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Thread: Kelly's Furnace Build Log

  1. #91
    Moderator DavidF's Avatar
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    Quote Originally Posted by kcoffield View Post
    No plutonium.........Fusion reactor with flux capacitor!

    K
    Thats sooooo 80'S
    A calm sea does not make a skilled sailor...
    http://thehomefoundry.org

  2. #92
    I wanna see this forced air natural gas burner please. Take lots of photos. I know your in a home and have residential gas pressure. I'm in the same boat. My NG service is literally 10 feet from my furnace and would like to make the switch.
    Visit me: WWW.HandcraftedLanterns.com
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  3. #93
    Quote Originally Posted by jagboy69 View Post
    I wanna see this forced air natural gas burner please. Take lots of photos. I know your in a home and have residential gas pressure. I'm in the same boat. My NG service is literally 10 feet from my furnace and would like to make the switch.
    Ill do that though it may be a while yet. Two years ago when I built onto my shop I had a 2 NG line run from the primary service line. I asked to have an auxiliary tap installed outside where the service entered the shop thinking down the road to supplying the foundry furnace. I was traveling for a week when the work was done and by the time I returned home,the mason had been by to do his duty and heres what I got.



    No auxiliary tap and probably have to break out some mortar and stone (and put it back!) to get one in there but still no sure how to get it apart other than a Sawzall.

    On the blower, I did start a thread over in the burner section on the central vacuum blower/motor. Ive tested that now and it kicks butt and is easily controlled. Not yet to the point of lighting it though.

    http://www.alloyavenue.com/vb/showthread.php?12741-Volumetric-flow-per-100kbtu-hr

    I figure its good for at least 500kbtu/hr

    Best,
    Kelly

  4. #94
    Senior Member Robert's Avatar
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    I gave Elon Musk this link in case he needs a furnace to go to Mars with the colonists. This thing is amazing!
    Robert
    "Whether you think that you can, or that you can't, you are usually right."
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  5. #95
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    Kelly:

    The engine lurking in the background in post #88's photos, what is that for? I seriously doubt that it's scheduled to go in the foundry. But then that furnace pretty much either has, or is going to get, everything but the kitchen sink already so I guess you could be building the forum's very first V-8 powered furnace. You've created some amazing shapes with the refractory.

    Don
    Too many irons, not enough fire,

  6. #96
    Quote Originally Posted by ddmckee54 View Post
    Kelly:

    The engine lurking in the background in post #88's photos, what is that for? I seriously doubt that it's scheduled to go in the foundry. But then that furnace pretty much either has, or is going to get, everything but the kitchen sink already so I guess you could be building the forum's very first V-8 powered furnace. You've created some amazing shapes with the refractory.

    Don
    That's the engine for my Pantera (actually, a couple of them). It's an all aluminum, stroker, small block Ford, with aftermarket aluminum block and heads that were popular with the Sprint Car guys. It's 404 CI with a solid roller cam, 650HP @ 6400 RPM. It has rear exiting 180 degree headers. Pantera's are mid-engine cars so it can except such an exhaust.

    Not for my furnace, but when I was a kid, I reckoned anything that didn't have an engine needed one.

    Best,
    K

  7. #97
    Quote Originally Posted by ddmckee54 View Post
    Kelly:

    The engine lurking in the background in post #88's photos, what is that for? I seriously doubt that it's scheduled to go in the foundry. But then that furnace pretty much either has, or is going to get, everything but the kitchen sink already so I guess you could be building the forum's very first V-8 powered furnace. You've created some amazing shapes with the refractory.

    Don
    I was wonder this myself as I am a Ford guy, it had my interest.
    Pantera, those are really neat cars that most people don't know even exists. 650hp 404, that should get the car moving a bit faster than the stock 351C did, WOW.

  8. #98
    Build Update 4-29-2017 Pyrometer

    I had been running my electric furnace with an 1/8” diameter Inconel sheathed K thermocouple inserted in the center of the lid but had always intended to build pyrometer that would work in molten metal contact.
    I had first tried a K thermocouple from McMaster Carr in a Mullite sheath that was an ebay cheapy. It always registered a temperature way below the Inconel TC next to it and failed within an hour in molten metal contact. I thought the temperature difference was probably due to so much of the sheath being on the outside of furnace but when I built the units below, I discovered I had a short in the thermocouple extension cord I built which was causing reading error. The metal contact failure was probably due to being reduced by molten aluminum and thermal shock.

    So I built a graphite sheathed version similar to what’s described in the pyrometer sticky of this sub forum. I bought a 5-pack 12”L x5/8”D gouging rods and two 24”L x 1/8”D Inconel sheathed K-Type TCs so I’d have a spare. I could have used a 3/16” or ” diameter TC but I wanted to keep the sheath as strong as possible and thought the smaller diameter, smaller wire gauge TC might have better response time.

    I also bought a 12”L 1/8” drill bit and made a collet to chuck rods in the lathe out of some ” OD .062” wall tube and slit it with a cut off wheel with the die grinder. Not sure this was necessary but the graphite is fragile. Then I center drilled and drilled as deep as I could witha jobber length drill before switching to the 12”L bit. I cracked the first tube trying to drill too much without clearing chips. I found I had clear the chips/dust every ” drilled by sliding the tail stock back then using thecarriage as a stop to resume where I left off. I was able to get four good sheaths and while they were chucked, trued the last 1 ” of the OD so they would just slide inside a piece of ” OD .062” wall piece of 304 stainless tube I nabbed from the scrap bin at work.



    I drilled and tapped the stainless tube for small stainless set screws to retain the graphite sheath and just made corresponding drill point indents in the graphite rod for retention. So only the graphite portion sees molten metal contact.



    I made a stand for the pyrometer to grip and position the height of the assembly in the furnace so it was easy to position it either above the crucible or in the melt. When lowered into the melt, I set the PID tothe pour temp and let coils control to the desire pour temperature. I also drilled an 1/8” hole in the lid to install the second TC.






    Hopefully this will lead to good control of pour temperature and repeatability. I also decided to mount my thermocouple switch box. This allows me to toggle between several thermocouples positioned at various locations in the furnace to see how the temperature varies and verify readings.



    I tested it with the furnace empty and it seemed very responsive and agreed with the other TC(s). Looking forward to using it.

    Best,
    Kelly



  9. #99
    Build Update 5-9-2017

    I completed my lid lifting mechanism over the weekend. Like the rest of the build, it isn’t simple but it does make using the rig easy and enjoyable.





    The lid lift has a separate mast carriage like the one used on the main furnace body lift except this one is split so it can be removed from the mast without disassembling the lift. This also pays further benefit asit is easy to tune the bearing preload at the split joint so I don’t have to shim each boss on the bearing perches. I have guide arms going to the square rear post to keep it aligned but with good bearing preload it doesn’t seem to slip/rotate around the mast. It can be lifted as high as twelve inches from the top of the mast. The crane needs to be swung out of the way to clear the thermocouple.



    The lid lift has separate counterweights that hang inside the mast like an old-style window weight. The counterweights allow the lid lift to be tuned to neutral weight for easy lifting without affecting the balance of the counterweight on the furnace body. In other words, both the furnace body and lid have separate mechanisms that effectively balance their lifting weight to near zero. Like the furnace body lift, the lid lift is also a block and tackle mechanism where the counterweight moves twice the distance inside themast than the lid and accordingly requires only half the weight to neutrally counter balance the lid and carriage assembly.

    The reason for the separate counter weights is so the lift can be configured for use on either my smaller (A20) electric or the larger (A60) furnace lids. The lift mechanism weighs 22 lbs and the smaller furnace lid weighs 15 lbs or 37 lbs total for both. The bigger lid weighs 52 pounds so with carriage it is 74 lbs total. So the counterbalance needs to be about half the combined lid and mechanism weight for each version of the furnace.

    About the only room left on the for the counterweight for such a mechanism was inside the mast and the only way I could get an enough counterweight with the travel I needed in there was with lead. The ID of thepost is 2 ” so at work I scavenged a 2 OD, 1/8” wall chunk of tube that was24” long. It was about 5 lbs. I cut it into two 12” sections. Filled with lead this worked out to the proper weight for each scenario. It’s just serendipity that one assembly is twice the weight of the other, otherwise the separate weights would not be equal. For the lighter lid, only one of the weights is active while the other is hanging by the button welded on top. The button is attached to as mall diameter steel tube that runs through the center of the second weight.The lifting cable passes through the inner tube allowing only the lower weightto be active when the second weight is hanging by the button. For the larger furnace, I just undo two bolts and pull the top pulley mechanism out of the way disengaging the button on the second weight. The second weight then sits on top the first making both weights active on the cable. This makes changing over from one furnace body configuration to the other easy.



    For the source of lead, I used wheel weights. Wheel weights are about the lowest value form of lead scrap at 10-20 cents a pound and I learned why. I phoned up a local small town tire place told him what I was after, and he said to come on over. I offered him 10 cents/lb and just gave it to me and told me I could have had ten times as much if I was there a week earlier. He sent me home with about 60 lbs in a bucket. I discovered they are made from just about everything these days. There were steel/iron weights, some things that were filled plastic, traditional lead weights, and probably other things too. I just pulled out the things that were obviously plastic and garbage and threw the rest in a steel crucible without sorting. The lead sinks when it melts and everything else floats. You can pour right through the scrap and just empty what’s left over after pouring out the lead; then start again. I’m guessing the 60 lbs will yield somewhere between 40-50 lbs of actual lead. Pretty good score for free and the guy says I can have all I want in the future.



    It’s kind of tight quarters behind the mast with the additional set of pulleys and cable but I gott’er done by fabbing a few mechanical gizmos from left over parts that properly (re)direct the cables.





    For the smaller furnace I fabricated the lift arm from 18 gauge sheet metal. It was fast since I could quickly shear, bend, punch-flare,and weld it up and this kept it light but plenty rigid. It just engages the handles on the furnace lid and has vertical play so the lid seats easily at the end of travel. The knob serves as a lifting handle and can lock the lid in place on the mast though it tends to stay where you put it without locking it. It can be operated with one hand and lifted literally with one finger. You can see both the Inconel and graphite sheathed TCs installed in the lid. They ride nicely inthe lid and there is enough TC cable to accommodate the travel. A switch box allows toggling between the two TCs.





    Here’s the lifting arm assembly for the larger furnace. A slightly different approach was taken here because it is more massive, but with the counterbalance it feels essentially weightless. There is an 1/8” mild steel band that clamps on the perimeter of the refractory lid and provides the attachment points for the lifting arm.



    The rod ends can be adjusted to center the lid and it can teeter slightly fore and aft to self-align when it seats on top the furnace. I just need to weld a plate on the back that allows it to be bolted tothe lift carriage and it will be complete.



    That’s it for this installment of “what else can I put on this thing”.

    Best,
    Kelly
    Last edited by kcoffield; 05-09-2017 at 06:59 PM.

  10. #100
    Senior Member Robert's Avatar
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    Outstanding. I will be curious to see the longevity of the carbon sheath.
    Robert
    "Whether you think that you can, or that you can't, you are usually right."
    - Henry Ford (1863-1947)

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