Member postings for PatJ

Some commercial furnaces have dual burners, with burner tubes located 180 degrees apart.

I decided to try this arrangement, but unfortunately I still had no idea how to tune foundry burners, so I was unable to determine if this burner arrangement worked faster/better than a single burner.

The velocity of the combustion air with dual burners is reduced by 1/2, and so the flame produced by two burners is much more even, and the flames begin lower in the furnace.

I discovered ferrosilicon, and so I cast some ingots in gray iron.

The cut and broken small ingots appeared free of chill, or hard white spots.

This was my 4th iron pour, and I was not yet comfortable with pouring iron.

I didn't know how much ferrosilicon to added to the melt, and too much ferrosilicon causes excessive shrinkage and sometimes hot tears.

And I learned that you do not need to clean scrap iron before you melt it.  A buddy of mine demonstrated melting scrape iron that had perhaps 1/2" of heavy corrosion on the surface, and he made perfect castings with it.

If the ingot molds are cleaned, the iron will stick to them, and thus the reason to allow your ingot molds to rust.

If the ingot molds are not preheated in the furnace exhaust stream to about 600F prior to pouring ingots, the slight residual moisture on the surface of the molds will flash as you pour the iron, and the iron will explode out of the mold (don't ask me how I know this).

Edited By PatJ on 04/07/2022 09:21:41

I cast two more bases in 356 aluminum, and each turned out perfect.

Results:

Success, and it all seemed easier and more routine at this point.

No problems at all.

I got the wise idea I would temper the aluminum bases to an approximate T6 level, and so I bought a pottery kiln that did not have an automatic regulator on it.

I cracked the lid to maintain the internal temperature while the aluminum parts were being tempered, and the radiant heat from the elements melted the sides of my two green twin bases.

The remainder of the parts did survive the tempering process (which is close to the melting point of aluminum), and they were noticeably less gummy than untempered aluminum 356 castings.

Sort of a story of three steps forward, and two back, but I was learning with every mistake.

A T6 temper is a two-step process, with a higher temperature step, water quench, and then a lower temperature step.

Results:

I was pleased with the approximate T6 temper on aluminum 356.

I am adding an automatic temperature regulator to the kiln.

The good thing about casting your own engine parts is that if you don't succeed, you can just cut them up and remelt them again, so you basically have a relatively infinite number of chances to get it right.

Edited By PatJ on 03/07/2022 19:49:09

Here was another use of the too long runner layout, this time with aluminum 356.

I intended to make a permanent metal flywheel pattern half, and so I left off half of the flywheel pattern for these castings.

Results:

I got quite a few usable parts out of this melt, but the runner is about twice too long, and I don't think I used this flask layout again.

I decided to continue this build in aluminum, since I did not have a solution for the chilled thin iron parts yet (I had not yet discovered ferrosilicon).

I was getting pretty decent surface finish at a 1,350 F pour temperature.

This was before I discovered ceramic mold coat.

Edited By PatJ on 03/07/2022 19:35:40

Another aluminum 356 green twin base casting.

Result:

Success but with a few air bubble defects caused by failing to vent the high points of the mold.

I purchased a MIFCO aluminum/bronze pyrometer, and used it for this pour, and so my pour temperature was exactly correct (1,350 F). I was still using a welded steel crucible, which is said to contaminate aluminum melts to some extent (probably not significantly).

I added the adjustable damper to the combustion blower intake, to control the amount of combustion air entering the furnace.

I was still using the very oversized burner.

I started using a pan to catch metal spills.

Edited By PatJ on 03/07/2022 19:25:33

Here is another aluminum 356 green twin base casting attempt.

I recall initially purchasing an inexpensive pyrometer to use with aluminum, and It seems like at some point it stopped working.

I don't see a pyrometer in use for this melt, and so I have to guess that I did not use one.

Results:

Another pour too cold, with partial mold fill, and lines where the two molten metal wave fronts began to solidify before they met.

Edited By PatJ on 03/07/2022 18:47:44

Here is round #2 with the same mold.

Resin molds will keep for perhaps 30 days or more if you keep them dry.

Result:

I dropped back to using aluminum, and the result was a very decent aluminum base casting.

There is a bit of flash on the nose of the casting, which was a result of the bound sand chipping off at that location when I pulled the pattern. This type of flash defect is not a problem, since you can just grind it off.

I used two runners, and two gates that were somewhat wide and thin.

This arrangement worked well.

The mold is down-filled, which is against one of John Campbell's 10 rules (no waterfall fills).

I think I used an upwards fill for later castings of this piece.

I used small holes in the high points of the cope mold, to vent off air that gets trapped in the mold.

Many will tell you vent holes are not necessary since the sand will absorb any air, but resin molds need vents since they really don't pass the air, and you will get a large trapped air bubble defect if you don't vent the high spots of the mold.

Edited By PatJ on 03/07/2022 17:41:11

New burner design, poor furnace lid lifter design.

I attempted to cast the green twin base in iron on this attempt.

I was under the impression that if a medium-sized oil burner was good, then a BIG oil burner must be much better.

This was a very bad assumption.

The combustion air blower was a sawdust collector blower, and the burner nozzle was a 4" diameter steel pipe with two siphon nozzles inside of it. The design was experimental, and so I used some PVC pipe for some of the burner tube. For a permanent burner design, one would not want to use any PVC.

As usual, I stumbled blindly ahead, still being totally ignorant of combustion dynamics as related to a foundry furnace.

My first iron furnace was also a bumbling affair, with an extremely high mass, a lid that was 5 times too thick, and a lid lifter vertical shaft that was supported by a band around the top of the refractory.

Multiple blunders.

The refractory expanded when it got hot, causing the band to slip and rotate, binding the lid lifter, and jamming the lid open just enough to prevent removing the crucible.

This was a miserable and bitter failure for me, and I lost a good Morgan B30 crucible as a result.

Good thing I was determined to learn iron or die trying, else this experience would have finished my desire to learn how to cast gray iron.

Luckily the mold was untouched, and so could be reused.

I was making progress though, and the resin-bound mold was a very nice design.

You can see a pouring cart that I made by adding wheels to a pouring shank.

I have gotten a lot of comments about how the wheels should have rubber tires on them, not bare metal rims, but if you have ever run a foundry, you would understand why you don't want rubber or plastic anywhere near a hot furnace or crucible.

Lessons Learned:

A small well tuned oil burner operates much hotter than an oil burner and combustion blower that is sized too large for a given furnace, such as the burner used during this melt.  This huge burner ran much cooler than my much smaller first oil burner.

I also notice that I had discovered ceramic filters, and was trying one of those with this melt.

Since I did not know how to tune my oil burner at the time, my iron was not hot enough to flow through a filter like this.  I have since redesigned my runner system so that I do not need a filter (more on that later).

Edited By PatJ on 03/07/2022 17:29:08

The 3D printed patterns for the green twin flywheel were printed at a commercial business, and were a bit on the fragile side.

I decided to make permanent metal patterns for them, using red brass.

The mold was sodium silicate I think.

The furnace was a small stacked insulating fire brick affair, that disintegrated the very first time I used it with an oil burner.

This melt used a naturally aspirated propane burner.

Results: Failure. The melt was too cold, and so the mold did not fully fill.

I was not versed on riser size or location either at the time, and so everything was guesswork.

Did not seem to be as much gas in the red brass as there was in the yellow brass.

One more addition to the cluttered "casting failure wall of shame" collection.

Safety Note:

Once again, don't operate a furnace anywhere near a house, and not near anything plastic either.

Don't do dumb stuff like I did in the beginning.

Here are the casting results from the above iron pour.

The flywheel casting turned out perfectly, but the remainder of the castings were dreadful, and unusable.

I discovered the alloy "nocutium", which is slang for thin gray iron without ferrosilicon added, that cannot be cut even with a carbide bit. It is basically gray iron that solidifies like tool steel before the graphite has time to disperse in the casting.

I took off all the teeth on a new Portaband saw blade trying to cut the chilled iron, and that was definitely a "what-the-flock" moment.

Any of these castings that were over about 3/4" thick did not need ferrosilicon for machinability, and any parts thinner than about 3/4" thick were un-machinable.

Edited By PatJ on 03/07/2022 16:45:35

Using my standard "bull-in-a-china-shop" approach to learning metal casting, I continued onwards and upwards (downwards?).

I was introduced to resin-bound sand by the art-iron folks, and it looked very versatile, and worked well with iron, so I decided to try that.

I was not familiar with how to lay out patterns in flasks, and so I made one giant flask, with a very long runner.

This was yet another of many blunders.

I was able to use a few parts from this flask layout, but generally in every attempt, the metal froze before it went very far down the long runner.

This pour used my original heavy-mass furnace (don't build your furnace with a heavy mass), my original siphon-nozzle burner, diesel, and I think perhaps a shop vac output for combustion air.

Results:

I think the only usable casting I made with this pour was the flywheel.

The other castings were either partially filled, or hard as tool steel.

I was not aware that ferrosilicon needed to be added to thin gray iron castings for machinability when I made these castings. 

I still did not know how to tune an oil burner, and so it was strickly guesswork at this point.

All of these castings were for the green twin oscillator that I was building.

Again, the tall sprue and risers were totally unnecessary.

Safety Note:

Never operate a furnace near the house/garage like I did.  I cringe sometimes looking back at these old photos of the early days.

Edited By PatJ on 03/07/2022 16:27:16

Edited By PatJ on 03/07/2022 16:28:16

Here is another attempt at the brass plaques.

I may have used Naval Bronze for this one.

I was under the false impression that the sprue and riser had to extend up above the top of the cope, and have since learned that this is not necessary.

My runner/gate system was becoming more refined.

And I discovered commercial foundry sand named OK85, which is a fine dry sand.

I also discovered sodium silicate as a binder, and so the entire mold is bound with sodium silicate.

Results: The results of this attempt were fair, but not great.

I did not use a degasser, and these brass castings tended to have a lot of small gas bubbles in them.

Brass and bronze turned out to be far more difficult than I imagined, and I consider casting good brass/bronze parts much more difficult than casting gray iron.

Thanks Dave, I really was about to throw in the towel before I figured out iron.

If it were not for the guy from Australia (goes by the screen name ironsided/luckygen, etc) and another local buddy of mine who started doing iron, I probably would have given up.

This story goes on forever, is the reason I broke it out from the other thread.

Noel-

My welds look bad, but they are solid. I have some really good all-position 6011 rods, and I leave quite a bit of gap so as to get a full penetration weld. I have never had any weld fail, so don't let the looks deceive you.

The slag has not been chipped off the weld yet, is why they look so rough.

My first furnace used a mild steel shell, and they are prone to corrosion, especially if left outdoors.

I should have bought a stainless 55 gallon drum for a shell, but hindsight is 20/20.

All of my foundry equipment is most definitely function over form.

My goal is to repeatedly make perfect iron castings, and since my fabrication time is very limited, I focus on the end product casting.

There was a bit of beer left over in one keg, and it looked and smelled to be drinkable, but I reluctantly poured it out.

It is great to see all these foundry threads. I have long dreamed of roping more folks into this hobby.

It is not necessarily easy, but loads of fun for sure.

.

Edited By PatJ on 03/07/2022 15:46:43

Some great casting work here.

Most impressive.

I have not gotten into the bronze work yet, but I am headed that way.

So far for me it has been mostly aluminum and gray iron, with a few haphazard brass/Naval Brass melts.

Furnaces can be relined and/or patched without too much trouble.

I will post the latest methods and materials I use in this post.

I have a long story going in another thread about methods and materials that should not be used (LOL).

I am somewhat of an expert at what NOT to do with a foundry.

.

Here was another attempt at the boat plaques.

I think this was an open-face pour.

Resut: Total disaster. I forget exactly what happened; perhaps the crucible slipped in my poorly constructed pouring shank.

A buddy of mine in Canada asked me to cast a plaque for his UK canal boat.

I needed foundry experience, so I decided to try and cast it in brass.

I had heard about the zinc fume danger when melting brass, so I wore a powered respirator.

Results:

The results were sub-par in my opinion.  I consider the plaque with the larger letters a marginal success, and the plaque with the small letters not acceptable quality.

Lots of zinc fumes.  This melt sort of cured me of the desire to pour brass.

I build a soft-fire-brick furnace for this small melt, and used propane for fuel.

Edited By PatJ on 03/07/2022 11:26:32

Thanks Dave-

I get asked that question a lot.

I fear the moisture that would be in the sand more than I fear the concrete exploding.

I have spilled a lot of metal including iron on my driveway, and since it is rather old concrete, it does not explode.

Spilling molten metal on wet sand could definitely explode, and you would only need a slight amount of moisture in the sand.

I know of an iron caster in Australia who has poured iron over concrete for 20 years, with no sand, and he agrees with me that sand is not necessary.

I have seen someone spill aluminum on some relatively new and hard concrete, and it did spald the surface.

I also saw someone use concrete to build a furnace, in lieu of castable refractory, and that furnace did explode violently.

The sand would probably serve more as a protection for the driveway, but my driveway is not so great, so I don't worry about it. And sand gets tracked everywhere, and gets into everything, and so I never use it.

Glad you like the posts. I have learned as more from looking at casting failure photos then from looking at casting successes. With casting failure photos, you can sometimes identify what is causing your problems.

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Having had some limited success with casting 356 aluminum, I decided to set my sights on casting gray iron.

I made my own siphon nozzle burner using a cutting torch tip, with the oil flowing through the center tip hole, and the compressed air flowing through the outer ring of holes.

This burner actually worked very well, but unfortunately I had no idea about what the optimum fuel/combustion air/compressed air levels where, and so I literally just stumbled through this melt with blind luck.

This was my first iron pour, and I used petrobond.

Petrobond can be used sometimes with iron, but it does not stand up to iron temperatures well, and so I did have a few sand inclusions in this casting, which I filled with JBWeld.

Result:

For a first attempt at an iron pour, I considered this a success, with a few defects that could be repaired.

I opened the mold while the iron was still hot (after removing my facemask), and the cloud of smoke burst into flames just as I leaned forward to look at the casting. I saw the flames coming and closed my eyes, and that is the only reason they don't call me Stevie Wonder now. Petrobond smoke is highly flamable; remember that.

The iron machined easily, even though I did not use ferrosilicon, being unaware of it at the time.

I made a pressurized diesel fuel tank from a NEW 40 lb propane tank (don't cut or drill into a used propane tank; it will explode), and this helped stabilize the burner.

I went to the used sporting goods store and purchased several weights to use on the top of the flask.

Crucible was a Morgan Salamander Super B30 (bilge shape).

Iron was Class 40 iron bar stock.

Fuel was diesel with home-made siphon nozzle burner.

Edited By PatJ on 03/07/2022 10:24:45

Edited By PatJ on 03/07/2022 10:25:28

Another green twin aluminum casting attempt.

Result: This one I consider a partial success, but with some heavy flash, which is most undesirable.

I see some shrinkage in places along the rim too.

Edited By PatJ on 03/07/2022 10:05:30

Another attempt to cast the green twin base.

I was still making rookie mistakes.

This time the melt was too hot, and so the metal degraded the petrobond, and ruined a lot of the surface finish.

Result: Failure, very poor quality surface finish, but complete mold fill.