What LEDs can produce light with focus heat?

[Squintz]

I'm looking for an LED that generates a beam of focused heat. Ideally this beam would be no wider than 1 - 2 inches when the LED is 2" above the surface. I want to put about 8 of these LEDs in a circle to shine down on a plastic object to keep it warm.

Currently I am using the heat lamp to accomplish this same task from rougly 10 inches away from the object. The melting point of the ABS plasic I am heating up is 105c (221f). I don't need to melt the plastic but I need to keep it fairly warm after melting it so that it does not warp. The goal here is to slow the solidfying speed of the ABS plastic so it remains flat.

As I said... This works with a heat lamp but the heat. The heat lamp is big and bulky so I would like to find a bunch of smaller lamps that I could use at a closer distance to generate the heat.

Do LEDs exist that can emit focused heat? What specs should I be looking for? I assume UV or IR LEDs could do this. What wavelength? What spec do I need to look at to determine how much heat it will generate?

 

[proffski]

I'm looking for an LED that generates a beam of focused heat. Ideally this beam would be no wider than 1 - 2 inches when the LED is 2" above the surface. I want to put about 8 of these LEDs in a circle to shine down on a plastic object to keep it warm.

Currently I am using the heat lamp to accomplish this same task from rougly 10 inches away from the object. The melting point of the ABS plasic I am heating up is 105c (221f). I don't need to melt the plastic but I need to keep it fairly warm after melting it so that it does not warp. The goal here is to slow the solidfying speed of the ABS plastic so it remains flat.

As I said... This works with a heat lamp but the heat. The heat lamp is big and bulky so I would like to find a bunch of smaller lamps that I could use at a closer distance to generate the heat.

Do LEDs exist that can emit focused heat? What specs should I be looking for? I assume UV or IR LEDs could do this. What wavelength? What spec do I need to look at to determine how much heat it will generate?

LEDs are virtually 'Monochromatic' or in other words they emit light energy at one frequency.
As an example a certain red LED will emit light at 630nm whilst a green may be at 525nm. If you want a device to emit Infra Red then it must be designed to operate at the portion of the spectrum you need.
So you may need one of the following:

Infra Red A = 750nm – 1400nm
Infra Red B = 1400 – 300nm
Infra Red C = 3000nm – 1mm

 

[Squintz]

Thanks for the help.

Can you help me select an IR LED that may be close to what I am looking for. I am willing to purchase a few different ones and test them to see if they meet my needs. However, I don't want to go aimlessly buying parts. I'm not savy when it comes to electronics. I know that LEDs are diodes and that current only flows in one direction through a diode. I have hooked up LEDs before. But I have never been able to pick an LED for a specific applications.

I could really use some assistance with this project.

 

[Nigel Goodwin]

You need to consider how many watts you need to provide the level of heat you require, I suspect you'll find LED's a waste of time.

What you need is a small heating element, you could easily wind one your self with some nichrome wire - or just a wirewound resistor.

 

[microtexan]

led heat

You need to consider how many watts you need to provide the level of heat you require, I suspect you'll find LED's a waste of time.

What you need is a small heating element, you could easily wind one your self with some nichrome wire - or just a wirewound resistor.

Yeah, it's one of the beauties of LEDs, low heat output unless they are over driven at which the life span dwindles rapidly.

 

[crutschow]

One solid state device that will generate a beam of heat is a high powered IR laser such as the kind they use to engrave wood or cut steel. For example Sony makes them from 90mW to 60W output **broken link removed**. But those are rather exotic and, I would imagine, expensive.

You could also try an array of small halogen bulbs, the type that have a built in reflector. They tend to put out a lot of heat as well as light. You could run them at a lower voltage to reduce the amount of light relative to the heat (but that can reduce the life of a halogen bulb).

 

[Squintz]

I am familiar with Nichrome wire. It's actually what I use to extrude the plastic in the first place. Check out WebHome < Main < Reprap if you want to see what this project is. Basically it's a 3D printer.

Nichrome might work if it radiates the heat through the air well. I don't know if it does or not without some type of fan. What I was looking for is a light source in a small package so that I can outline the plastic extruder head and shine a heat source directly on the object that I am printing.

I suppose an incadecent lamp would work as long as I could focus the light.

Does anyone else have suggestions? What are you thoughts?

 

[Squintz]

One solid state device that will generate a beam of heat is a high powered IR laser such as the kind they use to engrave wood or cut steel. For example Sony makes them from 90mW to 60W output **broken link removed**. But those are rather exotic and, I would imagine, expensive.

You could also try an array of small halogen bulbs, the type that have a built in reflector. They tend to put out a lot of heat as well as light. You could run them at a lower voltage to reduce the amount of light relative to the heat (but that can reduce the life of a halogen bulb).

After reading the above post and yours I know that LEDs are pretty much not the way to go. I like the idea of halogen. I need to look at the different shapes and sizes to see if there is something that would mount well on the plasic extruder.

What I was really looking for is a good amount of heat to get the job done but without having a large bulky lamp which uses a lot of power hanging over the entire RepRap machine.

 

[proffski]

After reading the above post and yours I know that LEDs are pretty much not the way to go. I like the idea of halogen. I need to look at the different shapes and sizes to see if there is something that would mount well on the plasic extruder. What I was really looking for is a good amount of heat to get the job done but without having a large bulky lamp which uses a lot of power hanging over the entire RepRap machine.

Tricky, you wish to project a fair quantity of energy onto a work sample.
The sources you need are not particularly efficient, therefore as has been already mentioned you need a different radiant source, such as a bar fire, possibly well under run by a variac?

That of course is dangerous and will still consume a lot of energy.
Have you considered low voltage contact radiant mats?
Will your workpiece tolerate contact? What about hot air as another alternative?

How big is your sample? These are an idea, but I suspect not what you want... https://www.electro-tech-online.com/custompdfs/2009/01/ir20sources20series204020issue2014.pdf

 

[user_88]

You should find some custom heating elements here:
Minco - Flexible Heaters; Flex Circuits; Temperature Sensors and Temperature Instruments
.... not sure about costs/economics though.

 

[oneslowz28]

I am building a reprap as well and if you read the builders blog you will see that Nophead and a few others have been using cheap hair dryers to keep the printed part warm to promote better adhesion. IIRC there was a lengthy thread in the reprap user forums about this very topic. BTW I am SCPhotog over there.

 

[Nigel Goodwin]

Nichrome might work if it radiates the heat through the air well. I don't know if it does or not without some type of fan.

Use a curved reflector behind it - think old bar electric fires.

 

[Squintz]

oneslowz28,

Nice to see a fellow RepRap builder here. I know about the different solutions that other have tried including the hair dryer and heat lamp. They do work well but I was looking for something a little more compact and that would look like part of the design instead of a makeshift solution.

I think I am going to try the nichrome wire with a curved sheild. That make sense to me and it could be fitted into the extruders design.

 

[oneslowz28]

What about a length of Nicrome weaved into a square pattern with 1/8"-1/4" holes and a low rpm 80mm fan to help move the heat to the part?

 

[Squintz]

I was thinking the same thing. I think a small fan would help distribute the heat over the entire object.

 

[oneslowz28]

you can build a simple fan controller using a rheostat and just adjust the power down until the fan is barely pushing any air. What I would do is build a bracket that would old the fan and wire off the extruder head by 4-5 inches.

 

[fuzzyt]

I am building a reprap as well and if you read the builders blog you will see that Nophead and a few others have been using cheap hair dryers to keep the printed part warm to promote better adhesion. IIRC there was a lengthy thread in the reprap user forums about this very topic. BTW I am SCPhotog over there.

An idea along these same lines but maybe with more accuracy would be a heat gun from a rework station. There are numerous tips available increasing the usability.

 

[duffy]

There are some flat toaster heating elements with no exposed wiring that might be suitable.

Those Reprap things look pretty cool. Hope you get it going.