Hey... I've got both a question and a comment... so lets go...
first off all... I did search... but didn't really find what I need.
So, how hot can MDF get before it starts to burn? I use 12mm MDF for the different panels and 4mm MDF for the outside. How hot until it burns? I used some other wood very close to my 400w MH lamp and it started to smoke, while the MDF I used about as close (3cm = 1.2 inch) did nothing... but I'm not totally confident.
I see all the guys at lumenlab plating their wood with aluminium... but this will reflect a lot of light that I dont want. So can one use unprotected MDF close to the lamp without risk? I found out that MDF DOES burn in a fire... but it didn't do anything at 60 degrees celcius.
Furthermore I found something called "Radiator folie" this is a one side foamie and the other side reflective foil, witch is used behind radiators... says it reflect 70% of the heat... and was very cheap (3 euro's for 1.25m2)... might be a cheap sollution... just wanted to share it
. I put it close to my lamp (3cm) and it didnt get hot at all... I think the wood behind it stayed cooler... but I'll test it a little better tomorrow.
Hope yall can help me out... thanx in advande
Jeroen.
first off all... I did search... but didn't really find what I need.
So, how hot can MDF get before it starts to burn? I use 12mm MDF for the different panels and 4mm MDF for the outside. How hot until it burns? I used some other wood very close to my 400w MH lamp and it started to smoke, while the MDF I used about as close (3cm = 1.2 inch) did nothing... but I'm not totally confident.
I see all the guys at lumenlab plating their wood with aluminium... but this will reflect a lot of light that I dont want. So can one use unprotected MDF close to the lamp without risk? I found out that MDF DOES burn in a fire... but it didn't do anything at 60 degrees celcius.
Furthermore I found something called "Radiator folie" this is a one side foamie and the other side reflective foil, witch is used behind radiators... says it reflect 70% of the heat... and was very cheap (3 euro's for 1.25m2)... might be a cheap sollution... just wanted to share it
. I put it close to my lamp (3cm) and it didnt get hot at all... I think the wood behind it stayed cooler... but I'll test it a little better tomorrow.Hope yall can help me out... thanx in advande
Jeroen.
Thermal considerations
Hey Jeroen.
I am running a 500W incandescent DAY/DAK lamp inside a 12mm thick MDF enclosure, with no troubles. Sharp QA-1150 projection panel for LCD source.
The lamp is mounted in a 1970's slide projector base, which is ~1/8" thick aluminum - and as you know, can be used to efficiently transfer heat into the air if used correctly. It was also necessary since it carries the base in order to accomodate the 4-pin lamp. I cut that aluminum base down to fit my enclosure with a band saw.
The lamp is roughly 3" away from the inside (rear MDF wall) of the enclosure. Between the MDF and lamp, - and roughly 2" from the lamp, I am using a 3" wide stainless steel parabolic reflector (a.k.a. fifty cent soup ladel) I cut the long, flat soup ladel handle down to a useful size, then drilled a mounting hole into the handle - then bent the handle so that the ladel reflects the light from the filament, and stands off of the MDF wall by about 1". This part also helps to dissapate some heat away from the lamp, and into the air. As you know, a large metal reflector like this will give you some of the 50% of the light back from the rear of your lamp, and fire it forward...where you need it... and can serve as a heat shield - if you let it. (stand it off from the MDF give it an air space).
Also, should note that I have a 4" 120V fan constantly drawing fresh 21°C air in through the bottom right side wall of the enclosure, directly passed the lamp, through a light blocking wall (also MDF) and the hot air eventually gets pushed out through a slot in the opposite top side of the enclosure.
Otherwise, the lamp is about 8" from any other MDF surface, and of no consequence.
What I did in order to control light reflection was sprayed the light engine enclosure with Flat Black Stove Paint. It does make the inside surface a bit warmer, since black absorbs light... but the paint layer can take it.
However, in practice - I have learned that it is not critical to control reflections in the light engine, if you plan to collumate the light before your panel with a fresnel lense anyway, you would actually be better off reflecting as much as you can through your fresnel. (or if you have a nice condensor lense system set up...through the condensor, then through the fresnel... whichever) - the fresnel is made to spread the light evenly over it's surface, so give it as much as you can. A point source of light is not critical.
Paper ignites at somewhere around 400°C. Plywood will act more like paper than MDF will, since there are air gaps in plywood. MDF is hydraulically compressed saw dust and carpenters glue. Not many air gaps to help ignition. Remember that everything on the planet will burn at some point, and if you check the installation info. on the bulb...the immediate enclosure should be able to withstand 2100°C temperatures in case of rupture. You do not want to mess with that, no matter how unlikely. I suggest using an outdoor fixture (you know to light buildings), or a work-lamp fixture. Metal and glass are just safer than MDF, and HID bulbs are different from incandescent. When my lamp goes, it just pops quietly, like an old fashioned flash bulb. When a hot HID ruptures... very different, potentially very dangerous.
You could also try an aluminum heat sink from the lamp mount to the outside air...light tight of course. And safely run your test for 4 hours - because this will be a more accurate / real test.
If you are wondering about my lamp choice, - DAY/DAK; they are $5.00. or free inside a used slide projector at a garage sale / re-use centre. Also, incandescents are 100CRI, and in this case roughly 12,000 mean lumens (best case of course). The "light temperature" is 3200K, as are most incandescents - but I have also learned that this is not critical either. Your eyes adjust. Whites are very white... and better yet, Reds are definetly Reds, and Oranges, Yellows, Greens, Blues, Indigo's, and Violets are also accurately rendered. There is a lot of talk about Metal Halides etc... giving off a "better" bluer 4200K white, -but most with a CRI of only 65? What this means is that the colours are inaccurately skewed to a "cool" blue hue. Having said that, I will be forced to buy another HID / ballast set (I have in the past) just for Lifespan...
Anyhow... I ramble... be careful, and I hope this helps.
-Jayson-
Hey Jeroen.
I am running a 500W incandescent DAY/DAK lamp inside a 12mm thick MDF enclosure, with no troubles. Sharp QA-1150 projection panel for LCD source.
The lamp is mounted in a 1970's slide projector base, which is ~1/8" thick aluminum - and as you know, can be used to efficiently transfer heat into the air if used correctly. It was also necessary since it carries the base in order to accomodate the 4-pin lamp. I cut that aluminum base down to fit my enclosure with a band saw.
The lamp is roughly 3" away from the inside (rear MDF wall) of the enclosure. Between the MDF and lamp, - and roughly 2" from the lamp, I am using a 3" wide stainless steel parabolic reflector (a.k.a. fifty cent soup ladel) I cut the long, flat soup ladel handle down to a useful size, then drilled a mounting hole into the handle - then bent the handle so that the ladel reflects the light from the filament, and stands off of the MDF wall by about 1". This part also helps to dissapate some heat away from the lamp, and into the air. As you know, a large metal reflector like this will give you some of the 50% of the light back from the rear of your lamp, and fire it forward...where you need it... and can serve as a heat shield - if you let it. (stand it off from the MDF give it an air space).
Also, should note that I have a 4" 120V fan constantly drawing fresh 21°C air in through the bottom right side wall of the enclosure, directly passed the lamp, through a light blocking wall (also MDF) and the hot air eventually gets pushed out through a slot in the opposite top side of the enclosure.
Otherwise, the lamp is about 8" from any other MDF surface, and of no consequence.
What I did in order to control light reflection was sprayed the light engine enclosure with Flat Black Stove Paint. It does make the inside surface a bit warmer, since black absorbs light... but the paint layer can take it.
However, in practice - I have learned that it is not critical to control reflections in the light engine, if you plan to collumate the light before your panel with a fresnel lense anyway, you would actually be better off reflecting as much as you can through your fresnel. (or if you have a nice condensor lense system set up...through the condensor, then through the fresnel... whichever) - the fresnel is made to spread the light evenly over it's surface, so give it as much as you can. A point source of light is not critical.
Paper ignites at somewhere around 400°C. Plywood will act more like paper than MDF will, since there are air gaps in plywood. MDF is hydraulically compressed saw dust and carpenters glue. Not many air gaps to help ignition. Remember that everything on the planet will burn at some point, and if you check the installation info. on the bulb...the immediate enclosure should be able to withstand 2100°C temperatures in case of rupture. You do not want to mess with that, no matter how unlikely. I suggest using an outdoor fixture (you know to light buildings), or a work-lamp fixture. Metal and glass are just safer than MDF, and HID bulbs are different from incandescent. When my lamp goes, it just pops quietly, like an old fashioned flash bulb. When a hot HID ruptures... very different, potentially very dangerous.
You could also try an aluminum heat sink from the lamp mount to the outside air...light tight of course. And safely run your test for 4 hours - because this will be a more accurate / real test.
If you are wondering about my lamp choice, - DAY/DAK; they are $5.00. or free inside a used slide projector at a garage sale / re-use centre. Also, incandescents are 100CRI, and in this case roughly 12,000 mean lumens (best case of course). The "light temperature" is 3200K, as are most incandescents - but I have also learned that this is not critical either. Your eyes adjust. Whites are very white... and better yet, Reds are definetly Reds, and Oranges, Yellows, Greens, Blues, Indigo's, and Violets are also accurately rendered. There is a lot of talk about Metal Halides etc... giving off a "better" bluer 4200K white, -but most with a CRI of only 65? What this means is that the colours are inaccurately skewed to a "cool" blue hue. Having said that, I will be forced to buy another HID / ballast set (I have in the past) just for Lifespan...
Anyhow... I ramble... be careful, and I hope this helps.
-Jayson-
65 cri? mines 90cri, has a colour temp of 5100k and quite frankly unless you have seen any different from 3200k you will not know the difference, hell im never going back to 4200k as the colour isnt clearly correct. Lcd monitors backlights are between 5000k and 6000k, you should run a lamp at the rated backlight colour to get the true acurate colurs of your lcd, if you dont, your colours will be forever messed.
Trev
Hello again Ace.
Most common HID are 65 CRI. Industrial applications, you know like overhead lighting in Home Depot...
I have the Sylvania Catelogue, & I am sure you do too. There are different types of course. Cost prohibitave. Yours is a specialty lamp, and good on you. 🙂 I have to get another one soon as I mentioned.. Lifespan.
Don't forget... my panel was designed to operate on an OHP. Tungsten Halogen at best...(glorified incandescent) so there is no Flourescent Backlight Specification... oh and you know as well as I how Flourescent lamps work... igniting gas that emits UV light. Just so happens that the phosporous they coat the inside of a tube with glows at (depending on the type) between 3200K and 5500K... you just have the interior designer pick whether you want warm light or soft light. So of course they spec LCD monitors with 5000K as an average. That is what they are naturally.
I should like to qualify, - just had family over to watch a movie last night. It was great. The whole system was about $230.00 CDN.
Anyhow, - be careful with your heat tests Jeroen.
Most common HID are 65 CRI. Industrial applications, you know like overhead lighting in Home Depot...
I have the Sylvania Catelogue, & I am sure you do too. There are different types of course. Cost prohibitave. Yours is a specialty lamp, and good on you. 🙂 I have to get another one soon as I mentioned.. Lifespan.
Don't forget... my panel was designed to operate on an OHP. Tungsten Halogen at best...(glorified incandescent) so there is no Flourescent Backlight Specification... oh and you know as well as I how Flourescent lamps work... igniting gas that emits UV light. Just so happens that the phosporous they coat the inside of a tube with glows at (depending on the type) between 3200K and 5500K... you just have the interior designer pick whether you want warm light or soft light. So of course they spec LCD monitors with 5000K as an average. That is what they are naturally.
I should like to qualify, - just had family over to watch a movie last night. It was great. The whole system was about $230.00 CDN.
Anyhow, - be careful with your heat tests Jeroen.
I would think ace is running a Ushio? maybe not. Ushios have a high cri around 85 and a 5200K temp. Link.
I have crisped cardboard and mdf with a metal halide, im only running a 250W too. If your bulb is too close you could always try a couple layers of aluminum foil on top of the wood. Shiny side towards the light is best! Im using half a beer can to save my wood until i buy a better reflector and/or finish my design.
I have crisped cardboard and mdf with a metal halide, im only running a 250W too. If your bulb is too close you could always try a couple layers of aluminum foil on top of the wood. Shiny side towards the light is best! Im using half a beer can to save my wood until i buy a better reflector and/or finish my design.
Fire retardant / heat resistant MDF is available.
I don't have specs for it, but it's considered OK for building fireplaces, etc.
I don't have specs for it, but it's considered OK for building fireplaces, etc.
k.. thanx for the reply's...
So to conclude... 6 inches away from a 400w bulb should be safe... but at 1 inch away I'd better cover it up with something? Would aluminiumfoil (multiple layers) be sufficient for this?
And how can you say that te reflection doesn't matter? I agree that nog much lightbeams will eventually go tru the objectlens and hit the screen causing a less quality picture, correct me if I'm wrong.
Jeroen.
So to conclude... 6 inches away from a 400w bulb should be safe... but at 1 inch away I'd better cover it up with something? Would aluminiumfoil (multiple layers) be sufficient for this?
And how can you say that te reflection doesn't matter? I agree that nog much lightbeams will eventually go tru the objectlens and hit the screen causing a less quality picture, correct me if I'm wrong.
Jeroen.
ACE' bulb
Trevor:
In the page you've posted doesn't appears the model of the lamp. Could you post it?
Thank.
Trevor:
In the page you've posted doesn't appears the model of the lamp. Could you post it?
Thank.
If you’re worried about heat, you could use compressed fibreglass isolation. Another possibility would be cement sheet; both of these will not burn.
I think you will find that light that doesn't enter the light path from the correct angle, will cause more harm than good.
Here is an exaggerated ray trace that might help.
I think you will find that light that doesn't enter the light path from the correct angle, will cause more harm than good.
Here is an exaggerated ray trace that might help.
Attachments
Hi trevor
I'm here waiting for the stuff to come !!!
In the meantime I managed the get the proj. working and I improvised a Condenser with a magnifying Glass, but I don't have here in Argentina something to replace the fresnel while I wait yours.
I found here an acrylic magnifying glass, plane, that has the measures of a credit card, and that could work. But I think its very small. So I prefer to wait.
The projection is not too bright, and of course I have the center more brighter thant the corners, but its a good begining.
I tried to take some pictures but my digiftal camera only takes the center and the rest is as if doesn't exists. I'll try with a common camera.
I think that the coating of my lens take a lot of light. I tried to replace the lens with a common magnifying glass and the picture was amazing brightly. But it was very difficult to have an all focused picture...
Well that's all for now.
bye
I'm here waiting for the stuff to come !!!
In the meantime I managed the get the proj. working and I improvised a Condenser with a magnifying Glass, but I don't have here in Argentina something to replace the fresnel while I wait yours.
I found here an acrylic magnifying glass, plane, that has the measures of a credit card, and that could work. But I think its very small. So I prefer to wait.
The projection is not too bright, and of course I have the center more brighter thant the corners, but its a good begining.
I tried to take some pictures but my digiftal camera only takes the center and the rest is as if doesn't exists. I'll try with a common camera.
I think that the coating of my lens take a lot of light. I tried to replace the lens with a common magnifying glass and the picture was amazing brightly. But it was very difficult to have an all focused picture...
Well that's all for now.
bye
Heya buddy, your gear is certainly out there, im sure it will rock up soon, probally next week as your postal service is abit slower then the rest so ive been told once before.
The reason your small experimental frensel isnt evenly lighting up the whole image plane is because the lamp isnt at the frensels focal point, normally on those small page maggs its about 310mm focal.
Trev
The reason your small experimental frensel isnt evenly lighting up the whole image plane is because the lamp isnt at the frensels focal point, normally on those small page maggs its about 310mm focal.
Trev
Last time I checked MDF won't spontaneously combust until it reaches over 600 degrees F. Yup, had to check years ago when I worked in a cabinetry shop building mantles for a gas fireplaces, the mantles were getting close to 300F and the white lacquer was turning brown but there was no fire.
so I'm pretty safe then.... well I started thinking and now I'm thinking about
makeing an black, metal plate around the lamp... but very close, about one inch away. This would meen no licht on the case (only a little) and little reflection because the metal would be black. But... can the lamp take this? I assume that it can get pretty hot... but this would make the lamp even hotter
Does this give issuse's?
thanx for everythin so far,
Jeroen.
makeing an black, metal plate around the lamp... but very close, about one inch away. This would meen no licht on the case (only a little) and little reflection because the metal would be black. But... can the lamp take this? I assume that it can get pretty hot... but this would make the lamp even hotter
Does this give issuse's?thanx for everythin so far,
Jeroen.
You also want to keep the lamp as cool as possible or you will get very short service life out of it.
General safety rule where I live is that wooden stuff and organic material should not be exposed temperatures above 80 degrees Celsius. That means long-term situation like hours, months and years. If aluminium or other thing is used as heat radiation shield you must leave ventilated space between the protected surface and heat source. Two shields and two ventilated air spaces between is even better.
I suppose MDF can take temperatures higher than that, but keeping it under 80 degrees celsius is quaranteed safe for continious use, be it few hours, weeks or months
I suppose MDF can take temperatures higher than that, but keeping it under 80 degrees celsius is quaranteed safe for continious use, be it few hours, weeks or months
Heat
Jeroen,
Not to disuade the entire project, only offering a point.
Any metal jacket, no matter the colour - located only one inch away from a lamp of this intensity is potentially dangerous. What happens is that the heat produced by the lamp is stored in the metal. Some will wick through the metal and away from the lamp, yes, but some will also return to the surface of the glass bulb in near contact to this metal shield. Painting the metal black or orange or green with dark yellow stripes is of no real consequence...aside from the added drawback that black will naturally absorb a bit more heat from the lamp, (a.k.a. it will not reflect it away from the lamp and to some other location.)... and therefore return more radiant heat to that area of the glass bulb surface. Not necessarily visible light reflection or a sum of those waves at a point in the glass, just returned stored radiant heat from the lamp's full spectrum of output.
The farther away the better. Choose Aluminum over Steel for heat transfer. If your shield has a heat sink on it to transfer the heat into another air space - even better. This will allow the aluminum nearest the heater (lamp) to more efficiently transfer heat through the metal to the outside airspace. (as Power Amplifiers in Audio, helping to maintain lower operating of - let's say - output transistors)
I have seen bulbs warp and rupture when not cooled properly when operating, and also have seen other material explode when cooled too quickly / unevenly. Be sure to supply lots of fresh, room temperature air across the lamp continuosly while it is energised, and equally as sure to give a clear path for the hot air to escape from the enclosure.
Sorry to sound like a concerned parent, but...this stuff is supposed to be fun afterall. And just after being completely safe. The dangers can be engineered out.
-Jayson-
Jeroen,
Not to disuade the entire project, only offering a point.
Any metal jacket, no matter the colour - located only one inch away from a lamp of this intensity is potentially dangerous. What happens is that the heat produced by the lamp is stored in the metal. Some will wick through the metal and away from the lamp, yes, but some will also return to the surface of the glass bulb in near contact to this metal shield. Painting the metal black or orange or green with dark yellow stripes is of no real consequence...aside from the added drawback that black will naturally absorb a bit more heat from the lamp, (a.k.a. it will not reflect it away from the lamp and to some other location.)... and therefore return more radiant heat to that area of the glass bulb surface. Not necessarily visible light reflection or a sum of those waves at a point in the glass, just returned stored radiant heat from the lamp's full spectrum of output.
The farther away the better. Choose Aluminum over Steel for heat transfer. If your shield has a heat sink on it to transfer the heat into another air space - even better. This will allow the aluminum nearest the heater (lamp) to more efficiently transfer heat through the metal to the outside airspace. (as Power Amplifiers in Audio, helping to maintain lower operating of - let's say - output transistors)
I have seen bulbs warp and rupture when not cooled properly when operating, and also have seen other material explode when cooled too quickly / unevenly. Be sure to supply lots of fresh, room temperature air across the lamp continuosly while it is energised, and equally as sure to give a clear path for the hot air to escape from the enclosure.
Sorry to sound like a concerned parent, but...this stuff is supposed to be fun afterall. And just after being completely safe. The dangers can be engineered out.
-Jayson-
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