YABF(yet another beerkeg furnace)

Discussion in 'Furnaces and their construction' started by Guster, Mar 13, 2019.

  1. Guster

    Guster Silver

    Have been wanting to get into casting again for a while now. NZ shares a similar remoteness to Alaska requiring either significant financial capital or other more resourceful means to get things done. Even in a world where you can order and ship anything online we have to be conscious of shipping often costing more than most products to start with. Casting itself lends to that by not being constrained to traditional suppliers for raw stock even before you ad the benefit of a casting being closer to final dimensions. Reducing machining to critical features. With 3D printing and CNC machining becoming more commonly accessible it just made sense to add metal casting to the line-up.

    I live by the sea and love working with stainless. Having seen a few keg furnaces online it just made sense to find one. Managed to buy 3 to recoup my shipping costs by selling off the 2 extra to home brewers. I set about preparing it.
    Removing the tap spear boss:
    [​IMG]

    Cutting it open:
    [​IMG]

    Drilling the drain hole:
    [​IMG]

    TIG welding in a vent tube and a drain tube:
    [​IMG] [​IMG]

    Then finally reinforcing the sheetmetal edges with some 10mm square bar bent around a wooden buck to the ID of the keg before securing it with a few tack welds. Notice I'd also holesawed the tuyere opening. Using a carbide bur to adjust the shape:
    [​IMG]
     
  2. Guster

    Guster Silver

    Refractory was presenting a challenge. I did not need industrial supply quantities and most other supplies are based around other DIY projects like fireplaces and pizza ovens. Often made to retain/store heat rather than contain it efficiently. I had some kaowool but wanted something more robust when I found some 25kg bag quantity of calcium aluminate cement. Then chose a bit of a NZ approach using pumice and sand as my aggregates for the refractory mix.

    Having made a hotwire cutting table I decided to try using a polystyrene plug for casting the refractory around inside the keg. Also made a base to index the mold plug in the drain.
    [​IMG]

    Wrapped the foam plug in a sheet of stiff plastic to produce a better mold surface and fit it after casting the base. The tuyere is molded using some stainless tube wrapped in the same plastic to aid removal and I just shoved it into the foam after cutting a hole in the plastic to match the cope of the tube
    [​IMG]

    Casting was straight forward. Just added some weight in the from of a piece of heavy steel(in a plastic bag) to stop the plug from floating:
    [​IMG]

    I did the lid about the same time as the base but the sidewalls came out looking decent, with only minor pinholes. The polystyrene foam mold plug did a great job and came out super easy. Having seen seom project struggling using other means.
    [​IMG]
     
  3. Guster

    Guster Silver

    Wanting to cast outside meant I wanted to make the setup mobile and stable. This also allows me to add a pedal lift to unweight the lid to swing open with one hand. That way I also don't need to put it down anywhere, especially while hot. So I made a trolley frame to the left.
    [​IMG]

    Added a fibrecement top and some castors with a very basic pedal lifting mechanism. Also happened to have an umbrella table mount bracket that fit the waste oil burner well so made a bracket that allows some adjustment to the tuyere opening. There is a steel ring that locates the furnace on the base and since added some hold downs that fit the existing strap holes in the keg to stop it tipping too.
    [​IMG]
     
  4. Guster

    Guster Silver

    Christmas came and went and I got a bit impatient to do the furnace dry out schedule. It had been raining a lot which prohibited me from working outside. I was also still waiting on some supplies and needing a fuel tank for the oil burner. I was also concerned that the waste oil burner won't have enough control for the lower temps in the dry out schedule. So I made a basic LPG burner using a 0.6mm MIG welding tip and some 3/4" pipe along with a 1 1/4" adapter.
    [​IMG]

    I wanted a bit more control out of the choke and modified the choke to be conical rather than flat, producing more linear control. This made the burner much more stable at lower burn rates.
    [​IMG]

    So without further mucking about I started early one Saturday morning. The dry out schedule I was advised on involved increasing the temp by a 100-175degC every hour until about 1200-1400C. I chose to hold it a bit at the earlier temps with 100C intervals to improve the chances of steam escaping.
    [​IMG]

    Burner performed well and stable:
    [​IMG]

    By lunchtime I hit just over 700C and started increasing things a bit by opting for 150C intervals
    [​IMG]

    Already starting to glow:
    [​IMG]

    By about 1200C I was running 150kPa on the reg. The LPG bottle was sweating but not freezing up while sitting in the sun on a nice warm day. I decided it was getting late and this was good enough after about 9-10 hours of burning. Removed the burner and blocked the openings with fire bricks to let it cool slowly. The outside shell was hot, just too hot to touch but not burning. The LPG tanks was still 30-40% full which earned me a lot of respect for the little LPG burner.
    [​IMG]
     
  5. Guster

    Guster Silver

    So last weekend I decided to recast some scrap I had using the SS crucible and ingot mold I had made using 40mm angle mild steel. Need to pour a little faster but not bad capacity for a charge :
    [​IMG]

    I was very gentle with the warm up but basically did two charges in under an hour with the second taking less than 10mins:
    [​IMG]
     
    oldironfarmer, Tobho Mott and _Jason like this.
  6. Tobho Mott

    Tobho Mott Gold Banner Member

    Looks good, sounds like a successful firing of your refractory.

    Jeff
     
  7. I noticed your burner swirls clockwise in your furnace. Most of the good guys have theirs going counterclockwise. Is this a Southern Hemisphere thing?
     
  8. Tobho Mott

    Tobho Mott Gold Banner Member

    It's tempting to use toilet based logic here. But the fact is, if the coriolis effect is strong enough to make any difference at all, it really only proves a bigger blower is needed!

    Jeff
     
  9. Guster

    Guster Silver

    Thanks Jeff! Time will tell. ;)

    The use of pumice is a little unconventional but not new. Right now it is working and very usable!


    Uh-huh... Yeah. Definitely how we roll downunder. Plus I prefer working with the time and not living in the past.

    Honestly, it wasn't planned, just happened that way. Is it nature or nurture? :rolleyes:


    Hehehehe... nothing can't be fixed with a bigger hammer, erm... blower. :cool:

    I made a coping template(the shape or area of two mating cylindrical bodies) for the port in the shell. Could have easily stuck it on going either way. Making the influence psychological or even psychosomatic if the southern hemisphere had any impact on it. I do stir my coffee anticlockwise with my right hand and clockwise with my left.

    I really don't know what I was thinking, if at all. But if it helps the metal melts just as fast and doesn't taste any different. :D
     
    Last edited: Mar 14, 2019
  10. It was a loaded question to start with, my furnace runs clockwise. Long time ago I was asked why. I just assumed it was because I am left handed.:D:D:D
     
  11. Guster

    Guster Silver

    I guessed so, though the fact that you were asked has me wondering what myth surrounds the burner swirl direction.
     
  12. DavidF

    DavidF Administrator Staff Member Banner Member

    When you flush your toilet which way does the water swirl ??
     
  13. A bit better question, when you pull the plug on a bath tub, which way does it swirl. I forgot to look when I was down there. I was only there six weeks so didn't bathe.
     
  14. Guster

    Guster Silver

    Down the drain... with a little right hand spin if we are lucky and the kids haven't half flush and blocked it up. :rolleyes:

    Hehehe... I know about the Coriolis effect. Though my furnace is actually designed to swirl clockwise with the tuyere intersecting in line with the circumference of the cavity(rather than perpendicular to it) forcing the flow along the curve so it can only flow that way. More luck that it happens to match the toilet in that regard. You can probably just make out the angle in the photo:
    [​IMG]
     
  15. Guster

    Guster Silver

    I don't know either as I never bath... I shower. Though it is meant to be clockwise in the south for large enough bodies of fluid where it can be impacted. Toilets on the other hand are often design to induce a strong swirl for various reasons so may have either direction by design. There was a video about a year ago where they did the tests using kiddy pools recorded in both hemispheres to prove it.
     

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