Author Topic: Shay Locomotive  (Read 57957 times)

Offline Dan Rowe

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Re: Shay Locomotive
« Reply #60 on: April 17, 2014, 01:27:23 PM »
My Shapeways order of 11 bronze patterns arrived a week ago. They look really good and the casting numbers came out just fine. I ordered them raw but it looks like they polished them anyway because they are really shiny and that makes it hard to take a photo. The parts that should fit together work fine having a replaceable brake shoe is really cool....just need working brakes.



I have been busy in the shop making cores for the truck patterns. Some of the patterns do not need a core they only need a sprue to be attached for a rubber mold.

Here are the simple ones. The top is the brake beam fulcrum, the right is the brake shoe, the left is the left box cover, and the bottom is the center column.


These two were a bit more complex. The right one is the right box cover with 7 pins, and on the left is the brake head with 6 pins.


The truck boxes were a bit more complicated and they will require a repair in the wax stage to fix holes left by removing the core. Here is the left side with the core in.


Here is the left box with the core removed. The brass pin is the oil hole.


Here is the right box which needed cores for the lineshaft bearing and the axle bearing.


Here is the right box with the core removed. The brass pin is the oil hole again.


Now to attach the sprues and make rubber molds.

Dan
« Last Edit: April 17, 2014, 01:39:04 PM by Dan Rowe »
ShaylocoDan

Offline tvoght

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Re: Shay Locomotive
« Reply #61 on: April 17, 2014, 02:18:59 PM »
I must have missed or forgotten that you were going to have these patterns printed by Shapeways. Fascinating.
I'm looking forward to seeing the molding process in detail.

--Tim

Offline zeeprogrammer

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Re: Shay Locomotive
« Reply #62 on: April 17, 2014, 03:29:33 PM »
Very cool stuff.
The Shapeways stuff is interesting. Reminds me of Jo's posts about the...don't have the right terms...cornice? The tops of the pillars/posts where tel had the suggestion of using a brass bullet cartridge.
Carl (aka Zee) Will sometimes respond to 'hey' but never 'hey you'.
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Zee-Another Thread Trasher.

Offline Dan Rowe

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Re: Shay Locomotive
« Reply #63 on: April 17, 2014, 11:51:33 PM »
Tim, I will take a few extra photos of the molding process. I have made variations of all these parts before starting with wax to make metal patterns these are a lot closer to to true scale models.

Carl yes I remember that Victorian column detail. I would have made a wax model to make a metal pattern, but it was interesting to see how others would tackle the problem.

Dan
ShaylocoDan

Offline steamer

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Re: Shay Locomotive
« Reply #64 on: April 18, 2014, 12:05:48 AM »
Nice parts Dan!   I would love to see the process!   Stan was telling me about a Jewelers casting medium...though I can't for life of me remember the name of it.

Dave
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Offline Alan Haisley

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Re: Shay Locomotive
« Reply #65 on: April 18, 2014, 02:22:56 PM »
Nice parts Dan!   I would love to see the process!   Stan was telling me about a Jewelers casting medium...though I can't for life of me remember the name of it.

Dave
I think that was Delft clay.

Alan
Near Raleigh, NC, USA

Offline Dan Rowe

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Re: Shay Locomotive
« Reply #66 on: April 23, 2014, 12:08:17 AM »
Thanks for stopping by Dave and Alan. I took some shots with my cell phone as I did the truck box molds to document the process.

Here is the setup with 8 rubber sections per mold. One side of the rubber has a yellow printed cloth cover and the other side has a thin blue plastic covering to keep it clean as the pattern is cut out. There are 2 pieces of the mold frame held with pins top and bottom.


Here is the first half of the molds done. I use the cardboard template to locate the 4-40 acorn nuts I use for mold locks. The top section of the mold frame has been added. I trace the pattern on the cloth back and then cut out the rubber to fit around the pattern. I use the cut cloth back as a pattern to mark the next layer of rubber.


Now both molds are full and the cloth cover was left on for the outside of the first and last layer of rubber.


Both molds in the vulcanizer at 3070 for one hour.


Still hot!!! The excess rubber just flows out between the mold frame and the heated plates.


Now to carefully cut the mold. I use the dental probe to locate the acorn nuts in the corners and cut them out first so I do not miss them. The can opener C-clamped to the bench has had the sharp edges removed and it acts as a fixed finger to hold the mold open as a sharp scalpel is used to cut the rubber. This is the left side pattern removed and the core pieces in the rubber mold.


This is the right box mold with the pattern removed and the core in place.


Now it is time to heat up the wax pot. I push the mold on to the valve and hold it for a count of 15 seconds. I have about 10psi on the pot. There is a thin section of plywood on the top and bottom of the mold so my finger clamp will have equal pressure on the mold.


Finally this enough of the boxes for one Shay. I need three times that plus a few spares. I only knocked two of the sprues off with clumsy handling. I like it when I do not have to add a sprue for casting metal.


Dan
ShaylocoDan

Offline Dave Otto

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Re: Shay Locomotive
« Reply #67 on: April 23, 2014, 01:21:41 AM »
Interesting process, thanks for the step by step.

Dave

Offline Dan Rowe

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Re: Shay Locomotive
« Reply #68 on: May 26, 2014, 09:46:45 PM »
I made all the molds and realized that this is way more molds than I have made at one time. The old method of plywood for holding the molds together needed an upgrade. I cut some 1/8 aluminum plate and some wood spacers. I used 4-40 acorn nuts and thumb screws to hold the plates. Now I do not have to wait until the wax cools before I can set the mold down.

Here is a set of truck wax parts cooling in the molds.



Two of the molds did not work out so I have to redo the wheel center and the spring plate. The rest of the parts came out really nice.
Here is a tray of parts for 3 Shays with a few extras just in case.



I still have to repair the bearing boxes and I will show how I did that in the next post.

Dan
ShaylocoDan

Offline steamer

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Re: Shay Locomotive
« Reply #69 on: May 26, 2014, 10:53:33 PM »
NICE POST!..... :praise2:


This is awesome.....lot's to learn here!

Dave
"Mister M'Andrew, don't you think steam spoils romance at sea?"
Damned ijjit!

Offline ths

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Re: Shay Locomotive
« Reply #70 on: May 26, 2014, 11:58:14 PM »
Daves right, it is awesome. Looking forward to more of this project. Hugh.

Offline Dan Rowe

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Re: Shay Locomotive
« Reply #71 on: May 27, 2014, 01:47:44 AM »
Thanks Dave and Hugh, using Shapeways for the patterns has really improved the the whole process of making wax molds.

Dan
ShaylocoDan

Offline Johnmcc69

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Re: Shay Locomotive
« Reply #72 on: May 27, 2014, 02:34:00 AM »
Fascinating! Thank you for the step-by-step pix & explanation!

 Beautiful work...

 John

Offline Dan Rowe

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Re: Shay Locomotive
« Reply #73 on: May 28, 2014, 12:12:09 AM »
Thanks John I am glad that folks are enjoying the step by step. It helps me to remember to snap photos as I work.

The left box has two sections that need repair. The first one up is the back door I needed to remove the core for the oil box.



I made a section of machinable wax that just fit in the door. I left a chamfer on three sides of the casting around the hole so I could glue the plug with wax. I set the calipers the thickness of the back wall and marked the wax section for depth. Then glue the sides and cut the wax section flush with the back and clean up the surface. The three left boxes show the process start to finish.

The other repair is to the back of the oil cellar. This is where the cotton waste is used to wick the oil back to the axle bearing. This is the same fix for both the left and right bearing boxes so I am showing the right side.

I made a section of 1/4" a bit less than half round in wax and steel and a section of aluminium square to fit the bearing box. I use a small miter box to cut the wax sections after I add a small chamfer on the round edge for the glue.



Here is the process. The middle photo shows the wax door ready to be installed and glued.



This is a larger view showing most of the tools. I use the alcohol lamp to heat a small fine point spatula that I use to glue the wax. The wax for glue is a soft flexible wax that can be easily scraped flush with blunt hobby knife blade.



It is time for my summer vacation so the casting the parts will have to wait until I get back in my shed.

Dan
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Offline ths

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Re: Shay Locomotive
« Reply #74 on: May 28, 2014, 09:24:24 AM »


It is time for my summer vacation so the casting the parts will have to wait until I get back in my shed.

Dan

Oh, how I hate summer.

Hugh.