DB-25 Panel cutout dimensions

Ugh. If possible I saw out out the side of the box and machine the connector holes on a flat cover plate.

A box like that can be set up fairly securely on a mill by cutting a piece of plywood thicker than the cover lip to fit inside, and clamping box and plywood to a shelf made of large angle plates. Extra supports under the plates and the back end of the box don't hurt. I mark the connector cutouts, drill near their centers and pull the sheet metal tight against the plywood with wood screws. After milling I reattach the screws with fender washers. Otherwise the cutter tends to lift the sheet metal.

Just a couple of notes on this topic: There is a lot of info out there on the panel cutout dimensions for the DB-(x) family of connectors, and my observation is that there is significant variation between one source and another on the dimensions, sometimes as much as .015" or .020". This stuff can almost always be found on websites of electronic parts distributors or sheet metal tooling vendors. You kind of have to just pick one and go with it (or, as Andrew noted dryly, just lay it out/design it yourself, how hard can it be?)

The issue about the panel thickness is very real, in my personal experience. My company suffered through some long-running issues with equipment reliability due to the on-again/off-again nature of connection quality from these connectors being used with panels of .

09" thickness, without the benefit of counterboring for the standard coupling nuts, or relieving the panel thickness on the inside to get the connector closer to the outside surface. I would not have the effective thickness between the coupling nut and the connector mounting flange any thicker than .045". This will allow sufficient engagement of pins into sockets for reliability. It works "OK" with .062, but thicker is big trouble.

Hi Matt,

Thanks for the detail, the customer has actually asked for the holes to be counter-bored for exactly the reason you describe. The panels are 0.081" thick and have had problems with the stand-offs preventing full pin engagement in the past.

Thanks for mention it though.

Dave

Hi Jim,

Thanks for the suggestions. I will try with a 1/8" carbide and see how it goes. I have the box clamped to an angle plate.

Your suggestion for using the screw holes to hold it to a piece of plywood is a great idea. If the bare cutter does cause serious lifting, I will do that.

I have other cut outs to make on the same side so maybe I will just go straight to the plywood inside. If there were a bunch of them I would get a reverse helix end-mil that pushes the metal down. Fingers crossed here.

I don't have the luxury of cutting a big hole and using a separate panel, but that too is a good idea. I'll mention it.

Dave