mogie
Well-Known Member
The Hood & Insert Subassembly
Transfer the dimensions from the layout to the sheet metal with a magic marker... Again, try to be very accurate and definitely use a square...
The pattern is then cut out with tin snips and scored for bending... Remember, the scoring is important to get a nice crisp bend... Here is the scored and cut sheet ready for folding...
Take note of this image... It is a rectangular section used as an insert, bent into a V shape, for reflecting light above the bulb... This is an important element of the design... Hopefully you can see the detail of the scored lines here... BTW- the fancy Kett Power Snips were borrowed from AF and worked well, but hand snips work just fine, and are required for getting into the little corners anyway...
Image shows the hood and V Insert folded... The bar on the top is used to secure a 90-degree bracket on the inside for holding the light fixture (note the wires sticking out)... It was salvaged from the security light housing...
Rivet the V Insert in place... You can see the 90-degree light bracket on the left... The rivet gun has a fancy swivel head that was more useful than expected, but any one should work ok just fine...
Finishing Up
· Join the two sub-assemblies together... Used a small piece of sheet metal at back end (end of bulb pointing toward it), and fashioned another piece for the end closest you in the picture...
· Paint assembly with flat white HIGH TEMPERATURE paint...
· Install the electronics (ballast, starter, power cord to timer)...
*NOTE: For details on wiring a security light check the "Lighting" folder in the Grow FAQ's...
The ballast is shown up front here and worked fine for 1st grow, but have since relocated the ballast to the back of the unit where the exit is located, thought it would add a slight bit less total heat, maybe, and no longer use carbon scrubber cartridge...
Looking at the final image at the bottom, you can see the exit with weather stripping around it that mates to exhaust port in cabinet... It is in here that the ballast is now located... Secured ballast with a sheet metal strap... I had a bit of issue with ballast humming... Wedging a metal shim under the ballast to make it snugger eliminated the vibration and it's practically silent now, even at startup...
· Now might be a good time to test your hood assembly!!! Yeay...
Unit Assembly Installed
· The remaining triangular shaped space on right side is used for power junction box and in front of that the timer... Keep all electronics upstairs and away from fluids... No separate utility room need for this cab!! There is an air space above the hood...
· Install glass shield... Tempered glass is best but I used regular 1/8" glass; as it's fairly small wattage and little stress is placed on it... A gap of 3/4" or so is left at far end for air to enter, pass across bulb, and then flow out hood and over ballast on way out of box... You might note the two channels bent along either side of hood for glass to slide in... Add another inch to the glass width to account for channel it slides into...
· Seal the front of the assembly... Used a material called " Reflectix". Version 1 of the cab had Reflectix on the walls and door, and when closed sealed off the front... Now I?m using Mylar, so it?s shown for current setup...
Light On!
The camera was placed on the floor of cab for this shot... Each image is simply a different exposure... The left image gives a good idea of where most of the light goes... It is said little light is emitted from end of bulb, and this picture makes that fairly clear... The right image shows the imbalance in my light distribution a bit more clearly, due to about a 3/16" misalignment of the bulb over the V Insert... Will tweak that before next grow when glass is removed for cleaning - however, it does demonstrate how important the V Insert is and also that accuracy does matter for some parts of the setup...
Carbon Scrubber Insert
Abandoned this for now...
This little module was made with a flouro light fixture grill cut to triangles and stacked and glued to achieve about 4" length... Channels are filled with activated carbon for scrubbing odors... It was inserted into back of cab through the opening, and then slid in... It caused too much static pressure for the single fan being used... (I had to go with active intake) So now use stacked scrubber modules on back of cab - oh well, so much for 100% containment with-in the little cab - still stealthy...
Conclusion
Well, there you have it, an air-cooled hood assembly with integral light trap - all for less than $100... This took me a full day and well into the night to design and build, however, the design part was probably 80% of the work... Also doesn't count a day of searching OG to see what others had done... Could probably build one of these in an afternoon now - or maybe just a bit longer than the time is took to prepare this post!
Works for me! On third grow with this setup and it performs well... The temperature increase is about 6 to 7 degrees above ambient... More fan power should bring this down; the flow is probably a bit low now (only 1 Rotron fan on intake at this point, another tiny one below glass in corner for circulation)... An active exhaust would be an improvement, as there isn't airflow through the hood when the door is removed... Didn't have fans that would fit at the time this was built... Have since picked up some smaller Rotron DC fans that will be used to add an active element to the exhaust at some point... I'd recommend this from the start...
Transfer the dimensions from the layout to the sheet metal with a magic marker... Again, try to be very accurate and definitely use a square...
The pattern is then cut out with tin snips and scored for bending... Remember, the scoring is important to get a nice crisp bend... Here is the scored and cut sheet ready for folding...
Take note of this image... It is a rectangular section used as an insert, bent into a V shape, for reflecting light above the bulb... This is an important element of the design... Hopefully you can see the detail of the scored lines here... BTW- the fancy Kett Power Snips were borrowed from AF and worked well, but hand snips work just fine, and are required for getting into the little corners anyway...
Image shows the hood and V Insert folded... The bar on the top is used to secure a 90-degree bracket on the inside for holding the light fixture (note the wires sticking out)... It was salvaged from the security light housing...
Rivet the V Insert in place... You can see the 90-degree light bracket on the left... The rivet gun has a fancy swivel head that was more useful than expected, but any one should work ok just fine...
Finishing Up
· Join the two sub-assemblies together... Used a small piece of sheet metal at back end (end of bulb pointing toward it), and fashioned another piece for the end closest you in the picture...
· Paint assembly with flat white HIGH TEMPERATURE paint...
· Install the electronics (ballast, starter, power cord to timer)...
*NOTE: For details on wiring a security light check the "Lighting" folder in the Grow FAQ's...
The ballast is shown up front here and worked fine for 1st grow, but have since relocated the ballast to the back of the unit where the exit is located, thought it would add a slight bit less total heat, maybe, and no longer use carbon scrubber cartridge...
Looking at the final image at the bottom, you can see the exit with weather stripping around it that mates to exhaust port in cabinet... It is in here that the ballast is now located... Secured ballast with a sheet metal strap... I had a bit of issue with ballast humming... Wedging a metal shim under the ballast to make it snugger eliminated the vibration and it's practically silent now, even at startup...
· Now might be a good time to test your hood assembly!!! Yeay...
Unit Assembly Installed
· The remaining triangular shaped space on right side is used for power junction box and in front of that the timer... Keep all electronics upstairs and away from fluids... No separate utility room need for this cab!! There is an air space above the hood...
· Install glass shield... Tempered glass is best but I used regular 1/8" glass; as it's fairly small wattage and little stress is placed on it... A gap of 3/4" or so is left at far end for air to enter, pass across bulb, and then flow out hood and over ballast on way out of box... You might note the two channels bent along either side of hood for glass to slide in... Add another inch to the glass width to account for channel it slides into...
· Seal the front of the assembly... Used a material called " Reflectix". Version 1 of the cab had Reflectix on the walls and door, and when closed sealed off the front... Now I?m using Mylar, so it?s shown for current setup...
Light On!
The camera was placed on the floor of cab for this shot... Each image is simply a different exposure... The left image gives a good idea of where most of the light goes... It is said little light is emitted from end of bulb, and this picture makes that fairly clear... The right image shows the imbalance in my light distribution a bit more clearly, due to about a 3/16" misalignment of the bulb over the V Insert... Will tweak that before next grow when glass is removed for cleaning - however, it does demonstrate how important the V Insert is and also that accuracy does matter for some parts of the setup...
Carbon Scrubber Insert
Abandoned this for now...
This little module was made with a flouro light fixture grill cut to triangles and stacked and glued to achieve about 4" length... Channels are filled with activated carbon for scrubbing odors... It was inserted into back of cab through the opening, and then slid in... It caused too much static pressure for the single fan being used... (I had to go with active intake) So now use stacked scrubber modules on back of cab - oh well, so much for 100% containment with-in the little cab - still stealthy...
Conclusion
Well, there you have it, an air-cooled hood assembly with integral light trap - all for less than $100... This took me a full day and well into the night to design and build, however, the design part was probably 80% of the work... Also doesn't count a day of searching OG to see what others had done... Could probably build one of these in an afternoon now - or maybe just a bit longer than the time is took to prepare this post!
Works for me! On third grow with this setup and it performs well... The temperature increase is about 6 to 7 degrees above ambient... More fan power should bring this down; the flow is probably a bit low now (only 1 Rotron fan on intake at this point, another tiny one below glass in corner for circulation)... An active exhaust would be an improvement, as there isn't airflow through the hood when the door is removed... Didn't have fans that would fit at the time this was built... Have since picked up some smaller Rotron DC fans that will be used to add an active element to the exhaust at some point... I'd recommend this from the start...