Mounting control boards inside PVC pipe

[Legomn132]

Hi everybody,
I'm trying to put a PCB inside a piece of 4 inch PVC pipe. The board is about 3"x4", but only fits reliably in the 3" dimension. It is about 3/4 of an inch tall, due to a MOSFET for driving lights and a capacitor for filtering power. I'm thinking about putting another board of the same form factor to hold more electronics for sensors and whatnot on top of this. I'd like to mount this a little below the center of the pipe looking from the circular end, along with two ESCs for motor control. I'd like it to be fairly secure, to withstand rough handling ( I may send this with my little brother on a school trip, and the frame is a bit bulky), but I'm not sure what to use to keep it in place. I'd also like to be able to slide the whole kit and caboodle out of the pipe for maintenance/repairs/upgrades. What do you guys use to keep PCBs secure inside pipes? is there anything you would recommend I do?

Thanks,
Legoman132

[ROZ]

I am a paramedic so I have easy access to these, But I used what is called a sam splint
http://www.sammedical.com/sam_splint.html
its basically i mold-able piece of metal covered in foam that i cut to fit directly in the center (snugly) and fits the length of the tube so when the end cap is screwed on it touches both ends. I used this to mount my lights so that i could remove them from the tube if i need to.
viewtopic.php?f=18&t=696
if you do use this method just remember to crease down the center to give it some rigidity.

(im going to be playing with my ROV at the lake over the next week, I will try and get some pictures of what im talking about.

[reHosea]

The PVC tube I use on my ROV is larger than yours @ 12" in diameter, and all of my circuit boards are approximately 2" wide, by 6" long, but this might still work for you. What I did was to glue two smaller 3/8" PVC pipes along the inside length of the main tube, one on each side, and approximately 3" away from the edge. That produced the correct 6" distance I needed for my CB's so that I'm able to slide all six of my CB's (with the trace side up) down on top of the 3/8" PVC's. To prevent them from moving around, I put a strip of foam in the small space between the trace side of the CB's and the PVC tube. It makes it pretty easy to remove and replace the boards from either end of the tube. Some of my CB's have 30 amp MOSFET's with heatsinks, and also other components that get pretty warm, so I mounted a small fan on a CB and put it in the middle of all of the other boards. It helps to circulate the heat around.

[Legomn132]

I like the idea of using PVC as rails, if understand you correctly. I may try putting all my components on a piece of Lexan or similar, then putting in some small pipe as rails to slide it on. I'm also wondering what to use to open and close the end of the pipe. I'm thinking about one of those drain cleaning ports with the screw-on cap, and putting a temporary silicone seal around the outside that I can pry off if needed.

[Rover]

Our ROV electronics is installed inside a 3" tube. I have three circuit boards and stacked two together and then placed the third one next to it to keep the over all height low. It's like assembling a puzzle to fit everything in a small space.

Good luck.