Mounting a circuit board in a box

[ArcMan]

Not just any box.  It's a cast aluminum box with gasket seals for my outdoor robot.  I want to mount my circuit boards in the box, but I don't want to penetrate the box for circuit board standoff screws.  I want to keep the outside of the box clean and free of any holes to keep it watertight as intended.  I have considered something like bonding screws to the inside of the box with epoxy, but I haven't had much luck with epoxy reliably holding things together.

Any ideas?

[Razor Concepts]

Maybe you could use neodymium magnets to hold some mounting brackets in place?

[ArcMan]

Thanks for the idea, but aluminum is non-magnetic.

[madchimp]

If the aluminum is thick enough you could drill holes and tap them for the standoffs and then when you go to put the standoffs in coat the threads with a sealant of some sort, silicone or even epoxy if you want something more permanent.

[Ro-Bot-X]

Use J-B Weld. I have read about people from R2D2 builders club are using it to attach things like hinges to the aluminum dome.

[ArcMan]

OK.  I'll give JB Weld a try.  Thanks.

[lanamor]

JBWeld is great stuff. You can actually tap a hole in that stuff once it's dried.

As an alternative you could make a sub platform to mount your stuff to that fits inside the box. A 1/8" piece of material cut to the length and width could have the stand-offs attached to it. Then attach the sub platform into the box with epoxy. You'll have the entire surface area of the sub platform to adhere to the inside of the box which will be much stronger.

[chelmi]

Wouldn't this kind of thing work?



http://www.mouser.com/Search/Refine.aspx?Keyword=561-187TAB

Chelmi

[lanamor]

Sure as long as the diameter matched your holes on the board and your metal box doesn't get hot. The sticky tape would probably release if it got too hot. Alternatively you could remove the double sided tape and epoxy.

I haven't seen those before though, cool find.

[chelmi]

Sure as long as the diameter matched your holes on the board and your metal box doesn't get hot. The sticky tape would probably release if it got too hot. Alternatively you could remove the double sided tape and epoxy.

I haven't seen those before though, cool find.

They are made for PCB, so if you use a standard diameter, they should work.

[HDL_CinC_Dragon]

You can protrude the box and still have it be water tight. Just use a rubber washer. I do it all the time and its perfectly fine.

[lanamor]

Sure as long as the diameter matched your holes on the board and your metal box doesn't get hot. The sticky tape would probably release if it got too hot. Alternatively you could remove the double sided tape and epoxy.

I haven't seen those before though, cool find.

They are made for PCB, so if you use a standard diameter, they should work.

According to the datasheet there are 8 different sizes for this part. I don't know the standard hole size used on proto/perf boards. You'll have to make sure the clip you buy is for the correct diameter and thickness.

[paulstreats]

sorry, off topicish...

if you dont want any holes in the box, how are you going to connect external wires like motor wires to the pcb?

[chelmi]

Sure as long as the diameter matched your holes on the board and your metal box doesn't get hot. The sticky tape would probably release if it got too hot. Alternatively you could remove the double sided tape and epoxy.

I haven't seen those before though, cool find.

They are made for PCB, so if you use a standard diameter, they should work.

According to the datasheet there are 8 different sizes for this part. I don't know the standard hole size used on proto/perf boards. You'll have to make sure the clip you buy is for the correct diameter and thickness.

8 different height, the diameter is the same (0.125 inches)

Chelmi.

[ArcMan]

Thanks for all the great ideas!

I guess I like the stick-on stand-offs the best.  I believe I'll buy me some of them.

paulstreets - I will have holes for mounting the box and a hole for running wires.  The box will be mounted on a square tubing pedestal.  The wires will run down into the pedestall it's mounted on.  I plan on using rubber washers for the mounting bolts.  I just wanted to minimize the number of penetrations.

[paulstreats]

  Sorry, i think i was just in a pedantic mood - i probably could have guessed you just wanted as clean a profile as possible.

 Rather than mount standoffs to the box, could you mount some kind of stand off to the pcb pointing in all directions. That way you wouldnt have to find a way of attaching them to aluminium. Maybe it would rattle a bit if the pcb had standoffs in all directions then it wouldnt touch the case at all. Obviously the flusher to the case the better. Just another approach...

[Admin]

Make a small flat board to mount your electronics on with short standoffs. Then use velcro tape to attach it inside of your larger aluminum casing.

[ArcMan]

Ooh.  I like that idea, too.  Thanks.