broken castings

Discussion in 'Hints & Tips' started by vanel, Oct 1, 2012.

  1. vanel

    vanel New Member

    An old posting by Lister 1961 shows a lovely example of a broken casting that could be rebuilt with cast iron cement. Among other things, I used this some years ago to replace a missing mounting foot on a Lister D and ran it quite happily bolted to a trolley. The cement is made up of the followsing (parts by weight) Iron filings (stuff of the grinding wheel is good) 40 parts, Sulphur 10 parts, Sal ammoniac 1 part and ordinary cement 20 - 40 parts. Mixed together with a little water the material sets like iron and can be filed and drilled. The best results are found with really fine filings. Watt used this back in the early days of steam using cow urine as the source of ammonia. Formerly the castings of many machine tools were coated with fine cast iron cement to give a smooth finish before painting. Hope this helps, Vanel
     
  2. vanel

    vanel New Member

    An old and tried way of sealing cracks, works well on water jackets. Drill a hole each end of the crack, tap and insert a brass screw, then progress along the crack drilling and tapping interlocking holes inserting screws as you go. Each screw locks the previous one and as brass expands a little faster than cast, as the machine warms the seal becomes tighter, once the engine has had a run usually any wepage stops.
     
  3. grendel

    grendel Member

    In stead of using cement and mix up your own, there are ready made polymer based solutions, that I think are better.
    There are differend kinds, like iron, copper and titanium putty. The brand name is "Devcon".
    I have used this stuff many times and if used properly, it can be regarded as a permanent repair.

    The second method is called metal stiching. You can buy sets of screws specially designed for this purpose.

    Fine for repairing holes or cracks, but I don't think it works when the crack extends to the edge of the cast iron, which is more than often the case.

    Cheers,

    Hubert
     
  4. petternut

    petternut Administrator

    I found an old recipe and used a similar iron cement with notable success on a Petter exhaust pot. I filled holes and cracks. You can't see the join and its lasted 7 years so far. I'm fairly sure I'd need a mortgage for an epoxy that would do the same.
    Similarly the stitching approach works very well within its limitations and is cheap, if very time consuming. Not something that can be said for any of the commercial solutions!

    cheers
    Roland
     
  5. vanel

    vanel New Member

    Cracks running to an edge are certainly a problem, then you could be looking at arc or gas welding techniques making sure you pre heat the casting and cool it over a longish period.
     
  6. Ferret01

    Ferret01 Member

    To add a new twist to this, I've recently got involved in refurbishing an 1860 water tank for the Swanage Railway. It's cast iron, sectional and until recently resided at Salisbury railway station. When we dismantled it we were puzzled at the material used for caulking.
    This posting solved the query - an iron filings based putty to the "recipe" given.
    Answered the question , but not where to get it ! Seriously though, we intend to use a modern product when reassembling.[​IMG]
     
  7. Elden

    Elden New Member

    When I was a kid, Dad used a product called "Smooth-On".

    It was a grayish powder that, when mixed with water and made into a paste, could be used to fill cracks, etc. I do t know if it's still commercially available but is probably similar to the filings/sal ammoniac/sulfur/cement compound earlier described.

    Personally, since I'm bone idle, I simply use metal filled epoxy (JB Weld, Devcon, Belzona, etc).
     
  8. robtheplumb

    robtheplumb Member

    This the stuff??

    http://www.smooth-on.com/
     
  9. Elden

    Elden New Member

    Rob:

    I took a look at the Smooth-On web site and didn't see the paoduct I remember.

    The company is probably the same but they've probably come-up with a better product using epoxy.
     

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