wow, even looks like the purchased ones.
good work chris!
DIY Silicone Heat Blanket
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MontuckyMadman
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skidesmond
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brianmwaters
- Posts: 23
- Joined: Thu Dec 27, 2007 10:12 pm
My buddy and I are about to build one of these.
He might be able to get 3 PID controllers from his brother, and I wouldn't be surprised if they each have multiple channels. If that doesn't work, I have an arduino (http://www.arduino.cc/) that I should be able to program to support a handful of temperature control channels.
With the ability to control multiple channels, what do you guys think about splitting the mat up lengthwise into separate circuits, and controlling them separately? Would this give a more even heat, or does one big monolithic mat do a good enough job as it is?
He might be able to get 3 PID controllers from his brother, and I wouldn't be surprised if they each have multiple channels. If that doesn't work, I have an arduino (http://www.arduino.cc/) that I should be able to program to support a handful of temperature control channels.
With the ability to control multiple channels, what do you guys think about splitting the mat up lengthwise into separate circuits, and controlling them separately? Would this give a more even heat, or does one big monolithic mat do a good enough job as it is?
if you're able to space the wires evenly and keep them all at the same length you should get even heat without multiple channels. the tricky part is to lay them out that way...one guy in this thread used nails, but i can't really wrap my head around how he did it exactly. that's why we used fiberglass tape. just lay down one length of wire, tape it down and so on.
btw, it goes without saying that if you're to build one of those blankets you're doing it on your own risk!
my walkthrough is just meant as a reference point.
we haven't tested our blanket in a press yet!
considering the recent posts about cassettes zapping people...we've experienced it too with our old blankets (the Hicotec TP ones), but proper grounding of your press/cassette should cover that.
as for the controller box part of our heating system, we're using dimmers to control the power output to our blankets manually (which is ok considering that pressing a board takes about half an hour with the epoxy we use).
with a just a PID and a SSR you're always allowing the blanket to draw all the power it wants, which could be too much for the silicone resin.
so you either want to keep the resistance of your wires pretty high or you could put a dimmer like the Kemo M028n behind your PID to manually set the maximum wattage (this would be a good addition to any controller box, even for purchased blankets to prevent them from burning down...i can't find the thread right now, but someone had that happen).
edit: just saw that it was endre and he actually posted the pics of the burnt blanket in this post. here you go: http://www.skibuilders.com/phpBB2/viewt ... c&start=45
a dimmer set to maybe 1500w max could have prevented this i guess.
my walkthrough is just meant as a reference point.
we haven't tested our blanket in a press yet!
considering the recent posts about cassettes zapping people...we've experienced it too with our old blankets (the Hicotec TP ones), but proper grounding of your press/cassette should cover that.
as for the controller box part of our heating system, we're using dimmers to control the power output to our blankets manually (which is ok considering that pressing a board takes about half an hour with the epoxy we use).
with a just a PID and a SSR you're always allowing the blanket to draw all the power it wants, which could be too much for the silicone resin.
so you either want to keep the resistance of your wires pretty high or you could put a dimmer like the Kemo M028n behind your PID to manually set the maximum wattage (this would be a good addition to any controller box, even for purchased blankets to prevent them from burning down...i can't find the thread right now, but someone had that happen).
edit: just saw that it was endre and he actually posted the pics of the burnt blanket in this post. here you go: http://www.skibuilders.com/phpBB2/viewt ... c&start=45
a dimmer set to maybe 1500w max could have prevented this i guess.
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brazgotine
- Posts: 15
- Joined: Fri Nov 05, 2010 1:57 am
re
hey,
First:
the hard part is to put wire in straight lines. I mad a long spiral like this:
http://www.p-wholesale.com/upimg/3/35a1 ... re-530.jpg
then I pull it back to nearly strait - now if I put the wire on the flor it's prfect strait and it's not moving around.
Second:
I have put firs silicone blancket on the table and nail nails in the line 1 cm apart. That was my planer - The nails made me prfect lines and corners.
After that I have put the silicon on it and spread it around. Then I put the second silicon blanket on top of it. I couldn't press it at the end because the nails were still in. After 40 hours, I have put the nails out and silicone the rest of the blanket.
First:
the hard part is to put wire in straight lines. I mad a long spiral like this:
http://www.p-wholesale.com/upimg/3/35a1 ... re-530.jpg
then I pull it back to nearly strait - now if I put the wire on the flor it's prfect strait and it's not moving around.
Second:
I have put firs silicone blancket on the table and nail nails in the line 1 cm apart. That was my planer - The nails made me prfect lines and corners.
After that I have put the silicon on it and spread it around. Then I put the second silicon blanket on top of it. I couldn't press it at the end because the nails were still in. After 40 hours, I have put the nails out and silicone the rest of the blanket.
haha, thanks for clearing that up! pretty nifty idea!
i always wondered what happened to the nails in your blanket
the spiraling sounds like a pretty good idea...what thickness is your resistance wire? ours is 0.2mm which is a pita to use. still, just taping it down worked well too. and since the tape we used is made of fiberglass it can stay in the blanket.
i always wondered what happened to the nails in your blanket
the spiraling sounds like a pretty good idea...what thickness is your resistance wire? ours is 0.2mm which is a pita to use. still, just taping it down worked well too. and since the tape we used is made of fiberglass it can stay in the blanket.
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MontuckyMadman
- Posts: 2395
- Joined: Fri Jun 20, 2008 9:41 pm
i mean these things:
also known as screw terminals. often used to connect lamps on the ceiling.
you have to remove the plastic parts of it and just use the inner metal parts.
we wound the resistance wire around the lead wire a couple of times to get a good connection and then we just slid one of those screw terminal pieces over it and secured it.
we've put it in the press once already but only for a couple of minutes. seems to hold up fine.
also known as screw terminals. often used to connect lamps on the ceiling.
you have to remove the plastic parts of it and just use the inner metal parts.
we wound the resistance wire around the lead wire a couple of times to get a good connection and then we just slid one of those screw terminal pieces over it and secured it.
we've put it in the press once already but only for a couple of minutes. seems to hold up fine.
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MontuckyMadman
- Posts: 2395
- Joined: Fri Jun 20, 2008 9:41 pm
I talked to smooth-on about the mold max 60. They have never heard of using this for this application. You have to post cure at 120F to get the full heat resistant benefits for 4 hours, not a big deal but FYI.
I called these people about this product http://www.eagerplastics.com/rtv325.htm who sell a bunch of different stuff and they recommended the P50 silicon from silicone inc. better strength and elongation at break but almost double the cost, they said it had a 600F rating as well. http://www.silicones-inc.com/p50.pdf
Eager has also never heard of this type of application.
I think the iron oxide in the mold max 60 is for color only and shouldn't conduct. Most of the euro high temp silicons and such are died red to indicate this heat resistance.
I called these people about this product http://www.eagerplastics.com/rtv325.htm who sell a bunch of different stuff and they recommended the P50 silicon from silicone inc. better strength and elongation at break but almost double the cost, they said it had a 600F rating as well. http://www.silicones-inc.com/p50.pdf
Eager has also never heard of this type of application.
I think the iron oxide in the mold max 60 is for color only and shouldn't conduct. Most of the euro high temp silicons and such are died red to indicate this heat resistance.
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MontuckyMadman
- Posts: 2395
- Joined: Fri Jun 20, 2008 9:41 pm
so my electrical engineering is weak at best.
110V cause I'm using American house current.
Best I can come up with is:
6 parallel circuits for a 45cm wide blanket and 2 meters long.
using 28ga wire at 13.94 ohms/meter
so each circuit will be 4 meters long.
11.84 amps and 1302 watts.
The wires will be 3.75 cm apart.
Is this right and will this be sufficient with the wires spread this far apart? I have several AL sheets in there.
Personally I would rather essentially duplicate Chris's setup with 24 ga wire at 5.47 ohms/meter and use 4 circuits at 8 meter sections and get 10.045 amps and 1105 watts of power but i am afraid the 24 ga will be too thick and make the blanket lumpy.
Help please?
110V cause I'm using American house current.
Best I can come up with is:
6 parallel circuits for a 45cm wide blanket and 2 meters long.
using 28ga wire at 13.94 ohms/meter
so each circuit will be 4 meters long.
11.84 amps and 1302 watts.
The wires will be 3.75 cm apart.
Is this right and will this be sufficient with the wires spread this far apart? I have several AL sheets in there.
Personally I would rather essentially duplicate Chris's setup with 24 ga wire at 5.47 ohms/meter and use 4 circuits at 8 meter sections and get 10.045 amps and 1105 watts of power but i am afraid the 24 ga will be too thick and make the blanket lumpy.
Help please?