Read HGO sticky right above your post everthing you need to know is here..
When I did it I used chains. Was definitely solid and safe but does block a minor amount of light. Dealing with multiple lamp cords and keeping things straight was my biggest issue.
Oh and BTW, there isn't a single picture, illustration or diagram of a double stacked vertical bulb. The only mention is this guy's: https://www.icmag.com/ic/showpost.php?p=4349609&postcount=77 which hardly constitutes for anything useful.
And I think you may be confused. The sticky he was referring to is this: Tutorial: How to build your own secure lamp holder for a stacked bulb vertical grow
I didn't have a tripod so I used chains.
Yes, those are the type that I have. I'm also curious of your distance between the two bulbs and how you came up with that distance?
Did it work for you? Anything that you would change?
That's all cool stuff but have u checked out ichabods thread. Simply hang the top light by the cord, and build a simple pvc holder for the base. this way u have ur pointed ends of lights shooting to the middle of ur grow and u can set the bottom edges of light where they go into the mogul, right at the start of growth at the top and bottom.
Not exactly...
I built lamp bases out of five gallon buckets and wood. These are made to place the filament at a specific height above the bottom of the cylinder. What specific height?
Allow me to digress into wave theory in physics; waves from point sources tend to interact in predictable ways., sometimes reinforcing and sometimes canceling one another's effects. In this case, we're trying to get uniform lighting intensity from two point sources on the inside surface of a cylinder.
Wave theory says that light acts as a wave, so I look at the height of the cylinder as a series of nodes, equidistant from one another up and down the center axis. Calculate for two light sources this way;
Divide your cylinder trellis height by four. Place one filament that distance above the bottom of your trellis, and the other that distance below the top of it. It may seem like they're too far apart, but each light's pattern will reinforce the other's and create ideal lighting in the center.
For three lamps; divide by six, then place your lamps at nodes one, three and five.
Okay, for two lights;
If your trellis height is six feet, one quarter of that is a foot and a half. Place your lamps a foot and a half above the bottom and the other the same distance down from the top.
I don't think that placement would yield the most. In fact I have tested that and know it to be true in my system.