# Rushton style stack project



## redbeard (Jan 2, 2008)

Rushton Stack Construction Log
I decided a while back to build a Rushton style stack for my Heisler as it would be somewhat prototypical for logging Heislers in the south. The project quickly became a large and long term endeavor. Here is the beginning of the Rushton Project! 

This is the prototype stack I decided to base my project on.



















These pictures found by searching for Rushton stack images and are listed as;
"Balloon/Cabbage stack on the Argent Lumber Company 2-8-0 No. 7 in Hardeeville, SC."

This is the wood (MDF) former I turned to provide the shape and size of the stack top.










The former is made in two pieces so I can cast the stack top in halves, and solder the pieces together. This is partly due to the size of my casting equipment and partly due to the difficulty in casting hollow pieces that have small openings compared to the total size. 











I have a good supply of these discs from a race car builder that builds formers to shape sheet aluminum body panels around. He uses 2 1/2 inch holesaws to cut holes for clamps etc. These discs are the plugs from the holesaw.
This picture shows two discs of MDF like the ones that made up the two halves of the former. 










This is the top half of the MDF former.










Here I am forming a piece of 12 gauge wax over the top of the former. I am using wax this thick so that the wax will not stretch out and be too thin in the spots where it makes fairly sharp turns. 










Because of the complex curves, I made this half of the wax in four pieces.



















The four pieces are trimmed to fit the top former.



















Next the pieces are "welded" together with a fine tipped hot wax tool.



















And this is the top half of the stack blank.



















The bottom former is slightly different in shape, but the process is the same. Four pieces of wax were formed around the wood former and welded together. The bottom half has a lip added to align the two halves for soldering.



















Here the two wax halves are trial fitted together.










Next the rivet details are added. A line was scribed around the "seam" between the center section and the upper and lower sections. The line was divided into 3/16 inch sections and holes drilled.










Short pieces of wax wire are pushed into the wax.










The tops of the wax wires are melted with the hot wax tool.










The top half rivet detail was done the same way as the bottom. 
Here the two halves with the rivet details are fitted together.











Much, much more to come!
Larry


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## Tom Bowdler (Jan 3, 2008)

Really cool Larry! 
Reminds me of the wax and casting work we did in dental school. We did a few "extracurricular" projects but a much smaller scale. 
Carl Malone made a similar stack some years ago from a doorknob. 
I'll be watching with interest, 
Tom


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## WES (Oct 31, 2012)

Since you have not included the scale, dimensions and the thickness of the stack (in wax) so I cannot be certain, but printing it in stainless/bronze might be easier than casting it.


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## Totalwrecker (Feb 26, 2009)

Larry, 
A hot beading tool would give more uniform rivets. 
When looking at a line of same details any variations stand out. 

Good work with the sheet wax. 

John


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## redbeard (Jan 2, 2008)

Hey Tom, I did look for an old fashion door knob, but what I found was too small. Thanks! 

Hey Wes, Project has been running in the background while I make jewelry, these pictures were made months ago. The first one cast measures 2-3/8 inch (+/-) by 1-3/4 inch (+/-) and is close to 7/8 scale. I am not at all to speed on printing, but doing it in my shop is better for me than farming it out. Probably worth looking into at some point. Thanks! 

Hey John, I am guessing you mean heating a beading cup (graver)? Or are you talking about another tool that I don't know about? (plenty of those are around, I now feel like my "hobby" is collecting tools to make jewelry with) Anyway when I looked at full size stacks that are riveted, and pictures of stacks the rivets looked like they were formed with a sledge-hammer. You can even see some of that in the two pictures of the yellow stack. The rivets are not even lined up well with each other. Please tell me about the tool and/or method either here or in a PM. ("A hot beading tool would give more uniform rivets.") 
Thanks! 

Larry


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## Totalwrecker (Feb 26, 2009)

I was taught many years ago when re-tiping, in the head stones, to use a beading tool to burnish the tips. They looked uniform because the curvature was constant 
Then it was a small shank with a polished concave lowdome tip. In this scale the size of the rod depends on your rivets. Graver wasn't attached to the description. Not a new tool, more of an over size adaption 

I would use an alcohol lamp to warm . Rivet wax lower temp. 

I hesitate to tell a craftsman how to do something, it was more of a passing idea. 

John 

John


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## redbeard (Jan 2, 2008)

This picture shows the bottom wax with the sprue wax attached. The wax sprues will become the path that the molten brass will follow. The top wax is sprued in the same manner.











This picture shows the sprued wax accurately weighed. This is important to melt the correct amount of brass for the casting. In this project the brass has a specific density of 8.4 , so the wax weight is multiplied by 8.4 and the weight of the correct size button is added. For this size casting and the base that I will use the button will be 25 grams of brass. Same process is followed for the top wax.











The waxes are fastened to the rubber flask bases. The "button where the wax meets the base will be the funnel for the molten brass to flow through the sprues into the mold. The funnel will fill with metal during the casting process and become the button at the bottom of the casting. The button will cool slower than the casting due to it's thickness. This allows molten metal to continue flowing into the mold as the far end of the casting cools and shrinks slightly. This prevents porosity caused by shrinkage.





















The flask is now placed over the wax and into the rubber base. This flask is 3 1/2 inch diameter and 3 inches tall.











"Splash shields" are placed on the flasks to control splatters during the investment process.











Investment is the name for the plaster-like material used to fill the flasks. The investment is weighed and mixed with a measured amount of water.





















Mixing is done with a hand held mixer and a timer. Once mixed with water the investment will be hardened in 9 to 10 minutes. So from here the process must be tightly controlled to keep the investment from hardening before you are finished pouring it.





















This is the vacuum casting machine I use.











After mixing for 4 minutes or less, the mixing bowl is place in a vacuum chamber and vacuumed to remove bubbles.











Next the investment is poured into the flasks........................











.............and vacuumed again to be sure there are no bubbles adhering to the wax inside.











Six smaller flasks are filled to use the entirely fill the kiln. I try to not cast until I I have an oven full to control costs.











Here the investment has set, or hardened.











Next the rubber bases are removed.











Now the flasks are placed in the kiln (oven).











The oven is uses a programmable oven controller to bring the flasks through four different ramps or cycles to first melt the wax, then using increasing temperatures burns out the residues of the wax completely.











The oven reaches 1350 degrees Fahrenheit, holds that temperature for a couple of hours and drops to 975 degrees for the actual casting.











The brass is accurately weighed and it is time to cast.











This picture shows the centrifugal casting machine used for casting. The machine has a large spring that is wound up to provide the centrifugal force to force the molten metal into the flasks. The metal is placed in the white crucible and a torch is used to melt the metal, when the metal is ready the flask is placed in the cradle and the crucible slides against the flask.











The arm is released and spins extremely fast, forcing the molten metal into the cavity in the investment where the wax was. After 5 minutes the flask (still very hot) is dunked into a bucket of water to break up the investment and expose the new casting. 











This picture shows the top and bottom castings just after casting and cleaning the investment off.











The next step is to cut the sprues off the casting.











Here are the two rough castings together. Now the castings will be ground, sanded and cleaned.











Since these pieces will be used to make molds, they are machined inside and outside to lighten them and make the halves fit together well.











More to come!
Larry


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## Phippsburg Eric (Jan 10, 2008)

Wow that is a neat project Larry! Well Done!


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## highpressure (Jan 2, 2008)

Here's one I made out of a scrap bar of brass on the lathe. Inside is hollowed out by boreing. Rivits are actually (RIVITS). The trucks are also of my own pattern, but cast. 







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## llynrice (Jan 2, 2008)

Hi Larry,

I really enjoyed you tutorial on lost wax casting. While I've long understood the basic process, it's wonderful to see all of the nitty-gritty details. Thanks for sharing.


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## redbeard (Jan 2, 2008)

Thanks Eric! Hopefully when I get a stack finished it will still be "a neat project" ! Larry 

Hi Larry, Wow! That's an incredible stack and Shay! Good to here from you! Larry 

Hi Llyn, Thanks for the comments! People who cast all do some things a little differently, but the main part of the process stays the same. Larry


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## Totalwrecker (Feb 26, 2009)

Larry 
Nice castings. 

I don't know if you are aware of these; 

http://www.ottofrei.com/Magnetic-Tumblers-and-Media/ 

Magnetic tumblers with steel pins do a great job of planish polishing with no metal loss. Will protect your rivit heads. 

Probably used ones out there. 

John


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## redbeard (Jan 2, 2008)

Hi John, 
When magnetic tumblers first came out years ago they were frightfully expensive. So I found plans somewhere to build your own. Later one of the companies that built an "All in One" lapidary machine offered a kit to convert their small flat lap machine to a small magnetic tumbler. I got a kit and built a tumbler around the kit. BEST addition to my tool collection since the vacuum caster. Unfortunately it is too small for the stack components. I will look into modifications for it to see if I can put i bigger "tub" on it. 
Thanks! Larry


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## redbeard (Jan 2, 2008)

Here are the two halves ready to make molds. The mold making process is as complex and varied (everyone has their own method) as the casting process. I will not go into the process specifics in this post, but basically layers of rubber are packed around the casting in a frame, which is placed in a vulcanizer and heated with pressure to make the rubber a single block. The block is then cut apart in a way to allow it to be put together, injected with wax, and opened without damaging the wax pattern.










Here is the mold for the bottom half of the stack.










And the mold with the first wax pattern made in it.










Here are the the mold and the first wax for the top half.



















Here are the two original castings and a couple of waxes from each mold.










Next the first bottom wax is sprued










Then the top half










The casting process is the same process as making the two halves for the mold.



















Here are the first pair of production stack components.




















These will be a new stack for my Ruby-Heisler! It may be a bit before I post next, have to switch back to revenue producing work for a while.
More to come..........
Larry


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## FH&PB (Jan 2, 2008)

Cool project, and a really nice overview of investment casting!


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## Burl (Jan 2, 2008)

I have always wanted to know more about the lost-wax process, so Iâ€™ve been following this post with great interest. 

I do have a couple questions though... why was it necessary to make the pattern for your 2nd generation mold out of brass? Does the green wax melt at such a high temp that you have to go with vulcanized rubber, as opposed to RTV â€" or is it just personal preference?


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## redbeard (Jan 2, 2008)

Hey Vance,
Good to hear from you, and Thanks! Larry

Hey Burl,
"_I do have a couple questions though... why was it necessary to make the pattern for your 2nd generation mold out of brass? Does the green wax melt at such a high temp that you have to go with vulcanized rubber, as opposed to RTV – or is it just personal preference?_" 

I am a jeweler by trade, so a lot of what I do in train parts is due to having tools and materials on hand. The green wax shown here is a "plasti-wax" with a melting temperature of 160°F to 165°F. I usually inject the wax at 170°F and 20 to 24 PSI. Over the last 25 years I have tried several types of RTV mold compounds and not been very successful with any of them. They worked OK if the pattern was open and I could "pour" the hot wax in, but under pressure they would flex and leak wax at all the seams. I am sure there is a technique that I just have not found with these compounds, but I know I can make working molds with rubber. So I guess the answer is that it is personal preference due to past experience. Larry


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## redbeard (Jan 2, 2008)

_It may be a bit before I post next..................._or I just can't stand it and want to see the thing finished! (Will D would call this "steam oil deprivation disorder"!)


In this picture the holes for the stack tube have been drilled open. 










Next the two halves are clamped to solder.










This is the solder used.










This is the flux used.










This picture shows the two halves soldered together.










The stack top is pickled and cleaned.










Next the stack top is chucked in the lathe.










Now the solder joint is turned off.










Just so I could see how it looks, I stuck it on a 3/4 inch brass tube.










More to come!
Larry


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## redbeard (Jan 2, 2008)

I have not had much time to work on the stack, but decided to finish it this week. I did not take pictures while I worked until today. Sorry








Here is the stack when I finished the soldering this morning. It still needs some grinding and sanding.










And here it is with i nice Flat Black coat (or 4) of paint.










I will try and get it on the Ruby-Heisler tomorrow.

Larry


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## Shay Gear Head (Jan 3, 2008)

Larry,

A jewel like piece that will make an unusual loco even more unique. BEAUTIFUL.


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## llynrice (Jan 2, 2008)

Amazing piece of work! Thanks for sharing the details of how you do it.


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## redbeard (Jan 2, 2008)

And here it is on the Ruby-Heisler!

Thanks Bruce and Llyn !










Larry


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## Totalwrecker (Feb 26, 2009)

Great job! Your passion for the job, shines through. 

John


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## redbeard (Jan 2, 2008)

*Finally*

Well I am finally making a couple of Rushton style stacks to sell. I am making two different versions of the stack, one has a bit more fancy top section. This is like the original that I made for my Ruby Heisler. The other stack is the same shape top and bottom. I am making both of these to fit Ruby boilers because they are the only boilers I have to measure. Here are the two stacks.










And here are the components to make one stack. (after the top pieces are cast and brazed together)










Here are the components assembled to be soldered.










Here is the first stack soldered.












And here are three shots of the first stack.
































And here are three shots of the second stack.




























These stacks will be in the classifieds and on e-bay(hopefully tonight). 
I will post painted pictures tomorrow.

Larry


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## redbeard (Jan 2, 2008)

Both stacks are posted in the classifieds and are listed on e-bay.

http://www.ebay.com/itm/161323440394?ssPageName=STRK:MESELX:IT&_trksid=p3984.m1586.l2649

http://www.ebay.com/itm/161323443714?ssPageName=STRK:MESELX:IT&_trksid=p3984.m1586.l2649

Larry


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## redbeard (Jan 2, 2008)

"Both stacks are posted in the classifieds and are listed on e-bay."

BOTH are sold !!

Larry


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## Chris Scott (Jan 2, 2008)

Will you be making more? Can we reserve one?


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## redbeard (Jan 2, 2008)

Hey Chris,
Sent you a PM.
Larry


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## Chris Scott (Jan 2, 2008)

Larry; 
Absolutely beautiful work.


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## Shay Gear Head (Jan 3, 2008)

What ring sizes does it come in. My anniversary is coming up later this month - I think?


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## redbeard (Jan 2, 2008)

Well, they may be sold and gone.....but I did take pictures after I painted them.



















Bruce..... Why........whatever do you mean? 

Larry


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## Shay Gear Head (Jan 3, 2008)

Larry,
Isn't it my turn to get some"jewelery"?


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