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Making a Hotbox...

post #1 of 27
Thread Starter 

After doing some tuning earlier this year for myself and my friends, I have decided to throw together a hotbox after several requests. I have the demensions figured out, all of the box components bought and cut, but I have found myself stuck on the heating and wiring component. I want to use a thermostat control and was wondering if something like this hooked up to this. There are a handful of similar thermostats  that I found that vary from temperature to temperature, and I plan on having atleast 2 different thermostats for the box (switchable).

 

Would this setup work?

 

Thanks.

post #2 of 27

I am also doing some research and investigation for a spring (post ski season) hot box build. I have looked at the therostat you linked and the item is a single temperature 135F. What if that is too hot, or not hot enough for say a cold wax? 

 

I have been looking at the hot water tank thermostats. They sell for $9 to $12 at any of the home improvement stores and have a dial control that starts somewhere around 90 F and goes up to 150 F.

 

I sent you a PM also about the project and questions on how far along you are into it.

post #3 of 27

I just built a 1000 Watt hotbox last fall- works great for both my nordic and alpine gear! Regarding the thermostat, spend the loot and buy an industrial model that is accurate with a remote sensor and can be set to close tolerances- a delaminated set of skis could get pretty spendy! My thermostat cost $70 or so (the most expensive bit of the whole rig), but works really well. McMaster DIN Mount Line Volt Heat OR Cool Thermostat 120 to 240 VAC, Spdt Switch, -30 to 212 Deg F. Item number 1760K77

 

As for temperature, using CH10 wax around 50 celsius sounds like it is the usual temp, maybe a smidge warmer, but go easy. Remember you are not trying to melt the wax, merely keep it 'molten' so it soaks in. (The concept is to then scrape the low temp wax off and apply the wax of choice over the top). I got all of my questions answered by Mark Waechter from Nordic Ultratune- he da man!- by the way as a heat source I started off with one 450 watt baseboard heater, it was not enough, but two in-line worked a charm!!!!!


Good luck

post #4 of 27
post #5 of 27
Thread Starter 

 

Quote:
Originally Posted by gibsoncasey View Post

 

I just built a 1000 Watt hotbox last fall- works great for both my nordic and alpine gear! Regarding the thermostat, spend the loot and buy an industrial model that is accurate with a remote sensor and can be set to close tolerances- a delaminated set of skis could get pretty spendy! My thermostat cost $70 or so (the most expensive bit of the whole rig), but works really well. McMaster DIN Mount Line Volt Heat OR Cool Thermostat 120 to 240 VAC, Spdt Switch, -30 to 212 Deg F. Item number 1760K77

 

As for temperature, using CH10 wax around 50 celsius sounds like it is the usual temp, maybe a smidge warmer, but go easy. Remember you are not trying to melt the wax, merely keep it 'molten' so it soaks in. (The concept is to then scrape the low temp wax off and apply the wax of choice over the top). I got all of my questions answered by Mark Waechter from Nordic Ultratune- he da man!- by the way as a heat source I started off with one 450 watt baseboard heater, it was not enough, but two in-line worked a charm!!!!!


Good luck

 

What did you use for a heater? Did you use any insulation in your box, and how many fans do you have running?

 

Thanks

post #6 of 27
Thread Starter 

Any advice here?

post #7 of 27

You really need something a little more controllable. Something with an adjustable Differential Range. That way you can tightly control the range of whatever heat source you are using.

Here is a link to the one that I will be using when I build my box this summer. It's prewired for 120 volts, has a temperature probe, and is already programmed. Just dial in the temp that you want and the differential you need and you're done.

It's really reasonably priced for something that is accurate as well.

Have a look. www.rancoetc.com/ranco-etc111000000-prewired-digital-temperature-controller-p-87.html

 

Mike

 

 

post #8 of 27

I just put a couple lengths of rope lights in the bottom of the box on top of a foil type thermal blanket.  Spliced a dimmer switch into an extension cord to controll heat.  Installed a good indoor / outdoor digital thermometer to monitor temp.  Cheap, simple, works like a charm.

 

50 to 55 centigrade seems to be the consensus on temp.  Go to hot and you risk warping or delaminating the skis.  Best to remove bindings so grease does not drip out.

post #9 of 27
Thread Starter 

This is what I have and am going to use for my build...

 

Thermostat:

http://www.mcmaster.com/#1760K77

 

Heater:

http://www.pexsupply.com/Qmark-2514W-4-Electric-Baseboard-Heater-120-volts-1000-watts-8310000-p

 

Wood:

3/4" Particle board

 

Screws:

Standard 2" Wood Screws

 

Other goods

2 x 26" Double rail bracket mounts & mount kit

6 x 18" Double rail brackets

8'x2"x3" wood (for structural re-enforcement in the corners)

1/2" insulation board

2 Computer fans

*plexiglas (for the front door to reduce weight)

 

*may not get due to budget

 

I'm going to be throwing it all together within the next few days. Should be able to hold 6-8 pairs of Alpine skis and around 18 pairs of XC skis.

post #10 of 27

I am avoiding the particle board (can crack easier if dropped) or plywood and looking at the OSB sheath board instead.

 

Also for the plexiglass- if you want that I would only do a smaller window not a full door. Also check for the insulation factor  on that- it could be a spot of heat loss much more so than the wood.

post #11 of 27
Thread Starter 

 

Quote:
Originally Posted by RShea View Post

I am avoiding the particle board (can crack easier if dropped) or plywood and looking at the OSB sheath board instead.

 

Also for the plexiglass- if you want that I would only do a smaller window not a full door. Also check for the insulation factor  on that- it could be a spot of heat loss much more so than the wood.

 

I'm not too worried about cracking, the pieces are pretty thick, and I don't plan on moving my box around much. I primarily chose particle board because it would be easier to put a finish on versus OSB, which would need sanding.

 

The conductivity of Arcrylic is much lower than wood, so there will be more heat being conserved in the system with plexi.

post #12 of 27

I've seen too many pieces of particle board split (just with say screws in them) or crack without dropping them.

 

Celluloid (Lexan, Plexiglass?) has an R value of approximately 0.7 per inch thickness, from what I have found. Then you have to decide the thickness of the sheet you are going to use (probably not a 1 inch thick piece) and compare it to particle board at a rating of 1.31 for 1 inch according the the site I looked at (Colorado Energy Organization)

post #13 of 27

Over built and over thought out.

 

R factor in the plexi..who cares.

 

I said it before I'll say it again, no need to build this thing to stand up to WWIII.  I made that mistake, the damn thing weighs well over 300lbs...so unnecessary.   If you build it all out of the thick Styrofoam that is used for home foundation insulation, maybe with a some 1/4" plywood on the backside for extra support to hold your ski brackets, it will do the job perfectly, will be light weight, cheap, and super insulated.   My box is so heavy that the steel handles I put on it actually bent when we went to lift it....talk about poor engineering on my part.


Edited by Richie-Rich - 4/17/2009 at 09:19 pm GMT
post #14 of 27

That foam (the blue stuff, right?) even glues well with the correct adhesive.  I think generic epoxy will work with that foam, but don't quote me on it.  Anyhow, I have seen various types of boxes, structures, etc.. glued up with that foam, and it works well.  It's thick enough to have a good stiffness.

post #15 of 27
Thread Starter 

Not too worried about wieght, the only problem may be getting it out of the house for senior expo. I have plenty of hands to help for that, and worst comes to worst, I could always take off some panels for transport.

 

3 hours of cutting screws and wood with a handsaw and bandsaw later...

 

hotbox.jpg

 

I have to get more 3"x2" for the back board because it is slightly warped out. Should be done with all of the electrical and structural stuff by Sunday. Then it's getting an electric blue and jet black gloss paint job.

post #16 of 27
Thread Starter 

Also, would it be safe to use polysheild sheathing for insulation? If my wiring is good, I should be fine, right?

post #17 of 27
Thread Starter 

 

 

 

 

post #18 of 27

Very nice job, I suggest you add some pipe insulation on the brackets so that when hot they do not damage the top sheets. 

post #19 of 27
Thread Starter 

 

Quote:
Originally Posted by Richie-Rich View Post

Very nice job, I suggest you add some pipe insulation on the brackets so that when hot they do not damage the top sheets. 


Has this happened to you before? It doesn't seem to be that hot in there (even though its at 140~ most of the time). I touched the brackets earlier and they didn't feel all that hot either. Should I be fine without a fan for now? I am trying to get a hold of a DC adapter for some CPU fans, and I probably won't have one for another week or so. If I keep the skis on the outer middle rack, they should be fine, right?

post #20 of 27

 

Quote:
Originally Posted by Rise To The Top View Post

 


Has this happened to you before? It doesn't seem to be that hot in there (even though its at 140~ most of the time). I touched the brackets earlier and they didn't feel all that hot either. Should I be fine without a fan for now? I am trying to get a hold of a DC adapter for some CPU fans, and I probably won't have one for another week or so. If I keep the skis on the outer middle rack, they should be fine, right?


 

On my first run I did notice marks on my older skis...the metal retains a good amount of heat after several hours....gets pretty hot to the touch...at least in my box. 

 

Running with no fan I would be a bit concerend about the heat centralizing on the most proximal skis.

post #21 of 27
Thread Starter 

Where should I put my fan? I had a 6v DC cpu fan running earlier (it was on the bottom tilted upward), but some of the skis got really hot (hot enough for the wax to be in liquid state). Should I put more fans in, or just reposition the one I have?

post #22 of 27

I'd put the fan(s) near the top, since the hot air will naturally convect up there, and the fan(s) would be able to circulate it. Knowing there will be a natural upward convection current, place the fan(s) to generate the recirculation pattern you think makes sense.

post #23 of 27

I'd make a heat deflector shield.  I dont think location of a fan is really crucial you just want the air to move.

post #24 of 27

 

Quote:
Originally Posted by Basement Ski Tech View Post

.....Best to remove bindings so grease does not drip out.


I'm regularly hotboxing at 150F & the binding grease is totally unaffected.
 

post #25 of 27

 

Quote:
Originally Posted by Rise To The Top View Post

Where should I put my fan? I had a 6v DC cpu fan running earlier (it was on the bottom tilted upward), but some of the skis got really hot (hot enough for the wax to be in liquid state). Should I put more fans in, or just reposition the one I have?


How did you eventually get on? Any chance of a 'latest' picture?
 

post #26 of 27

RTTT, see Jon's box, he has the heat sheild I was speaking of...I have one similar. 

Quote:
Originally Posted by spyderjon View Post

 


I'm regularly hotboxing at 150F & the binding grease is totally unaffected.
 



 

post #27 of 27

I added that makeshift heat shield in the centre of my box (cardboard covered in tin foil) as the heat was rising too quickly making the centre third of the ski noticably (+20F) hotter than the tips'n'tails. It worked a treat so it's now been replaced by a sheet of galvanised steel. The air now circulates in an anticlockwise direction & the temperature of the skis are within a couple of degrees along their whole length. My fan/blower creates a noticable air flow which I feel is very important in obtaining even temperatures. I can't see how a little 6v PC fan can create sufficient air flow to be effective.

 


Edited by spyderjon - 6/1/2009 at 09:23 pm GMT
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