silver solder mask

[Tmoose]

We need to silver solder some tungsten tiles to some forged carbon steel parts. There are 2 threaded holes in reasonably close to the solder area. Normally we tap the holes after the soldering/brazing operation, as there were reports of distortion of the tapped holes that go thru the brazing oven.

It was suggested that putting setscrews in the hole it may limit the distortion to an acceptable level.
Is there some paste or putty that would keep the brazing from possibly creeping into the thread inter-stitials ?

 

[CoryPad]

Nickel anti-seize might work:

http://www.henkelna.com/product-search-1554.htm?nodeid=8804744232961

 

[MintJulep]

You could also consider a masking sticker over the hole after the setscrew is installed.

Something like:

http://www.bradyid.com/bradyid/cata...searchTerms=solder&searchDimention=01&x=0&y=0

designed as a solder mask. So it should be ok for brazing temps. Maybe.

 

[Duwe6]

Solder/braze will not 'wet' over a soapstone mark. Try rubbing that setscrew on some soapstone [welder/fitter's layout chalk stick]. Most fitters have it, all welding & brazing supply houses do.

 

[btrueblood]

Or apply a paste of powdered boron nitride and water (comes in spray cans too, but that can be harder to control). There are dozens of other "stopoff" formulations that work better with varying combinations of alloys.

 

[MikeHalloran]

Jewelers' supply houses sell 'anti-flux' that you can paint on where you don't want silver solder to stick.



Mike Halloran
Pembroke Pines, FL, USA

 

[tomwalz]

We use Nicobraz from Wall Colmonoy

Been told that Milk of Magnesia works

Nitric acid can make Tungsten Carbide non wetting

Free carbon is non -wetting.

Still and all we prefer the pens form Nicobraz.

Thomas J. Walz
Carbide Processors, Inc.

http://www.carbideprocessors.com

Good engineering starts with a Grainger Catalog.

 

[EdStainless]

MgO slurry works well, and that is what Milk of Magnesia is (with flavor and color).
I have used the BN trick also. We sprayed the bolts before putting them in place.

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, Plymouth Tube

 

[Tmoose]

thanks everyone,

Dan Timberlake

 

[btrueblood]

We used to use MgO paste a lot, but it tends to be much more crumbly, and falls off the parts when dry, sometimes reducing its effectiveness. BN tends to stick better.