hot or cold air, forge project

  1. jimmy shoes Member

    Messages:
    179
    south wales
    hi,

    im gonna be building a very basic forge soon, and i wonder what will give a better heat, hot or cold air

    heres a simple design of my forge.

    advice is welcomed
     
    • Forge2.jpg
  2. brightspark

    brightspark Member

    Messages:
    30,443
    Location:
    yarm stockton on tees
    what u putting in it coke ?? the hairdriers a bit tame innit use sumthing a bit more substantial something u can regulate the air suply with cold air best
     
  3. brightspark

    brightspark Member

    Messages:
    30,443
    Location:
    yarm stockton on tees
    what are u making with it??
     
  4. chunkolini

    chunkolini celebrity artiste

    Messages:
    8,779
    Location:
    Swansea
    Cold air, you theoritically get a more dense charge of air, will it make a diference? who knows.

    hair dryer? is that beefy enough? my neighbour uses a vaccuum cleaner to feed her forge with good results.

    Chunko'.
     
  5. brightspark

    brightspark Member

    Messages:
    30,443
    Location:
    yarm stockton on tees
    not suprised :laughing: a hoover on blow would melt iron in coke
     
  6. jimmy shoes Member

    Messages:
    179
    south wales
    i thought i'd just put BBG coal in it.

    well i saw a video on youtube of a guy making a knife out of an old file, so seems that i got a few old files i thought i'd give it a shot. plus if i get any future projects where i need alot of heat i can use the forge.
     
  7. brightspark

    brightspark Member

    Messages:
    30,443
    Location:
    yarm stockton on tees
    cokes best clean and hot
     
  8. mart

    mart Member

    Yep-i would agree with the coke idea. Burns clean and is hot. The ash is very fine & dusty when cleaning out though-just use a simple mask.

    The idea that Chunkolini mentioned about a vacuum sounds good.
     
  9. astro_al Rocket Scientist

    Messages:
    1,824
    Winchester-ish
    Air volume is more important than temperature, plenty of industrial size forges run on cold air, just with MUCH more airflow than a hairdryer. Also you'll pay for the power to heat the air (most of the hairdryer's power consumption) which is a waste of money.

    You need a throttle on the air supply too, for regulating flow and to shut it down when you are working on the metal in between heats. Just put a sliding 'gate' in the pipe, with a handle so you can slide it across. You'll burn through a LOT of fuel otherwise - when my forge is on full pelt you can literally see the coke being used up - almost like pouring liquid into the middle of the fire.

    BBQ fuel is useless - too much ash in it, too sulphurous and won't burn hot enough. Plus the lumps are too big, you need to be able to push your workpiece between the lumps, you can't do that if they are too big - always ends up hitting one and getting stuck. Look for coke 'beans', or anthracite beans, or forge coke. Corrals sell it - google them to find a depot.

    Run a straight air pipe - easier to make, better flow. make sure you give yourself a way of getting the crap out of the air pipe that falls in (without killing the fire). Bottom blast forges (which is what you've drawn) usually have a gate underneath to release the 'clinkers' (crap) that build up.

    You can't really go wrong, just experiment, the worst that can happen is a hole burns through something it shouldn't. Good luck, Al.
     
  10. busa Member

    Messages:
    250
    GB
    The last place I worked had a forge which was blown with a 'Henry' vacuum cleaner. The flexible hose was connected to a steel air supply pipe which ran through a water tank and then into the back of the forge base. The blacksmith used a mixture of coal and slack on the fire.
     
  11. jimmy shoes Member

    Messages:
    179
    south wales
    ah ok, yea i'm gonna change the hairdryer for a vacuum cleaner.

    thanks for the advice guys, shall make a thread in the projects section when i actually start, just ran out of welding gas so im gonna get some flux cored wire.
     
  12. Bsmith Member

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    2,048
    Location:
    Leyland UK
     
  13. pidgeon chit welder sticking metal since 1962

    Messages:
    961
    Carmarthenshire
    If you have a coal merchant see if they have a bit of best welsh steam coal , it has one of the highest calorific contents that you can get .

    From my apprentice days in the early 60's we made a wigwam of sticks & paper about 8 inches in front of the horizontal air inlet ( the bosh end ? on a proper forge ? ) lit it ,then heaped on a 3 inch covering of 3/4 inch steam coal and set the blower to minimum once you get a fire going turn the coal to a part coke and feed fresh coal from the edges to the now burning coke middle always feed from the edges once you get it going .

    You can make a vertical forge using a lined cylinder of silver sand fire cement and mica insulation and proper lump charcoal once it has dried ( not BBQ stuff )

    If you want a simple quick field forge dig a neat 350 x 350 x 1000 long channel in the direction of wind flow. Line it on the three faces with common house bricks frog down/outwards to give you a fairly smooth wall & floor and lay paper wood at the up wind end and fill the rest with about two feet of charcoal ( fill the trench completely top to bottom end to end, ready for setting on fire . Cover most of the tunnel to leave a 250mm working area at the down wind end using a slab or tin sheet with earth over the top , so that you now have a fire trench with a chimney effect and an open flame work area area .

    If you have a fan OK if not wait for a windy day and build so as to allow wind to blow the fire down the channel ,erect a wind channeling/ diverting screen from canvass to direct the wind down the field forge .. you can get enough heat from this type of field forge to make a full set of heavy horse horse shoes from 1 inch bar.

    Feed the forge from the up wind end and push the burning fuel down the fire trench as & when needed.

    You might also Google " Gingery lathe " and locate the links for making various forges for coal , bottled gas ( fixed or variable gas pressure ) and charcoal etc.
     
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