Shed conversion for casting

Discussion in 'Foundry tools and flasks' started by Tobho Mott, Oct 31, 2019.

  1. Tobho Mott

    Tobho Mott Silver Banner Member

    I have 2 decent sized sheds that I work in and around doing hobby projects, etc. One attached to the house, which we call the Woodshed since that is what it was originally used for. And another out in the back yard that we named the Back Shed in a rare outburst of creative thinking, which has always been mostly used for storage, including the storage of my furnaces. I roll them out when I want to melt something, and set down the flasks nearby. Then I roll them back in with the vent and tuyere blocked up when I'm done.

    Thing is, all that other crap being stored in there? I don't want it. A lot of it belonged to a friend who stored it in there when he moved back into town after finishing university and only had an apartment for a while. Since then he's been in his house for a good 15 years now though, so I've been making him take stuff back (not his old homemade double bed though, much of that is now the wooden part of my molding bench). The rest goes this weekend, or so he promises. Other stuff was left behind by the previous owners, which I still have to get rid of a bit more of, but which has provided most of the scrap steel and wheels for building my crucible tools and my furnace cart and a few other projects.

    The back shed was built by the same previous owners, who wanted a small stable they could keep a horse in. Then they learned you're not allowed to keep horses on our lot, honestly it's only a 1/2 acre, not sure what or if they were thinking... So there was this half-wall built strong enough to contain a large mammal in there, cutting the shed into two sections and eating up SO much useful space. It was built from heavy 2X10 lumber. Meanwhile, the woodshed has been getting more and more cluttered with tools and (broken down) lawnmowers, etc.

    So, I ripped out that stupid half wall and used half of the 12' 2X10's to build a long workbench/shelf in the woodshed to give me space for some of the stuff that's been piling up in there.


    Right now it's acting as shelf helping me clear up some room to rearrange other things and make more room to move around. It's a start, and there's another wall on the left side of the pic that can fit another heavy duty 10' of similar 20" wide bench space, and I have enough boards left to build it. I've already made it so I can actually get to the back of the woodshed again which doesn't sound like much, I know, but it's progress for sure... Soon I'll have room to keep the (working) lawnmower in there to free up more space in the back shed. Which now already has a TON more free space in it than it did before, and could now almost be called... tidy.

    Up to this point, I was only trying to make more room to move and work in both sheds. But then I got to thinking about that casting session I assisted Josh the blacksmith with a few months back, when we melted a bunch of copper to make an argon condenser, and melted and poured it INSIDE his smithy.

    Or forge, or whatever it's called. :D


    That's the wrong pic from that day, but I could not find the one that shows the furnace running indoors.

    The way he's set things up there, there are chimneys on each of the 4 coal forges, but we did not set up underneath those or anything, we just set up the furnace on the dirt floor near the one end of his shop where there is a fan up high blowing all the bad air out that may have missed going up the chimneys. I was running diesel that day. It went just fine; only if the door to the shop got closed did it start to get really hot and a bit stuffy in there, after a bit. He's also got 2 small propane forges with small fans on the wall next to them to bring in more fresh air, but those forges are not near the end of the shop with the big ventilation fan up near the ceiling, and we didn't have those fans (or forges) running that day, other than just for a few minutes when he showed off how they work (they were still his "new toys" at that time).

    Well, if it can be done there, and running diesel in my drip burner no less, then why not at my place? For now I'm just talking about using the little Red Dwarf furnace in there, which I find I'm normally just using propane with lately, since it melts metal so fast that way, it hardly seems worth hanging up the oil tank for. Not thinking about running the big oil guzzling Black Dread in there. (Yet?)

    So, I found one of those ventilation fans for $20 on Kijiji and installed it. It's a 15" fan and I am thinking of setting the furnace under where I have it installed, near the wall, with some fireproof heat shielding on the wall down near the furnace, just to be safe.


    I actually already tested this idea before even buying that fan - when I cast that bronze ball to roll down the drainpipe on my roof to get a string pulled through it a couple weeks ago. I didn't have the new fan yet, but I stood outside the shed while the furnace was running, fire extinguisher in hand, holding my breath to occasionally dash in and poke at the melt, and after about 20 minutes, to pour the molds. The rafter directly above the furnace vent didn't even get warm. Seemed like a good sign to me, so that's when I started looking for vent fans.

    The back shed is missing the bottom panel off one of its doors, and when the fan runs you can see the wind coming in through that opening, blowing dry leaves inside etc. This will be close to where the blower will sit for the burner, so the blower should have plenty of fresh air to pump into the furnace, not just sucking its own exhaust back into it. Seems like the natural current that develops there will carry the furnace exhaust right out the fan-hole too, with a little luck.


    And there are 2 other doors (aka escape routes) that can be opened if more fresh air is needed. I'm thinking about maybe digging up one of those big box fans to sit in one of the doorways on the far end of the shed blowing inwards when the furnace is running, just to be on the safe side of asphyxiation. My new bouncy castle blower may get used instead, or else it may have some other role to play in replacing fresh air in the shed instead, not sure yet. Maybe blowing warm air from up high above the rafters back toward the end of the shed with the vent fan? Still bouncing a few ideas around in my head.

    I've already got the muller moved in. I still need to build a new stand for the molding bench and move it into the new space as well. I still have a bunch more of that reusable double bed lumber taking up too much space in there, so that works out well since I won't have to move it if I use it up building that stand. Would be nice to add some more lights in there too. Then I'll have molding and mulling and casting all contained in one shed out of the rain and snow, and I'll do my patternmaking in the woodshed.

    I've got my eye out for some free used bent up crappy metal barn siding or something to line the indoor walls with, something will show up on Kijiji eventually. Maybe I'll slap a couple of square concrete patio stones against the wall near where the furnace will be too. Josh had that going on in one area of his shop, stacked 2 high, on edge, with lag bolts and washers between them holding them upright and in place against the outer wall. This looked difficult to accidentally burn through.

    Now is the fun part where you guys kill all my fun by pointing out how I'm busily setting up my own death-trap, then tell me how to do it right and safely.

    I've only cut one 15" hole in the wall so far, so these plans are all still very flexible, in case anyone has some great ideas, or spots a fatal flaw in my plans so far. But generally speaking, I am really looking forward to my 'fair weather' foundry going all-weather at long last!

    I might be working on this for a while, free time to spend on fun projects like this is hard to come by these days, what with the kids and the commute and the wife and maintaining the old house to keep up with and all... Luckily, I'm still only a hobbyist at this, so there's no big rush.

    Last edited: Oct 31, 2019
    joe yard likes this.
  2. joe yard

    joe yard Silver

    Now you are talking Jeff
    I will watch this thread closely as i am also in the process of cleaning and modifying a shed to be used as a foundry. How big is the shed you are converting?
  3. Tobho Mott

    Tobho Mott Silver Banner Member

    It's 12' on the short side... I will have to measure the other side.

  4. Petee716

    Petee716 Silver Banner Member

    You've got a real adventure going on there Jeff. My workshop is an old 20x30 barn built in the 30's. It's a 2-story with. 20 x20 loft. The home inspection guy from when I bought the house 5 years ago described its condition as "normal for a barn that age", whatever that means. I put a concrete floor in it before I moved in and had a steel roof put on it a couple years ago, so I put a few bucks in it. I ran power to it underground as well. The roof had the characteristic dip in it with the second story walls bowed outward. I drew the walls together, pushed the roof up level, and installed collar ties. (It took a month or so). I'll weld and grind in there, but no furnace for me. Ceiling is only 8ft and the thing is a board and batten tinderbox. My horse stall only takes up about 20% of the floor space, so I treat it like a storage area.

  5. Tobho Mott

    Tobho Mott Silver Banner Member

    I measured it, the long side of the foundry shed is 16'.

    I do plan to line the interior in metal (maybe with some rock wool behind it), so I'm keeping my eyes on kijiji for used barn siding. But if I absolutely have to, I'll buy some eventually. There's an ancient barn down the road that finally collapsed a year or so ago, maybe the old man will let me pick through the wreckage if I can catch him when he's picking up his mail. I don't mind prying out some nails and hammering some sheet metal out so it's straight again, if the stuff comes free!

    Got some more tidying up done in the shed over the weekend, now I have room to actually do a melt and pour in there. Had a friend come by to grab all his crap that I've been storing for 17 years that hadn't already been torn down and upcycled into foundry gear, and he sat in for the first test run with me (and him) staying inside the shed for the whole duration. The thought being, if the ventilation fan wasn't sufficient, one of us would drop first and the other could drag him to safety. Then I would know, and also live to tell the tale. Don't want to learn I need more ventilation when I'm melting solo!

    The air stayed cool and fresh throughout the 15 minute melt, a great sign! It was a lost foam pour, just another 3" skull paperweight from my hoard of halloweeny foamies, they are pretty goofy but also my go-to to cast when I want to test a burner or furnace or just need to feed the inner pyro or what have you, but I don't have a sand mold rammed up or need to cast anything else. Even the burning foam stink was almost non-existent within a minute or so after the pour.

    I still need to move a bunch of lumber out of the foundry shed and into the other one. I may put it where the molding bench is now, then I'll have room to move the molding bench to where the lumber is stacked up now. The goal is to have mulling, molding, melting, pouring, and shakeout all happen in one building, out of the weather. And I'm finally getting really close.

    Also making room to set up a set of shelves in the non-foundry shed, which should help a lot with the clutter I'm fighting in there. I have a long weekend coming up, so next weekend should see me making more good progress. And getting some pictures, once things are more presentable...

    joe yard likes this.
  6. joe yard

    joe yard Silver

    Sounds great Jeff
    as I had mentioned I will be watching this thread closely as I will be following a similar path with my shed. Now that you will be inside. You can start to think about more permanent accommodations for the equipment. No more will you be dragging the equipment outside to accommodate the melt.
    It will be interesting to see the floor plan when you are finished. The width of the shed appears to be around 12' X 16' length will give you 172' . A very nice space for a foundry indeed!
    My shed when finished will be just about the same size but be oval at 10' wide by 23'. The different shape will make it very close to the size you have.
    Have you thought about the floor plan yet? I have been giving mine a lot of thought lately.
    With everything inside. I am considering a rail and carriage arrangement to carry the crucible.
  7. Tobho Mott

    Tobho Mott Silver Banner Member

    I've thought about the floor plan a little and changed my mind about it a couple times already. I definitely think the furnace should go under the vent fan. The molds should be be laid out near the furnace, but also near the molding bench, which should also be near the muller. I've got a couple of barrels and many buckets for storing extra greensand and lost foam sand too so I'll have to leave room for those. All without blocking any of the 3 doors. I'll be needing some shelves too for molding tools etc. But I still have to move a bunch of stuff around and build legs or a new stand for the molding bench before everything can go in its place. Plus put up some sort of fireproof covering on the walls... This may keep me busy for a while...

  8. Al Puddle

    Al Puddle Silver Banner Member

    I've been using a propane fueled furnace in a space about the same as what you are working with. My ceiling is about 9ft. and I have an exhaust fan. The ceiling never gets above 90F in the summer. I suggest using the PYLE PCMM05 carbon monoxide meter to ensure the air is okay. I found CO levels can get dangerous in a short amount of time if there is not enough ventilation and the levels vary with location in the shop depending on prevailing winds.
  9. Tobho Mott

    Tobho Mott Silver Banner Member

    I hadn't mentioned it yet, but a CO detector is on my short list, I think that is a really good idea. Ill look that one up, thanks.

  10. Jason

    Jason Gold Banner Member

    I've been swamped with work but Rod beat me to it. Besides the heat, I would be concerned with large amounts of carbon monoxide. The fan is a good idea. I'd guess so it goes up? Or is it down?
    Probably depends if you are asking a climate activist.:confused: Where is your snow? Is it late this year?

    And I'd love to see you be able to continue casting through the winter. Imagine how toasty warm your shed will be. You'll need a supply of cold brews!
  11. OMM

    OMM Silver Banner Member

    If you can’t get the metal for free, I’ve done it just with cement board. A 4 x 8 sheet cost around $40.

    I screw the sheets to the wall (like drywall) with just four screws. I lay out my studs and with a 1/8 Masonry bit I drill in 6 to 8 more holes (making sure I hit studs). I remove the sheet. With some scrap half-inch copper pipe I cut a bunch of pieces 3/4 Long. I RTV Silicone them to the backside and with fender washers and 2 1/2 inch deck screws I screw it back on.
  12. Al2O3

    Al2O3 Administrator Staff Member Banner Member

    Hey Jeff do you remember Robert's indoor set up with the hood? You might consider a hood above your furnace ducted to your exhaust fan. I think Yoda weighed in on the subject of dilution rate too but your furnace exhausts a couple hundred cfm or so and the exhaust fan likely a thousand or two and that dilutes the exhaust temperature to modest temps. One thing is for certain, whatever you exhaust out must come into your shed somewhere else or you'll suck the walls in so may as well insure it evacuates the exhaust gas a well as possible.

  13. Tobho Mott

    Tobho Mott Silver Banner Member

    Up, down, side to side or doing a fancy little spinning dance, I don't care long as the fan is blowing OUT of the shed. Also, snow is never late to arrive, it's always too soon. But we don't have any... yet. It's been damp and rainy, and most nights lately it's been just above freezing. I had to scrape frost off my windshield yesterday morning.

    Interesting, I'm not familiar with cement board. I'll look that up, thanks.

    Saw it, and yes, a hood above the furnace to funnel the exhaust into the fan has always been part of the plan. I was thinking I could make it out of some sheet metal I have saved which was once the outer skin of an apartment-sized combination clothes washer/dryer I tore apart for its motors and gearbox a few years ago. I was also thinking about running another duct through the hood to the fan from above, to catch any bad air that gets past the hood, as seen in blue on this impressive CAD drawing:

    Any thoughts on that?

    To replace the air being blown outside, I'll be keeping some number of the shed's 3 doors cracked (if not wide) open any time the fan is on. One of those old doors is about 1/3 wide open even when it's closed already, I think there's a pic of that somewhere above. (And in the drawing)

    Thanks for all the suggestions guys, this needs to be safe and I am definitely capable of overlooking details that might matter more than I realize. Much appreciated!

  14. joe yard

    joe yard Silver

    Carbon monoxide is heavier than air and will settle in low spots. Do not allow it to collect in a basement or pit. I am also very concerned with CO1 and plan on using a bit different blower configuration. I plan on pushing air through a duct with a deflector designed to produce a vacuum
    over the furnace where it will mix with the hot gas before being exhausted. shed.png
    Tobho Mott likes this.
  15. rocco

    rocco Silver

    How readily does carbon monoxide mix with air? In Tobho's drawing, he's exhausting the air up high, if he also put a few air inlets close to ground level, could that create sufficient mixing to allow the carbon monoxide to exhaust out the top?
  16. Al Puddle

    Al Puddle Silver Banner Member

    I have a 12x25 space with a 2000cfm exhaust fan up high. The actual exhaust is between 1000 and 1500cfm I have to open wide the access doors (36" doors) at both ends of the shop with the fan on high speed to keep the CO levels below 30ppm. The shop gets to outside temp within 10 minutes of furnace operation. The biggest contributor to CO levels is the heating of iron over the exhaust port of the furnace. The CO does seem to cloud up in certain areas depending on the wind direction.
  17. Tobho Mott

    Tobho Mott Silver Banner Member

    I've already got an opening down near the ground, and am planning on keeping a door or 3 open anytime the furnace is running, but from what Al Puddle has said I guess the hood I'll be building better work really well...

    Oh, and we did get snow last night, I guess I jinxed it by mentioning there wasn't any yet. :(

  18. Jason

    Jason Gold Banner Member

    Ya should have ignored my snow comment. Sorry bud. lol
  19. OMM

    OMM Silver Banner Member

    Here too. Went from raking leaves on Monday to shovelling snow Thursday:mad:.
  20. Tobho Mott

    Tobho Mott Silver Banner Member

    That's life in Ontario this time of year... At least you got your leaves raked up! :D

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