Last updated 2 April 2018
This is a working document. (captions, video, and more pics coming)
Meet Rose. Rose recently had a brand new (welded with frivets) boiler made and is certified for 165 PSI operating pressure. All photos on this page courtesy of Wes Harcourt (And he did all the work too!) Thanks Wes!
Front wheels with new rubber vulcanized on
Working on the whistle
Another 6-chime Southern Pacific whistle all polished up
Bell in the working state
Bell all polished up
See Rose make her public debut at Maker Faire 2018 in San Mateo at the end of May!
content coming soon
Here is the first gear we cast. Notice that the pattern was messed up- something in the CNC mill shifted as it was cutting so the right thickness is almost paper thin, while the left side is too thick. This will manifest itself later when we do our test pour.
Mounds of sand are piled on for risers- this increases the hydraulic pressure of the metal on the mold cavity. We could have made them neater with a can or something, but this worked ok and was quick.
Here is a mold waiting to be poured. The smaller furnace in the background uses a rudimentary AC motor blower with a light dimmer for speed control. A couple pigged ingots are in the background.
Troye looking into the furnace. The gloves are off. Deciding if it's ready to pour yet.
Troye looking at the dross siduation. Stephen is getting ready to assist by lifting the crucible with lifting tongs into the pouring shank. This is a lift-off furnace design- very lightweight furnace body is lifted off (behind Stephen on the floor)
Troye getting some of the last bits of dross off before pouring.
Results of the pour. The 4 risers are completely filled and you can see discoloration in the sand as the pink foam board vaporizes and gets absorbed by the sand, turning it green, black, and gray.
Here is a second gear. Notive that the pattern is even on this one.
The shakeout of the second gear. Everything looks good.
Here is the furnace melting some metal. Notice the angle iron pig mold just to the right of the yellow brush/broom
Stephen's hands are a blur as he quickly works on the molding process.
Stephen is getting ready to flip over the cope and set it onto the drag. Notice the many small vent holes poked through the sand in the middle of the gear teeth.
Stephen is setting the cope on top of the drag.
Very careful to line the pins up while setting it down and also trying to not disturb the sand so as to not have loose grains in the mold.
A second mold is readied for pouring. We used an A16 (the largest this furnace can accomodate) and were just able to pour two gears with a bit left over for the pig mold
Result of one of the castings. You can see where the metal was so hot and fluid that it actually travelled back up the vent holes poked in the sand. This is also because of the high sprue/risers that were pushing molten metal into the mold.
Here are some "finished" castings along with the first failed one (because the pattern was too thin on that side) as well as a few of the pink foam patterns off the CNC mill.
We used the design of Colin Peck in his book "The Artful Bodger's Iron Casting Waste Oil Furnace", except we scaled it up a bit. The inner bore is 18", we have 2" for castable refracatory and 2" for Vermiculite insulation
The 30 mesh sand I had bought originally to make greensand with for the iron, but right now, we're just pouring it in the center of the cardboard sonotube to hold it in place so we can ram refractory against the other side without fear of collapse.
I am test fitting the air delivery tube I cut to match the inner curvature of the sonotube (which will be the inside of the furnace)
Side view of the inlet tube
I drew this out using Colin's "parallel line development" procedure and cut it with a plasma cutter (thanks Nathan!) and cleaned it up with an angle grinder.
Stephen is measuring out and weighing the proper amounts of Southern (Calcium) Bentonite and Western (Sodium) Bentonite to add to the 60 mesh silica sand to make our greensand. The cement mixer with the paddles removed and a bowling ball added (blue ball on top of the sand in the left, backbround) because our muller until we can build or acquire a proper one.
We used Mizzou castable refractory as it's good for 3000 degrees F which will be good enough for cast iron. This was purchased from High Temp Inc on eBay in Portland Oregon for about $40 a bag. We got about a third(?) of a pallet of that stuff and of some Greencast 94 (94% alumina) which is good for something like 3450 degrees, which should be good enough for STEEL if we ever get to that point.
We mixed the water according to the instructions. It's a very dry mix. Thankfully, we had John on hand to do QA/QC of our mix. It's very much like a very dry concrete mix.
We're packing in the refractory around the holes in the furnace shell. It's like very stiff cement at this point. We put a piece of wood and a ratchet strap on in so it wouldn't fall out while it cured.
We had a team of people mixing the refractory and people tamping it in the 2 inch gap between the sonotube and the next shell. The sonotube is lined with a plastic trash bag so the cardboard wouldn't absorb moisture from the mix as it cured. The rest of the shell is sheet metal that we cut, ran through a set of slip rollers and welded the ends together. We used little blocks of wood to keep the spacing even and pulled them out as the refractory filled up.
John and Pat are tamping the refractory mix.
Stephen, John and Pat are tamping refractory while Texx mixes it some more. Yes, it looks very dry. Yes, this is correct.
Here is the lid. We welded nails facing inward (iron-maiden style) to keep the refractory from falling out. Other people had said that wire or rebar going all the way through accellerated cracking. That's a 6 inch can in the middle, cut down one side and slightly tapered, which will act as the exhaust port. The lid alone took over 2 bags of refractory (55 pound bags each)
Here's another view. The lid is sitting on a trash bag so the refractory won't stick and all that is sitting on a 3x5 foot granite surface plate so that it will be flat.
Filling up the lid. It looks really dry, but we actually had water bleed out (a very little) when we were done, so it actually had a little excess water.
The inlet tube did not want to be level (wanted to tilt downward as it went in) so we grabbed a random hunk of metal to put some weight/torque on the outside to bring it down while the refractory cured.
Here's whe it looked like once the refractory was smoothed. I added a groove along the top for a fiberglass rope gaasket to seal it up better at a later point in time.
Here's the second time we fired it up- we got it to run completely on oil this time, but are still having some problems. We hope that Colin will have some advice on how to modify this larger (than his specified) design and get it working properly.