Silver soldering question

I am silver soldering a large & a small sprocket onto a bush to sit on a layshaft. i wanted to drill the bush between the two for a grub screw just to locate the bush on the shaft rather than place collars each side of it. I do not need any keyway & have no facility to cut one anyway.

i have to drill & tap the hole before I silver solder the sprockets onto the bush as the diameter of the largest bush is 100mm & the grubscrew is 4mm from it with the smaller sprocket another 6mm from that so there is only a 10mm gap.

My problem is how to prevent the silver solder filling the grub screw hole. If I place the screw in , sod's law dictates that it will solder itself in place. if I do not then the hole will fill with dross

Is there a simple trick to prevent this?

Do I have to re think the process & forget the grubscrew hole altogether?

FWIW - IIRC from other members comments / posts if you coat the areas you do not want to solder with Tippex correction fluid then the solder won't adhere, include the tapped grub screw hole...

George.

Sam, a trick that I have used successfully in the past is to put a rusty screw of the same thread in the threaded hole before you carry out the silver soldering. This will prevent the solder from adhering although you might get some of the flux sticking to the screw but that will be easily removed by the pickling after soldering, or at worst by mechanical means ie wire brush or scaping.

Phil

Not so much a trick but a point to remember that may help is that the solder tends to follow the hottest point, I would use something like mechman said to "mask off" the area so to speak,

but it would be easier to avoid overspill, if you can control where the hottest point is with a smaller burner head. And a "softer" hard solder like 55% silver will make it easier to flow and therefore use less solder.

Michael W

As Mechman says tippex correction fluid will keep the solder off, must be the solvent based one.

Here are some bits pegged to a steel plate to keep them in place while soldering, you can see the tippexed areas

All came off the jig OK

Same again stainless steel parts screwed to a steel jig

And finished part

A trick I use all the time to stop silver and gold solder running where you don't want it is to paint the area with rouge powder mixed with a little water into a paste. Its also good at stopping an already soldered joint from coming undone or the solder flowing out of an already soldered joint

Adam, thats very interesting would you provide a little more information on "rouge" powder, is it something that is obtainable from jewellery suppliers? I particularly like the sound of its use to stop previously soldered joints from coming undone.

Thanks, Phil

Hi Phil

Rouge powder is obtainable from Cousins who sell watch parts and tool,Cooksons gold. and H S Walsh in hatton garden. It realy comes into is own when soldering next to an already soldered joint. Paint it on and then warm the job but be careful when you put on any flux if the Rouge mixes into the flux your solder won't flow. I bought a 120 gram jar about 10 years ago and I'm not even 1/4 of the way through. Item no p8984 from cousinsuk.com

This is a good page for beginers **LINK**

Another mask if you can't get solvent Tippex or rouge is a simple lead pencil. Just rub it where you don't want the solder to run.

Dave
The Emerald Isle

Thanks

Parts suitably tippexed ready for a go tomorrow