Natural Gas Furnace build.

Discussion in 'Furnaces and their construction' started by Bldr J, Sep 2, 2021.

  1. Bldr J

    Bldr J Copper

    Ok, it's taken me quite a while to get this finished. Thank you all for the contributions in all the (useful to me) posts on this forum.

    FB8C811D-C056-400C-9F48-1EA4015FFC1F.jpeg
    I finally got to hooking up my vent hood with some surplus 600v blowers, so I fired it up!
    I could not for the life of me keep a slow enough temp rise (50C/hr) so went slow as I could with recommended holds as per the Unicast directions.
    I put two thermocouples in the furnace expecting them to burn up after a while, one in the 1" hot face and the other behind it.
    Stopped at 1000 or so Celsius.
    DBF833F9-EB0B-4E81-B78E-514645268F3C.jpeg Went back after supper and couldn't resist trying some aluminum... 79756705-13CC-4ED3-978E-0504CFB1010C.jpeg

    Pretty rough, but I didn't have any ingot molds or muffin tins and that seemed pretty boring for a first melt so I went for some real pieces I'm making (a trim piece for a shower valve - layer to be done in brass and a failed box)

    Now that I've used the crucible for aluminum, what can happen if I melt brass or bronze in it? (Decorative pieces only for now)

    I want to see how hot and how long it will take to melt brass with nat. gas and the burners and design I used.

    I'll post some build pics if it works tomorrow. Otherwise I'll just go hide and get a blower and go propane...
     
    Jason likes this.
  2. Jason

    Jason Gold

    What pressure is your NG supplied to you at? Are you on household or residential?

    No real harm by using the same crucible for both metals. You'll get a little cross contamination, but for decorative stuff it's probably, MEH!
     
    Bldr J likes this.
  3. Bldr J

    Bldr J Copper

    Although it's not residential, this section of the building is on low pressure NG, just under 7" W.C. from what I remember.
    Charles Hones said that they should work for my purpose. I'd have to look up how many BTU each burner can do.
    I'll go get some Everdur...and some better gloves...and to make crucible tongs.
     
  4. Al2O3

    Al2O3 Administrator Staff Member Banner Member

    Don't give up too easily. Is that a supply regulator? If so, what is it regulating to pressure-wise? You may be better off without it for heat potential depending upon your supply and the flow rating of the regulator. At <7", NG can almost always be tuned solely with the blower.

    Furnace looks nice. Is that a stainless shell?

    Best,
    Kelly
     
  5. 3Dcasting

    3Dcasting Copper

    Looks good to me!
     
  6. Bldr J

    Bldr J Copper

    I'm not sure what the regulator is set at, I used the '60s era regulator as it was I stalled when there were 3 burners. Worked fine for aluminum melt.

    I started the furnace up today, added what I thought was bronze (Jason: I hit it with the tig torch and was able to use some Si Bronze rod with it-no zinc fumes. So I tossed some in the crucible and went for it.

    It didn't look like it was melting so I thought, maybe it's not bronze? It's magnetic. So maybe a manganese bronze?
    Either way, it was getting late in the day so I thought I'd pull the pieces out and try another day.
    When I tried to grab the "bronze" it squished and went into a slush in the bottom of the crucible, but not enough to pour.
    I ran out of time and dumped what I could out, but I now have a crucible of slowly solidifying bronze.
    I'm assuming I just wrecked a clay graphite crucible. Anything I should do? I put it back in the furnace to cool. Should I let it air cool?

    I'll try again next week....
     
  7. Bldr J

    Bldr J Copper

    My slush covered tongs... 992661A3-7A3A-4580-AB80-E8FBABBC5E60.jpeg
    the little bit that poured out (could've been the few chunks of brass I threw in on top to see:) FF444446-53E5-4FFC-B184-06118368FD78.jpeg
    and the mystery piece I melted. 175742D4-388D-4108-AA27-5B195D625B88.jpeg
    Going to get some Everdur. $10cdn a pound here, just so I know what I'm working with.
     
  8. Bldr J

    Bldr J Copper

    The heel fell out. 536A2875-FB2F-4F0A-9794-C2B5D8B334AD.jpeg I guess I get another shot at getting up to temps.
     
    Jason likes this.
  9. Al2O3

    Al2O3 Administrator Staff Member Banner Member

    Good for you. Doesn't always turn out that way. Good luck on next go.

    Best,
    Kelly
     
    Bldr J likes this.
  10. Jason

    Jason Gold

    You are doing excellent on 7"wc! I'd love to see some more details on your burner setup when you have the time. I've long wanted to switch to NG for my furnace. You might not know, but my forge has a single ribbon burner running on NG and it works really well. For now, I just stick with jet-a. It works well.

    In this day and age, I don't think 10bucks a pound for everdur is too far out of line. (did I really just say that?o_O)
    Using a known metal is worth the money to me. Too many hours often goes into this stuff to risk trying to save a few bucks.
     
  11. Petee716

    Petee716 Gold Banner Member

    You’ve got some mystery metal there. As far as I know only iron, cobalt, and nickel are magnetic (recalling from high school metallurgy class). Also, my experience with bronze would indicate that a heal of molten bronze would not have fallen out of the crucible so easily. I think you dodged a bullet with your crucible.

    Pete
     
  12. Bldr J

    Bldr J Copper

    I melted some brass today! Had some scrap lying around so thought I'd try while I was cutting my ingot of Everdur. (How do you cut it down to size?)

    From cold, and not full bore for the first bit, it took 1.5 hours to get up to temp. Natural gas. Naturally aspirated. Less than 7" w.c. I'm happy.
    So much to learn.


    FABE86B7-A571-4FC7-A00A-D57FDAE87498.jpeg 1B610C11-D443-42D3-9968-FF2170285F9C.jpeg
     
  13. Jason

    Jason Gold

    I use an angle grinder and a diamond Lennox disc from lowes. A metal band saw would be better or dare I say try a skill saw with a cheapy blade in it. My ingots are 3inch fat bastards and I know it's not fun to cut them in half.
     
  14. Bldr J

    Bldr J Copper

    Tried my cordless metal cutting saw and lost a few teeth. I think I wore out a new bandsaw blade too. I think it took more than an hour to cut through. I should've used coolant?
    I'll try those diamond lennox discs.
     
  15. Bldr J

    Bldr J Copper

    Yes, had a stainless tank and a lid from another that I cobbled together. Thought I'd practice some welding. Handle stays nice and cool.
    2" Kaowool, 1-1.25" Mizzou (Unicast). Domed lid. Dimples/bumps on the inside to increase surface area - saw it in an old patent, supposed to increase infrared radiation...
     
  16. amber foundry

    amber foundry Copper

    I just use an angle grinder with 1mm or 0.6mm stainless steel cutting discs, dont force the discs and they slice cleanly through. I only melt bronze.
     
  17. Jason

    Jason Gold

    I've sliced a dozen 3inch ingots and my diamond blade is just about to need to be chucked. It does take me about 10mins to cut one in half. Not horrible. I've tried different abrasive cutting discs and they will work, but ya might need a couple of them. Besides, I hate breathing that shit. Bronze dust is bad enough.
    Whip out one of your covid face diapers, best use I've found for them so far!
    20210911_025038.jpg
     
  18. DavidF

    DavidF Administrator Staff Member Banner Member

    Yes but smoking a cigarette while grinding copper kills the Corona virus. o_O
     
    Jason likes this.
  19. Bldr J

    Bldr J Copper

    I have noticed a big reduction in black snot from grinding/sanding since I've been wearing a mask. Can't always see what I'm doing because everything fogs up...
     
    Jason likes this.
  20. Melterskelter

    Melterskelter Gold Banner Member

Share This Page