Rick6a
Well Known Member
Tip: Make your own (conduit) Adel Clamp Brackets
I needed a way to secure electrical conduit through the wings. Since the ribs already have lightening holes galore, I really didn't want to add yet another hole that would approach 1" in diameter to accept the conduit. Thinking back on my production days, I remembered that military aircraft make extensive use of clamp brackets used to secure wire bundles, conduit, ducting, hydraulic lines....you name it. Such brackets are made in an astounding number of sizes and shapes. Brackets can be generic and multi-use, others may be designed for a single application.
For my particular needs, I required a design that would allow the conduit clear passage through the wing yet the bracket had to lie flat just off the reinforcing rings pressed around the lightening holes. Believe me, that simple specification proved easier said than done! Using a 6" piece of conduit bolted to scrap .025 material, I made several "mockups" until I settled upon a suitable design. In the end, it required a longish "ear" to work. My stock of 3/4" angle was unsuitable if I expected to maintain acceptable e.d. around the bolt hole. So....this bracket and over a dozen more just like it were quickly fashioned out of a stick of 1"X1"X.062 T6 angle stock purchased from Wicks. Outlined with a Sharpie then cut out with a bandsaw and shaped with my 12" bench sander and pneumatic pencil grinder it really didn't take much time, maybe an hour more or less. I then drilled a slightly oversize hole through its extended "ear" to accept an AN bolt. Finally, I primed the lot of them with Akzo epoxy primer. Installing Van's famous black plastic conduit with WDG13 adel clamps, I used a total of 7 brackets and clamps to secure the conduit in each wing using AD4 rivets to attach the brackets to the ribs. The only thing I would do differently next time is to go ahead and add two #40 pilot holes for the AD4 attach rivets before priming. That would have made it easier to prime the small parts. Still, the conduit is very secure and ramrod straight too.
If you decide to roll your own, be sure to use angle stock. I think .050 would be the ideal thickness if you can find it but .062 is commonly available and works well although it is a bit beefier than strictly required. If you cheap out and try to use flat sheet bent to 90 degrees, it will suffer a much greater risk of failing later on due to fatigue cracking, especially in high vibration environments. So....whether you are installing conduit, wire bundles, or whatever, you too can design a special bracket for virtually any application.
A 1 foot length of Vans conduit weighs 1/2 ounce. My calculations assume 10' of Vans conduit (5.0 ounces) plus all associated installation hardware (4.2 ounces) results in at a total weight of 9.2 ounces per wing.
I needed a way to secure electrical conduit through the wings. Since the ribs already have lightening holes galore, I really didn't want to add yet another hole that would approach 1" in diameter to accept the conduit. Thinking back on my production days, I remembered that military aircraft make extensive use of clamp brackets used to secure wire bundles, conduit, ducting, hydraulic lines....you name it. Such brackets are made in an astounding number of sizes and shapes. Brackets can be generic and multi-use, others may be designed for a single application.
For my particular needs, I required a design that would allow the conduit clear passage through the wing yet the bracket had to lie flat just off the reinforcing rings pressed around the lightening holes. Believe me, that simple specification proved easier said than done! Using a 6" piece of conduit bolted to scrap .025 material, I made several "mockups" until I settled upon a suitable design. In the end, it required a longish "ear" to work. My stock of 3/4" angle was unsuitable if I expected to maintain acceptable e.d. around the bolt hole. So....this bracket and over a dozen more just like it were quickly fashioned out of a stick of 1"X1"X.062 T6 angle stock purchased from Wicks. Outlined with a Sharpie then cut out with a bandsaw and shaped with my 12" bench sander and pneumatic pencil grinder it really didn't take much time, maybe an hour more or less. I then drilled a slightly oversize hole through its extended "ear" to accept an AN bolt. Finally, I primed the lot of them with Akzo epoxy primer. Installing Van's famous black plastic conduit with WDG13 adel clamps, I used a total of 7 brackets and clamps to secure the conduit in each wing using AD4 rivets to attach the brackets to the ribs. The only thing I would do differently next time is to go ahead and add two #40 pilot holes for the AD4 attach rivets before priming. That would have made it easier to prime the small parts. Still, the conduit is very secure and ramrod straight too.
If you decide to roll your own, be sure to use angle stock. I think .050 would be the ideal thickness if you can find it but .062 is commonly available and works well although it is a bit beefier than strictly required. If you cheap out and try to use flat sheet bent to 90 degrees, it will suffer a much greater risk of failing later on due to fatigue cracking, especially in high vibration environments. So....whether you are installing conduit, wire bundles, or whatever, you too can design a special bracket for virtually any application.
A 1 foot length of Vans conduit weighs 1/2 ounce. My calculations assume 10' of Vans conduit (5.0 ounces) plus all associated installation hardware (4.2 ounces) results in at a total weight of 9.2 ounces per wing.
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