Silver soldering zinc-coated steel

[Bert Coules]

I know that silver soldering galvanised steel is possible with low-melting point solder, but is it feasible to file down the steel sufficiently to remove the coating and thereby make standard silver solder take?

Thanks. Bert

[John Rumm]

The more common way to solder zinc or zinc plate with soft solder is to use a highly active flux like bakers fluid. Just paint it on where you wan the solder to adhere.

[Bert Coules]

Thanks for that, John. I was thinking of using silver solder for extra strength, but perhaps I'm being over cautious.

This is for the suspended (ie hanging) shelf I asked about some time back. Threaded rods hold a shelf, passing through holes drilled in it. The straightforward next step would be to add nuts to the emerging ends of the rods, but I would prefer to use something less visually intrusive, so I thought about a steel disc, drilled and tapped, much thinner than a nut and attached to the rod. I suppose I could use Loctite or a more permanent adhesive, but maybe soldering would be even more secure. Here's a very rough sketch:

Bert

[charles]

I'd expect a disc not to have enough room for thread to hold any weight. How about 'half nuts".

[John Rumm]

Ah, ok. Is the shelf deep enough that you could counter drill the underside to allow the bottom of the nut to sit just below flush with the surface? Then the nut can do the heavy lifting, and the washer (or whatever cover you choose), can just make it look pretty.

[alan_m]

If into solid wood maybe

If into metal

Hank bush (rivnut, rivet nuts, nutserts)?

DIY fixing (watch both)

?v=z73P_7OysR8

[Bert Coules]

Hence my thinking about soldering, silver or otherwise.

That's something I didn't know about; thanks.

Bert

[Bert Coules]

I don't believe so: it would reduce the shelf to around half its thickness at that point, which I would feel wary about loading too much. Thanks for the thought, though.

Bert

[Bert Coules]

idea, thanks.

I had another thought: a coach bolt or similar(with the square shank sunke into the shelf) joined to the threaded rod with a coupler:

[Fredxx]

Could you use something like this?

It could be screwed in from below for more security against pull-through.

[John Rumm]

ok fair enough. Half of 3/4" ply I would trust, but probably not MDF. If it is only 1/2" to begin with, then definitely not - especially as the load is valuable!

I guess if I were doing something similar I would weld the washer to the end of the threaded rod, rather than solder. One of the threaded inserts, or your suggestion of the bolt through from the bottom and into a coupler seem like the best ideas...

[Brian Gaff]

Yes, and don't inhale the smoke!

Brian

[Bert Coules]

Yes, I've heard that the effects can be less than pleasant. Thanks, Brian.

Bert

[Bert Coules]

It could be screwed in from below for more security against pull-through. Thanks for that. I'm not clear from the Screwfix illustration if those teeth (probably not the correct term) are in parallel rows or arranged like a screw thread, but I imagine it must be the latter. I'll investigate.

Bert

[Bert Coules]

I'm using 18mm MDF.

Welding is something I haven't attempted since my metalwork classes in my schooldays. Getting the gear together for just four joints would probably not be viable, though I confess I would like to try it again.

The bolt and coupler idea stands as favourite at the moment.

Bert

[Robin]

That seems quite close to reinventing

which as you said could be fitted from below, sunk into the MDF. You could hide it the whole thing so the screws (or better bolts) with were not visible with whatever material you had in mind for your disc

[alan_m]

If you do go down that route try it on a representative bit of scrap first. I've had something similar pull out of flat pack furniture but that was made from chip board.

[Fredxx]

That was an idea where a fitting can be threaded. Some similar items like Rivnuts could be used as they have a flange that could be on the under-side. Where your studding enters the 'wrong' side and the Rivnut is left as-is.

As Alan has indicated, a trial test piece would be advisable.

[Animal]

soft solder has sod all strength

[wasbit]

Dome nuts are available in chrome plate or stainless steel. Flanged ones save having to use a separate washer & can look decorative. Also they only require the correct size hole drilled through the shelf.