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  1. #1
    Join Date
    Jul 2003
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    Sydney
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    Default Fixing an antique forge

    I found an old portable farrier forge in good nick for a song and bought it, couldn't help myself.
    The brand on the blower is Sydney.
    It is in good nick considering it is probably 70 years old, yet it has a few things I can rectify, plenty of rust is one.

    I need to sleeve the blower's fan shaft since it has a lot of play and rattles at low speed making the cranking rather heavy, that is a simple fix. The rest of the mechanism is in perfect shape and well greased.

    Yet the reason for this post is to find out if it is possible to restore two broken bits from the cast iron covers.

    The hand cranked blower is made in two halfs, 3 really but the back cover is a bullet proof lump of cast, and they are bolted together by well ... bolts. Each bolt goes through a half ring on each of the sides and as it is rather classic in this blowers, when someone is careless and overtighten they brake. Fortunately both broke not completely but half way from the hole up so the bolt still holds the sides together. Each of the two halfs has one of these ears broken but not in the same place.

    I was wondering if it is possible to make this holes whole again ... I know I can patch them up by making some sort of bracket and tap a couple of screws to the body, but that would be a rather unholy butchery. May as well leave it as it is since it is perfectly functional. I am sorry I forgot to take pictures and the forge is in wup wup, so maybe I can bring back some photos on Sunday.

    However I hoped that since it is a very common occurrence with this cast iron blowers, that someone has an idea of the quality or lack of it of the cast used, and if it can be welded and how or by who. I have never attempted to weld cast before. Thickness is about 1/4" and like I said, it is a small semicircle that is missing from the bolt hole.
    Any suggestions very much appreciated.

    PS it just occured to me that I don't really need to rebuild the whole semicircle, I could just build up the two little stumps left, to the height of the opposite side so that the bolt head or the washer has a full surface to push against. it would be easy to shape them with a file (?)
    “We often contradict an opinion for no other reason
    than that we do not like the tone in which it is expressed.”

    Friedrich Nietzsche


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  3. #2
    Join Date
    Sep 2010
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    Lebrina
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    Default

    I would guess that the casting is a good quality. Most old castings are.
    Without seeing the components it is hard to say, but I am guessing oxy/fuel brazing or nickel cast iron electrodes will be your two most likely processes to succeed.
    A couple of photos would help.

  4. #3
    Join Date
    Dec 2013
    Location
    San Antonio, Texas, USA
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    Default

    I had a similar problem with a saw vise. I managed to tip it over on a cold day and broke the tip off of the opening handle. See: https://www.woodworkforums.com/showth...ight=acme+vise
    I tried oxy-acetylene with every kind of braze-flux combination I had with no luck, the iron had too much graphite in it to wet. I managed to get it welded up nicely using MG260 welding rod.
    With a complex casting like a blower housing you will want to pre-heat it to about 300 C, weld up the cracks, and then bury the part in a box of ashes or hot sand to cool and mitigate the potential to crack.

  5. #4
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    In situations where the cast is not playing fair and refusing to take the brazing alloy, I have found that the pre coated brazing rods are nowhere near as good as the old uncoated rods with separate flux. There used to be a tinning flux available that was much more aggressive than the standard flux but I have not seen any new for quite some time.
    Good advice about the need for slow cooling and preheat. I used to use a bed of lime for cooling large or awkward castings and they remained too hot to touch with a bare hand up to 16 hours later.

  6. #5
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    Quote Originally Posted by Karl Robbers View Post
    In situations where the cast is not playing fair and refusing to take the brazing alloy, I have found that the pre coated brazing rods are nowhere near as good as the old uncoated rods with separate flux. There used to be a tinning flux available that was much more aggressive than the standard flux but I have not seen any new for quite some time.
    Good advice about the need for slow cooling and preheat. I used to use a bed of lime for cooling large or awkward castings and they remained too hot to touch with a bare hand up to 16 hours later.
    Hi Karl,

    I tried the fluxed rods, canned flux and straight borax. I got some silver solder to stick, but only after superheating with a strongly oxidizing flame.
    I've since done a variety of cast iron tool repairs using the MG260's as well as the Certanium 889's and Auralloy 300. For the high graphite cast irons I like the MG product the best.

    Cheers,
    Rob

  7. #6
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    Quote Originally Posted by rob streeper View Post
    Hi Karl,

    I tried the fluxed rods, canned flux and straight borax. I got some silver solder to stick, but only after superheating with a strongly oxidizing flame.
    I've since done a variety of cast iron tool repairs using the MG260's as well as the Certanium 889's and Auralloy 300. For the high graphite cast irons I like the MG product the best.

    Cheers,
    Rob
    The worst castings I have found were those where they had been exposed to long term high heat and/or flame.
    I am quite a fan, where practical of heating the casting red hot and then using low hydrogen stick electrodes to complete the repair. This method is both cheap, quick and effective. The main downside being the non machinable weld produced.
    I will look those electrodes you mention up, you never know when I may need another weapon in the arsenal.

  8. #7
    Join Date
    Dec 2007
    Location
    Melbourne
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    I have had success getting old cast iron stick welded.
    …..Live a Quiet Life & Work with your Hands

  9. #8
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    Here are a couple of shots from the bits to be welded.
    So you think that a nickel rod for a stick welder will do the job?
    Make up the missing part with 10mm plate, bevel with grinder,
    take the cover off, heat up with a torch, weld and chuck on the barbecue?
    I guess there will be no need for pinning such a small weld?



    forge3.jpgforge2.jpgforge1.jpg
    “We often contradict an opinion for no other reason
    than that we do not like the tone in which it is expressed.”

    Friedrich Nietzsche


  10. #9
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    If you have the equipment/abilty to braze cast iron, I would just build the lug up, shape it and drill it to suit. Failing that, do the same with a nickel electrode.
    Don't forget that the idea with a nickel electrode is to generally keep the workpiece as cool as possible, so avoid successive long runs and allow the cast to cool in between.
    Yours should be a simple repair due to the fact that you are working on an extremity where ecpansion and contraction forces are more easily dissipated.

  11. #10
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    You could do it if you wanted to be pedantic, but the way it is it looks like it will still hold so I'd just leave it alone.
    …..Live a Quiet Life & Work with your Hands

  12. #11
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    Quote Originally Posted by Marc View Post
    Here are a couple of shots from the bits to be welded.
    So you think that a nickel rod for a stick welder will do the job?
    Make up the missing part with 10mm plate, bevel with grinder,
    take the cover off, heat up with a torch, weld and chuck on the barbecue?
    I guess there will be no need for pinning such a small weld?



    forge3.jpgforge2.jpgforge1.jpg
    A lot depends on the composition of the base metals. The Auralloy I mentioned above is useful for joining steel, assuming that your 10mm plate is steel of course, to cast iron. Peening such a small bit may just break it off again.
    If I were planning this repair I would bevel the cast iron and steel heavily, to within about 3 mm minimum thickness, heat the whole blower shroud on your grill until it is ~200 C. and weld the 10mm bit on in the form of a bar to ease handling. Then cool the whole assembly very slowly. After cooling drill out the bolt hole and shape the added piece by grinding to suit.

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