Do I need to insulate the center bolt securing a toroidal transformer?

[srdjant]

I got mine from Amazon: RacePro - 12x White Tough M6 Hex bolt/Washer / Hex Nut Combo - Nylon Plastic - 70mm Length : Amazon.co.uk: DIY & Tools


70mm long M6 nylon bolts with nylon washers and nylon nuts.


You could probably find something like that on Amazon that fits your size requirements. I had to cut mine down a bit so that it fits in my compact case.

 

[Mark Tillotson]

I did not know stainless is usually non-ferromagnetic...

There is no such thing as just stainless steel, there's a vast range of very different alloys all under the same umbrella term, varying greatly in composition and microstructure.

As for magnetism:
Is stainless steel magnetic? - thyssenkrupp Materials (UK)

 

[kodabmx]

Copper isn't ferromagnetic, either. Just because a metal doesn't stick to a magnet doesn't mean you can't make a short turn with it, right?

 

[rayma]

Right, a "shorted turn" generally refers to a shorted copper wire turn fault in a transformer.
A badly designed mounting system can mimic such a fault.

 

[kodabmx]

Yes. Long ago before I learned, I used a piece of copper "all-around" in a loop to mount a big toroid. This of course made a very hot piece of copper, but I didn't notice for months besides thinking "Why is this PSU running so hot?" lol

 

[wg_ski]

You would think that you would have noticed the voltage drop due to the excessive load as well as the heat.

 

[kodabmx]

Nope. It was oversized.

572VA coil, but the load was 34W.

 

[Kay Pirinha]

I use stainless steel bolts, because usually but not always stainless steel is non-ferromagnetic.

A stainless steel bolt doesn't prevent from a shorted turn, if no other measures are taken, because it is a conductor, too. This is the point of this discussion, isn't it?
Best regards!

 

[Vovk Z]

I did not know stainless is usually non-ferromagnetic...

Stainless alloys can be both non-magnetic and ferromagnetic . But stainless steel bolts I have seen were almost always non-ferromagnetic (luckily).

 

[SoaDMTGguy]

I guess I should bring a magnet to the hardware store and see what jumps...

 

[Vovk Z]

This is the point of this discussion, isn't it?

I'm not sure it is only one point of discussion.

I'm talking about a fact that a ferromagnetic bolt itself in the center of a toroid increases a parasitic magnetic field (and thus a hum and noise).

 

[ferret]

I only use stainless bolts for mounting a toroidal. Fortunately all of mine are custom made with potting, so the bolt is also shorter and does not protrude out the top too much. With a flat and spring washer and a nylock nut, it is not going to go anywhere.