Foundry.

  1. DAPPH

    DAPPH Member

    Messages:
    1,423
    Location:
    Near to Cross Hands Llanelli SouthWales GB
    I've made my burner out of 44 mm scaffold tube for the main diameter of the venturi , added three legs at one end 75 mm x 12 mm cut from same tube & welded back on to the major diameter . at the free ends I welded on a turned a 1/4 " thick walled ring x 1 inch long , big enough to easily allow a half inch galv steel pipe to slide though it for tuning the flame by 3/4 " long to slide over a halt inch galv steel water pipe & set a locking screw in a welded on nut into the side to hold the 1/2 tube in position
    The 1/2 " tube has had a steel plug with a 1.2 mm hole drilled in the end , TIG welded on at one end & a brass ribbed turned up hose connector brazed in the other end for the gas supply hose . The hose is gas tube crimped on at both the hose connection points .

    Assembled by sliding the !/2 " tube in the venturi assembly , putting the propane gas on via a variable pressure regulator & lighting it whilst the steel tube was held in the vice away from all flammable stuff inc the garage roller door :ashamed: .
    I slid the venturi assembly back & forth till I got a maximum tuned flame about 16 inches long by six inches wide , it roared like a Chieftain tank going full bore .

    That was all done a couple of months ago, the furnace was cast the same time & by now should have dried out considerable . I cast the refractory lining from refractory concretes around a galv 5 mm thick wire 40 x 40 mm square steel mesh former to help it stop splitting when heated & help it retain it's shape when hot .The furnace throat was made using some thick pliable plastic sheet rolled up round a Dulux 5 litre plastic paint can as it had no bottom rim to catch on when it was removed ......unlike a metal tin .
    Under the paint can I screwed a 1" nipple of polystyrene in tot he hole where the filler valve had been so as to allow exit of any metals should the crucible disintegrate

    Before doing the casting I found some tube that the 44 mm venturi would easily slip into so welded on an angled entry to the steel cylinder body so it touched through to the inner former plastic , again the steel tube has a simple welded on nut & bolt to lock the venturi into a set /known position .

    The former was removed a few weeks ago & I cleaned up any bits of crud with a bit of coarse glass paper
    Next step for me is to work out a way of placing the graphite crucible down in the furnace & still be able to lift it out when it's full of molten brass .
    I've also got to wait till I can afford another sack of furnace concrete to make the furnace lid as well as fabricate some form of rotating horizontally hinge mechanism as I don't fancy the idea of flipping back a red hot tank commanders hatch style lid .
     
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  2. Kram

    Kram Member

    Messages:
    484
    Location:
    Sussex
    Ordered a 4kg sized (brass?) crucible. Think it is A4 or A5.

    Looking at insulation to use behind the refractory face, any reason I should not use rockwool instead of superwool? It is a lot cheaper. Unsure on safety, do not want to mess up my lungs with ceramic fibers but I realise there is a lot of eu bullpoo in the safety classification
     
  3. Welderpaul

    Welderpaul Moderator Staff Member

    Messages:
    12,625
    Location:
    Yorkshire
    @doubleboost do you have any video of making your foundry/melting set up?
     
  4. doubleboost

    doubleboost Forum Supporter

    Messages:
    2,463
    Location:
    North Easr England
    I have some pictures I will have a sort out
     
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  5. julianf

    julianf Member

    Messages:
    3,723
    Location:
    devon, uk
    Get your plumbing blow torch out, point it at some rockwool, and you will have your answer.

    (In short, it melts)

    If its behind a decent hotface, you might get away with it though.
     
  6. DAPPH

    DAPPH Member

    Messages:
    1,423
    Location:
    Near to Cross Hands Llanelli SouthWales GB
    Would coarse vermiculite insulation poured & tamped in the cavity then weld capped in place be of use ?
    it is poured around chimney fire backs & cheeks etc. for heat insulation .

    Last time I got 22 cubic feet bag approx 1200 x 60 mm it cost me £25 four years ago .
     
  7. Screwdriver

    Screwdriver Member

    Messages:
    4,489
    UK London
    I hope so. I just bought 100 litres of vermiculite (£23.50) and a bucket of sodium silicate. Going to make up my own castable refractory for lining the forge. I'll be using kao wool (ceramic fibre wool) to insulate, I think rockwool is rated only to 800C which will probably melt in a forge and definitely melt in a furnace!
     
  8. Kram

    Kram Member

    Messages:
    484
    Location:
    Sussex
    Perlie and vermiculite are great insulation but they will melt if they are the hot face.

    The perlite attempt is mostly intact Ive been intending to use the rest and give it a coat of fireclay and see if any better.
     
  9. Kram

    Kram Member

    Messages:
    484
    Location:
    Sussex
    [​IMG]

    Crucible is a good fit but need to make it a couple inches taller.
     
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  10. DAPPH

    DAPPH Member

    Messages:
    1,423
    Location:
    Near to Cross Hands Llanelli SouthWales GB
    If that has already been cast & set in the plastic bucket , think how you are going to lift a full crucible out of the thing once it is full of red hot molten metal before you cast the last part of the kiln . It might be a good idea to also slip a few strengtheners of 10 mm threaded rod right across the cast stuff in several places & at differing heights as you pour the final part to give it a lot of strength when it's glowing hot .

    Most folk use a cut down gas cylinder as the outer skin to keep things together .
     
  11. Kram

    Kram Member

    Messages:
    484
    Location:
    Sussex
    I did another test with wood kindling, coals, butane torch and a blower. Couldnt get the coals to light, even with some very impressive meter high flames from the wood.

    Got another hot air gun as I have 7kg of coals to use up.
    Might get an old parrafin burner/stove and use the tank part for a waste oil supply.

    Fireclay stood up well but was not fully dry so has bubbled out in places.
     
  12. Screwdriver

    Screwdriver Member

    Messages:
    4,489
    UK London
    Fireclay will take at least a week to dry out. More like two weeks if left outside in this weather. After that it will still need to be gradually fired.

    I have just taken delivery of a bag and chatted to the seller (castle tree). I'm planning to mix it up with some fine vermiculite, dose it with sodium silicate and hope for the best :dontknow:

    I say that because I asked the chap at castle tree and he didn't think it would work!

    Well, that's what "tests" are for...
     
  13. DAPPH

    DAPPH Member

    Messages:
    1,423
    Location:
    Near to Cross Hands Llanelli SouthWales GB
    Sounds like you had so much blown air that you blew most of the flames & burnable gases up above the coals .

    Normally you'd get the fire going on a sheet of screwed up newspaper & put hand full of small bits of smashed up wood as soon as you lit the paper , then put a dozen or so 1/2 " lumps of coal in a pyramid on top of the burning paper & wood , leave the coal to heat for 30 or so seconds then gently introduce the air , straight away adding more small coals in an even pyramid , it should ignite the extra coals easily . You'll then have to turn the coal into coke by turning the burning till the tars burn off . once you have made your small bright red almost going to yellow hot coke it will be hot enough to use as a melter or for forging heat .

    You can then add true broken up ready made coke to keep the heat going .

    Tip
    Bagged pre pack stuff sold as coals that looks like eggs or has a defined casting mark on them are not suitable fuels . you need real high calorie coal .. steam coal if you can get it .
    Failing to get hold of real coal ...... real lump wood charcoal can be used but the burning characteristics are different to coal
     
  14. outofthefire

    outofthefire Member

    Messages:
    1,928
    Leeds
    I'd sell the coal to someone with a fire and just buy some coke beans and make life easy.
     
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  15. brightspark

    brightspark Member

    Messages:
    25,409
    Location:
    yarm
    a decent blower and proper coke and your melting iron :)
     
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  16. DAPPH

    DAPPH Member

    Messages:
    1,423
    Location:
    Near to Cross Hands Llanelli SouthWales GB
    Describe coke beans please , do you get them from a coal merchant or are they often available on garage forecourts etc. ? .
     
  17. outofthefire

    outofthefire Member

    Messages:
    1,928
    Leeds
    Google coke or forge beans or breeze to hopefully find a coal merchant who can supply it near you, you won't find it on a forecourt (or i'd be amazed if you do). There's a good description of what it is here http://www.cwfuels.co.uk/products/coke-beans/
     
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  18. Kram

    Kram Member

    Messages:
    484
    Location:
    Sussex
    It is pre bagged smokeless coal. It might not be ideal but when lit it will give plenty of heat. New heat gun works perfectly.

    [​IMG]

    [​IMG]

    Success.
    [​IMG]

    I had a lidl sweet tin I wanted to use but I lost it! So used a tuna can.
     
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  19. captain-destructo

    captain-destructo all the gear no idea

    Messages:
    991
    Location:
    Thornaby Teesside uk
    try using an old cake tray the ingots come out easier
    and fit in the crucible when you need to re melt them
     
  20. grim_d

    grim_d Member

    Messages:
    1,376
    Location:
    Scotland - Ayrshire
    I do this and it's great but keep some even smaller bits as it takes forever to melt a crucible full of ingots.
     
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