Brazing rod - hydraulic cylinder's rod, that is

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This hydraulic cylinder rod took a nasty hit. Even before the depression, the rod's  replacement cost would have raised an eyebrow.  No way the damage  could continue to pass through the gland packing without causing serious problems. Decision was made to repair the rod's  "divot" with braze filler. The injury was cleaned up with a flap wheel and carbide bur.Sorry, I forgot the dime.It took a lot of heat input to get a good tin and flow.This repair would have been a good candidate for two torches, one for heavy heating and one with a low soft flame for depositing filler. But Alfred was grumpy about taking on such a repair in the field; he kept talking about furnaces lathes and and all that jive like they have in Massachusetts,  so I went it alone the old-fashioned way, with one big torch. After a good preheat the filler "took" to tinning and then I built up the divot with filler.After build-up I started to roughly size the filler using a rotary-file, or carbide burr.After the initial rough finishing of the filler I found low spots and then had to heat and fill and rough cut again.After the rough cutting I switched to hand filing with frequent checks against a straight edge. Worked progressively from hand filing up to 800 paper. Final finish with buffing wheel and compound.Bibliography:Common old 1/16" coated filler of AWS A 5.27 spec.Common old Harris 62 cutting torch; propane fuel gas.Work was done "off the tailgate,"  in the field, outdoors. Last edited by denrep; 10-05-2012 at 11:01 PM.
Reply:Looks nice and smoove from here.  Pretty good for a by hand tail gate job.  I kept looking for a bigger discolored area from all the heat but just didn't see it."The things that will destroy America are prosperity at any price, peace at any price, safety first instead of duty first, the love of soft living and the get rich quick theory of life." -Theodore Roosevelt
Reply:Looks good. A true craftsman with the ability and knowledge to make it happen. I dunno what kind of environment this cylinder operates in, but are you worried at all about debris scratching the brazed area and wrecking the seal?
Reply:Looks good,Denny! I keep some sticks of the flux coated rod. It has it's good uses at times.                                       MikeOl' Stonebreaker  "Experience is the name everyone gives to their mistakes"Hobart G-213 portableMiller 175 migMiller thunderbolt ac/dc stick Victor O/A setupMakita chop saw
Reply:Nifty repair. I suspect many more years of service.  Is this a fairly common approach to this kind of gouge repair or did you cross your fingers and hope for the best? I wouldn't have thought to braze it because I'd be afraid the heat would mess up the chrome... but it looks like it held up wonderfully. Amazing.
Reply:I kind of in the same frame of mind as Forhire.  You did a good job on the braze, but why not weld it with mig or tig and have a harder surface?  I'm sure there is a good reason for choosing brazing.... I'm just not snapping to it.Last edited by DougAustinTX; 10-06-2012 at 01:40 AM.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:Originally Posted by DougAustinTXI kind of in the same frame of mind as Forhire.  You did a good job on the braze, but why not weld it with mig or tig and have a harder surface?  I'm sure there is a good reason for choosing brazing.... I'm just not snapping to it.
Reply:I have made many similar repairs over the years, but have always tig or mig welded. I have always told the customer that it is a temporary repair, but I know of cylinders that are still in service 10 to 11 years later. I have always been afraid of the amount of heat required to braze and also the chance for the braze material to seperate and cause more damage.Just my 2 cents.
Reply:It's good to see some good old craftsmanship.I have used this process also -http://www.thermioninc.com/With the arc spray process the key is a clean bonding surface and some sort of "teeht" in the base metal for it to bond to.Lincoln SA200's... at least 15 - 20. They come and go. Growing partial to the "Short Hoods" in my old age. Last count on Short Hoods was 13 in possession.
Reply:You need a lathe....zap!I am not completely insane..Some parts are missing Professional Driver on a closed course....Do not attempt.Just because I'm a  dumbass don't mean that you can be too.So DON'T try any of this **** l do at home.
Reply:My dad has a forklift with a scar in the mast cylinder fixed like this.  The hydraulic shop did it for him and it's really quite brilliant.  Reasons: the brazed area won't rust.  Like stated above- easy to use surrounding steel as a guide when shaping it, and easy to polish when done.  I really doubt it would ever wear enough to be an issue.  I wouldn't hesitate to do one like this.
Reply:I did that repair once in the field with a cylinder for a D8.  It was a crap shoot to save money & to finish the job due to time constraints on replacing the cylinder.  Worse case scenario was rebuild or replace.  Best case was back in service.It is still in service as far as I know.  My biggest fear was warping the cylinder.  I had not questions as to getting it polished.  I loved the feeling I could fix it.  Great post.
Reply:Thanks for all the cements.I'll try to reply to some of the discussion.Braze vs Weld - Although brazing requires lots of heat input to the work, the heat is at a  relatively low non-critical temperature over a large area, and so brazing temperature requires relatively little concern or precaution with  the base metal or chrome plate. Whereas concentrated welds in heavy sections require lots of tedious precautions to prevent "pull" shrinking and cracking. Also, weld would be very difficult to wash at the edges in a way that  creates an actual bond with the chrome plate adjacent to the repaired area.Feathered edge - Unlike most steel weld filler, braze filler easily  "wicks" and bonds tightly to steel or chrome, even when just "washed" over in a very thin "clad" coating.  Braze filler's ability to flow and bond in a very thin cover makes possible  a strong bond with a feathered blend at the edges of a repair; thus not leaving potential seal-destroying  "knives" of peeling chrome.Machining - Braze filler  is easily machined and is mostly corrosion resistant as-finished. Since a free-hand "field machined" repair is not likely to be absolutely perfect, braze filler, being malleable and  with imbedability, allows for a  non-destructive  "wear in" with adjacent pieces, if necessary.Durability concerns -  No doubt the repair area  is more vulnerable than the original hard chrome finish, but most of the time the rod's safely  tucked away in the oily environment of its barrel, after passing through a wiper ring to get there. As it is with this cylinder, so long as any one area of a cylinder's rod doesn't usually spend a lot of time "working" at the seal or bushing area, then wear isn't a big concern and what's most important is to have a smooth surface that wipes clean and doesn't damage the seal on its way through. With any luck at all the braze filler should be fine. Lathe suggestion - This rod was whacked hard to take that chunk out of it. Maybe by a meteorite, since no one seems to know exactly what happened.  Anyway, I wouldn't be surprised if the rod has a few thousandths of bow to it - just enough to make lathe machining not so workable  with preserving the chrome plate.Summary - I'd have to say that the repair method is an old-skool  poor-boy  program, not so common, but completely practical and workable. The price quoted for the only on-the-shelf rod was in the thousands, while the braze repair (repair itself, not disassembly, etc) was about four hours total. That weighs things heavily towards  repair over replacement. Anyway, it's assembled and back on the job; all seems fine. I don't recall seeing a fix  like it on Welding Web, so I thought I'd post it up. I hope that the thread's  helpful to someone one day, and that meanwhile y'all enjoyed it.  Good LuckLast edited by denrep; 10-06-2012 at 10:01 PM.
Reply:Denrep,  thanks for the explanation.  I hadn't thought of all that.  I did my repair with the cylinder still as one.  The damage on my repair was near the end and when fully extended and with the use of thermal gel/paste I used what I thought would produce the least heat (thinking less warpage).  I didn't want a weld pool to shrink and pull or not knowing the full make up of the steel cause laminar tearing that would cause some failure.  I knew the bronze would be more forgiving than a weld bead.Some knuckled operator wanted to weld a sight bar on the edge of the blade and drug some old cables across the cylinder.  They arced all over the cylinder and buggered it up real nice like.  I just happened to be scrounging for work when I came upon that repair.  It got me some more work after that.I would have liked to have thought of all that explanation when talking to the owner.  he was skeptical but said hey if it works then I will pay you, if it doesn't I won't; either way, I think I will be either rebuilding or replacing this one.  He didn't
Reply:Loved the meteorite explanation too.  My kids could have used that one on some of their misadventures.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