns, we were pulling out skis after 90 minutes, but with your space heaters you might be better off going 180 min. Anyhow, you should be pleased with your outcome.

The guns allowed us to really keep the box tight, as we could carve out tight fitting holes for each. Also, we used plywood to trim out the bottom edge of the long sides of the box, and extended them well past the ends of the box, so we could use them as handles. You may find that the raising and lowering of the box can cause a lot of damage, so the more bracing you can add to it the better!

The tighter you can keep your box the happier you'll be, especially the bottom seem.

After a few fires (hehe) we decided we were ready to shell out for the blankets, so be careful, good luck, and have fun!

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