# Can I silver solder repair this crack



## buffdan (Apr 5, 2020)

I was bronze sleeving this bracket  after I bored it our, BUT, I forgot to grind down some hard raised spots in the bore before I pushed the sleeve in, and I mis-measured the OD of the sleeve.. It was .004 larger than the bore.. I was aiming for .001... So 2 stupid mistakes.

This  bracket Holds drive shaft for table power feed on a horizontal mill.

Anyway, now I have to repair this CI bracket before I re-sleeve it with the proper OD sleeve.. I was thinking about silver soldering, then make the sleeve slightly under size, and JB welding it in place..
I am thinking brazing might warp this bracket..

The crack closes up when i clamp in vise.

Or just make a slightly undersized sleeve and JB welding, without silver soldering.

Any thoughts on this, or or other suggestions..

And it was going so well...  

Thanks
Dan


----------



## GunsOfNavarone (Apr 5, 2020)

Me personally...I'd bevel that broken edge a braze it with silicon bronze. If you don't have a tig, Blue Demon make some brazing rods you can use a torch with them. (Blue Demon Triple Play I believe) How precision of a fit is that part?


----------



## AGCB97 (Apr 5, 2020)

It looks like cast, is that right? If so I would braze it and then ream or bore it for a new bushing which I would set in with sleeve retainer from Loctite or other.
My thoughts,
Aaron


----------



## Ulma Doctor (Apr 5, 2020)

if you can silver solder it, i would

i would be tempted to take bore skim cuts to restore some kind of concentricity.
then i'd be tempted to make a bushing , and lock the bushing in place with locktite


----------



## buffdan (Apr 5, 2020)

Thanks guys for the inputs.
I did bore it before attempting sleeving. and it was concentric and round.

I should have  undersized the sleeve OD and loctited in place.. As AGCB97 indicated.. Lesson learned..

I have silver soldered some, only brazed once..  (not sure if I'm brave enough to braze.. 

If silver soldering should I slightly grind out the crack, or expect the solder to flow into the crack ?


----------



## Cadillac (Apr 5, 2020)

Silver solder is a lower melting point so I'd go that route for hopefully less distortion. Flux it and it should flow into the crack. I personally would feel more comfortable making a new piece. Make out of two pieces and bolt together from the bottom. IMO that would be the strongest and most reliable.


----------



## buffdan (Apr 5, 2020)

Cadillac said:


> Silver solder is a lower melting point so I'd go that route for hopefully less distortion. Flux it and it should flow into the crack. I personally would feel more comfortable making a new piece. Make out of two pieces and bolt together from the bottom. IMO that would be the strongest and most reliable.


That is plan B, make a new one.. Its not that complex.. I will try silver solder first, curious to see if that will work..


----------



## Norseman C.B. (Apr 5, 2020)

If it were me I would vee grind the crack down to the last 1/8"  or less ( preferably less ) at the bottom for a witness mark
I would then gently close it in the vice to close the remaining 1/8" or less witness mark and then after preheat to around 400 deg. and not smoking. braze it up and cover it with a welding blanket and let it cool slowly. Re bore and re sleeve.
I have done many jobs like this in my professional career and had great success ...........................YMMV..........................My $ .02


----------



## Ken from ontario (Apr 5, 2020)

I would braze it if you have the proper torch ,  there's another option , which is to stick weld using Hobart( H500531-RDP Nickel 99 Electrodes, 3/32-Inch )
Watch this video if you're not sure how it's done, :


----------



## buffdan (Apr 5, 2020)

ok, so which braze should I get.. I have some old flux coated.. But the flux is probably deteriorated by now..

Thanks guys for all the inputs, I really appreciate it!


----------



## GunsOfNavarone (Apr 5, 2020)

Triple play braze
There are plenty of videos on youtube on brazing cast iron, I just prefer Blue Demons triple play personally....


----------



## buffdan (Apr 5, 2020)

GunsOfNavarone said:


> Triple play braze
> There are plenty of videos on youtube on brazing cast iron, I just prefer Blue Demons triple play personally....


I looked up the Blue Demon triple play and it doesnt look its for cast iron


----------



## GunsOfNavarone (Apr 5, 2020)

I used it on a cast aluminum intake, but they have brazing rods for other materials.... very easy to use, great results. There are many options though.


*RBCuZn-C*
This low fuming bronze (bare and flux coated) is a general purpose, copper base alloy brazing rod. It is used extensively for gas brazing steel, copper alloys, cast iron, nickel alloys, and stainless steel. It's low fuming characteristic and good mechanical properties make this alloy a widely used general purpose product. Preheating is recommended for some applications and a bronze brazing flux must be used if the rod is not coated. This brazing rod has a low melting point making it easily machinable and excellent for sheet metal work. RBCuZn-C also possesses high tensile strength and good ductility. 1630° F melting point & 1595° F solidification.


----------



## Norseman C.B. (Apr 5, 2020)

buffdan said:


> ok, so which braze should I get.. I have some old flux coated.. But the flux is probably deteriorated by now..
> 
> Thanks guys for all the inputs, I really appreciate it!



I use either white flux coated or bare rod more often bare rod cuz it's cheaper and 20 mule team borax as a dipping flux.
heat the end of the rod up some and dip it in the borax it will stick to it and melt into the groove as you go, dip frequently
so it will work as a wetting agent to make the brass flow into the joint and itself.
Practice doing beads on some scrap sheet metal to get a feel for it then try a lap joint with scrap sheet
it won"t take long to git the hang of it............


----------



## Briney Eye (Apr 6, 2020)

I have used Harris Safety-Silv 45 rod and Hot Max 24000 flux on several cracked cast iron parts with excellent results.  When the joint wets put a clamp on it to squeeze it closed and wrap it up so that it cools more slowly.


----------



## aliva (Apr 7, 2020)

Gouge the crack, braze with silicone bronze, re bore to size, Loctite


----------

