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I realize this subject may be elementary to experienced live steamers on the forum, but for the sake of those newer to the hobby I thought I would share my recent experiences adding a steam take off to an existing boiler.....Hopefully sharing the info will be of assistance to others....
Here's a delimma most of us have faced at one time or another....I wanted to add a Weltek Whistle to my Mike Chaney Catatonk Shay. Mike leaves an extra steam port on the boiler in the form of a capped off bushing in front of steam regulator. Unfortunately on my Shay this is already occupied with a Goodall valve fitting.
So how do we obtain a steam take off for the whistle?....time to turn to the model engineer's best friend, the banjo fitting. A banjo fitting looks like a very thick donut like washer and has a tube silver soldered to the edge with a hole reaching to the inside of the "donut". Equally important is the banjo bolt which is hollow with a turned down outside section and a hole which provides a route for steam to flow through the bolt, into the banjo "donut" and out through the tube. This explanation is really better served by looking at some photos, so let's get on with how I added a banjo fitting on my Shay. This "tutorial" of sorts is not meant to be a "how to" for every situation, but rather is offered as an example of how a banjo bolt can be adapted to a variety of situations. Making a banjo bolt and donut fitting is extremely easy and can be done on any lathe...let's get on with the show:
Here's a photo of the cab area of my Shay before the whistle installation. Whistle gets mounted on the cab front to the right, with the actuator valve to be mounted on the cab rear to the left. The vertical brass looking piece just in front of the regulator arm is the Goodall valve.....we'll be remaking this into a new version with a banjo bolt added to the lower section:
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Here's the original Goodall Valve. Great for the boiler refilling function it is made for, but we'll be scrapping the main body and turning up a new piece which incorporates the banjo bolt:
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This is a typical example of how I do my "drawing work" for a one-off project like this. Scratching out the needed dimensions quickly on these post it notes allows me to sort out the shape of the needed part and check clearances. As you can see I didn't hit the numbers the first time and had to scratch through things a few times. But this sort of figuring goes quickly, and having all the machining dimensions worked out before going to the lathe makes turning work go more quickly:
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Here's the new Banjo Bolt after first turning operations. I started with a piece of hex so I could have a built in means of tightening the bolt on the boiler. Easily seen in this photo (just in front of the cutting tool) is the turned down section which will provide the passageway for steam to travel from the inner bore of the bolt out through the banjo fitting:
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Now we come to drilling the hole through the Banjo bolt. Normally this hole would only extend up to the turned down area with the upper portionof the bolt remaining solid. In this application, however, I wanted to keep the Goodall valve function so the bore extends clear though the bolt and we will later add treads to the top for the Goodall valve to screw into:
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Next comes cutting threads on the lower end of the banjo bolt. In this photo I am using a tailstock die holder....it makes quick work of cutting the threads...I recommend adding this tool to your arsenal of lathe tooling. Note that up to now we have performed all operations without removing the stock from the 3 jaw chuck. Doing everything in one set up keeps everything lined up properly and makes the project go quickly. If you look closely you can see that the turned down area on the banjo bolt starts just above the threads. This will be more clear when we look at the finished product:
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Finally the banjo bolt is parted off and now begins to look more like it's finished form:
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Now that the banjo bolt has been cut off, it is turned around in the lathe chuck, and in this photo is being faced off in preparation for boring and internal threading. This is the top of the banjo bolt where the Goodall valve will screw into. Note also that small pieces of shim stock are being used on the jaws of the lathe chuck to protect the finished outer surface of the banjo bolt:
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Here's the finished banjo bolt showing the Goodall valve and also the banjo fitting with steam tube. The banjo fitting "donut" is a simple straight turned piece with a bore just large enough to slide over the shoulder on the banjo bolt. This shoulder is seen just above the cross drilled hole in the turned down area of the banjo bolt. In use the bolt tighens down on the banjo fitting donut and with the red fiber washers shown creates a steam tight seal.
The idea behind the banjo bolt is that when installed there is an air gap all around the banjo bolt where steam flows from the bolt bore out to the banjo fitting. The hole and attached tube of the banjo fitting donut carries the steam out to whatever accessory is being added. In this case the tube is the steam supply line for the whistle:
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And here's two views of the new banjo bolt and fitting in use with the whistle installed and functioning. Using the custom made banjo bolt and fitting retains use of the Goodall valve, and makes for a neat and tidy installation:
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For those interested in studying this installation up close, I'll have the Shay at Cabin Fever next week and will keep it out on the table so it will be easy to look at.
Hopefully this tutorial has provided some food for thought and given some ideas for your next live steam project.
Regards,
Cliff
Cliff Ward
Cary Model Railroaders
Cary, North Carolina.
Here's a delimma most of us have faced at one time or another....I wanted to add a Weltek Whistle to my Mike Chaney Catatonk Shay. Mike leaves an extra steam port on the boiler in the form of a capped off bushing in front of steam regulator. Unfortunately on my Shay this is already occupied with a Goodall valve fitting.
So how do we obtain a steam take off for the whistle?....time to turn to the model engineer's best friend, the banjo fitting. A banjo fitting looks like a very thick donut like washer and has a tube silver soldered to the edge with a hole reaching to the inside of the "donut". Equally important is the banjo bolt which is hollow with a turned down outside section and a hole which provides a route for steam to flow through the bolt, into the banjo "donut" and out through the tube. This explanation is really better served by looking at some photos, so let's get on with how I added a banjo fitting on my Shay. This "tutorial" of sorts is not meant to be a "how to" for every situation, but rather is offered as an example of how a banjo bolt can be adapted to a variety of situations. Making a banjo bolt and donut fitting is extremely easy and can be done on any lathe...let's get on with the show:
Here's a photo of the cab area of my Shay before the whistle installation. Whistle gets mounted on the cab front to the right, with the actuator valve to be mounted on the cab rear to the left. The vertical brass looking piece just in front of the regulator arm is the Goodall valve.....we'll be remaking this into a new version with a banjo bolt added to the lower section:
Here's the original Goodall Valve. Great for the boiler refilling function it is made for, but we'll be scrapping the main body and turning up a new piece which incorporates the banjo bolt:
This is a typical example of how I do my "drawing work" for a one-off project like this. Scratching out the needed dimensions quickly on these post it notes allows me to sort out the shape of the needed part and check clearances. As you can see I didn't hit the numbers the first time and had to scratch through things a few times. But this sort of figuring goes quickly, and having all the machining dimensions worked out before going to the lathe makes turning work go more quickly:
Here's the new Banjo Bolt after first turning operations. I started with a piece of hex so I could have a built in means of tightening the bolt on the boiler. Easily seen in this photo (just in front of the cutting tool) is the turned down section which will provide the passageway for steam to travel from the inner bore of the bolt out through the banjo fitting:
Now we come to drilling the hole through the Banjo bolt. Normally this hole would only extend up to the turned down area with the upper portionof the bolt remaining solid. In this application, however, I wanted to keep the Goodall valve function so the bore extends clear though the bolt and we will later add treads to the top for the Goodall valve to screw into:
Next comes cutting threads on the lower end of the banjo bolt. In this photo I am using a tailstock die holder....it makes quick work of cutting the threads...I recommend adding this tool to your arsenal of lathe tooling. Note that up to now we have performed all operations without removing the stock from the 3 jaw chuck. Doing everything in one set up keeps everything lined up properly and makes the project go quickly. If you look closely you can see that the turned down area on the banjo bolt starts just above the threads. This will be more clear when we look at the finished product:
Finally the banjo bolt is parted off and now begins to look more like it's finished form:
Now that the banjo bolt has been cut off, it is turned around in the lathe chuck, and in this photo is being faced off in preparation for boring and internal threading. This is the top of the banjo bolt where the Goodall valve will screw into. Note also that small pieces of shim stock are being used on the jaws of the lathe chuck to protect the finished outer surface of the banjo bolt:
Here's the finished banjo bolt showing the Goodall valve and also the banjo fitting with steam tube. The banjo fitting "donut" is a simple straight turned piece with a bore just large enough to slide over the shoulder on the banjo bolt. This shoulder is seen just above the cross drilled hole in the turned down area of the banjo bolt. In use the bolt tighens down on the banjo fitting donut and with the red fiber washers shown creates a steam tight seal.
The idea behind the banjo bolt is that when installed there is an air gap all around the banjo bolt where steam flows from the bolt bore out to the banjo fitting. The hole and attached tube of the banjo fitting donut carries the steam out to whatever accessory is being added. In this case the tube is the steam supply line for the whistle:
And here's two views of the new banjo bolt and fitting in use with the whistle installed and functioning. Using the custom made banjo bolt and fitting retains use of the Goodall valve, and makes for a neat and tidy installation:
For those interested in studying this installation up close, I'll have the Shay at Cabin Fever next week and will keep it out on the table so it will be easy to look at.
Hopefully this tutorial has provided some food for thought and given some ideas for your next live steam project.
Regards,
Cliff
Cliff Ward
Cary Model Railroaders
Cary, North Carolina.
