Glue for glass mercury switch (not strictly electronics..)

[Blueteeth]

Well, I know this isn't really an electronics question but I know a lot of guys here have experience in full project construction, including mechanics, molding and model making, so thought I would just ask here. If its the wrong place, my apologies.

I am trying to make a small tilt sensor with adjustable angle. This will be a 'yes/no' type affair with a sounder, and to keep things simple I've decided on a tilt switch as opposed to using accelerometers and a micro. After being disappointed with non-mercury switches - the ever bouncy 'ball in a tube' job - I got hold of some small mercury switches that of course still bounce, but at an acceptable level.

In order to make it adjustable for the user - range about 45 degree's - I thought I could simply glue this to a trim-pot. The trimmer is used purely as a small turntable with friction to hold it in place, and to allow the user to use a small flat-head screwdriver to adjust it as necessary. As I mentioned before, absolute angle is not necessary - they can adjust it until the sensor beeps at the correct angle.

As its a very small glass tube (3.3x8mm) full of mercury, I am wondering if certain glues may crack this as they shrink. I even thought about encasing it all in hotmelt glue, but thats probably over complicating matters.

So, the question. I have epoxy (JB weld, JB plastic), super glue (don't think it could take the torsion) and hot melt. Do you think any general purpose adhesive will be ok? As it will be turned, the wires from the switch may provide a bit of pull, so if the user turns the pot with too much force, I don't want the mercury switch to shear off (as I suspect will happen with super glue) so a rubbery adhesive might be better, thus the hot melt. The trim-pots I am using are old skeleton types where the mechanical parts are metal, so we're talking metal to glass tube - not a neat fit.

I always ask such convoluted questions lol, but hopefully someone has experience making up things like this.

Blueteeth

 

[tomizett]

I'd try epoxy as my first port-of-call - Araldite is my answer to most things. You'll have to be careful no to glue up the trimmer in the process!

 

[Blueteeth]

Yeah thats the trouble with the skeleton trimmers - its all exposed. Although I have never used it, reckon RTV silicone would do? its rubbery, and wouldn't need to stand much in the way of stress.

Picture is worth a thousand words.


The reason I'm using these trimmers is because I have a bunch in my junk box of a value I rarely use, they're old and crackly, and lastly - they have a screw on the back so can be adjusted from both sides. This means the part that is on the underside in the picture can be flush against in the inside of the enclosure, with just a small hole needed for a screw driver. Its ideal really.

Trouble with epoxy is, although its tough as anything, if I make a mistake, there really is not removing it.

 

[shortbus=]

I'd use 'rear view mirror' adhesive. It's formulated to adhere glass and metal. And any auto parts store will have it. And it comes in a small quantity.

https://www.permatex.com/products-2...permatex--rearview-mirror-adhesive-kit-detail

 

[alec_t]

I'd go with the hot melt glue or silicone. At least you could remove either if necessary.

 

[tunedwolf]

I'd second that, general silicone sealant is the way to go, it will stick just about anything to anything and is re-entrant should it need to be

 

[Blueteeth]

Right, I'll get some ordered. Cheers lads! My knowledge of adhesives is limited.. A thick blob of the white silicone stuff will do nicely, and should fill the gap.