The following are somewhat detailed instructions for constructing a shielded hood/reflector with an integrated light trap designed for a small cabinet... It can certainly be scaled up for larger lights, but a 70w HPS (Home Depot security light) was used here...

Final Product


*Note: While researching on other hoods/reflectors (Jackerspackle, Nimby, NGB, Tick, etc...) this problem often popped up... How do you bend sheet metal w/out a proper press brake? This method works like a dream and requires only a few pieces of scrap wood...


Primary Tools:

· Tin snips
· Rivet gun
· Square / Straightedge
· Utility knife
· Drill
· Good marker for layouts

Materials:

· Sheet Metal - Picked up large sheet of decent gage sheet for $8 at The HomeDeopt...
· HPS Light
· Glass Shield
· Plug and Wire
· Paint - White & Black - Use HIGH TEMPERATURE only... (For BBQ grills/Engines/Radiators?)
· Weather Striping
· Foil Tape
· Scrap Wood


Layout

*Note: The dimensions are for a 70w HPS bulb... If you are building this to use with another size bulb you must alter the dimensions accordingly... So scale/adjust to suit other bulb wattages...

Illustration for the Light Trap's Layout...



Illustration for the Hood's Layout...



The Light Trap Subassembly

Start out by transferring the dimensions from the layout to the sheet metal with a magic marker... Try to be very accurate and definitely use a square...

In this image you'll see A) the sketch on cardboard in the background used to plan hood to fit in the small filing cab, B) the dimensioned flat pattern layout on paper, C) a section of sheet metal with the layout already transferred...


The pattern is then cut with tin snips and "scored" for bending... The scoring is important to get a nice crisp bend... Use the utility knife, and make like you?re going to cut on a "fold line" and take a few passes... The score should be on the outside of the bend...


Folding technique - using 3 scraps of plywood... Two sheets sandwich the section of sheet metal that will be stationary during the bend... The third sheet is placed as shown below the section to be bent, and butting up against the bottom of the sandwich, meeting right on the bend line... Be careful not to get any of the 3rd sheet below a section not to be bent yet...


While standing on the "sandwich", pull the 3rd sheet up with confidence... The resulting bend is shown and is very crisp, accurate, and straight due to the score... Don't bend completely; just as shown... The remaining degrees in the bend will be completed by hand later...


Continue bending... Here, you'll stand where the hammer is sitting...


A narrower piece of scrap wood is used here for easier bending...


The final bends are made by hand - simply grip the sheet metal with the V in the fold facing your palms and squeeze... It will bend easily, and again, the score will help here... A bottom view of fully folded trap...


Note that the tabs have been drilled and riveted... This would be a good time to seal the seams with high temperature foil tape... I didn?t do this at first (I was trying for 100% metal unit) and ended up with tiny light leaks, so I had to add the tape later... With the airflow through the hood it runs fairly cool anyway... A top view...