Silicone Heat Blanket

[xray]

Hello and i can say its good to be back in the shed getting amongst the wood shavings again. I have recently decided to purchase a heat blanket which looks to be great quality however my understanding of these things is limited. My guess is they are powered by a source from the 240v main power supply. The blanket is 1300watts in total.
Can i run the blanket from the power supply only or is this a silly idea as there is no way to properly control temperature? Anyway If i was to vary the voltage with a router speed controller, would this allow the blanket to successfully work. As you can tell, my knowledge is limited (as is my budget) on this topic but its a wealth of knowledge here. I am also not wanting to go with an LMI controll unit as they are very pricey.
here are some pics of the culprit and what im working with.

[vandenboom]

Hi XRay, this question has come up a few times in recent years. I asked it myself once. I can't comment on the router speed controller bit, but I can tell you that after being overwhelmed by all the options concerning temp regulation, I simply ended up fiting a power plug to the cable, buying a temperature probe at Dick smith, and making a promise to myself never to walk away or do another thing else while heating/bending a side. Given that it's all over in a couple of minutes, that has been doable.
My approach is a bit of a combination of approaches published here by others (Bob & Allen I think)
- spritz side with water, wrap in brown paper, wrap that in foil (tear a small hole to show waist position)
- heat to approx 150C
- let it cool to about 120C
- heat again to 150C
- let it cool to about 120C
- heat again to 150C
- let it cool to room temp, then remove. I think Allen gives it another burst after allowing to cool for an hour or so.

In thinking about the router controller, I imagine it would just allow you to regulate power output and hence how quickly the blanket heated up.
I would be more interested in something that can cut out once it reaches a particular temp (thermocouple option, but it doesn't look like u have that) or even just a timer that cuts out after eg 2 mins.
Frank

[John Maddison]

Hi xray

If you were to use the basic high-school-level physics equation:

Power (1300watts) = Volts (240v) x Amps ...

... then you would need a 'minimum' amperage rating of ANY control device rated to at least 1300/240 = 5.4amps or ideally higher. Not sure what a router controller is rated at, but certainly worth checking the specs on such a device before plugging in.

BTW - where did you score this blanket ... Oz or O/S?

Cheers

[Allen]

I have mine wired into a normal household light switch box for easy access to an on off switch. That box just has a long lead to reach a power point. No controller. I use to use a thermometer but have got to use the blanket so much that now I just plug mine in for 2 minutes, then start the bend. Turn off after bending. Never takes more than 2 1/2 minutes.

[woodrat]

Hi Andy,....I basically do exactly as Frank describes in the first post. I too promised myself never to walk away from the bender and do something else while I am bending. It needs a could of minutes of your 100% concentration. As he said its doable and that is what I do (as well as many others too methinks). I set the timer on my mobile phone and flick the switch as I start the bend and start the timer. All over in a couple of minutes:) I am not quite as fast as Allen describes maybe 4 minutes...

John

[xray]

much obliged guys thanks alot.
John the unit was bought quite obviously with no instructions from over seas most likely china or hong kong. Im not a fan of going off shore but at $135 delivered in three days after ordering im fairly happy with the product.
here is the link. The lady who looks after the emails is the most efficient secretary i have ever come accross. If i sent an email it was replied to minutes after sending it from my end. Paypal is available too.
http://www.jymengyou.com

[matthew]

I don't use a temp sensor or controller or a timer. I have put an on/off switch a meter back from the blanket, and a long lead to the powerpoint. I turn on, wait till I hear a good sizzling from the damp wood/metal sandwich or if the wood is too hot to touch, flick off the power and do the bend. Repeat if necessary.

[graham mcdonald]

Been having a quiet chuckle over this thread. When such a question gets asked on a US discussion group there are usually many answers pointing out all the dangers and/or morality of using such things and the necessity of timers, controllers, sensors and such. It seems like just about everyone here just plugs them in and goes for it. I love it

Mind you, I did bend some sides once and walked away for ten minutes and forgot it was on. Very cooked sides, and I reckon another ten minutes and it would have been no workshop.

cheers

graham

[kiwigeo]

How many of us have left a pot of boiling water on the stove and come back an hour later to the smell of a smouldering saucepan? On more than one occasion Ive had to deal with a kitchen floor awash with sudsy water from an overflowing sink.

I'm at an age where I know that I'm getting forgetful and to have to watch my tonewood stash go up in smoke would be the death of me.....my blanket is on a timer.

[matthew]

Bellson Electric Pty Ltd in Sydney sells clockwork timer switches in a number of ranges (5, 15, 30, 60 ,90 ,120 min etc) for $132 + $15 postage.

Expensive but simple and ideal for this sort of thing if you have cash to spare.

[matthew]

Or if you search "time lag switch" you can find a pneumatic pressbutton version for about $20. But the clockwork ones are nicer!

[Graham Long]

Hi,
I had the over cooked experience. After that I bought a pair of temperature controllers.
I've installed them in the base of my side bender. The temperature measurement is done with thermocouples, which are also stored in the base when not in use. My heat blankets have a standard 10A three pin plug top on them, which plug into the controlled power points on the base of the bender.
I still have to watch the time, but havent had a charcoal experience since.

Cheers
Graham