Back yard foundry casting iron.

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100model

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I watched this video about some one making a crazy amount of cores for a iron cylinder casting. This video would have to be the best one I have watched all year. If you are thinking of using cores in your model engine this is a must watch.

 
That is an impressive casting, especially for iron.
I did not see him add any ferrosilicon, so the thin spots may be a bit hard (perhaps he added it and I missed that).

His cores came out easily.
I was a bit surprised at that, but apparently epoxy breaks down pretty easily at iron temperatures.

One trick I learned from looking at the Soule Speedy Twin engines is the use of chaplets.
The Speedy Twin has three passages that cross the engine from side-to-side, and they have to be precisely located in the upper chamber of the engine, so a number of chaplets are used to secure these passages.

I went out and looked at my Soule Speedy Twin block, and the chaplets are visible in strategic locations where the pasages are located.

The chaplets become part of the casting, and are imbedded permanently in the casting.

These are not my images.

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Fancy Chaps those. The smaller caster can get away with a couple of old style cut nails as seen here poking out the bottom of this casting. These supported the core that forms the water space which also had large coreprints to support the top where the water space is open. You can see at the bottom of teh slope where iron has flowed between core and the cavity left by the print.
 

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You should try epoxy one time and maybe you will like it.

The thing about the 3-part resin binder is that you can easily control set time by varying the catalyst.
On a hot day, I use a bit less catalyst, and on a cold day, a bit more.

And for a complex mold, I increase the set time.
For a simple mold, I can work fast and use a 5 minute set time.

Being able to vary the set time is very handy, and you can make a lot of molds very quickly due to this.

Epoxy seems to be a good substitute where resin-binder is not available, and it seems to work very well, but not sure about set times, but it would seem you could increase the amount of hardener to make it set faster.

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As with most 2 part systems you can just vary the amount of hardener to alter setting time and allow for ambient temp no different to what you are using now. I do it with Bondo, Fibreglass resin, etc.
 
Epoxy seems to be a good substitute where resin-binder is not available, and it seems to work very well, but not sure about set times, but it would seem you could increase the amount of hardener to make it set faster.
Where I live there is no chance of getting proper foundry sand resins in small quantities. I can use a epoxy core in 60 mins by using a hair dryer or one of those cheap electric room heaters. Another quick way to harden it is to put it into a microwave oven.
 
The fumes from burning off epoxy are awful, and even worse they get into all the sand and make it stink forever after.

It breaks down easily at aluminium temperatures, my epoxy cores basically just wash out.

I started using a local brand of epoxy that is made from glycerol rather than bisphenol A. The fumes are far less noxious, and performance is no worse. But I think I want to switch to sodium silicate for cores where that is possible.
 
I watched this video about some one making a crazy amount of cores for a iron cylinder casting. This video would have to be the best one I have watched all year. If you are thinking of using cores in your model engine this is a must watch.


Thanks for showing this vid. Fascinating stuff and that guy sure has a ton of patience and dry humour to add!
 
Speaking of putting it in the oven reminds me of the old foundry book I have that talks about various formulas for making cores involving molasses or other ingredients - can't remember what all now, but it sounded a lot like baking! :)
 
The Soule "Speedy Twin" was the workhorse of the lumber mill industry, driving the sawmill carriage.
Luckily the Soule factory and foundry was saved, and converted into a museum.
The core dry-out ovens are still in place at Soule, as is the big multi-story cupola.
I think the Soule cores were of the linseed-oil variety.
I have seen some of them, and they are very tough and durable.

The semi-circle long channels held round cores.
The large box with the slide rails is one of the core ovens.
The larger cores were rolled into the oven on a cart (on the left), and the round cores slid into the oven on tracks.
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I believe the last Speedy Twin was manufactured in the late 1950's.
I am not sure how old the cores in these photos are, but I would say some are close to 50 years old, and a close inspection of some of them shows that some are still usable I think.

And shown is the machine that makes the round cores; an extruder-type machine.
Changing the die size would allow round cores of multiple diameters to be made with the same machine.

And some of the chaplets that were used extensively to support the complex steam passages that are found in the top of a Speedy Twin steam engine.
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Speaking of putting it in the oven reminds me of the old foundry book I have that talks about various formulas for making cores involving molasses or other ingredients - can't remember what all now, but it sounded a lot like baking! :)

I've tried it, it smells like baking too ! Quite pleasant actually

Regards Mark
 
Thanks for posting the video. Very dense information Watched a few of his other videos
I did see he uses sodium silicate for aluminium castings, changing to epoxy for iron work as the sodium silicate sets to hard. - I have seen remedies for this problem.

Interestingly in the story of designing the cosworth v8 they mention the problem of core sands not turning to free sand when cast.

Can I just say…. That has to be most convoluted method of mixing epoxy I have ever seen!!

In my past life making model airplane Molds I made a lot of epoxy sand as mold stiffener/backups. It was always wiser to mix more than was needed- the cost penalty was low compared to the results of a poor mix result. We also put colouring in the epoxy to see what had received the epoxy. When dealing with very low ratios metho/ethanol was added in low ratios to make the epoxy flow like water. Thinning with metho even works with 2 part 5minute so that you can wet out glass cloth sets really fast 😱😱

Cheers Jeff
 

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