Chirpy regarding richness

ChirpyYesterday at 8:46 AM

lol

[8:46 AM]

usually I just tune it with an ingot at the side of the exhaust

[8:47 AM]

if you see no smoke and it looks to be burning cleanly, and on the ingot, it forms a little bit of soot, then it's perfect for copper/brass/bronze alloys

ChirpyYesterday at 8:47 AM

if it runs clean on both no smoke and none on the ingot, but doesnt clean it off from too rich, then perfect for aluminum(edited)

[8:48 AM]

last few times, Ive used an cheap adjustable leaf blower

ChirpyYesterday at 8:55 AM

you can also turn the fuel down a little bit to match the blower, which technically, it'll create as much or more heat with less fuel usually

dustyToday at 12:37 PM

@Chirpy Does the ingot test for rich/lean work for propane too?

ChirpyToday at 12:38 PM

yea, it should

[12:38 PM]

color test is easier tho unless your furnace is glowing bright orange, lol

[12:39 PM]

Ive never tried it really for propane, but in theory, it should work fine

[12:39 PM]

same with the galvanized sheet metal trick

dustyToday at 12:52 PM

WIll have to look up the color test

ChirpyToday at 12:53 PM

if you have orange wisps in the flame, it's slightly rich, or if it's got a green'ish color, then it's oxidizing

dustyToday at 12:53 PM

Made a 1/2" pipe for the burner yesterday.  Man does that look small LOL

ChirpyToday at 12:53 PM

lol

dustyToday at 12:53 PM

OH ok

ChirpyToday at 12:53 PM

and if you have all orange flame or lots of orange wisps in it, then your really running it rich, lol

ChirpyToday at 1:04 PM

for a furnace tho, you dont want any orange color to it

[1:04 PM]

just a nice blue color that's solid

[1:04 PM]

that's a neutral propane flame

SciFiMindToday at 1:04 PM

I'm talking at the vent hole not the burner

[1:04 PM]

For a slightly rich burn

NEW

ChirpyToday at 1:05 PM

I never let it get to the vent hole, it just swirls around the inside of the furnace and only goes the first few inches at most, then swirls up to the top

[1:05 PM]

oil burner tho, thats a different thing tho

SciFiMindToday at 1:11 PM

Yes I like blue

NEW

[1:12 PM]

If you are running your furnace and you dont have the slightest lick of flame at the vent hole it means all of the fuel is combining with oxygen in the furnace. Where is that oxygen coming from? If all of the fuel is finding oxygen then you aren't truly running a reducing atmosphere in your whole furnace

ChirpyToday at 1:12 PM

for foundry furnace, you dont need to flood the furnace with flames, otherwise you are just wasting fuel because when your melting metal, you dont need that much fuel and air, lol

SciFiMindToday at 1:12 PM

It's like a back draft

ChirpyToday at 1:13 PM

yea, Im talking about a neutral furnace atmosphere, which is what we were talking about

[1:13 PM]

little blue whisps at the tips of the flames inside of the furnace means very slightly rich, and you dont need them shooting out of the furnace

SciFiMindToday at 1:14 PM

You were talking about how to tell if it was rich or lean by flame color

ChirpyToday at 1:14 PM

it's like using a 1 million BTU hot air balloon burner when you only need a propane torch for soldering plumbing pipes, lol

SciFiMindToday at 1:14 PM

You dont need them shooting out

Regarding Sand

I'd start at 4% and add more till it passes the squeeze test

[10:49 PM]

it's usually between 4-10% depending on the grain size

[10:49 PM]

finer the stuff, the more you have to add I believe

NEW

[10:50 PM]

I personally added around 3% of each, so around 6-7% overall in my sand, but it's pretty fine

[10:50 PM]

after it passes the squeeze test, toss it up in the air and catch it a few times, if it doesnt go into pieces, then it should be good for making molds with

[10:51 PM]

last test to do is to do the same as the squeeze test, but create an air tight seal around your hand with the sand in the middle of it tightly, and blow through it, that'll show if it can breathe easily or not

---------------------------------------------------------

More Richness

I may need to readjust my burner then, all I really do is aluminum and copper at the moment

ChirpyToday at 2:30 PM

yea, you should be fine then

[2:30 PM]

at copper temps, the crucible and plinth may want to stick, but the cardboard should easily fix the problem tbh(edited)

[2:32 PM]

also, are you using propane for a burner?

[2:32 PM]

depending on what metal your melting, you want to run your burner slightly different

[2:33 PM]

aluminum, you want to run a neutral or slightly oxidizing flame, copper, brass, bronzes, copper alloys, they want a slightly rich flame

[2:34 PM]

aluminum absorbs hydrogen from the burning flames, so you end up with porousity from that but oxygen doesnt affect it other than a little bit of oxidization, but as long as your burner is set right, then you shouldnt have much loss to oxidization tbh

@Chirpy

also, are you using propane for a burner?

ArindurToday at 2:35 PM

Yeah I'm running propane

ChirpyToday at 2:36 PM

and copper and copper alloys, they absorb oxygen and forms gas pockets, so by running it slightly rich, you can take up free oxygen and not have any problems

[2:36 PM]

best way Ive seen to do the propane flame is just by looking at it, if it's solid blue, then it's neutral, if it has a tint of green to it, it's oxidizing, and if it has any orange flames, it's running rich

[2:37 PM]

for aluminum, I always try to go for solid blue, and copper alloys, I go blue with just the very tips of the flames coming out as little orange tips

Tobho son of TimettToday at 2:39 PM

A rich burner also tends to make flames come up out of the vent hole in my experience. If you see that happening, leaning it out until the flames just fill but do not overflow out of the furnace should put you at about neutral.

2

ChirpyToday at 2:40 PM

when Im running propane, I dont really have flames ever come up to the exhaust tbh, usually only like a 4-5" tall band in the bottom of the furnace

[2:40 PM]

that tends to heat it up and melt the stuff easily enough

[2:41 PM]

you have an open style burner tho, no orfice, so lots more propane than what I use tho, lol

Tobho son of TimettToday at 2:43 PM

I definitely can get propane flames jetting up out the vent hole if I run more than maybe 6psi with the hair dryer on full blast. But with a venturi and orifice setup, wouldn't the same thing happen if you had the air intake choked way back?(edited)

ChirpyToday at 2:44 PM

it might, but you would have such a lazy flame that you'd never be able to melt anything at all, lol

Tobho son of TimettToday at 2:45 PM

Maybe less choked back than that but still rich, I mean. Maybe not, I've only used forced air

ChirpyToday at 2:45 PM

lol, yea

[2:46 PM]

even with forced air, I still have mine running through a 0.025"/0.6mm mig tip

[2:46 PM]

so that restricts things pretty hard

[2:47 PM]

even with my self aspirated one, it still only got that much of a band of heat still

Tobho son of TimettToday at 2:47 PM

Ok