Bronze Repair

admin

How do you do it?  I had a bronze impeller with a crack in it today.  I tried braze-welding it with low-fume bronze but the base metal was off-gassing so much this would never work.  I attempted to arc weld it with UTP 34N, a NiBrAlFe alloy and seemed to work until everything spiderwebbed on me.  I ended up scrapping the impeller, I found out later a new one was only $127.But, what would you guys do?  O/A and stick are the only available options.  Is this an unreasonable repair?  The impeller was either aluminum bronze or silicon bronze, I can't remember.
Reply:I'd like to hear some expert opinions on this myself.  Bronze was one of the first metals that Man learned to work with, but I certainly don't know the answer to your question.Miller Syncrowave 350Millermatic 252/ 30A spoolgunMiller Bobcat 225g w/ 3545 spoolgunLincoln PowerArc4000Lincoln 175 Mig  Lincoln 135 Mig Everlast 250EX TigCentury ac/dc 230 amp stickVictor O/AHypertherm 1000 plasma
Reply:Tig maybe with Nibralidealarc 250/250 ac-dc tigidealarc 250/250 ac-dc tig #2 used for sticklincoln sp100hh125dual arbor grinder polisher30 yrs of hand tools52 pitch blocks 6p-26prake gauge -pitch gaugeG&D prop repair 918-207-6938Hulbert,okla 74441
Reply:Hey 76GMC,From an 'ol timer who's repaired many bronze/brass/copper, steel/cast iron/cast steel, & even old RR tin cups, your friend is silver-solder with O/A. I have repaired everything from clock gears to a cast milling vice broken in half with sil-sol. I like O/A because the flame has a tremendous range of heat with the proper tip.That repair would have been quite easy, the repair very solid, & without seeing the extent of the damage, I would guesstimate that it would have been a 30min or less fix. Sil-sol is a brazing process, low temp, that utilizes the capillary action to adhere to the surface & bond very fluidly. It fills the tiniest voids & crevises without porosity & has good elasticity properties which allows it to flex a bit because of its' softer characteristics. It has superb conductivity for any electrical application, seals most every fluid except an acid, quite resistent to salt water & alkylies, & won't rust. It just works when other methods fail or are not conducive to a welding process because of the effect of heat with expansion/contraction.Pick up some 60/40 or 55/45 & some good brazing flux(I use Lucas-Milhaupt) at your LWS or online. I generally use .035 wire & have some .028 flat ribbon sil-sol. It is quite easy to use with some practice & you will be surprised how easily you can control the flow & coverage of sil-sol & make very strong repairs. Anyway, just some mental fodder you can contemplate. Try it.... you'll like it. Easy $$$.DennyAddendum: Sorry, had a senior moment. I forgot to mention that sil-sol also works marvelously with SS & will bind tungsten to steel as with all the tungsten tip cutters for lathe & mill work.Last edited by yorkiepap; 11-30-2010 at 11:51 PM.Complete Welding/Machine/Fab. ShopMobile UnitFinally retired*Moderator*"A man's word is his honor...without honor there is nothing.""Words are like bullets.... Once they leave your muzzle, you cannot get them back."
Reply:Silicon bronze is considered very easy to weld, OA, TIG, or MIG.  It is what sculptures are made of, and most cast sculptures are cast in several pieces and then welded together.   Silicon bronze TIG rod is readily available, and I assume it could be use with OA without difficulty.Aluminum bronze wire should also be available, , and aluminum bronze should be weldable, although I know less about welding aluminum bronze.The outgassing I am a little confused about, although low fuming brass still outgasses some, in my limited experience.I would note that aluminum is also commonly used for boat propellers, although I am sure that you would not mistake aluminum for brass or bronze.  I understand that aluminum props are typically painted.RichardSculptures in copper and other metalshttp://www.fergusonsculpture.comSyncrowave 200 Millermatic 211Readywelder spoolgunHypertherm 600 plasma cutterThermal Arc GMS300 Victor OA torchHomemade Blacksmith propane forge
Reply:You know, I didn't think about using silver alloys for the repair.  That's a good plan, I always keep some 50N on hand for such repairs, too.  The only problem here, though, was that the crack was loaded with the black oxides you get when working with copper based alloys.  I had to get this thing nearly red hot and it took several cycles to free it from the shaft.  Lets just say that this impeller is held on the shaft with a clamp and it was so stuck that the clamp wasn't exactly necessary or even present.  These heat cycles are also probably why it cracked.I did some research on the UTP 34N rod.  It's the only other rod I had available besides flux coated low fume bronze.  The UTP 34N appears to be more or a hard-facing rod.  I would assume it was used for bulding up edges on NiBrAl propellers and possibly even stainless props (it says for ferrous and copper based alloys on the package).Whatever, I've got a new shaft and new impeller coming tomorrow.  This went from your basic $100 preventative maintenance to a $500 overhaul.  Let me just say, if you have a mechanical seal pump and it's leaking, the insides of the pump are usually corrosion resistant but everything outside is usually not.  So, if the corrosive liquid is leaking to the outside of the pump it's generally in your best interest to repair the pump as soon as possible or the cost of repair is only going to get substantially more expensive.  Whoever had worked on this thing in the past drilled a hole in the base so it would simply leak into the bilge where nobody would notice the leak (except it was corroding away the hull sides).