Enclosures with multimeter selection switches?

[rea5245]

Handheld multimeters have those distinctive rotary selection switches. I've been thinking of making a gadget that uses that kind of switch. It requires a PCB with circular traces, which might be tedious to lay out but is otherwise no big deal. The challenging part is the mechanics. I can't find any source of handheld enclosures with those selection switches.

Does anyone know of a source? Alternatively, can anyone speculate on why there isn't one? It's such a common UI for multimeters, I'm surprised there's no desire to use it elsewhere.

- Bob

[ataradov]

Standard case manufacturers are generally not good at coming up with a variety of case designs. No idea why.

In this case it may be hard to come up with a universally useful case, since the number of positions would be fixed, and may not match the needs of a lot of projects.

You best bet may be to buy those cheapo meters and reuse the case if it otherwise fits. They cost cheaper than simple plastic project boxes anyway.

[Neomys Sapiens]

When a rotary switch is designed into a product like the multimeter switches you are referring to, it means that all the parts have to be designed to work together. How should a standard enclosure implement this?
Various parameters, like the stiffness of the PCB, the makeup of the slider, the required contact force and the characteristics of the various spring elements have to be considered. The position count and contact size will determine the necessary precision, which has to be balanced against ease of action. Those go into the design of the detent mechanism, as the force to leave a switch position should not be too high and involuntary 'overswitch' avoided.
A high contact force gives good contact but results in high contact wear - leading to early failure except when special surface materials are used.
Having an enclosure with a recess for a large knob is nearly an afterthought here. And into the enclosure design there are other inputs too, like position of the jacks, fuse and battery access, isolation barriers.
Given, the cheap multimeters look all very similar. So by testing some of the abovementioned characteristics empirically, you could reuse such components. But to make it work right? I did not try.
For low-volume, I would rather separate the Switch from the PCB. For that, there are solutions in the form of good rotary switches. 

[NiHaoMike]

If you're only making a few, you can 3D print the mechanism. If you use capacitive or optical sensing, you can eliminate the need for physical contact and eliminate the contact wear problem. Or put a few detents on the edge of the knob that push on switches.

Of course, rotary encoders are another choice.