I bought a polycarb box to house a PCB I'm creating. IP65, marvellous. In in the corners inside the box are threaded stand-offs, but no documentation was supplied and running the product code through google hasn't helped. Is there some sort of standard defining case sizes and the centre to centre dimensions of the stand-offs?

  • \$\begingroup\$ Do you know brand and type? How do you know it's IP65? It must have some kind of spec. \$\endgroup\$ – stevenvh Aug 15 '12 at 16:03
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    \$\begingroup\$ I feel like this is an odd question. If you have the box in your possession, what prevents you from measuring the dimensions yourself? \$\endgroup\$ – dext0rb Aug 15 '12 at 17:03
  • \$\begingroup\$ @dextorb - ingress protection 65. He can't get inside. \$\endgroup\$ – stevenvh Aug 15 '12 at 17:07
  • \$\begingroup\$ Even if I could get my calipers in there it would still be a reasonable question, since someone managed to give me a reasonable answer. I will be contacting the store for details. \$\endgroup\$ – Peter Wone Aug 16 '12 at 2:04
  • \$\begingroup\$ Peter, if the enclosure is too deep to get your calipers in, cut a strip of carton and use that as a ruler. mark for two holes the left and right edge, and measure like I suggested in my answer. Using two measurements and average those should give you a more accurate result. \$\endgroup\$ – stevenvh Aug 16 '12 at 2:08

I'm afraid you're on your own. A single manufacturer may have a hundred types of enclosures, all with different mounting dimensions. If you can't get a drawing(*) use you calipers to measure the distance. First the minimum distance measured inside the holes, with the outside jaws (1), then the maximum distance with the inside jaws (2). The average of both readings is the center to center distance.

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(*) I would start with downloading a mechanical drawing of the enclosure before I bought it. No drawing, no sale.

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    \$\begingroup\$ +1 for the "no drawing, no sale" - it bugs me how many mechanical/electronic components are sold with no (or inadequate) datasheet/dimension information. I wonder whether it's a cynical attempt to force people to buy one to test for suitability. \$\endgroup\$ – Oli Glaser Aug 15 '12 at 19:12

No spec no sale doesn't always work, sometimes you don't get to be picky.

A way around not being able to use calipers on holes recessed in the case is to buy some long screws and put them in the holes. This depends on the threads being very close to normal to the back plane of the case but I found that this assumption was valid for the cases I needed to measure.

When manufacturing several identical units it may be worth buying an extra case and butchering it until you can reach with the calipers, and also keeping your own datasheet. I have taken to printing a label with all this information plus the supplier and product code and sticking this inside the lid.

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