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ajoeiam

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I am glad to share, and hope others can get into the hobby, or improve their methods perhaps if they are already in the hobby (we have several very talented backyard casting folks right here on this forum).
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Unfortunately the Alloy Avenue forum stopped working a year or so ago, and a lot of information was lost.
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I checked using the wayback machine (your search term) and it seems like there were a lot of 'snaps' (snapshots) of the forum.
You would be able to tell if everything is still there but to me it looked like everything was.
My problem would be that I would have to page through each tread to find what is useful and that's time consuming!!!!

Any suggestions on highlights or things to look for?
 

SmithDoor

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GreenTwin !
Thanks for sharing !!
Maybe I will build a small smelter to test
At time a foundries was simple.
They locate the foundry witch had good molding sand.
The furnace was just stack of bricks and used coal or charcoal AKA Blacksmith forge. The curable was just a household clay pot.

Today most use think oil bonded sand but large foundries still use water not oil.

I started a thread using Sodium Silicate with great for just few parts needed for model engine.
It is very strong and buy all materials from local stores.

Any can melt aluminum in simple backyard BBQ.

Patterns are still same as clay sand but less is need.

Hope this helps

Dave
 

minh-thanh

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Hi Dave !

Thanks for informations .
I have read a lot about casting here , watched many youtube videos about casting , but the Big Problem is not practice
I want to cast some parts for the engines I will make - just a few parts - like the picture attached
Build a small smelter - cast a few small samples - to practice before I can cast something more complex

Part15 EX - IN 1 Pipe.jpg
Part15 EX - IN 2 Pipe.jpg
 

abby

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If you are hoping to eventually cast something as complex as the above manifold then forget sand moulding , investment casting is the way to go.
Although some extra equipment is required and the process costs more , the learning curve is far less steep and results are easily achieved which far outway anything that the home sand foundry could produce.
This is a very simple steam manifold for a 5" gauge railway engine cast in red brass (gunmetal)

DSCF5168.jpg


DSCF5167.jpg

To cast this in sand would require core boxes to produce cores for the internal spaces as well as patterns .
As an investment casting the cement flows inside the hollow wax pattern to create the cores , this makes the production of such parts quite easy.
 

minh-thanh

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abby !​

Thanks for your opinion !
There is a problem: I only cast a few parts so I don't want to invest too much money
 

GreenTwin

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I checked using the wayback machine (your search term) and it seems like there were a lot of 'snaps' (snapshots) of the forum.
You would be able to tell if everything is still there but to me it looked like everything was.
My problem would be that I would have to page through each tread to find what is useful and that's time consuming!!!!

Any suggestions on highlights or things to look for?

I was on Alloy Avenue (backyard casting forum) from 2011 to about 2017, and I read everything that was posted, daily, for about 8 years.
In the beginning, people were trying a lot of different methods/materials/techniques, and there was not so much a consensus about what worked and what did not work.

One guy who was learning how to cast gray iron was called "scavenger", and his posts were very interesting, since he poured a lot of iron for about 2 years, and he tried quite a few furnace and furnace lid designs, as well as burner designs.

The racing motorcycle cylinder castings by Jeff Henise "jhenise" were very impressive.

There were a lot of failures by myself and others over the years, and it became important to understand why a certain process or technique failed, and everyone weighed in on how best to do things.

Alloy Avenue was somewhat of a collective thing, group learning over time.
If you have a particular interest, such as "lost wax", or "investment casting", you could perhaps do searches for that, if searches work on the wayback machine.

I tried many types of burners and burner configurations, including siphon nozzle, drip-style, and Ursutz oil burners, propane burners, large burners, small burners, two siphon nozzles in a single burner tube, two siphon nozzle burners mounted at 180 degrees on a furnace, combination oil and propane burners, etc.

In the end, I decided to use a siphon-nozzle burner with diesel as a fuel, and I really like the controllability (wide operating range), and the fact that it will operate down to at least 34F without any problems with the diesel fuel being too cold, etc.
A siphon nozzle burner will light instantly using diesel, and no propane preheat is required, and can output full power without any warmup.

I still use a propane burner for small aluminum melts.

Several backyard casting folks use drip-type oil burners, but I could never get any significant fine control out of those, and they don't operate as smoothly and consistently as a siphon-nozzle burner.

Every type of homemade refractory was tried, and the consensus was finally reached that commercial refractory was well worth the expense, and it will typically hold up well over time.
I use a Mizzou 1" thick refractory hot face in my furnace.

And another big advantage to that forum is you could post your casting defects, and folks could generally zero in on what type of casting defect it was, and tell you how to avoid those defects.

The moderator for the Alloy Avenue forum was a mechanical engineering student named Ben Baker, and wrote a backyard casting guide, which is a pretty good resource in my opinion.
Ben's book is not the final word in backyard casting ideas, but is definitely a good start, and is free.


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GreenTwin

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Here is a pretty good summary of common casting defects.


Casting defects that I have experienced include sand inclusions, when I used Petrobond with an iron casting, and the sand eroded due to the iron temperature and metal velocity, gas bubbles in aluminum castings, caused by overheating the aluminum and holding the aluminum for too long at elevated temperatures, and hard spots in thin gray iron parts due to a lack of the correct amount of ferrosilicon, and cooling that was too rapid.

I have seen hot tears in other's castings, and that can be caused by uneven solidification in the mold, where one part of the casting solidifies before the other, and thus metal is drawn across the mold from the hot part to the cold part during shrinkage/solidification.

I have seen people use too much ferrosilicon in iron, and this causes excessive shrinkage and hot tears.
You only need a slight amount of ferrosilicon in gray iron.

Pouring at too high of a temperature is probably the #1 cause of poor surface quality on castings.
The pour temperature should be as low as possible while still allowing full mold fill.

I often seen interrupted pours on youtube, where someone begins to pour metal down the sprue, then pauses for a fraction of a second (for whatever reason), and then begins to pour again. This should always be avoided.

And people often fail to keep the sprue full, and thus they entrain air into the metal stream.

You should always try to avoid any waterfalls, ie: keep the lip of the crucible as close to the top of the sprue as possible.
I often rest the crucible on the top of the mold when pouring, to eliminate almost all of the vertical column of molten metal.

Youtube backyard casting folks can often be seen vigorously stirring their aluminum melts, which is about the worst thing you can do with aluminum, and this mixes all sorts of oxide bifilms, slag, etc. into the metal, which will show up in the casting as defects. One should NEVER stir aluminum melts. Heat aluminum as fast as possible to pour temperature (about 1,350 F), then a quick skim to remove slag, and pour immediately.

Degassing is seldom required for aluminum if you don't overheat the melt, and if you pour immediately after reaching pour temperature, before the metal has time to absorb gas.

I failed to vent the top of one mold, and it trapped large air bubbles, and ruined the castings by leaving two voids that were perhaps 2" across, and about 1/2" deep.
The high points of the cope mold (cope is the top half of the mold) should be vented with small holes, perhaps 1/16" diameter holes or even a little less.
Some say that greensand does not need to be vented, but why take chances with something that can be added so easily and quickly?

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minh-thanh

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GreenTwin !​

Thank you very much !!
After reading, watching, listening to advice......I think it's time to practice :) .
 
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