Sheet metal and Electrics

[Blondie3160]

Hey! Has anyone ran into a problem with putting electrical units on sheet metel??? We'd like to know soon. Thanks!!!

[wireties]

We always mount them on lexan and have no problems.

[Blondie3160]

But can we do it on sheet metal?

[Grim Tuesday]

We mount all of our electronics on sheet metal. We have not run into any problems using 1/16 aluminum, and just punching and drilling holes in it.

[EricVanWyk]

You can, but you increase the risk of shorting out your electronics. I strongly recommend mounting your electronics on a non conductive surface.

If you do mount it on sheet metal, double and triple check the common faults:

1. Check your crimps with a tug test.
2. Insulate your cRIO from the sheet metal, and be sure to use an insulated mounting method.
3. Insulate your camera's mounting post.
4. Seriously, re-check your crimps. I mean it.
5. Make sure you have no exposed copper. This may mean trimming your wires to length.
6. How are those crimps looking?

[wireties]

Originally Posted by Blondie3160

But can we do it on sheet metal?

Just be careful. Remember the cRIO and the camera need to be electrically isolated from the frame of your robot. The ground reference (negative terminal of the battery) can't be shorted to the metal frame of your robot or you will fail inspection.

HTH

[philso]

Our robot has Victors mounted on the sheet metal chassis. I noticed that one of the mounting screws is very close to one of the motor terminals so I had the students change to using nylon screws. The nylon screws have held up through one Regional. Other teams are using cable ties through a pair of holes. We would do that too but would have to drill more holes in the sheet metal.

[James Kuszmaul]

Nylon bolts, PEM nuts, and plastic washers seem to work fine for most of the electronics.

[KennyLives]

We always make an electrical box out of sheet metal. Works great.

[DonRotolo]

Metal is legal, even if not always optimal as others have noted. Most components are electrically isolated when properly mounted (the cRio being a notable exception)

If running wires through drilled holes, be sure to have some way to prevent the wires from damage from the sharp edges.

[wireties]

Originally Posted by KennyLives

We always make an electrical box out of sheet metal. Works great.

But more dangerous to add/change wiring while still hot! ;o)

[MrForbes]

We've been using wood for our electronics enclosure for the past several years...it just seems to be the natural material. It's easy to screw the components to it, you don't have to worry about shorts, the extra weight isn't a problem since we put it down low, it's easy to work with plywood, etc. I guess there are good reasons to use something else, but I can't think of them....

Then again, we made our chassis out of steel again this year, so I may be totally out to lunch.

[Tom Line]

I strongly recommend against mounting electronics to sheet metal.

With all the things that can go wrong on a FIRST robot, why wouldn't you take all the easy precautions you can?

Mount on lexan, corrugated polycarb, foamed pvc, plywood, composite (not carbon fiber, as it conducts). Use nylon bolts with nylon thumb nuts. Run wiring in convolute, anti abrasion sleeve, or plastic channel where possible. Avoid running wires inside inaccessible places like towers, arms, etc.