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Old 03-03-2020, 12:11 PM   #41 (permalink)
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Pete
Have you ever noticed a clack valve leaking back while the boiler is coming up to steam?
The reason for that is water is getting into the valve and the valve doesn't have the proper design

The rule of thumb is that the amount of lift of the ball should be no more than 1/6 the ball diameter or it will leak when there is turbulence of boiling water.

The cylinder drain design is to have way more than the 1/6 diameter which allows the ball to be knocked off the seat by the water turbulence.
Thus water present and it leaks, no water and it seals
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Old 03-03-2020, 02:38 PM   #42 (permalink)
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I assume the D-bit is to create a flat bottomed hole? Or should the hole bottom have a slight reverse angle like your sketch shows?
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Old 03-03-2020, 08:10 PM   #43 (permalink)
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Flat is good, reverse angle is better
The sharp seat makes for a better seal when the sacrificial ball is tapped down with a hammer.
I try to do this on all of my ball valves - pumps, safeties, etc
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Old 03-05-2020, 09:35 AM   #44 (permalink)
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In the past I think you made referance to this design also. Is one or the other better?
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File Type: jpg Automatic Cylinder Drain 2.jpg (30.7 KB, 63 views)
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Old 03-05-2020, 02:33 PM   #45 (permalink)
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The second one is the same but it lists the step by step procedure so you get everything done in the right order.
The one you just posted is just the original converted to CAD.
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Old 03-07-2020, 10:11 PM   #46 (permalink)
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Quote:
Have you ever noticed a clack valve leaking back while the boiler is coming up to steam?
Bill, when my clack valves leak, I have no idea why. I have to admit to no proper engineering education, so your posts and descriptions are extremely edifying. Thanks.
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Old 03-16-2020, 12:10 PM   #47 (permalink)
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The Skookum received steam directly from the dome. This was a flaw in the design as the compound engine really needed superheated steam to start up and run correctly.
My model will have a superheater but I will have faux steam pipes coming from the dome.
The prototype has steam pipes with insulation covered with sections of thin tubing.
I get this look by turning the shape out of 1/4" brass stock.


An elbow which took about eight milling procedures is then attached to the dome with a concealed 0-80 socket head screw and the brass bar is annealed and bent to the correct curvature.
Here you can see the unpainted setup with the painted version in the background.
You can also see the running boards and the power reverser.


The cabs receive arm rests, grab handles. and rear roof supports before priming and painting.




Doors and window frames are cut out on the laser by Dennis and painted greeen.


I then cut polycarbonate squares that have a 1/16" overlay and attach them to the frames with canopy glue.
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Old 03-21-2020, 07:56 PM   #48 (permalink)
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I got most of the parts painted and one engine mostly assembled.
I still have a few detail parts and the front and rear deck & buffers but here it is
The photos don't really do it justice as they seem very bright






Here is the power reverser


And the clack valve- there is one on each side


The faux steam generator does emit steam


The air pump and piping The long pipe from the pump is the exhaust which goes into the smokebox on the prototype.
note how the hand rails stop at the steam pipe and have round knobs at the ends.
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Old 03-21-2020, 08:08 PM   #49 (permalink)
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Beautiful!
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Old 03-22-2020, 01:24 PM   #50 (permalink)
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I am curious as to why the real locomotive was considered a failure. I am going to guess that without superheating the "wetter" steam caused more condensation in the steam lines running to the LP cylinders which if I understand steam locomotives (and I only know the very basics) would cause problems. I know a bit off topic but curious.
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