To help strengthen the reflector I added a 1/8” x 1/2” 304 stainless bezel which will be spot welded to the reflective sheeting.

       Tabs were welded onto the bottom of the bezel to accommodate rubber feet that will support the light head when it is off of it’s tripod.

       I had never had the excuse to use a spot welder until now so naturally I was eager to give one a try ;0) I got this one for around $150.

       Next the bezel was clamped to the reflector very carefully as to align the sheeting at the proper angles required.

       I placed the electrodes of the spot welder (not shown) near the ends of the sheets and pulled the switch to tack the reflector and lock it into place on the bezel. Man this spot welder is fun to use :0)

       I then used a marker to indicate where I wanted the rest of the spot welds to take place.

       The spot welder worked extremely well and was quite easy to use with the exception of its weight. It is quite a workout holding the heavy welder at the needed angles over and over :OP

       My son Vincent was inspecting my work :0)

       I now needed to add the final detail to the reflector which was the corner pieces. These pieces would shore up the strength of the reflector and keep the geometry square.

       I made a paper template (seen above) that I used as a guide to fabricate four angle pieces which were made of the same 22 gauge stainless as the reflector.

       I bent all of the corners on the sheet metal brake and then marked them where they would need to be spot welded.

       In a matter of minutes I was able to weld the corners to the reflector with minimal effort.

       The spot welder worked very well and should prove to be a useful tool in my future builds.

       Lastly I added rubber feet to the bottom of the reflector bezel and also made a third tab/rubber foot on the fixture yoke as seen below...

       The three rubber feet provide a stable way to store and transport the light head.

       Now that the light head was complete I could weigh it on my digital scale (not shown) which indicated a whopping 52 pounds!!! This light is definitely a two person lift when putting it on the tripod.

       At last the the studio light was ready to be put to the test. Would this experiment be a success or an expensive failure??? Either way it does look very technical so that was a win in my books ;o)

       I performed a series of tests with a light meter to see if the COB chips could produce the lumens that they are rated for. Unfortunately I do not have the sophisticated equipment needed to properly measure luminous flux but I can get a ballpark measurement with my light meter.

       To get a rough idea of how the light performs I needed to simulate a lumen reading by using a meter that measures in “lux””.  This type of meter cannot account for surface area of which lumens measurements are based on however you can take measurements at different distances from the light source to simulate a given surface area.
       Since lumens are equal to one lux spread over a one square meter surface I will have to take measurements at a distance that would represent one square meter of curved radial surface area. This surface area should be projected at a uniformly equal distance from the light source (a radius). In this case the surface can be represented in a hemisphere with the center of the radius being the array itself. This is not a perfect solution as my reflector changes the geometry of the radius but will be close enough for what I am doing here.
       The radius of a one square meter (curved area) hemisphere is 39.89cm or equal to 15.7” so I used this distance to position my Lux meter away from the light. After taking several readings from along the 15.7” radius I averaged out about 103,000 Lux. Earlier I suggested the light would produce 112,00 lumens according to the manufacturer’s ratings so it is close enough for me to believe I am on the right track.
       When I take into account for the 93% light output correction due to the 70° C thermal junction heat level it comes to 104,160 which is really close to what I measured. Math is cool!!!

       I took a few more measurements at three meters away from the light which would be equal to about 56.54 square meters of curved surface area. These readings averaged out to about 1,740 lux which interestingly enough came to 98,379 lumens. This is a bit lower than 103,000 reading but only by 5% or so. Very interesting indeed ;0)

       To further my testing I moved the light to the front of my house to be used as a visual reference of the intensity of light. As you can see it does a very good job of simulating bright sunlight. The power is very similar to a commercial 5K Halogen studio light.

       The final light specifications are as follows:

Fixture weight: 52 pounds

Fixture dimensions: 18” wide x 18” tall x 21” long

Power requirement: 120 volts (1-phase) @ 16.4 amps max = 1,968 watts

Light output in lux @ 15.7”: 103,000 lux

Color temperature: 6500K “daylight”

Fixture heat load: 2559 BTUs per hour

Output power selectivity: 20%/40%/60%/80%/100%

Expected service life: 40,000 hours @ 70° F ambient temperature

       I look forward to seeing what new uses I will have for the mega light. At the very least I can use it to “modify” the circadian rhythm of my neighbors.

Just kidding :O>

       Overall this project was fairly educational and fun to build. I look forward to using this light to illuminate some sort of scene in one of my short films in the near future. Thanks for visiting my site and checking out my creations!

Till the next time, stay inquisitive my friends!!!

Don R. Giandomenico

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