Best practices enclosure/panel mount PCB connectors (RJ10, RJ45, usb, etc.) ?

[onesixright]

Hi All,

I'm new to the form and a total newbe, so bare with me.

I have a very simple PCB design with a RJ10 on it. I want to place the PCB inside a simple universal enclosure and i'm looking for some 'best practices' doing so.

The enclosure is similar to this: http://www.directindustry.com/prod/bud-industries/small-plastic-enclosures-15209-845723.html

Obviously i need to cut-out on the space for the RJ10 connector (but i can imagine the same problems is with RJ45, USB, etc..). So my question is, whats the best way of doing this?  I never did any enclosure and a bit afraid i will end up messing-up my enclosure (wrong cuts, etc.).

Looking for some tips how you deal with this:

• best way to measure
• best way to cut (tools)
• there might me some strain ont it, so how you make sure it robust (i.e. doesn't brake of)

Many thanks!

[Len]

a bit afraid i will end up messing-up my enclosure

Me too, but I’ve done a couple of them so here’s my advice.

Most of all, take your time. Take plenty of time measuring and test-fitting.

For the connector, you can use either a panel-mount connector wired to the PCB, or a PCB-mount connector that sticks over the edge of the board and pokes out of the box.

Measuring: Get the dimensions or mechanical drawings for the enclosure and the connectors, switches, etc. If you only need one hole for a panel-mount connector, the location of the hole may not be critical and you can just eyeball it. However the size & shape of the hole always matters. If you don’t have proper dimensions for the parts then measure or trace them.

If you need things to line up properly then you have to measure everything from one fixed point. This is where you want a drawing of the enclosure that gives the locations of the PCB mounting holes.

Make a sketch that shows the measurements required to put the holes in the right places.

Cutting: The tools I use most are:
- drill
- nibbler
- files
- X-acto knife (for labels, templates etc.)
Dremel tools are popular, I’ve just never used one.

If the edge of a hole is going to be visible, you might want to cut it a bit small and carefully file it to size.

Robustness: A panel-mount connector will be strong if it’s installed properly. For a PCB-mount connector, use one that has a couple of mounting tabs, not just 4 tiny pins.

[notsob]

for drilling plastic enclosures use a step drill bit

example
http://www.ebay.com/sch/i.html?_trksid=p2050601.m570.l1313.TR0.TRC0.Xstep+drill&_nkw=step+drill&_sacat=0&_from=R40

[tszaboo]

Or if you have a good soldering iron (and you can set the temperature), you can probably buy a hot knife holder for it, and cut it with a scalpel blade.
One advice: Buy one more box.

[JackOfVA]

Sometimes I will take a piece of thin cardboard, such as from a cereal box, and make a test panel from it. Much easier to cut cardboard with scissors and a knife than to hack around with aluminum or plastic.  When the cardboard panel is right, it's then time to make the real panel.

It's also a good idea to lay out the panel with a computer drawing program. You can then glue that to the cardboard as a template and cut the holes. Adjust the drawing as needed, make another cardboard panel and when everything fits the way you want it, print the layout again and attach it to the aluminum or plastic panel with double sided tape so that the drawing can be used as a template.

I assume you are not well equipped beyond typical hand tools for metal work; if so to cut rectangular holes, a hand nibbler tool is the most practical and faster than chain drilling and cleaning up with a file.

Now that my shop is better equipped, I use a digital readout milling machine for complex prototype panels, or for simple jobs a hand punch, as I have both a Roper-Whitney XX and it's smaller version, the 5JR.  A punch is faster and leaves a nice smooth edge hole compared to an electric drill, assuming the material being punched is within the punch rating. Some cheap enclosures have panels made from soft "gummy" aluminum that is difficult to cleanly drill, even with the proper tools and cutting fluid. A punch, on the other hand, makes a clean hole. Also, drilling plastic can melt the nearby material throwing up a ridge around the hole - not a problem with a punch.

[nctnico]

Sometimes I will take a piece of thin cardboard, such as from a cereal box, and make a test panel from it. Much easier to cut cardboard with scissors and a knife than to hack around with aluminum or plastic.  When the cardboard panel is right, it's then time to make the real panel.

It's also a good idea to lay out the panel with a computer drawing program. You can then glue that to the cardboard as a template and cut the holes. Adjust the drawing as needed, make another cardboard panel and when everything fits the way you want it, print the layout again and attach it to the aluminum or plastic panel with double sided tape so that the drawing can be used as a template.

Thats the way to do it. Having plastic or aluminium laser cut is pretty cheap nowadays even if you need to make a few cases. A quick way to make a rectangular hole in a plastic panel is to cut two slots with a hack saw to the proper depth and then use pliers to break the excess material. It helps to use an enclosure which is just as high as the connectors otherwise you'll see the holes.

[envisionelec]

Locating the opening is probably the hardest. I build a lot of one-off prototypes and my favorite method is to use a grease pencil to coat the connector face. Chalk also works, but often rubs off too easily.  The marking is then transferred to the panel. Using a tiny drill, I 'mark' the corners of the connector through the panel. Then, I simply connect the dots, so to speak.

[poorchava]

Buy enclosures that have removable panels like this one:


If you screw up then you can buy only panel, not the whole enclosure. If you have access to laser cutting or cnc machining, then you can make yourself a few dozens of spare panels (but then you need to stick to one case style/size).

As for the technique of laying out the holes, I also glue paper stencils to the panel. Actually this method is pretty accurate if you take your time and works also on metal and wood (I made whole CNC mill out of plywood that way ).

There's also a guy who's master in using paper templates (for woodworking). Search youtube for Matthias Wandel.

As for the procedure I draw the panel in CAD (usually Solidworks) then print a 1:1 image on paper. I glue the paper to panel and then use a scalpel to mark all the hole edges except for round holes. For round holes I mark center with a cross. The round holes you can make with a drill, but you need to use wood drill, not a one meant for metal. Drill bits for metal have a tendency to grab into plastic and wood so you will most likely end up with off center hole. For non-round holes I first drill a small hole, then I take a length of magnet wire, wrap one end around a tip of soldering iron, put the wire through the small hole and grab the other end of wire with pliers. Finish the holes with a file. The downside is that if the plastic starts burning, your work area will smell funky for a few days