Foundry Furnace for the Tiny Shop

[vtsteam]

Rob,

I didn't mean a safety hole.

Some solid fuel furnace designs I have seen incorporate a "Dump Flap" that allows you to drop the coals out of the cold furnace.
(In paricular cupola designs).

Otherwise you have to turn it upside down to empty it out!

I have a dump gate at the bottom of the cupola I built, but the smaller aluminum charcoal melters get dumped by hand. Usually at the end of a pour, I cover the exhaust port and tuyere with a brick. This extinguishes the charcoal, saving quite a lot of it for starting the next time. It also slows the cooling of the furnace interior, so reduces cracking. I also leave the hot but empty crucible in there for the same reason. It's easier on crucibles (I believe.......warning, personal opinion!)

[Joe d]

VT Steam

Completely O/T here, but I really like your dog!  Looks remarkably like
my late and still lamented friend Max who enlivened my life for 16 1/2 years.

Give him/her a milk-bone on my behalf!

Joe

[vtsteam]

Certainly will, Joe.

He's a long legged dachshund. Half border collie, half long hair dachshund.

I don't know which half is which, though.

[RobWilson]

Rob,

I didn't mean a safety hole.

Some solid fuel furnace designs I have seen incorporate a "Dump Flap" that allows you to drop the coals out of the cold furnace.
(In paricular cupola designs).

Otherwise you have to turn it upside down to empty it out!

Aarh you mean a drop bottom Will , I have one on my cupola 



When I was a young lad doing cast iron coke fired there was never much left in the bottom of the furnace .




20 odd years on and I am still making blowers and furnaces ,,,,,,,,,,,,,,,,,, me thinks I could have a problem 


Any way enough 



Cheers Rob
 

[vtsteam]

New foundry toys????? Whadidjaget??  Huh? Huh? Huh? 

Hi Steve ,

I bought myself , a few of each /different sizes  ;  Scotch cleaner ,English cleaner , Scotch club cleaner ,flange cleaner ,girder tool ,flange bead  upset ,boss tool ,straight bead ,spoon tool

Huh????

Could you repeat that in English, Rob?

(me gazing down at a clementine crate with a stolen bent kitchen spoon, a rusty artist's pallette knife, and a baking poker thingy, a clothes pin, a candle, some bits of dowel, pieces of round bar and tubing, a sawed off table leg, a clothes pin, and a piece of galvanized tin bent into a "U".) Ahhh, me I can see jealousy in my future. No longer, how you say.......a nice bit o kit?

And I thought I was stylin' 

You know......havng it all organized like that in one crate?   

[vtsteam]

Joe, Fletcher said, "Thanks for the cookie!"

I told him it was from joe, overseas. He said he owes you one...... 

[Joe d]

Tell Fletcher he's welcome.  Curious though, when did Quebec get to be overseas from Vermont?

Lake Champlain getting salty? 

Cheers, Joe

[vtsteam]

Ooops! Didn't look at the flag before posting! 

Well the official name on some maps is Lake Champlain Inland Sea, so maybe I can get away with that.......

nah.... apologies neighbor! 

[Joe d]

It's all good Steve, the rest of Canada often wishes Quebec WAS overseas too!

One of these years we'll get together for a cup of coffee at the show in Windsor.

Joe

[Will_D]

Mmmmmmmmmm, rebar! 

1/2" dia, here. Actually these are mostly cupola tools....... but you get the idea!

Thanks VT,
Nice pictures

Colour coded as well!

[vtsteam]

Joe that would be really great!

Thanks Will!

I took a break from casting today and drilled and tapped two 5/16" holes in the back of the cone pulley casting and bolted it directly to the lathe faceplate. Then I slowly worked off the machining allowance in this small lathe -- about 1/4" on the diameters of the sheaves. I couldn't dig too deep without chatter on something ths large -- I'm looking forward to a bigger spindle and bearings when the pulleys are finished!

When supper time came around I had it roughed out to 5",4",3" and 2" diameters. I haven't bored it yet, and I haven't started cutting the grooves for the J type Poly-Vee belt. I did make up a 40 degree gauge from some galvanized tin, and then sharpened a lathe tool using that to compare it with.

Here's the pulley on the faceplate:

[vtsteam]

Hmmm, thinking about this in the morning here. I am going to have to come straight in 90 degrees with the lathe tool to cut the grooves, but I have to work up to very near the left edge of each sheave because the lands aren't much wider than the belt. In other words, groove right close to the base of the next larger sheave. So the tool I made with the cutting point at center was no good. I need to put the point as close as possible to the left side of the tool. 


Rob, you okay? I don't know what A&E is, but guessing it isn't a good thing.....

I do want to see those tools (kidding of course, earlier)! 

ps your foundry photos above are crude enough to make me think that, following your lead and calculating from an equivalent skill level, that in 20 odd years I'll be turning out tooling as beautiful as the stuff you do now. Which fills me with hope! Assuming the underworld has a furnace...... 

[Manxmodder]

A&E usually abbreviate for accident and emergency,though ass & elbow seems more apt on some occasions.  

Edit to add: A & E could also stand for awkward and eccentric,like all good MadModders should be.

[vtsteam]

Not the Arts and Entertainment channel then? 

[RobWilson]

[

Huh????

Could you repeat that in English, Rob?

(me gazing down at a clementine crate with a stolen bent kitchen spoon, a rusty artist's pallette knife, and a baking poker thingy, a clothes pin, a candle, some bits of dowel, pieces of round bar and tubing, a sawed off table leg, a clothes pin, and a piece of galvanized tin bent into a "U".) Ahhh, me I can see jealousy in my future. No longer, how you say.......a nice bit o kit?

And I thought I was stylin' 

You know......havng it all organized like that in one crate?   

  I have just gone up market Steve , moved on to a Dows port wooden box 

Rob, you okay? I don't know what A&E is, but guessing it isn't a good thing.....

I do want to see those tools (kidding of course, earlier)! 

ps your foundry photos above are crude enough to make me think that, following your lead and calculating from an equivalent skill level, that in 20 odd years I'll be turning out tooling as beautiful as the stuff you do now. Which fills me with hope! Assuming the underworld has a furnace...... 

Yer I am fine , just had a few chest pains and decided to get get back some of the national insurance money I have payed for years , ended up doing a bit "Train spotting " on the NHS  and they gave me a canny bottle off easy start too 



Aye my foundry/crucible  tools were  a bit ruff back then , that blower was canny though ,cast iron did not stand a chance  ,,,,,,,,,,,,aaaarh happy days 


Rob

[vtsteam]

  I have just gone up market Steve , moved on to a Dows port wooden box 

Gee, Rob, does sound like an improvement, how do you get one of those? 

Yer I am fine , just had a few chest pains and decided to get get back some of the national insurance money I have payed for years , ended up doing a bit "Train spotting " on the NHS  and they gave me a canny bottle off easy start too 

Hey, don't downplay it. Take it easy, man, we really need you!  

Aye my foundry/crucible  tools were  a bit ruff back then , that blower was canny though ,cast iron did not stand a chance  ,,,,,,,,,,,,aaaarh happy days 

Those days are still here. Rob I watch you grab a handful of cast off junk, see the potential, and turn it into some graceful celebration of skill and utility. That's so amazing! Some say what differentiated human beings from other animals in evolution was the ability to make and use tools. It created a different form of life. But then Jane Goodall discovered a chimpanzee that fished termites out of a mound with a grass stem -- so tool making wasn't totally unique. Which kind of explains my own background.....
)

[vtsteam]

I started turning the grooves in the smallest sheave -- getting chatter even though this is a single point tool, and I took apart and cleaned and adjusted all of the lathe slides, and tightened down on the split spindle bearings. It just won't behave. Basically I need what I'm trying to make -- a more robust spindle and bearings.

Though the speed is the slowest, and the sheave the smallest, I think the chatter is a result of the distance from the faceplate, and it may be less of a problem with the other sheaves which are closer.

I dunno, I was thinking of boring it insted, and then putting the pulley on an arbor and then doing the grooving between centers. But I don't know if that would help or make things worse for this particular piece.

I guess I could wait a few weeks for warmer weather and then just turn it on the Craftsman 12". But a Gingery should build itself, without help, seems like.

[RobWilson]

Morning Steve


Animals with tools    , My favourite is the Sea otter using a stone as an anvil  .

Could you bring your tail stock up to give the outer end a bit support  . Also mounting the tool upside down and running in reverse can do the trick . or make a spring tool   





Just the job for what your doing , Excellent  for screw cutting , and you get to make use of snapped centre drills/milling cutters   


Rob

   

[vtsteam]

Rob, that's a very nice holder!

re. bringing up tailstock center -- the bore is still just the raw cored hole not centered, I could bore it out now, but the hole would be bigger than my tailstock center (MT1).

Maybe I should make a pipe center. Or maybe plug the hole with hardwood -- that might work and I wouldn't need to bore yet.

re. boring -- I should have put spacers behind the pulley -- the spindle is solid, so boring will mean removing the pulley, and re-centering it to get the spacers in. Otherwise everything could have been turned at one go.

I could try to make a spring tool like yours (I'd like to), but there are some complications -- I'm at the limit of my cross carriage back travel on the larger sheave. Maybe I can do it though if I substitute my boring table and make a tool holder to fit on that, since it is much longer and has more travel.

Running in reverse with upside down tool -- I don't think I have reversing capability with this washing machine motor -- haven't tried figuring out if the wiring would allow it -- I'm still confused on that subject for mystery motors. One thing that would work well though: no worries about chuck or faceplte unscrewing in reverse -- all fixtures/backplates are cast on their arbors. I change arbors to change fixtures.

But I might be able to make a rear toolpost for the boring table. So maybe I wouldn't need reverse to do that, and gain  parting ability, too?

[vtsteam]

I ended up plugging the hole in the pulley with a tapered hardwood plug, cutting it off and drilling with a center drill, and then bringing up the tailstock center as you suggested, Rob. That worked well enough for the first couple of sheaves. It got progressively better as I moved toward the headstock, and for the third sheave on, so I stopped using the tailstock -- it was getting in the way of measuring the groove spacing.

[vtsteam]

Today I cast a base for the new lathe I'm building in the furnace, and after 10 heats in winter, no functional problems with the plaster lining so far, despite the extreme cooling after a melt. There is some cracking, due to expansion and contraction of the lining -- but they seem quite stable. I've noticed that they disappear when the furnace is hot, and reappear when it cools down. Basically expansion joints. And no worse than my old fireclay and sand furnace refractory, which lasted ten years. In fact, better so far -- no patching has been necessary with the plaster furnace.

There are a few small chunks broken off around the top of the lining, but these occurred when the furnace fell over (long after a melt) because the warmth gradually metled a layer of ice under the soil. The furnace gradually leaned over and toppled with the lid on and an empty crucible inside. I was eating dinner at the time. A few linilng dings were the result, but nothing needing repair.

After the melt today, the furnace was hot. Spying on a shelf the old brass POV valve removed from the propane tank I had made the furnace from, I thought maybe I should try to melt that. If the lining is going to fail, that should do it -- temps are a lot higher and a lot longer heats needed for brass.

And curious to see whether my small atmospheric propane torch was man enough to melt brass, and if it did, what kind of brass would I get out of an old valve? Lots of interesting questions to explore! If the lining gave out, it wouldn't owe me anything -- the whole furnace cost me $22, I think, and I'd had a good number of heats already.

So I popped the valve into a small clay lined crucible and turned on the propane at partial throttle and 10 psi.

[vtsteam]

And the results after about 20 minutes:

Yes indeed, an atmospheric burner made from 1/2" EMT can melt brass in this furnace. 

Nope, the lining showed no change after melting brass. 

Yup, the brass looks halfway decent (Vermont expression, meaning "good") 

Guess the furnace owes me even less than it did.....

Brass muffin:



The furnace lining, 11 heats incl. 1 brass melt:

[awemawson]

Looks like you've hit on a useful formulation there Steve with your Plaster of Paris and sand - certainly seems to hold up well. Realistically it's only the first few mm that take the full heat I suppose. The temperature gradient from 'flame facing' outwards must be quite steep I expect.

[vtsteam]

Well I'd been thinking about using plaster for quite some time Andrew, after some references to sprue pouring liners (for insulation), and a reference to using gypsum blocks in a bronze furnace, and plaster in statuary practice. The sand part was in a video posted on the forum, and I used a sand and clay liner before, so it seemed reasonable -- I just wasn't sure how well it would hold up and if calcining would be a problem. It's working so far. And the insulation value seems very good. 2" is fairly thin, but the outside of the furnace doesn't get very warm after an aluminum pour.

Another point of interest -- melting crucible of aluminum in the furnace took 20 minutes with propane and 15 minutes with charcoal briquettes. Propane is neater, and faster to light, but more expensive and slower to melt.

Charcoal is easier to do other things around -- I don't like straying from the furnace when using propane in case of a flame out.

While charcoal is starting (no blast) i can ram up a mold, and have a hot furnace ready to melt metal when the mold is set down. In fact, I've had aluminum in the crucible begining to melt a little if I took longer than usual making up a mould, even without a blast in my old furnace. That was quite a surprise the first time it happened! And a very fast melt afterwards. My usual procedure building the first lathe was, a little lighter fluid in a furnace 1/4 full of charcoal, light off, and when the embers had just started, add the crucible with initial charge of alumnum. Cover the furnace, and go make up the mould(s). When finished, things were already hot, and the blast made short work of the melt.

I can see using both fuels on different occasions for different purposes. It would be interesting to see how well charcoal melts brass. Might try that soon.

[mattinker]

Hi Steve,

This is looking really good so far! definitely worth a try. Just a thought, any sign of glazing from the silica sand melting, the silica sand with the calcium from the plaster (if there's enough in the plaster present) should glaze over, if there isn't enough calcium, it should form water glass.

Time will tell, regards, Matthew

Edited to include glazing thoughts.