Is there an advantage to using IR to heat bed?

I was thinking about the heating of my larger build plate. It's 300mm by 650mm. Sharp, clean, flat; Misumi gives nothing but quality.
I've got a 300mm X 300mm silicone heat pad that draws 20A at 12V. I would need two of them to effectively cover my bed. That's a fair amount of heat, and more than any one board I've seen can handle. An SSR would be in the works and a high power consumption.
I got to thinking about environmental heating as well, for ABS. I was tipped off that two 100W incandescent bulbs on the sides would work better than simply heated air. One, that's ugly, two, that's also not going to heat effectively over such a large area as my printer has. Now if I could use LEDs to heat my printed objects, that allows for so many more ways to place them along with looking a lot better. For those who have read my progress you know I'm all over making it look good over pure functionality.

Would using LED IR strips [or whatever else I find] like these be effective for heating not only ABS objects as they print to prevent warping, but also the heated build plate? It's aluminum, 5mm thick, and painting the bottom black or with other special IR absorbing material wouldn't be an issue. Would it heat faster than the classic heaters? Those need time to get up to heat, IR heaters are essentially instant on and off, as far as I know. I assume power consumption would be around the same, heat is heat, but with the full heat on start and possibly more efficient heat transfer it would be more efficient? It would also make building it much more simple for me, even if it requires more electronics for temp measurement, the mechanical build advantage for me would far outweigh extra electronics. I am building the plate to be removable.

Thoughts, corrections, questions, scientific evidence?

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Realizer- One who realizes dreams by making them a reality either by possibility or by completion. Also creating or renewing hopes of dreams.
"keep in mind, even the best printer can not print with the best filament if the user is the problem." -Ohmarinus

pretty sure those are not heat producing. just used for night vision. you want heat from a light go with halogen. LEDs are not the answer,

Keeping on IR, what about ceramic heaters? Halogen would be way too bulky and would remove a lot of vertical printing area. If I place two 250W ceramic heaters under my print bed, covered in IR absorbing material, would that be better than two 250W silicone pad heaters?

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Realizer- One who realizes dreams by making them a reality either by possibility or by completion. Also creating or renewing hopes of dreams.
"keep in mind, even the best printer can not print with the best filament if the user is the problem." -Ohmarinus

not sure anything will work better then a pad designed to be a heater.
I think placing 2 heat sources in an area won't give you much thermal spread. and you will just end up with hot spots and hard to control temps.
Maybe a coil wire type heater (like in a electric dryer) would work, but do you really want to mount a moving wire coil on a moving platform at 120VAC?

Why not the silicone heaters? is it the power consumtion? or cost? looks?
While building my printer I looked for alternitives, but in the end the $20 heatbed won.

The bed only moves on the Z.

Silicone still needs to be mounted on the build plate, and that would make mounting the plate extremely difficult, they're not something I can just drill a large hole through. I don't mind power so much as heating time.
I also am trying to really up the ante on looks. Besides the heating for bed and environment, I've got almost everything figured out in a slick, pleasing to the eye manner. I want the printer to look as good as it prints. I've done some out of the ordinary testing and an easily removable bed would be very useful, especially not having to worry about components attached to the underside of the bed.

I was also hoping to get premade components, but it looks like making my own heater is going to have to be the option taken to get what I want out of it. Looks like I have a lot of math to do. Any tips on where to start for calculating required power and wire/foil requirements?

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Realizer- One who realizes dreams by making them a reality either by possibility or by completion. Also creating or renewing hopes of dreams.
"keep in mind, even the best printer can not print with the best filament if the user is the problem." -Ohmarinus

here is a little heatbed theory.

[reprap.org]

Edited 1 time(s). Last edit at 08/29/2014 07:10AM by cat.farmer.

Quote
MrDoctorDIV
The bed only moves on the Z.

Silicone still needs to be mounted on the build plate, and that would make mounting the plate extremely difficult, they're not something I can just drill a large hole through. I don't mind power so much as heating time.
I also am trying to really up the ante on looks. Besides the heating for bed and environment, I've got almost everything figured out in a slick, pleasing to the eye manner. I want the printer to look as good as it prints. I've done some out of the ordinary testing and an easily removable bed would be very useful, especially not having to worry about components attached to the underside of the bed.

I was also hoping to get premade components, but it looks like making my own heater is going to have to be the option taken to get what I want out of it. Looks like I have a lot of math to do. Any tips on where to start for calculating required power and wire/foil requirements?

Well given the constrains you have placed on everything. What you should be looking at is a radiant heater in a insulated reflector box mounted under the printbed. A good source of parts would be a toaster oven or a waffle iron and the power draw is going to be pretty huge. Heating time is going to be less than a couple of 100w light bulbs but more than a directly attached heater. Also anything under the bed is going to get warm so any printed parts will need to be thermally isolated/replaced with a all metal construction.

Actually now that I am thinking more about it a waffle iron type setup with a little latch to release the printbed could work really well in your situation. Something like This!

Thanks Mike

I like the idea of using an IR heater for your bed, but two immediate probelms come to mind:

1) Does this constitute a fire risk?
2) Is the IR heater fixed while the bed moves towards/away from it. If so, the controll may be problematic. If the heater moves with the bed then there is a significant mass penalty when the hot end lifts (bed lowers) which it may do when crossing perimeters etc..

One possible IR heater is the type used in IR soldering stations although I think you will need a bunch of them for coverage.

Thanks for the suggestions, but something as bulky as a waffle iron would be too much weight for the benefits in my mind. If worst comes to worst I know a few companies that will make custom shaped silicone/polymide film heaters.
I don't have any printed parts, and I plan to keep it that way the entire build. At a maximum, aesthetic parts will be printed, but I hope to avoid even that. I've most definitely got a thing against printed parts being on my printer, having had way too many breakdowns as a result of printed parts.
I wouldn't think IR would constitute any greater fire risk than direct if given the proper care in construction. The heaters would be fixed to the bed and move along with it, if not that would most definitely pose a fire hazard.

Right now I'm just looking at using my 300mmX300mm silicone heater until I get a supplier to custom make a polymide heater [keep weight and heat up time down] or figure out the overly complicated math and make one myself. Making your own heater seems to be an entire project by itself.


Any idea what heaters are used in these mats? If I could get a high power version of them, that would be splendid as they're flat.

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Realizer- One who realizes dreams by making them a reality either by possibility or by completion. Also creating or renewing hopes of dreams.
"keep in mind, even the best printer can not print with the best filament if the user is the problem." -Ohmarinus

What about using carbon fiber? There are carbon fiber heating tapes [for clothing], though those are high resistance what if an entire sheet was used? I couldn't find anything on the resistance of carbon fiber composites except that they were conductive.

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Realizer- One who realizes dreams by making them a reality either by possibility or by completion. Also creating or renewing hopes of dreams.
"keep in mind, even the best printer can not print with the best filament if the user is the problem." -Ohmarinus

Foil heater

Perhaps you could make up a 300 x 650 foil heater?

see [forums.reprap.org]

Size the foil/wire for your bed size, how fast a heatup and how much power supplied.

Got my carbon fiber sampler pack yesterday, did some tests today and it seems to have everything I want except being pre-made into what I need. Held under a flame it spreads the heat well, take the flame out and it's literally cool to the touch in less than five seconds. Conducts electricity and generates heat as a result. Easily cuttable and shapeable.
Now all I need is to find an electrically insulating way to mount it to the bed and an electrically conductive way to mold it to itself, all at high heat resistance.

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Realizer- One who realizes dreams by making them a reality either by possibility or by completion. Also creating or renewing hopes of dreams.
"keep in mind, even the best printer can not print with the best filament if the user is the problem." -Ohmarinus

Quote
MrDoctorDIV
Thanks for the suggestions, but something as bulky as a waffle iron would be too much weight for the benefits in my mind. If worst comes to worst I know a few companies that will make custom shaped silicone/polymide film heaters.
I don't have any printed parts, and I plan to keep it that way the entire build. At a maximum, aesthetic parts will be printed, but I hope to avoid even that. I've most definitely got a thing against printed parts being on my printer, having had way too many breakdowns as a result of printed parts.
I wouldn't think IR would constitute any greater fire risk than direct if given the proper care in construction. The heaters would be fixed to the bed and move along with it, if not that would most definitely pose a fire hazard.

Right now I'm just looking at using my 300mmX300mm silicone heater until I get a supplier to custom make a polymide heater [keep weight and heat up time down] or figure out the overly complicated math and make one myself. Making your own heater seems to be an entire project by itself.


Any idea what heaters are used in these mats? If I could get a high power version of them, that would be splendid as they're flat.

What about using a pair of these Kapton Heater mat 300x300 should work out at about $30 each?

Doug

Doesn't solve my mounting issue. I need four points of contact on the underside of the build plate.
That also runs into the SSR required power issue. For printing this large, I will not be printing ABS.
I hope to be printing PETG, so I only need PLA level bed heat to make sure the first layer is perfect and easy. My favorite supplier is looking to expand their range of filaments, PETG included, which makes me entirely happy. At the highest, I'll need 80C, although I can typically get away with 45C on my current printer. Carbon Fiber has a nice high resistance so I can slap a fair amount of it on, not needing to watch weight as much, and it'll look good while making it myself will allow space for the four areas I need.

Edited 1 time(s). Last edit at 09/10/2014 02:01PM by MrDoctorDIV.

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Realizer- One who realizes dreams by making them a reality either by possibility or by completion. Also creating or renewing hopes of dreams.
"keep in mind, even the best printer can not print with the best filament if the user is the problem." -Ohmarinus