Author Topic: Kozo A3 Switcher - use of cylinder castings  (Read 659 times)

Offline matthew-s

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Kozo A3 Switcher - use of cylinder castings
« on: December 23, 2021, 02:05:26 PM »
Hello - winter is upon us - so back in the shop after a long break.

I want to start on my 3/4" scale A3 Cylinders. I ordered the brass castings quite some time ago. As I started to plan my machining, I realize the castings are WAY oversized - - I really expected the outside base-diameter of the cylinder would not require machining  - but that does not seem to be the case.

Searching the web, I see a few examples online of folks making these cylinders from bar stock, but only one using castings - that was for a 1.5" model, and that person used a CNC mill to machine the major diameter! Not an option for me.

Sooo .... has anyone used the castings with success? Is my only home to treat this like the machining operations in the book, and even though I have the castings, use the lathe-as-a-shaper method as shown my Kim? https://www.modelenginemaker.com/index.php/topic,8552.msg237992.html#msg237992

Offline kvom

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Re: Kozo A3 Switcher - use of cylinder castings
« Reply #1 on: December 23, 2021, 02:16:27 PM »
If you machine the cylinder bore first, it will give a datum for the rest of the faces.  Using a mandrel and rotary table will allow the cylindrical face to be machined. 

Offline matthew-s

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Re: Kozo A3 Switcher - use of cylinder castings
« Reply #2 on: December 23, 2021, 02:30:17 PM »
Thanks. That is my current thinking. I guess I'm a little bummed that the castings are not saving machining steps, or for that matter, providing with the a "sand cast" surface finish for the final model. Those are the two reasons why I sprung for them!

Offline internal_fire

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Re: Kozo A3 Switcher - use of cylinder castings
« Reply #3 on: December 23, 2021, 03:14:32 PM »
A machined surface is probably more realistic looking than a "sand cast" surface. As pointed out by others on this forum the sand used for casting is not significantly scaled for model castings. Therefore the grain size is 16X too large for the A3 model.

Gene

Online RReid

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Re: Kozo A3 Switcher - use of cylinder castings
« Reply #4 on: December 23, 2021, 03:51:28 PM »
Keep in mind that the cylinders and boiler of a steam locomotive were wrapped with insulating lagging and jacketed, and that's the outline that is normally modeled. The actual cast surface of a cylinder was typically hidden. This picture is a good illustration of what you usually don't see.
Regards,
Ron

Offline matthew-s

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Re: Kozo A3 Switcher - use of cylinder castings
« Reply #5 on: December 23, 2021, 05:21:21 PM »
That is all true - the comment about surface finish was secondary.

The bigger surprise is that I'm not saving much in the way of machining by having purchased the castings. Oh well, no big deal.

I think I'll just put a shaft through the bore and nibble away at the outer diameter on the mill. I'm don't have the fixtures for the lathe, and not sure my late would be rigid enough to use it a shaper anyway ...

Offline steamer

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Re: Kozo A3 Switcher - use of cylinder castings
« Reply #6 on: December 23, 2021, 11:58:06 PM »
There are few and far between "good hobby castings" around the US, though there are some VERY notable exceptions to this!!!

Bar stock is probably a very safe way to get what you want....

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

Offline matthew-s

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Re: Kozo A3 Switcher - use of cylinder castings
« Reply #7 on: December 25, 2021, 09:57:55 PM »
Thanks for the input. I seem to be unblocked. The casing is machining pretty well (it had better, I believe it's bronze!) on my marginal 7x18 lathe.

The wheel castings were helpful, and I'd recommend to folks. With the amount of machining I'm doing, I think people would be equally well of with bar stock for the cylinders.

Offline crueby

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Re: Kozo A3 Switcher - use of cylinder castings
« Reply #8 on: December 25, 2021, 10:37:08 PM »
This is an old Rolling Stones song,   


You can't always cast what you want, but if you mill some bars, you get what you need....



 :Lol:

Offline cnr6400

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Re: Kozo A3 Switcher - use of cylinder castings
« Reply #9 on: December 26, 2021, 04:21:17 PM »
What higher endorsement could you get than the Rolling Stones, for cutting from solid!  :lolb:

Wonder if Keef or Mick or Charlie ever had lathes or mills? Ronnie Wood probably stuck to the brown stuff (wood, not hashish, I mean)  :Lol:

Offline matthew-s

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Re: Kozo A3 Switcher - use of cylinder castings
« Reply #10 on: December 26, 2021, 09:58:38 PM »
Keef was a Boy Scout, loved that it allowed him to carry a pocket knife. There was at least some whittling?

Ronnie works in paints.

That's all I know of their possible outside creative interests!