Furnace measurements.

Hi everyone.

Not sure where to put this post.

I made another video, this time it is about my furnace measurements.

A lot of backyard casters have a very small space between the crucible wall and the furnace lid, also a lot have small exhaust vents. My furnace is the exact opposite, there is a lot of clearance in all those places and works really well melting iron from an A6 crucible to an A20? Crucible. So what does everyone think, is there a standard clearance for small melting furnaces like ours?

As you will see in the video, pouring from a full A12 crucible with a pouring trolley and not putting the aiming points in the right place a lot of iron ended up on my concrete floor. You would think that there would be a huge explosion with the iron hitting the floor not once but three times.

In the past I have gotten away with interrupted pours but not this time and it happened on the mold that took the most time to make. Also the ingate was too small so it restricted the flow into the mold. I hate having to repeat another mold/pour when it should have worked the first time around!

 

I have spilled large amounts of molten bronze on my concrete floor with no result. I live in a hot climate (perpetual summertime) which may have something to do with it.

Richard

 

I wonder why. It seems people grab some kind of small sized steel cylinder and get married to it. A galvanized garbage can is plenty good for a furnace shell. It will last for years and years. A nice big vent hole in the lid allows you to drop in ingots; just cover part of it with a brick if it's too much. Mine are five inches and I wish they were more.

Richard

 

I would recommend hosing down the floor so it is damp before you pour next time....
Beautiful castings.
Robert

 

Cool stuff man.
That is a really nice plaque.

 

If the concrete blows out or not is going to depend a lot on the moisture of the concrete. I do know if I blow a hole in my driveway, my wife is going to be pissed at me!

 

Just when I think I have some good rules of thumb for a foundry/burner setup, somebody (porositymaster) comes along and turns over the apple cart.

He uses the following:

1. An external burner which works like a champ (officially called the Ursutz burner, patented in 1945), but needs to be made from stainless steel or refractory in order to last.
2. A very tall pinth that puts the crucible just an inch or two below the lid opening.
3. A vent opening large enough to allow metal charging and skimming without opening the lid.
4. Easy start on diesel without using a propane preheat.

I think his furnace is relatively low mass, and I know ironsides furnace is very low mass (a zircon-coated creramic blanket).
Regardless of anything else, the low mass seems to have the greatest effect on the speed of a cast iron melt.

I have a high-mass furnace, and with aluminum, I can just go to full power and the aluminum melts quickly without the furnace needing to reach its maximum temperature.
For melting cast iron, I have noticed that no melting occurs in my high mas furnace until the entire mass is very hot, and so the beginning of iron melting in my high-mass furnace is generally delayed by 30 minutes.
I think my new low-mass furnace will shorten iron melt times significantly.

My new furnace refractory wall and floor thickness will be 1", with stainless needles mixed in to prevent cracking, and it will have two 1" layers of ceramic blanket around and below it.

I have seen several people use a variety of crucible sizes in their furnace, and I have not really seen a connection between crucible size and melt time since both small and large crucibles seem to work equally well.
Again, I think much of it is about furnace mass, and very little else matters, assuming that your burner an such are functioning correctly.

When it comes to metal melting performance, and especially iron melting, it seems that less is more with regards to furnace mass.

 

I have seen people (I think ironsides included) who easily melt iron with propane (assuming they properly handle the tank cooling, or have a large enough tank), and it is just a matter of adding the right amount of combustion air.

Vegetable oil seems to work, as well as waste oil, diesel, etc.

Increasing the flow rate of fuel and oil does make for a faster aluminum melt, but with iron, there is no overcoming the time it takes to bring my large furnace mass up to temperature, and I am guessing that the iron needs the high temperature radiant heat reflected from the walls to the crucibe, and that radiant heat is only generated when the wall is approaching white hot.

Burning X amount of fuel (enough to melt iron) requires Y amount of combustion air, and so it seems that you are going to get Y amount of air out the furnace lid opening.
Short of some sort of heat recycling scheme, I don't see any way around having Y amount of air and the heat associated with it going out the flue.

 

He made his burner from a piece of heavy wall stainless pipe and it does not have a lining. His entire furnace is also stainless.

Porositymaster has another video of his Ursutz burner running outside the furnace, and "oil burner" makes the statement "Far better way of doing the job IMHO and I have a spray burner for comparison and balanced viewpoint".
This is pretty humorous; there is no balanced viewpoint; it is one burner or nothing, but that is another story.

But porositymaster has proven that the Ursutz burner does work well if built correctly in stainless or refractory, and he has over 200 iron melts to prove it.
Don't be fooled, some johnny-come-latelys would claim this burner as something new that they came up with, but it has been around long before them.
I have not seen any video on y-tube that shows how to correctly build a Ursutz burner for a furnace setup. Blowing out big flames does not mean a burner will work with a furnace.

I built a larger Ursutz burner, and could not get it to do anything, so you have to pay really close attention to details to get it right to prevent pulsing and to allow it to work correctly.

I watched Clarke run his burner at Soule in November, and he easily started it without propane (running on diesel), and he easily melted iron with it, as he always does.
The video above of him starting on propane is an old one; he no longer uses propane to start.

But ironman has a standard drip-style burner, and his works as well or perhaps better than Clarke's, without the problems associated with the Ursutz burner such as burner degradation from the hot temperatures, and without the bulk/weight and radiant heat.

Clarke stated that he had to dial his burner back because it was destroying his furnace lining, and shortening the life of his crucibles dramatically.
So there is a limit as to how fast you can melt iron, assuming you want your furnace and crucible to survive.

For me right now I will stick with my siphon-nozzle burner, but at some point in the future I may switch to an ironman-style drip burner. Note that the ironman burner is not just a standard drip-type like the Brute, although they are similar. The ironman burner drips the fuel at the furnace/burner junction, not back in the burner tube.

I just don't want to deal with having to rebuild a burner frequently as may happen with the Ursutz, and there are some real benefits to having a very lightweight burner (ironman-style) as far as carrying it in and out of storage, and just handling the thing.

Edit:
Here is another one of Clarke's burner videos. Clarke has made some minor modifications since this video to stop the pulsing. Little details matter a lot with the Ursutz burner.

 

Thank you for your comments.

What I have found in the many years of casting is that someone can make a furnace work and then someone will come along and say that is not the way I do it but both furnaces work really well. For most casters they use what they can find locally and cheaply. Another factor is experience, they may not know of other methods and materials. For me I have made a lot of furnaces over the years and each one is made to correct shortfalls in knowledge and materials. If you want to get more serious I had to spend a lot more time and money to get the results I lacked in the last furnace.

As I have a large shed all pouring is done under cover so the concrete will be dryer, as Robert said I should have hosed down the floor before pouring.

 

Quote "What I have found in the many years of casting is that someone can make a furnace work and then someone will come along and say that is not the way I do it but both furnaces work really well. "
Does this apply to degassing methods too Ironsides? Why not make a video showing why their furnaces do not work?

 

I start my burner without propane preheating. Jet-a is easy to light... just saying....

 

No it does not. Have a look at my latest video debunking degassing with sodium carbonate

 

where did the above 2 videos go?

 

"Where did the above two videos go?"

Somehow big-G or whoever hijacked my email account and renamed it to the same name as my G/Y-tube account.
All my business emails suddenly appeared with my G/Y-tube account name, and my clients were saying WTF (pardon my french, but I was saying it too), and all my company email was getting deleted by their spam filters.
Nothing I did could get it straightened out, so I had to delete the G/Y-tube account.

If I can figure out how to start another Y-tube account without having it link itself to everything else I have, I will do so, but otherwise no.
The more I use the net, the less I like it, and especially anything to do with big-G.

Edit:
Not to choose sides in the above, but I used washing soda for degassing and also noticed no effect at all, and I did this independently of anyone else.
The blob of washing soda simply rose to the surface; no bubbling or anything.
I tried it several times.

If it works for some, then more power to them.
Perhaps I am doing something wrong. I did use real washing soda, not baking powder, and I did heat it prior to use to drive out any residual moisture.

I have not had a lot of trouble with gas in aluminum, but I overheated some aluminum once and noticed some microporosity.
If it becomes a problem (microporosity) I will probably try either nitrogen or argon.

I have heard a lot of pro's and con's about the size of bubbles when using either of the two above gasses, and some claim that the larger bubbles add more gas than they remove.

I noticed that jhenise seemed to use coarse nitrogen bubbles, and his cylinder turned out very nice, but that is not to say there was no microporosity in it.

It seems like you could just add a lid over the crucible while you are applying the nitrogen/argon, and create a blanket of inert gas inside the crucible, so coarse or fine bubbles would work.

The commercial units use a motorized affair that makes very fine bubbles, but I am thinking a crucible cover would work just as well, and would eliminate the need for a motor.




The lance is graphite
I wish someone would run some tests on one of these without a motor, but with a crucible lid cover.





Here is Jeff and his degassing rig.
I think he mentions using argon.



This is a link to Jeff's motorcycle cylinder thread (for reference). I don't see any visible porosity.
http://www.alloyavenue.com/vb/showt...racing-cylinder&highlight=motorcycle+cylinder