I juts had an idea,. lay the glass on wood and drive the nails, run some wires and then tape it down and remove the nails. You could get he connections allot closer without them touching and in tension.
I would be combining all the techniques in this thread for blanket construction in one.
> MontuckyMadman wrote:I learned some cool new stuff, the blanket draws 11.9 amps at load on the controller, it cycles but tops at 11.9.
[...]
I don't know the wattage but it seemed sufficient to get it hot in moderate time when we ran it.
that's the easiest calculation of them all
wattage = volts x amps = 120v x 11.9a = 1428watts
the thing with the nails you describe is exactly what we're going to do for our second blanket
well yeah, I know what it should be but what does the blanket actually deliver is another maybe right?
you've already measured what it delivers by measuring the amps
second blanket is curing atm.
this time i used nails to lay out the resistance wire and then taped it down with the usual drywall tape. worked like a charm!
all wires are spaced evenly. even after pulling out the nails nothing slipped under the tape.
> chrismp wrote:second blanket is curing atm.
this time i used nails to lay out the resistance wire and then taped it down with the usual drywall tape. worked like a charm!
all wires are spaced evenly. even after pulling out the nails nothing slipped under the tape.
Pics?
i only took a couple of pics of the wire around the nails...i will upload them together with pics of the finished blanket soon.
btw, i think you once posted that you weren't going to use lustre terminals to connect the lead wires with the resistance wires...i talked to my electrician friend about that and he said to get a good connection you either need soldering or a force to push the wires together. since it's hard to solder resistance wire, he recommended using terminals.
hmm. oh well.
I'm not putting those lumpy things in there. I think the pressing in the press will stick them together well enough. I wound them up pretty good around the lead. Only time will tell if this holds up.
Its still a homemade gig so it won't be left alone and maybe someday we will get some from mei. I learned allot about electricity and resistance circuits and some math to boot. Thanks again. This forum is awesome.
Still haven't made a ski with them so still a bit unsure.
> MontuckyMadman wrote:hmm. oh well.
I'm not putting those lumpy things in there. I think the pressing in the press will stick them together well enough. I wound them up pretty good around the lead. Only time will tell if this holds up.
Its still a homemade gig so it won't be left alone and maybe someday we will get some from mei. I learned allot about electricity and resistance circuits and some math to boot. Thanks again. This forum is awesome.
Still haven't made a ski with them so still a bit unsure.
Wrap the wires tight and use a piece of shrink tube to hold them in place?
When you have a chance, can you please send me a list of your silicone suppliers? If you have any liquid samples left (I think you had some liquids) I might be able to buy them from you as well.
Working on a little project @ work. BTW, I work in the carbon fiber industry now
Diversified silicon for sheet socal rosencranse ave
Eager polymers in chicago carries the silicones inc P45 high temp silicone rubber and lots of other stuff.
Most of these places charge for samples. I just gambled. Its still more cost than it should be. The sheet is 60 so with wire and glass and cheaper rtv maybe done for for 120?
its very posible any rtv will work and i went overkill. I am also using high temp lead wire.
Das it man.
I have used smooth on in the past. In reality i did not investigate workable viscosities just found one that got real high markes with good mechanics.
I looked ar the heatshrink. But the conections are a T. Dunno.
here you go:
Pressed a double load with my new blankets last night. Just a repress of some old skis to try and change the rise a bit. I relize thats not good for the epoxy its cool just a test. The blankets are awesome. Rips to temp no prob. Im pretty happy with myself.
The last blanket we pressed and it came out very flat. Few wrinkles near the lead wires from air bubbles i assume. Very happy.
thanks yall
After read all this posts and after what happen to my shop ( same as ENDRE) and the need to buy a new heta blankets, i decided to build my heat blankets---
ill post my progress.
You all are amazing
hey Montucky
did the tape result good bonding with the fiberglass and silicone???
i am araid the glue of the tape provoques delam... tomorow ill start wiring stuff...
If you look at my picks I didnt go full length tape like chris. Just small chunks.
Seemed fine. Bonded as well as everything else.
You can peel it apart if you try but they dont see that kind of stress.
i try to place the tape to the fiberglass but its very dificult to hold the wire straight...
if you use nails like shown in my last photos it's easy to get the wires straight
> hugocacola wrote:i try to place the tape to the fiberglass but its very dificult to hold the wire straight...
Its a 2 person job or use the nails.
And chrismp
for sure that the tape holds together when fully embebed with silicone???
how long are you using your heat blanket, it holds the pressure variations among temperature variations, doesent delam in the midle for ej. get some bubles in the midle etc...
Best regards
heat blanket almost done.
i connected the wires etc. it consume 12 at 230v same as 12A is a quit alot, it gets hot to quick, and ive tried a cheaper silicone White one because i dont nedd to much temp to the top, so he said the white silicone hangs something like 120º and i nedd 90ºC so it could be good, if not ill do a new one with the red one to the top...
my concern it is to avoid a PID controller, to do that i need to cut the power ( voltage) and iamm trying to find the best solution, and i thought about the oil heater (home ones) they have a good potenciometer to regulate the voltage...
any thoughts???
best regards
E-mail this guys - very prompt service
here we go once again: DON'T TRY TO REGULATE THE VOLTAGE...way too expensive!
the link rich posted is good...they have a couple of dimmers that allow you to regulate the wattage. this is the one i'm using: http://cgi.ebay.co.uk/M028N-LEISTUNGSRE ... 4aa5d96e71
btw, with those homemade blankets it's always a good idea to use a dimmer to make sure they don't go up in flames.
this one works up to 15A, but needs cooling like the kemo: http://www.conrad.de/ce/de/product/1831 ... Detail=005
Imade 2 mats the way described in here: wire kept in place with nails and glass tape, silicone etc.
I did a "dry run" when the wires where ready attached to one glass mat with out any silicone rubber yet. i regulated the current with an output controller and at a certain spot the glue of the glass tape started to burn in an area of 30cm. i think it could have only been the glue, everything else is glass or wire. now i m afraid to set my mould on fire like endre showed us couple of posts ago.
did anyone had this problem too? i can t tell you what electric power there was, as i was on teh fly to extinguish the fire...but it was more power than i will use for heating skis.
anyway,i m flustered as this glue seems to be the weak point in the mats..
..and i found a method to solder resistance wire. i just pressed cable end sleeves around the wire so it was easy to solder them. it holds good without sliding or any problems so far.
that's genius!! definitely looking good! one more good example that it's not that hard to build a nice heat blanket
This thread has inspired me. And I believe I may have to attempt it. It's funny how when I started researching things a year and a half ago I thought I'd go super cheap. Fabric press with no heat. I've had so much fun figuring out ways to build crap in my garage that I'm actually putting a lot more time and money into this hobby than I thought I would. Now I guess, I'll add some heat blankets to the equation.
You guys have done some good work. Thanks for sharing.
where to buy the wire and what type of wire is it
> WhitePine wrote:This thread has inspired me. And I believe I may have to attempt it. It's funny how when I started researching things a year and a half ago I thought I'd go super cheap. Fabric press with no heat. I've had so much fun figuring out ways to build crap in my garage that I'm actually putting a lot more time and money into this hobby than I thought I would. Now I guess, I'll add some heat blankets to the equation.
You guys have done some good work. Thanks for sharing.
I'm going through about same process
same wood/fabric press with no heat at first ...and everything else you said about the same lol
I'm not a electrician and little hesitant to tackle this project. Afraid to burn down my garage. Actually blankets itself shouldn't be difficult to make but PID controller and stuff I'm not sure.
sorry found the type of wire nichrome.. right and what gauge should i get for the right resistance
Is this the right dimmer?? http://www.ebay.com/itm/POWER-REGULATOR ... 2213wt_982
Just throwing around some ideas.
Has any of you guys ever thought about making your own silicone heat blankets á la MEI?
The construction seems pretty straightforward with resistance wire laid up in loops laminated between some fiberglass mats impregnated with heat resistant rtv silicone resin.
The materials aren't that expensive and building one doesn't seem overly complicated to me.
Am I missing something?
I think plywood do some work in this - using CF tows? Can't find the thread right now : (
i remember his thread, but CF is pretty expensive and harder to connect compared to resistance wire. with wire you just have to figure what length you need and how much wattage you want and then you simply choose the wire with the correct resistance for these needs. plus, i think he didn't mention any kind of insulation.
You make it sound easy.
if it was that easy I'm all for it. I talked to a builder who said he uses plumbers heat tape for years in the cassettes but I don't have a comprehension of electrical stuff so I have no idea how he ramped the temp, more resistance?
well, i talked to an electrical engineer and he said that it should work the way i described it.
ramping the heat could be done via a PID just like everyone else on here uses, or you could ramp manually by using a dimmer to adjust the wattage.
i guess i'll have to shell out the bucks and try building one. a rough estimate came out at about 70-80 EUR for materials worth two blankets with 40x200cm.
won't happen till the end of this year though, since university needs all my attention now.
I am all for it. Post some links to some materials. I have done allot of work with RTV silicons and Polyurethanes for mold making. Just need a high heat pourable silicon.
I have a PID for my single blanket but I need it wider and longer and another for the top with the new press.
Could I use the pid to ramp the temp on heat tape you suppose?
> MontuckyMadman wrote:I am all for it. Post some links to some materials. I have done allot of work with RTV silicons and Polyurethanes for mold making. Just need a high heat pourable silicon.
I have a PID for my single blanket but I need it wider and longer and another for the top with the new press.
Could I use the pid to ramp the temp on heat tape you suppose?
I am in the EXACT same boat as you. I've got one nice blanket, but its just big enough, would be nice if it were a little larger... and I'd like a second to heat from both sides. Very curious about the DIY route now too!
I've been looking into picking up some nichrome wire to mess with...
It won't be hard to get a parallel/series combo to get a desired wattage.
I was thinking of getting some cotton fabric or burlap and stitching the wire to it, then coating the top and bottom in silicon. Then you could literally press the laminate like a ski with a waxed cassette.
Unfortunately I have negative free time right now... I may get to this during the holiday season...
Cost should be ~$20 for the tubes of Si, ~$20 for the wire... At least it looks good on paper!
yep, a pid should work for heat tape as well.
leboeuf, i wouldn't use fabric since it doesn't take heat that well. fiberglass has the advantage of being an electrical insulation and a very good heat conductor at the same time. plus, it's not that expensive compared to cotton fabrics.
here's some links:
www.resistancewire.com (US)
www.distrelec.com (Europe)
you can find the silicone on ebay or amazon.
and i'm pretty sure you all know where to find fiberglass
one thing that came to my mind: does silicone resin stick to fiberglass?
Yeah, I'm not too sure how fiberglass and silicon mix... kinda why I was leaning towards canvas or something.
I know from a couple of bathroom remodel jobs that silicon sticks very well to canvas pants lol.
IIRC tight weave canvas should be able to handle fairly high temps, a lot higher than ski pressing temps at least
This is straight off the MEI website, looks like they use fiberglass as the bonding medium
Technical Information
Silicone Rubber Flexible Heating Blankets
Michaels Enterprises flexible heaters are constructed using UL and CSA approved materials and components. Silicone flexible heaters are constructed for temperatures up to 450 degrees F.
Heating Element
The resistance heating element is high temperature Copper-Nickel and Nickel-Chrome alloy wire, wound around a fiberglass cord to provide added strength and flexibility.
Sheath Material
The prewound heating element is vulcanized between two layers of fiberglass reinforced silicone rubber to form a strong flexible assembly. Vulcanizing agents are removed during the hot press and out-gassing cycles to produce a flexible heater with high dielectric strength that is resistant to moisture, chemicals and acids.
Heater Sizes
Flexible heaters are available in sizes up to 37" x 143" without splicing. Longer heaters are available 30" wide or less. Complex shapes, contours and power densities in single or multi-zoned heaters are available with voltages ranging from 6 volt single phase to 480 volt three phase.
Heater Fasteners and Attachments:
yep, i found that info too. unfortunately that doesn't rule out the possibility of a special process to bond silicone to fiberglass.
edit: just found this http://www.answerbag.com/q_view/2284631
In hindsight its funny to poke fun at the fact that I was wondering if RTV type silicon would stick to fiberglass.
RTV type silicon is engineered to adhere to SiO2.... as in textile fiberglass...
> leboeuf wrote:In hindsight its funny to poke fun at the fact that I was wondering if RTV type silicon would stick to fiberglass.
RTV type silicon is engineered to adhere to SiO2.... as in textile fiberglass...
That's funny, I was thinking silicon? Doesn't that have silica in it in some form? But In my chem-jongness I said nothing.
very interesting project!
i was thinking about the same things last winter, but i never thought using FG for reinforcement (!)
after reading this thread, i looked for some draft notes i kept.
plan was for 170x40cm blnkt.
0.2mm dia nichrome wires running length wise, parallel connected on the 40cm sides.
27 wires in total, at 15mm intervals.
i had in mind to run a low dc current for safety, with a dimmer.
if my notes are right, with some 14~17 volts (8~9 amps) i could get it to ~90 oC.
the temp on the wire will increase inverse to the heat flow out of it.
so probably a thermostat is a must have to control the circuit when the environment (mold, laminate) approach to target temp.
i never did a test, but that thread warms up the idea!
cheapest 2-parts heat resistant silicon i 've found, was quite expensive, >50euros/kg. a bit less was standard silicon film sheets.
rtv si weights ~1.25kg/lt, so for a mm of thickness 1 kg will give 0.8m2.
The cheap, standard -not high temp, 1-part silicon (caulking tubes) wont burn at 90C, so it might be a viable alternative for the low temps im after.
(during this summer i experiment with 1 part Si for a different project, and I've found that it can be thinned with acetone, or some paint thinners.
this silicon sets with air moisture, so curing time is accelerated by mixing in very small amounts of glycerin that holds water -i came up with 1 or 2 drops per 100cc.
A friend gets good results by adding some drops of acrylic paint as well, but i never tried it.
People use it for mold making and they prepare it not to be sticky, by working it inside a bucket of water).
I know 1 part silicon contains acid (that's where that smell comes from) so it might be corrosive for the wire. It stings so bad, i would n dare to experiment inside the shop ever again with this stuff.
Silicon bonds very well to silicon.
