Propane Gas Forge Orifices?

Discussion in 'Shop Talk' started by Ken Scharabok, Nov 1, 2004.

  1. Ken Scharabok

    Ken Scharabok In Remembrance

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    I'm reverse engineering a propane gas blacksmithing forge (see eBay: 6128063183). Problem I have encountered is these require an extremely small gas orifice. Smallest drill bit in my set is .040 and it is too large. In the one I am copying the gas ports (drilled into 3/8" pipe nipples) are so small you have to look for it (about like a pin end). I drilled using the .040 and then used a set punch in the hole to try to close up the bottom some. I'm close, but still oversized, causing too much propane to get into the chamber at once.

    I'm considering dabbing some JD Weld over the .040 holes and then using a very thin pin to keep a small holes open as it dries. Any other suggestions? This part does not get hot as the propane doesn't ignite until it gets into the chamber.

    Ken Scharabok
     
  2. owhn

    owhn Well-Known Member

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    Hi Ken:


    I'm not sure if I know a way to drill smaller holes.
    There are, however, ways to reduce the flow rates that MAY have a similar effect.

    The first concept that comes to mind is making off-center holes in TWO circular plates with your smallish drill bits (typically simultaneously, so they will be perfectly aligned.)

    Then, with one fixed, rotate the other one, so the opening will be a "fishmouth" (ie like a new moon). The degree of rotation defines the flow through the doubled orifice.

    Alternatively, you might consider a powder metal design, wherein the device is inherently porous, like a brass gasoline fuel filter.

    Alternates to consider include a pressure regulator, to reduce the pressure that reaches the orifice. Since you are dealing with explosive materials, I also might consider you BUY what you need (including the small orifice), it may be so cheap as not worth trying to design/manufacture.

    owhn
     

  3. unioncreek

    unioncreek Well-Known Member Supporter

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    Ken,

    When I built my propane forge I used a grease zerk as the orfice. I drill i through the threaded end with a bit that would just fit. You only need to drill in a small ways and the spring and ball will fall right out. I also built one that I drill a hole in the side of an 1/8 inch pipe, but I don't remember the size . I'll look and see if I can find the instructions for it..

    Bob
     
  4. unioncreek

    unioncreek Well-Known Member Supporter

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    Ken,

    Me again. I just looked at the forge and this is almost exactly like the one I have. Mine only has one burner though. I use it to forge knive and it works great. There is an updated burner out that you can also use to forge weld with.

    Bob.
     
  5. Ken Scharabok

    Ken Scharabok In Remembrance

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    May have found a solution. I go through a lot of spray paint cans. I noticed the nozzle is just about what I need. The push top comes right off and it is actually two pieces, with a small mushroom white piece in the black head. I can take out the small piece with the point of a knife. I have drilled a hole just large enough for the stem of it to go into the pipe and am trying to glue it onto the pipe; however, I think I will still need something like JB Weld as an adhesive.

    Pressure is already regulated coming off the propane bottle. Gas forge operates at about 15 psi. Thus, adhesive needs to be strong enough to withstand at least that pressure.

    Ken Scharabok
     
  6. unioncreek

    unioncreek Well-Known Member Supporter

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    And it's me again Ken,

    Here's the link for the Mongo burner http://www.reil1.net/design1.shtml#Mongo I'm going to built one to try on my forge, The one I have right now is the "Easy Burner", I think. I haven't had much time in the last year to do any, but now you have me going. I think I will have to try some this week. I've had quite a bit of trouble with my arms and have a hard time hanging onto a sledge hammer or I would do quite a bit more.

    If you run the forge in an enclosed room you need to have some ventilation. They use up the oxygen pretty quick.

    Have fun and if you need anymore help just let me know. You can email me at unioncreek@colfax.com. There is a lot of good info on the link that I gave you.

    Bob
     
  7. moopups

    moopups In Remembrance

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    www.backyardmetalcasting.com one of the links suggests you use a number 51 drill bit for this application. There is a lot of forge info there.
     
  8. Ken Scharabok

    Ken Scharabok In Remembrance

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    OK, I have two spray paint can nozzles glued onto the pipe with Gorilla glue. Seems a good bond. Connected nozzle assembly to propane tank. Good flow out of one, poor on the other. Reamed it out with a sewing needle and both seem to blow about the same. I don't want to take the other forge apart to switch nozzle assemblies yet again. Will wait until the two bell couplers I have ordered at the hardware come in and I can do the required drilling on them. Go to the eBay auction number I cited above to see the rig so far. For a chamber I used a 30 pound Freon tank. Kao-wool will cost more than the parts so far.

    I am not building this to forge weld. Used the 80/20 rule of 80% of results come with the first 20% of effort. This one is a prototype. I can easily build more if they sell on eBay.

    Ken Scharabok
     
  9. agmantoo

    agmantoo agmantoo Supporter

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    Ken,
    Your question is out of my "comfort zone" however I suggest that you look at hypodermic needles to get different orfice sizes.
     
  10. insanity

    insanity Well-Known Member

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    What about using an air needle, like /used for filling football/basket balls? You could cut the end off with snips then open up the collapsed flat end with a needle to the size you need.Figuring since there threaded they could be used and changed easily.
     
  11. Ken Scharabok

    Ken Scharabok In Remembrance

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    New listing on eBay:

    Gas Burners for Forges, Furnaces & Kilns, by Michael Porter, published by Skipjack Press, Ocean Pines, MD, 2004. 8 x 10 paperback, 216 pages, with 111 illustrations by the author. ISBN: 1-879535-20-3

    Please note this book is new, not used.

    Gas Burners for Forges, Furnaces, & Kilns is a do-it-yourselfers dream book, showing beginners how to make highly efficient gas burners inexpensively. These burners use simple gas accelerators as their central operating principle. All that is needed is a $2 MIG tip and some plumbing parts. This eliminates the need for a blower to supply combustion air, allowing the burners to be built in any size. Burners are featured, which are small enough to be used for a jewelry torch or large enough to heat any ceramic kiln. Because these burners are both powerful and portable, they can be combined with low cost space age insulating materials and common containers to build light compact heating equipment. Also described is a blacksmith's forge that can be carried anywhere and stored under a workbench; a portable metal melting furnace; a portable farrier's forge; a portable glass furnace/glory hole; and a mobile hot-work station that aids in combining several crafts. The burners and equipment provide an inexpensive way to get started in blacksmithing, foundry work, ceramics, or glasswork. General information and specific designs are given, enabling the craftsperson to build equipment tailored to their own desires.