variable controlled heating element

[JLDragon]

I am wanting to know what would i need to make a small heating element that reaches approximately 200-250 F degrees.
The heating charge would only need to last for 15-20 seconds at a time.
The element will be heating a small aluminum plate 1w x 2L x 0.5h inches.
I would like to be able to make the temperature variable controlled with an on/off switch
I would prefer using outlet power instead of battery powered.

I was think along the lines of using the heating element from a wood burning iron and adding a small variable control switch to be able to adjust the temperature.

Any idea's, suggestions, or thoughts on this would be much appreciated

 

[KMoffett]

You can calculate how many watts you will need to add to your block in that time to raise the block from ambient to the 200-250°F:
**broken link removed**
Joules(J)=WattSeconds(W/s)
You will also to have to allow for the thermal resistance (imperfect contact) between your heater and block.

Ken

 

[Reloadron]

I would consider using a cartridge hearer as can be seen here. The link also has details on what Ken mentions above so you can determine the wattage of the heater. Any number of controllers can be used with any number of temperature sensors.

Ron

 

[JLDragon]

ty all for the information..
to be more precise, I am looking for a small heating element such as what you find inside a wood burning kit that can possibly be modified to fit into a 3 x 2 x 2 aluminum enclosure, and doesn't cost alot of money.

I am not very familiar with the electronics jargon, formula's, etc.. as well so forgive me for being somewhat of a noob at it LOL.

 

[ChrisP58]

The specific heat of aluminum is 2.42 joules per cubic centimeter. Your one cubic inch piece is 16.4 cc. So, in round numbers, you will need about 40 watts of heat to raise your block one degree C per second. Of course, more power will raise the temperature faster.

These numbers are just for the heat that will be absorbed within the block itself. Heat will be lost from the block due to conduction and radiation, so you will need even more heat to offset those losses.

 

[alec_t]

you will need about 40 watts of heat to raise your block one degree C per second

So to raise it, as per your target, ~100C in 20 secs would need at least 200W ignoring losses. In practice you might need double that. It's not going to be a small heating element .

 

[KMoffett]

We also might ask, exactly what you are trying to do with this metal block?

Sometimes it's easier for us to help solve your problem, than help solve your solution!

Ken

 

[JLDragon]

I rather not go into too deep of details about what I am trying to accomplish due to after many months of searching to make sure what i want to make is not on the current market or being sold in any locations.
I am basically trying to make a small portable prefabbed dye unit that can shape small areas of a plexiglass sheet with the use of heat. I am trying to keep it small so that it can be used in small hard to reach areas.
hence why i was thinking about the idea of gutting a wood burning tool and use its parts along with some kind of variable control knob so i could dial in the right temp for what I am trying to accomplish.
If this helps any I thank you all for ur help and input.

 

[Reloadron]

Did you look at the cartridge heaters in the link I provided? Here is another link. Heaters like you want run about $55 to $60 EA. for quality units. You bore a clearance hole in your block and slip them in. An alternate method would be to hack the elements out of a cheap wood burning tool but the used elements in those are not really designed to do what you seem to want to do. Temperature control is another story. There are ways to experiment with control using for example a cheap lamp dimmer. Obviously if you develop something and start manufacture the cost of elements and parts comes down.

Ron

 

[ronv]

Ron, Those are cool! Makes me want one just looking at it. Don't know what I'd use it for, but I still want one.

 

[Reloadron]

Ron, Those are cool! Makes me want one just looking at it. Don't know what I'd use it for, but I still want one.

Want some to mess around with? I had a bag of them somewhere around here at one time. They might be 30 Volt though. Also had some 120 Volt but forget what the wattage was.

Ron