Author Topic: Casting a Model Westinghouse-Type Twin Steam Engine in Iron  (Read 9762 times)

Offline vtsteam

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Casting a Model Westinghouse-Type Twin Steam Engine in Iron
« on: March 20, 2022, 02:31:41 PM »
Yesterday I cast a block for a model Westinghouse style twin in iron. I'd tried this a few weeks ago with some questionable iron using an old pattern and without cores, just as an experiment to see if the iron would cast well. This second time around, I made a new corebox, and a baked sand core (mentioned in another thread). This time also I used brake rotor metal, which I'd tried successfully earlier in casting a lathe chuck back plate.

My furnace has been acting up a little for the last two casting sessions -- not sure of the reason why other than repairs to the lining lately, but I'm beginning to suspect the jet in my burner might be partially obstructed. Symptoms are, the furnace is harder to light, and  slower to melt. I was earlier getting phenomenal melt times of 20 minutes for a pour of this size. Now it's more like 40  minutes -- still reasonable, but I'd like to know the reason for the difference.

The other possibility is that disk rotor metal takes longer to melt. Or a maybe a combination of all of the above.

Anyway, I made up the mold and placed the core in it without any hitches. The facing sand was a little dry (I should have checked in advance). So there was a little breakaway/flash at the seams, but no biggie.

The melt took much longer than expected, as mentioned, and I took some pains to slag the melt twice and thoroughly. Perhaps too long with the crucible out of the furnace, or too cool in the melt, because when I poured the sprue filled and stopped accepting metal before the riser was full to the top. I don't think I've ever had that happen before.

But I was still hopeful because the riser had filled to well above the casting's height.

Here's the breakout about 4 hours after the pour. Notice how well the cylinder cores in the block have worked, and burned to black sand:
I love it when a Plan B comes together!
Steve
https://www.youtube.com/watch?v=4sDubB0-REg

Offline vtsteam

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Re: Casting a Model Westinghouse-Type Twin Steam Engine in Iron
« Reply #1 on: March 20, 2022, 02:34:44 PM »
I was pretty hopeful, the detail looked good and the core had worked perfectly:
I love it when a Plan B comes together!
Steve
https://www.youtube.com/watch?v=4sDubB0-REg

Offline vtsteam

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Re: Casting a Model Westinghouse-Type Twin Steam Engine in Iron
« Reply #2 on: March 20, 2022, 02:38:13 PM »
But nope, the metal just wasn't hot enough to fill the thinnest area furthest from the sprue. The riser had been closer to the sprue and in a thicker part of the casting, so it filled. I'm pretty sure this would have been a perfect part if the metal had been hotter. Oh well, next time.....

I'll relocate the sprue and give it two gates to either end of the thinner part, plus, of course, pour hotter.
I love it when a Plan B comes together!
Steve
https://www.youtube.com/watch?v=4sDubB0-REg

Offline tom osselton

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Re: Casting a Model Westinghouse-Type Twin Steam Engine in Iron
« Reply #3 on: March 20, 2022, 05:39:59 PM »
That is pretty close to working.

Offline awemawson

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Re: Casting a Model Westinghouse-Type Twin Steam Engine in Iron
« Reply #4 on: March 20, 2022, 05:52:13 PM »
Do you have any way of checking the temperature of the melt Steve?

I used to use a ‘disappearing filament optical pyrometer’ ,  basically just an incandescent filament run through a rheostat   Tweak the rheostat until the filament disappeared against the melt and read off the temp from the rheostat dial. Sadly when I dug it out a few weeks ago I found that it had succumbed to dampness and ended up chucking it out. 
Andrew Mawson
East Sussex

Offline vtsteam

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Re: Casting a Model Westinghouse-Type Twin Steam Engine in Iron
« Reply #5 on: March 20, 2022, 07:29:09 PM »
Andrew, I've actually got instructions for making one of those, which I downloaded awhile ago. I haven't made it yet.

But there's also the Terry Aspin method, which actually works if you pay attention to it strictly (I didn't this last melt because of a dumb belief that it had taken so long it MUST be ready) And that is, just look at your 1/4" dia steel stir stick. If you give the pot a poke or stir and there's a glob of slag or metal stuck to the end, it's not ready. If it comes out perfectly clean and coming to a sharp point like a pencil because it melted a little, well, time to pour!

Steel melts at a bit higher temp than iron, so it's a simple perfectly straightforward thermometer. You do have to pay attention to it though, for it to work. :wack:
I love it when a Plan B comes together!
Steve
https://www.youtube.com/watch?v=4sDubB0-REg

Offline tom osselton

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Re: Casting a Model Westinghouse-Type Twin Steam Engine in Iron
« Reply #6 on: March 21, 2022, 04:49:41 PM »
That’s what it says to check the temp in the metal casting bible by C.W.  Ammem

Offline vtsteam

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Re: Casting a Model Westinghouse-Type Twin Steam Engine in Iron
« Reply #7 on: March 21, 2022, 05:32:41 PM »
I had a point and a gob. Shoulda just been a point. I now think the point was from the prior melt. Gob shoulda melted off, point shoulda been shiny and sharp
Lesson learned: No gobs, period.
 :smart:
I love it when a Plan B comes together!
Steve
https://www.youtube.com/watch?v=4sDubB0-REg

Offline ironman

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Re: Casting a Model Westinghouse-Type Twin Steam Engine in Iron
« Reply #8 on: April 03, 2022, 10:11:14 PM »
[quote author=vtsteam link=topic=13496.msg162471#msg162471 date=1
If it comes out perfectly clean and coming to a sharp point like a pencil because it melted a little, well, time to pour!
Steel melts at a bit higher temp than iron, so it's a simple perfectly straightforward thermometer.
[/quote]
A low carbon steel rod will quickly absorb carbon from molten cast iron and it will lower the melting point so that is the sharp point that appears after 10-20 seconds  of stirring. If you hold that stirring rod above the crucible for 10-20 seconds it will not melt because the flame temperature is not hot enough. I do have a R type pyrometer and the final temperature before pouring is 1550C-1570C above the crucible which is just above the melting point of a low carbon steel.

Offline vtsteam

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Re: Casting a Model Westinghouse-Type Twin Steam Engine in Iron
« Reply #9 on: April 04, 2022, 08:36:43 AM »
Ahhh, interesting, Ironman, so you're saying that the best place to check (without a pyrometer) would be just above the crucible, rather than stirring the molten iron itself.
I love it when a Plan B comes together!
Steve
https://www.youtube.com/watch?v=4sDubB0-REg

Offline ironman

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Re: Casting a Model Westinghouse-Type Twin Steam Engine in Iron
« Reply #10 on: April 04, 2022, 09:29:37 PM »
Pushing a steel rod into molten cast iron is still the best way to test for temperature just do not stir it otherwise it will dissolve. If you pull out the rod and slag, iron sticks to it your iron is too cold to pour. Another way to test the temperature is to look at the crucible to see if is brighter than the molten cast iron, if it is it needs more time to get to pouring temperature.

Offline vtsteam

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Re: Casting a Model Westinghouse-Type Twin Steam Engine in Iron
« Reply #11 on: April 05, 2022, 01:29:06 PM »
Oh, okay, great tips Ironman. I'll be sure to check both next iron pour. :beer:

I have a couple questions about slagging. I know you slag in the furnace at least once -- I'm guessing just before adding ferrosilicon. What is the end of your slagging tool made out of? It looks relatively thin, and must be some heat resistant material -- stainless steel?

I find that in my furnace, the ITC HT-100 reflective coating soon gets covered with a brownish glaze -- I'm guessing from vaporized slag, mainly from slagging in the furnace. A little slag always escapes the slagging tool.

The brown slag glaze on the furnace walls reduces the reflective property of the HT-100 and melting time goes up from the initial very fast melts. I think my first few melts were 20 minutes long, now that are around 40 for the same 6 to 10 lb melts in an A6 crucible.

To try to see if I could improve that, I've re-coated the furnace with Satanite as a base over the blanket, and then a paint coat thickness of ITC-100 over that.

But, because of the slag glazing problem I'm wondering it the ITC 100 really is worth it on a foundry furnace (as opposed to a forge where people use it a lot), and maybe just the Satanite would give about the same results after the first few melts. It's much less expensive and also seems tougher and more heat resistant than the ITC-100.

Finally, speaking of looking at the crucible and iron to compare temps, I'm curious about what you use for eye protection. I see you use a face shield with a filter -- I've tried filters and it seems like a shade 5 is too dark for safe maneuverability, so I'm thinking of a shade 3 filter. What do you find works for you?

Thanks for all your advice and information over the years! I still have a copy of your early website from nearly a couple decades ago when I first saw it, where you were melting with oil, and also a cupola.
I love it when a Plan B comes together!
Steve
https://www.youtube.com/watch?v=4sDubB0-REg

Offline ironman

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Re: Casting a Model Westinghouse-Type Twin Steam Engine in Iron
« Reply #12 on: April 06, 2022, 12:27:22 AM »
Yes you are right it is stainless steel, 2mm thickness 40mm wide and is bent to a simple "L" shape. Welded to it is 6mm dia rod about 2 meters long. I do scrape off the slag just before adding ferrosilicon but I try to keep my hands as high as possible on the steel rod to keep them as far as possible from the exhaust vent. I try not to put the stainless too far into the molten cast iron as chromium absorbs carbon many times quicker than steel does. After about ten melts the stainless steel has absorbed enough carbon to make it brittle and also looks like swiss cheese so I cut that piece of and rebend another "L" shape. The stainless scraper part starts out at 200mm long but ends up a lot shorter after many melts.

I have never tried ITC HT-100 to coat kaowool and the same goes for satanite but I have heard a lot of good reports about satanite. I still have half a 25kg tub of zircoat and would love to try satanite but it will not be happening soon.

My face shield is a shade ten filter and is great for working around the furnace but when I get into my dark shed with my pouring trolley it is a blackout, way too dangerous. So before I push the trolley into the shed I put on cheap safety sun glasses which has a light tint and a clear face shield. I have tried lower filters but my furnace gets so hot and the glare hurts my eyes plus they are briefly dazzled which can cause a nasty accident. Here is a tip when using a shade ten filter, as soon as I don't need to look at the furnace I lift up the shield to see where I am walking.

That was not my website, I was featured on another metal casters website who took all  the photos.

Offline vtsteam

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Re: Casting a Model Westinghouse-Type Twin Steam Engine in Iron
« Reply #13 on: April 15, 2022, 08:58:34 AM »
Thank you again, Ironman.  :beer: I think the shade number on some of my headgear is off. I have some gas welding/brazing goggles from Harbor Freight that claim shade 5, but they are darker than the Shade 9 setting on my same brand auto-darkening arc welding helmet. Hard to see anything out of the goggles except the furnace barrel. Too hard to maneuver,  even outside

Actually I've discovered that the auto darkening helmet seems to work well for me in iron melting. At the lowest setting, it dims the open furnace enough not to be blinding, and when the furnace is closed it reverts to a light green shade that seems right for carrying the crucible to the mold.

I have a couple more questions for you if you have the time:

First, do you adjust your furnace for a neutral flame, or do you vary that a little either way?

Second, I remember that you use copper wire to lower additional iron into the melt. I'm guessing transformer wire from scrapped gear. Is there any advantage to copper wire vs thin ferrous wire (like thin uncoated florists iron wire -- which I happen to have -- I don't have any scrap transformers).

Thanks!

I love it when a Plan B comes together!
Steve
https://www.youtube.com/watch?v=4sDubB0-REg

Offline ironman

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Re: Casting a Model Westinghouse-Type Twin Steam Engine in Iron
« Reply #14 on: April 19, 2022, 12:02:39 AM »
When melting iron I adjust the flame to be slightly reducing.

The copper wire is from the field winding from a car alternator. I found through trial and error that if the wire is too thick it takes too long to melt so burning my fingers even though I have gloves on. If the wire is too thin there is not time to aim for the crucible and the wire melts too quickly.

Offline vtsteam

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Re: Casting a Model Westinghouse-Type Twin Steam Engine in Iron
« Reply #15 on: April 19, 2022, 08:24:48 PM »
Thanks again, Ironman.  :beer:

Ah,slightly reducing probably explains why you have so little loss in your pours compared to mine.  :clap:

I take it there is no problem with a small amount of copper in the iron melt. I guess the wire probably mostly vaporizes anyway. I'll have to experiment with the wire types I have and see what works.

If you get a chance, could you measure the diameter of your alternator field wire? That would helpful as a starting point for finding similar copper wire.

I'm going to give the Westinghouse engine block another try when I get another core made up.
I love it when a Plan B comes together!
Steve
https://www.youtube.com/watch?v=4sDubB0-REg

Offline ironman

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Re: Casting a Model Westinghouse-Type Twin Steam Engine in Iron
« Reply #16 on: April 25, 2022, 07:45:04 PM »
The wire I use is 1.15 mm Dia. Small amounts of copper do not matter in a iron melt. I look forward to seeing you to recast the engine block.

Offline vtsteam

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Re: Casting a Model Westinghouse-Type Twin Steam Engine in Iron
« Reply #17 on: April 26, 2022, 08:17:37 AM »
Great, thanks so much :beer: I'm glad you measured it as I imagined it was quite a bit finer. Now I have a good starting point. Here that would be 17 ga. AWG.

I'm re-thinking the corebox. The plaster of Paris version has a crack in it -- I can repair it, but I'm thinking now about fabricating or casting one in metal. Since I'm using a baked sand core for this engine, it would be convenient to bake the core in a corebox, or corebox half, unless that causes release/clean-out problems. Or I could  make a core plate for that, since I'm going traditional. Then the corebox could be wood, which is easy for me------- well, still thinking about it.

It's interesting to think about....making a corebox from the solid has pretty much the same shaping considerations as making a die, the alternative being molding it with some compound from a plug, eg. plaster, etc
I love it when a Plan B comes together!
Steve
https://www.youtube.com/watch?v=4sDubB0-REg

Offline vtsteam

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Re: Casting a Model Westinghouse-Type Twin Steam Engine in Iron
« Reply #18 on: May 03, 2022, 08:04:33 PM »
I repaired the plaster corebox and baked a new core in preparation for another go at the small Westighouse steam engine casting. This is really a test piece, rather than an engine I want to build at present. But it's an interesting challenge, and it helps me understand how to design a better engine pattern, core and corebox, and I can also try different types of scrap iron I have on it.

To me the ideal corebox for baked sand cores would be made of aluminum so you could not only mold it in the box, but bake it there as well. And the best aluminum corebox would be relatively thin around the core -- say 1/4 or 3/8 inches thick (6-9mm). That way it would heat up quickly, and also use the minimum amount of aluminum.

Plain Plaster of Paris is fairly resistant to heat, but is still rather delicate, and the temperature must be kept around 200F if the Plaster is to last for repeated use, when ideally you'd be able to bake at 350F. Also plaster coreboxes like the one below, poured into a containing box, are massive. That bulk plus the fact that plaster is an excellent insulator means extended bake times for the core.

I would think that an aluminum core box would bake a small core out like this one in about 15 minutes in a small toaster oven at 350F. The existing plaster box took about 45 minutes, and I still had to finish the ejected core for ten minutes at 350.
I love it when a Plan B comes together!
Steve
https://www.youtube.com/watch?v=4sDubB0-REg

Offline vtsteam

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Re: Casting a Model Westinghouse-Type Twin Steam Engine in Iron
« Reply #19 on: May 22, 2022, 01:51:59 PM »
After replacing the furnace lid with a new one built from scratch, I did a melt this morning. I think everything went right as far as I could tell, plenty of metal and it was hot enough. I melted 7 lbs even thought the casting only needed about 3. I useddisk brake rotor, and 11 grams of ferrosilicon was added. It took about a half hour to melt from a loaded cold crucible, and then another half hour to add more iron, slag the melt, add ferrosilicon and get it hot enough to pour.

Not sure why my earliest melts with this furnace this year were about half that time, but I'm starting to suspect the iron itself. I think the first iron I used was an easy melting variety, and the latest disk rotors are not. That might fit with disk rotor metal tending to chill easier, increased toughness and hardness. Maybe rotors are lower carbon. I dunno.

There was a fair amount of really thick chunky slag in this melt. Disk rotors in Vermont get a lot of salt corrosion --especially in the hollow ventilated part.

Anyway, here's the pour....nice and neat. The ingots, less so -- I need to level the base here better...
I love it when a Plan B comes together!
Steve
https://www.youtube.com/watch?v=4sDubB0-REg

Offline vtsteam

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Re: Casting a Model Westinghouse-Type Twin Steam Engine in Iron
« Reply #20 on: May 22, 2022, 02:58:32 PM »
While I'm waiting for it to cool, I broke one of the ingots on half to see what it looks like inside. Well, nothing like I've seen before...

I don't really know what I'm looking this time around for cast iron -- it's very uniform and silver, not white and not gray.

It isn't really chilled because I can file it, though it is tough. It was VERY hard to break. I had to go 4 tries with a sledge. Also it rang when it fell on concrete, In other words, it sounds like white iron, breaks like semi-steel, files like somewhat hardened steel.

Some new kind of animal....

The photo just doesn't show the shiny silvery quality...
I love it when a Plan B comes together!
Steve
https://www.youtube.com/watch?v=4sDubB0-REg

Offline vtsteam

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Re: Casting a Model Westinghouse-Type Twin Steam Engine in Iron
« Reply #21 on: May 22, 2022, 05:45:00 PM »
The shake out. Looks like the core did its work:

I love it when a Plan B comes together!
Steve
https://www.youtube.com/watch?v=4sDubB0-REg

Offline vtsteam

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Re: Casting a Model Westinghouse-Type Twin Steam Engine in Iron
« Reply #22 on: May 22, 2022, 05:48:24 PM »
Free of the sand the casting looks good:
I love it when a Plan B comes together!
Steve
https://www.youtube.com/watch?v=4sDubB0-REg

Offline vtsteam

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Re: Casting a Model Westinghouse-Type Twin Steam Engine in Iron
« Reply #23 on: May 22, 2022, 05:54:31 PM »
I cut off the runners -- they were in awkward locations and didn't respond well to a hacksaw blade -- chilled at the junction, so I used an abrasive cutoff wheel.

Otherwise I found that most of the casting filed well, with the exception of a couple of small chill spots. I took off most of the flash with a file, and roughed in some other areas just to see how workable it was.

I think I'll try annealing the whole casting tomorrow. No idea if this will work with this disk rotor metal, whether the general hardness is an alloy contribution, or whether like other types of cast iron, it will respond to annealing....guess we'll find out tomorrow....


Anyway, success on the third attempt at the Westinghouse Twin casting! :ddb:
I love it when a Plan B comes together!
Steve
https://www.youtube.com/watch?v=4sDubB0-REg

Offline tom osselton

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Re: Casting a Model Westinghouse-Type Twin Steam Engine in Iron
« Reply #24 on: May 22, 2022, 07:05:34 PM »
That is a good casting I would expect it to anneal with no problems.
Would coating the pattern with graphite smooth out the casting?

Offline vtsteam

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Re: Casting a Model Westinghouse-Type Twin Steam Engine in Iron
« Reply #25 on: May 22, 2022, 07:44:10 PM »
Hi Tom, the core was coated with plumbago (graphite), per Ironman's practice, and the facing sand had coal dust in it like his @ 4%.

It will clean up nicely if it anneals -- there's a generous machining allowance, particularly in the upper and lower flanges, and the bores are well undersized. There are no casting flaws apparent at all.
I love it when a Plan B comes together!
Steve
https://www.youtube.com/watch?v=4sDubB0-REg

Offline vtsteam

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Re: Casting a Model Westinghouse-Type Twin Steam Engine in Iron
« Reply #26 on: May 23, 2022, 05:39:10 PM »
Annealing worked. I simply put the casting back in my oil furnace, lit it up for a couple minutes until the casting was glowing a dull red, shut the furnace down, covered the exhaust port with a brick, and plugged the burner blast opening. Four hours later, I opened it up and took out the casting, which was still too hot to hold.

It filed easily, and the hacksaw, which skated before, now had no problem biting into the iron.
I love it when a Plan B comes together!
Steve
https://www.youtube.com/watch?v=4sDubB0-REg

Offline tom osselton

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Re: Casting a Model Westinghouse-Type Twin Steam Engine in Iron
« Reply #27 on: May 23, 2022, 06:08:44 PM »
She’s a beaut! What size crucible did you use? I’ve bought a extra #6 clay graphite for when I give it a shot but am thinking I’ll get a larger one later on. Now to find some Ferosilicon I’m pretty sure I saw some in Dads chemical collection otherwise ebay.

Offline vtsteam

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Re: Casting a Model Westinghouse-Type Twin Steam Engine in Iron
« Reply #28 on: May 23, 2022, 08:33:07 PM »
Hey Tom, I've only used a #6 and not run into anything yet that I couldn't cast, including a 7" chuck backing plate. 10 lbs is no problem, and technically it should hold 20 to the brim, but that would be nuts as far as I'm concerned.

I think 12 lbs is about the limit I'm comfortable with. To put it in perspective, this casting weighs 2 pounds 2 oz. If you multiply by three for sprue, riser, losses, and some extra insurance to pour in ingots if everything goes well, that gives you 6.6 lbs. I melted 7, and had a fair amount in ingots. I haven't felt the need for a larger crucible.

However one advantage I can imagine with a bigger crucible is that for smaller melts, they wouldn't require adding more cold metal during the melt, because you could pack a full charge in it to start with. This would probably cut the time to melt by 30% -- judging by my last melt. -- and fuel, too. I was thinking about that very possibility.

Too bad an A8 costs proportionately much more than an A6 or A10. Must not be a common size....but it would be quite a convenient one for me.

As far as ferrosilicon goes -- I'm tempted some time to try a session without it, and then annealing the casting to see if that works. Ferrosilicon can't add more carbon, so it mainly must control crystallization on cooling. If you could get a similar result by annealing, that would be a boon.

I've also been thinking that the time to anneal, would be for a prior session's castings, placed in the furnace after the present one has been poured, and the furnace shut down -- they stay hot for quite a while after. No fuel needed, that way.
I love it when a Plan B comes together!
Steve
https://www.youtube.com/watch?v=4sDubB0-REg

Offline tom osselton

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Re: Casting a Model Westinghouse-Type Twin Steam Engine in Iron
« Reply #29 on: May 24, 2022, 03:42:14 PM »
That’s nice to know about the #6 crucible I have my dads kiln in the basement so annealing isn’t a problem for me. I’ll have to dig out my furnace from the shed mind you first I’ll have to cut the grass and see if the quads battery charges. Patterns won’t be a problem I have dads in the basement for his steam engine.

Offline vtsteam

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Re: Casting a Model Westinghouse-Type Twin Steam Engine in Iron
« Reply #30 on: May 24, 2022, 09:41:49 PM »
Tom, what kind of steam engine? How big? Details, man!

Tom have a look at this video by Ironman using an A6 crucible -- he fills that thing to near the brim, 6.6 kg (14.6 lbs), and look how many castings he pours!

I love it when a Plan B comes together!
Steve
https://www.youtube.com/watch?v=4sDubB0-REg

Offline vtsteam

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Re: Casting a Model Westinghouse-Type Twin Steam Engine in Iron
« Reply #31 on: May 26, 2022, 08:55:58 PM »
Well the Westinghouse Twin casting has some hard spots, discovered after chewing up a couple mills. Very disappointing. I blame the disk rotor metal. Maybe different rotors have different compositions, but the one I used for this engine was tough to cast with -- took a very long time to melt, and was chilled even with .35% ferrosilicon. A subsequent trial melt of radiator metal took half the time, and produced nice gray iron with the same amount of ferrosilicon.

I should factor in, though, that the Westinghouse engine casting is pretty thin. Maybe the rotor metal would have worked better for a thick casting. Though going by the ingot, that was completely white (I think, now -- the fact that it looked silvery didn't mean anything). So I might have needed more ferrosilicon even for pouring a thick casting with it.

I've got another half dozen rotors -- from mixed vehicles, so I'm not sure if they will all behave the same. I'm wondering if I mix half radiator metal in with half rotor metal if it will get something with reasonable melt times and better softer iron.

As for the Westinghouse casting -- probably the best for that job would be straight radiator iron -- since that scrap is in thin castings to begin with, that might be a good match. But I'm a little tired of making cores, etc at this point, so it may be a few weeks before I attempt it a fourth time.

ps... After praising the A6 above, I actually went ahead and ordered an A10. I want to cast a faceplate for my new lathe, and that's going to take nearly 20 lbs of scrap iron. I skipped an A8, because it was only 10% cheaper than the A10 but substantially less capacity.
I love it when a Plan B comes together!
Steve
https://www.youtube.com/watch?v=4sDubB0-REg

Offline vtsteam

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Re: Casting a Model Westinghouse-Type Twin Steam Engine in Iron
« Reply #32 on: May 27, 2022, 09:39:13 PM »
Reboot on the third Westinghouse Twin casting:

I didn't have enough time before predicted thunderstorms today to do a full iron melt, so I thought I'd try annealing that last casting one more time. I was thinking maybe I didn't get it hot enough -- dull red, so this time I went for cherry red, and really let it have the full furnace blast. I also put a sprue and an ingot in there from that melt as test pieces -- to see if they changed.

When red hot, this time, I plunged them into a bucket of wood ashes for slow cooling.

This evening I'm really encouraged tio report that the ingot definitely went to gray iron, and the engine seems like it may have done the same. We'll know for sure once I get it on the milling machine. But I'm hopeful!  :dremel:

I love it when a Plan B comes together!
Steve
https://www.youtube.com/watch?v=4sDubB0-REg

Offline RussellT

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Re: Casting a Model Westinghouse-Type Twin Steam Engine in Iron
« Reply #33 on: May 28, 2022, 05:07:33 AM »
You have me wondering whether it might be possible to anneal some sash window weights.  I have tried machining them previously and found they were very hard.

Russell
Common sense is unfortunately not as common as its name suggests.

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Re: Casting a Model Westinghouse-Type Twin Steam Engine in Iron
« Reply #34 on: May 28, 2022, 06:02:22 AM »
I'd definitely give it a try Russell!  :dremel:
I love it when a Plan B comes together!
Steve
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Offline tom osselton

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Re: Casting a Model Westinghouse-Type Twin Steam Engine in Iron
« Reply #35 on: May 28, 2022, 02:32:43 PM »
I’ve been watching “ Windy hill foundry “ on YouTube and he seems to anneal everything that needs machining.

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Re: Casting a Model Westinghouse-Type Twin Steam Engine in Iron
« Reply #36 on: May 28, 2022, 04:28:52 PM »
Yup, me too, just working up from the earliest videos so far. Though he calls it "stress relief", which would make sense for larger castings, but doesn't for much of the small stuff he does. I think the real advantage is he's probably annealing which is a legitimate benefit since he uses disk rotors as melting stock. I see he adds a lot of ferrosilicon, too.

Maybe he gets better in the later videos, but wow, IMO he over-rams stuff in the early ones, and then you definitely need vents, which means more cleanup and rougher castings. On the other hand he doesn't seem to get any side packing near the pattern at all so he gets a lot of flash and breakaways.

I really think Ironman has got the most impressive molding finesse, and beautiful looking castings as a result. But Windy Hill is good fun to watch, and he has some good and interesting ideas (I like the long screw for pulling patterns, and his disk crusher is cool) and he gives a good idea of what's required for a small production business.
I love it when a Plan B comes together!
Steve
https://www.youtube.com/watch?v=4sDubB0-REg

Offline vtsteam

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Re: Casting a Model Westinghouse-Type Twin Steam Engine in Iron
« Reply #37 on: May 28, 2022, 07:26:47 PM »
Had high hopes for the second round of heat treatment for the third casting attempt, but milling showed it still had some hard spots on the thinnest part of the casting -- the lower crankcase around the base flange ( < 0.25", 6mm thick).

The upper flange machined nicely, and the exhaust boss did as well so there was improvement. But I have to face it, there's no saving this casting. For thin casting sections, disk rotor metal appears to have been a poor choice -- unless additional ferrosilicon might have made a difference. But .35% was already a substantial amount. I do think steam radiator iron might have been a better metal to use, and If I had done, the casting might have been successful.

But another possible approach would be not to core out the crankcase and bores at all, and just open out those spaces after casting. That might actually be easier anyway because coring leaves hard to remove inner surface sand inclusions and scale particularly on a small size casting. And those rough surfaces would requiring milling anyway. So there's not much savings in machining.

Also, small cylinder bores in a twin are unlikely  to be perfectly centered and aligned when cored, that makes a milling cutter the only way to adjust those locations. If machining a solid casting, however, the centers can be accurately located by drilling.

I think it makes sense to core larger cylinders because they can be more easily cleaned and bored afterwards, and you're eliminating a lot of excess metal in the casting, but these were only 3/4" in diameter. Better to drill that out from the solid.

So, one more lesson learned....well several lessons learned!  :coffee:  I may try a solid casting of the twin next.  :dremel:


I love it when a Plan B comes together!
Steve
https://www.youtube.com/watch?v=4sDubB0-REg

Offline vtsteam

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Re: Casting a Model Westinghouse-Type Twin Steam Engine in Iron
« Reply #38 on: May 29, 2022, 03:29:13 PM »
Fourth attempt:
1/3 Disk brake rotor iron
2/3 Radiator iron
increased ferrosilicon to 0.45%
no cores
About 8 lbs charge
Melt time 40 Minutes to pour

Slag was quite fluid and tended to reform quickly

Pour went well, 1 small ingot left over.

This ingot broken in half shows very fine grained gray iron throughout.

I love it when a Plan B comes together!
Steve
https://www.youtube.com/watch?v=4sDubB0-REg

Offline tom osselton

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Re: Casting a Model Westinghouse-Type Twin Steam Engine in Iron
« Reply #39 on: May 29, 2022, 05:05:22 PM »
That ingot looks good but the ferro silicon seems way high. It would be interesting to see how the two types of cast turn out with the regular amount of ferro silicon and I wonder if the fluidity of the slag is a indication of pouring temp or ferro silicon needed.

Offline awemawson

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Re: Casting a Model Westinghouse-Type Twin Steam Engine in Iron
« Reply #40 on: May 29, 2022, 05:12:07 PM »
I’d be very interested to find out the composition of the brake disks you’ve used, obviously there’s something in them that’s making them slower to melt so presumably raising the melting point as well as influencing the final casting properties. I wonder if they are actually a semi steel ?
Andrew Mawson
East Sussex

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Re: Casting a Model Westinghouse-Type Twin Steam Engine in Iron
« Reply #41 on: May 29, 2022, 05:46:40 PM »
Agreed Tom it's high. But I'd like a good casting first, then start reducing the ferro, and increasing the brake disk content gradually to see where the middle ground is:

Also remember, we already have tested single iron types with normal additions of FeSi:


1.) 1.34" dia iron bar, 100% radiator iron, (0.35% FeSi)  --> 100% gray iron.
2.) Westinghouse twin #3, 100% brake disk iron (0.35% FeSi) --> white iron ingots, and chilled spots in casting

Andrew, I wish I had your metal analyzer -- might explain a lot! And for sure the metal is longer melting (higher temp) than the radiator iron. The brake disk melt took an hour, the radiator metal took a half hour, and the latest pour of a combo took 45 minutes.

Of interest, not 15 minutes ago I broke up another disk rotor, and the inner rim bent for several blows of the sledge before breaking -- much more bending than you would normally see in thin cast iron. Ductile iron, perhaps???

What might also complicate things, guys is, I'm pretty sure these rotors (from different vehicles) probably vary in composition. So it may be hard to come up with a hard and fast rule for rotors.
I love it when a Plan B comes together!
Steve
https://www.youtube.com/watch?v=4sDubB0-REg

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Re: Casting a Model Westinghouse-Type Twin Steam Engine in Iron
« Reply #42 on: May 29, 2022, 07:09:51 PM »
Well the operation was a success, (gray iron), but the patient died  :bang:, Faulty riser position allowed a major shrink depression.

I should have known better. This particular engine pattern really needs a riser bang in the middle of the casting, right on top of the exhaust port boss. I've seen this particular problem before, and solved it. Not sure why I tried a different riser location -- I guess I just thought a really big one off of the casting would preserve the boss detail.

Here's a photo of the new 4th casting on the left with shrink depression (looks much worse than photo shows) and the third casting on the right, which had the riser on top of that boss and no shrinkage. The riser did kill the detail of the boss, but I could have whittled it back into shape. I'm going to guess that radiator metal also shrinks more than disk rotor metal -- I did get some shrinkage in the iron bar I cast. Oh well.....  More to keep in mind.

Sometimes I long to go back to aluminum casting. Iron is tough. But there is the thrill of really hot scary iron and a roaring furnace, and the reward ......some day....... of seeing what you want finally accomplished.  Uh...I hope.
I love it when a Plan B comes together!
Steve
https://www.youtube.com/watch?v=4sDubB0-REg

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Re: Casting a Model Westinghouse-Type Twin Steam Engine in Iron
« Reply #43 on: May 30, 2022, 09:03:25 AM »
Nope, probably not ductile iron. According to online sources, ductile has a lower melting point than regular gray cast iron. Probably not semi-steel either -- that's an old low grade of iron scrap mixed with steel, according to online defs. Unlikely to be used in rotors

One possibility is a modified gray iron with Titanium. Another possibility is "Automotive Malleable Cast Iron", which has the highest melting point of the common cast irons, lowest carbon, and produces a solid white iron that must be annealed @ ~ 1650F. At least in characteristics, that sounds like the particular brake rotor metal I had. If brake rotors were frequently of that type, it would also explain the Windy Hill foundry always kilning the castings.

Brake disk compositions do vary, so that one rotor may act completely differently than another. In fact it was the second rotor I've tried and I don't think that the first one I melted behaved similarly.

Modifying the rotor metal with radiator metal would raise the carbon, silicon, and phosphorus contents, and lower the melting temp. I could also try adding carbon itself -- similar to the way Ironman made cast iron from steel.

Much to experiment with and think about....  :coffee:
I love it when a Plan B comes together!
Steve
https://www.youtube.com/watch?v=4sDubB0-REg

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Re: Casting a Model Westinghouse-Type Twin Steam Engine in Iron
« Reply #44 on: May 30, 2022, 09:59:04 AM »
Andrew, if I sent you a small sample of that disk rotor, would you be interested in giving it a go through your metal tester?
I love it when a Plan B comes together!
Steve
https://www.youtube.com/watch?v=4sDubB0-REg

Offline awemawson

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Re: Casting a Model Westinghouse-Type Twin Steam Engine in Iron
« Reply #45 on: May 30, 2022, 11:12:24 AM »
Steve I'd happily do it, but my tester is intended for aluminium alloys so I don't think that we'd learn much sadly.

Andrew Mawson
East Sussex

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Re: Casting a Model Westinghouse-Type Twin Steam Engine in Iron
« Reply #46 on: May 30, 2022, 12:25:28 PM »
Didn't realize that, Andrew!   :doh:

I think on today's menu, we will re-melt the last casting, sprues and riser and try again. I will have to make up the roughly 20% loss with new scrap. Choices are:
radiator iron
left over disk rotor iron
or a combination

I'm favoring using more of the disk rotor iron attempting to reduce shrinkage. But that probably will also reduce carbon (already reduced from a second melt, as well) so maybe add some plumbago (graphite) to the charge?

The big question is how much ferrosilicon to add.
Normal is  .25%,
disk rotors (Ironman) .35%,
last pour (gray iron) .45%

Since re-using the last pour metal, it may have a reasonable amount of silicon in the iron already, but I've also heard somewhere that ferrosilicon's benefit only lasts about 5 minutes after addition. And re-melting the last pour will cook it for a lot longer than that. So do I trust that It is okay now to add none, or 25%, or .35%  (I'm guessing .45% won't be necessary.)  :scratch:

Well, let's pick a number..........ehhhhh  .35% ..........let's go for it
I love it when a Plan B comes together!
Steve
https://www.youtube.com/watch?v=4sDubB0-REg

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Re: Casting a Model Westinghouse-Type Twin Steam Engine in Iron
« Reply #47 on: May 30, 2022, 03:27:11 PM »
eh, no good. Really bad melt. Crucible tipped to one side of the furnace, and I didn't notice until near the end. Also lots of clumpy sticky slag that stuck to the walls of the crucible. Maybe it was sand in the sprues, maybe it was the plumbago, too. Anyway, slagged it twice, but then watched bits of slag detach from the walls of the crucible while pouring and slide down the sprue. I'm sure this casting will be scrap, even without breaking the mold open. Bummer!

Well, I ain't quittin'!  :dremel:

I have to check the condition of the furnace because I think I'm getting some leakage through the lining in one area. Anyway, next time, all new metal.

I love it when a Plan B comes together!
Steve
https://www.youtube.com/watch?v=4sDubB0-REg

Offline vtsteam

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Re: Casting a Model Westinghouse-Type Twin Steam Engine in Iron
« Reply #48 on: May 31, 2022, 06:33:26 PM »
Post Mortem:
Yup to the plumbago being a problem. It was found in a clump in the bottom of the crucible -- still powder ---which is odd because it is far lighter than iron and should have floated. It was at an angle and the only thing I can figure is since the crucible was tipped over against the wall of the furnacethere was a cold pocket of slag and colder metal trapping it.

I cleaned out the crucible thoroughly.

Also yup to the furnace having leaks. I found some cracks in the hotface near the bottom, and oil under blower pressure was building up in the blanket insulation behind. This led to copious long lasting smoke through a few small holes in the stainless steel jacket after the furnace was shut down. It also meant difficult to control mixture settings while burning. And loss of fuel and heat.

I patched the interior with ganister and then satanite, and did a small wood burn to set them.

Finally late today I decided to re-melt the metal from the last pour to see if the problems were external, and not the actual metal itself. I put sprue, casting and riser back in the newly cleaned crucible, and added 2.5 more pounds of mixed disk rotor and radiator metal to bring it to 7 pounds again. I added 14 g of ferrosilicon and poured into two vertical bar molds, one round (1.335" dia.)  and one rectangular (1"x2" section). The melt went much better, slag was manageable. Melt took 1/2 hour. The furnace hardly smoked, and seemed to heat more quickly.

I'll be interested to see how much shrinkage I get in these test pieces and how hard the resulting metal is, and how much slag got in. Yesterday was a major disappointment, but today, i feel like I'm back on track, and there's the possibility of not only salvaging the metal from last time, but getting some more useful stock out of it. Fingers crossed!

ps. On the off chance that one more try might soften up the hard spots on casting #3, after the pour, I put the casting in the empty crucible and fired up the already hot furnace for a couple minutes, then shut it down and covered the openings. Couldn't hurt!
I love it when a Plan B comes together!
Steve
https://www.youtube.com/watch?v=4sDubB0-REg

Offline vtsteam

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Re: Casting a Model Westinghouse-Type Twin Steam Engine in Iron
« Reply #49 on: June 01, 2022, 04:46:23 PM »
Well great day in the mornin'! June 1st and all the castings did well, but especially Westinghouse Twin #3, which was fully annealed by the last (and third) go at it. I was able to machine all mating surfaces with absolutely no chill hardness anywhere.

What was different? Well putting it in the furnace immediately after another iron melt, inside the crucible, and then giving it more blast for about 5 minutes really heated it up. Then shutting the furnace down and plugging the exhaust with a brick, and the ituyere with a rag. Then leaving it overnight to cool.

That was a real demonstration of the furnace's blanket insulation's efficiency, because when I took the casting out it was still quite warm after 20 hours of cooling! There's not a large amount of thermal mass in this furnace. It's really the insulation doing the job of heat retention.

What was different than the other attempts at annealing this same block?

Well, the in the first annealing attempt I added it to the furnace after a melt, but didn't fire up again, thinking that residual heat would be enough.

The second time, I heated the part up in the furnace from cold -- it was a brief firing to get the part cherry red, and hadn't been preceded by a melt, so the walls of the furnace hadn't stored much heat. Instead, I buried the part in a bucket of wood ashes to slow cooling.

So the third time was the charm, and lots of initial heat in a sealed furnace overnight seems to work the best.

As for the other two castings using "bad metal" from the fourth Westinghouse casting attempt....well the metal wasn't all that bad after all. Must have been the operator. in the photo are the resulting two bars. The round one cleaned up nicely to 1.25" with only a few tiny slag imperfections. Little slag at the very top. No apparent shrinkage. Nice gray iron easily machined. Certainly useful as a post for a Drummond style QCTP, etc.

The rectangular bar shows a little more shrinkage mainly because the center cools slower than the faces and corners. This results in slightly concave sides near the top, reducing as you get to the bottom. Not a lot of shrinkage but some. Little slag near the top. I haven't machined it yet, but expect it will be similar to the round bar, if not better. It would probably be fine to make a couple of tool holders to fit the above Drummond style post, or any other similar purpose.

Anyway a red letter day -- where everything that seemed to be going wrong last week did an about face, and went right!  :ddb: :beer:
I love it when a Plan B comes together!
Steve
https://www.youtube.com/watch?v=4sDubB0-REg

Offline PekkaNF

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Re: Casting a Model Westinghouse-Type Twin Steam Engine in Iron
« Reply #50 on: June 02, 2022, 02:46:11 AM »
Good job! So.....did the plan B work or is this allready plan B23? :D

I always though that brake disks are worst cast iron to work with, but what do I know, I never cast cast iron, very little aluminium and other low meltpoint stuff.

Offline vtsteam

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Re: Casting a Model Westinghouse-Type Twin Steam Engine in Iron
« Reply #51 on: June 02, 2022, 09:07:22 AM »
Thanks Pekka!  :beer:

When it comes to iron, I'm probably at Planet B -- a world of unknowns! With aluminum or zinc alloys. I know what I'm doing and what to expect. Brass, eh, a few more wrinkles. But iron! It is a different world.

You don't worry about chill hardness with aluminum. Casting thin sections? No problem. Facing sand? Just finer than the backing sand -- no need for reactive additives to control sand fusion. Time to melt? About as long as it takes me to ram up a mold, and I often do while the aluminum is melting, because the furnace is a quiet thing gently heating instead of a roaring oil smoking jet engine, intent on destroying refractory linings.

The noise level alone in an iron melt has the adrenaline rushing, and meanwhile you're covered in leather no matter how hot the day and proximity to your homemade inferno. And the radiated heat and light are intense, actually dangerous. Cooling time? Even a small iron mold takes 4 -6 hours vs 1 for aluminum, and even then the iron and sand are still hot. Wooden flasks? Short life with iron -- decades with aluminum.

And the results? For me always iffy, because I'm constantly changing variables -- often by necessity. Iron is not easy to come by, and varies greatly in qualities. Disk rotor iron is one fairly available source for that, so that is why it is of interest.

It does have good qualities for use: high strength, high temperature resistance, high wear resistance (hardness) -- all to be expected in its original purpose. I think it has reasonably low shrinkage. It seems clear to me now that it almost certainly is annealed/stress relieved by kilning after casting. And I'm sure there are very specific heats and times for whatever particular alloy a brake mfr is using.

For the home caster, however, yes it is a difficult metal to cast with compared to older traditional massive forms of gray  iron. Rotors have lower carbon content, and a higher melting point, by, as a guess about 3-400F (~200C). That nearly doubles melt time, especially noticeable if cold iron is added during the melt to fill a crucible. My furnace seems to be operating with a relatively low margin of temperature above rotor iron's pouring point, so heating is not linear over time. The last few degrees take the longest.

Not so with aluminum or zinc alloys in even a charcoal furnace -- the temperature difference of the furnace interior and the melt is high. And even with non-rotor grades of cast iron, melting in my oil furnace can begin in as little as ten minutes.

I do think that rotors are a good source of iron, but that additions of other lower melting point iron will probably help the home caster. Radiator iron is a fast melting type, and very fluid, but produces a fair amount of difficult slag, and also has a high shrinkage rate on cooling. For me, I would like to find a good mix of the two, since I have both on hand. How much of each, I don't know. Ideally less of the radiator iron, and more of the rotor iron, because the radiator iron is in finite supply.

I'm guessing that a larger than necessary crucible would help with speeding up melting rotor iron, so that you can avoid adding metal after the initial full charge. Or, in a smaller crucible, using mixed metals, adding radiator metal to a molten rotor metal charge, rather than rotor metal to molten radiator metal charge. But these things are to be worked out in practice.

Same thing for annealing to get machinable metal from rotors. Or, and I haven't reached that point, learning just how much ferrosilicon will correct it. So far, it's been too little.

Pouring, slagging, riser and gating methods are critical to getting impurity free castings. Again, slag quantity and type varies according to a lot of factors, including metallurgy, scrap cleanliness, furnace flame mixture control, time to melt, etc.

So yes, large number of variables, I guess I'll probably always be at least plan B, or C or Q with iron. But it keeps you coming back to try to figure out what you did wrong and could do better.
I love it when a Plan B comes together!
Steve
https://www.youtube.com/watch?v=4sDubB0-REg

Offline vtsteam

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Re: Casting a Model Westinghouse-Type Twin Steam Engine in Iron
« Reply #52 on: June 02, 2022, 10:49:05 AM »
As a follow-up here is the rectangular bar cut open -- nice clean metal inside. The outside was rough because it was simply poured into a rammed vertical open topped single-flask mold -- like a sprue. No facing sand and no parting line.

Shrinkage measures a total of 1/32" across both wide sides. The thickest section at the corners is 1-1/16". the thinnest near the center is 1-1/32". That's roughly 3% shrinkage due to differential cooling. The metal was roughly 1/3 rotor iron and 2/3 radiator iron. Remelted from a failed casting and sprue and riser.

The original pattern (a steel bar) was a true 1" across by 2" wide. The casting is thicker and wider than the steel bar because rapping makes the mold cavity larger.

If the finish is better it is sometimes possible to machine back to true size using this molding method..
I love it when a Plan B comes together!
Steve
https://www.youtube.com/watch?v=4sDubB0-REg

Offline PekkaNF

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Re: Casting a Model Westinghouse-Type Twin Steam Engine in Iron
« Reply #53 on: June 02, 2022, 05:34:04 PM »
That is pretty small shrinkage. Last bar looks good industrial quality. It's really nice to read your stories, there is a lot of experiment and though there.