Paul,

And what did you think of MY tone?

Tony

I am greatly insulted by your tone and it appears that you have not put any thought into your comment.  Seriously?  You are trying to tell us that ALL the metal in a casting cools to freezing point at exactly the same moment?  You might know a lot about metallurgy but I know a bit about building things from metal.  I hadn't bothered mentioning that the brass caster's tale matched my own experience gained building steel ships because it didn't seem important, but fine: the metal might eventually shrink equally, but not all at the same time because cooling happens from the outside in, and this can be used to our advantage.  I have dealt with plenty of  castings, such as A-frames for supporting ships' propeller shafts, with significant variations in section size.  The orientation of the casting as it is poured is quite important, with the thicker part intentionally placed above the thinner part so that it acts as a reservoir keeping the thin section filled as it cools....as a metallurgist you should be aware of the high density of metals such as steel and brass, and thus the pressure that will be exerted that can keep pushing semi-molten metal down towards the bottom of a mould when it is cooled slowly enough - that is the key, achieving a slow enough rate of cooling.  You can't tell me it doesn't work because I've already done it; yeah sure, the metal shrinks but if it's done right it is possible to control WHERE the shrinkage occurs.  The column that lost-wax brass parts are stuck to when they are cast serves as one heck of a big reservoir of molten metal as the 'branches' are freezing so I don't have any reason to doubt what the caster said.

Paul Woods
retired mechanical engineer

Mea culpa.  Bill Welch points out that I had an incorrect model photo for door number 622 the "upside down" door.

 

My apologies.  Please discard yesterday's and keep today's.

 

Thanks.

 

Steve Hile

 

I find that I cannot push these into the Files section on the Groups site.  I am not sure why.  Is that closed?

Attachments:

• Southwest Scale Productions Doors in HO.doc
• Southwest Scale Productions Doors in HO.pdf

Dennis Storzek wrote:

I've only ever done one investment cast project; I wanted some bracket grabs that were more robust than the typical styrene parts, so back when Intermountain was still molding parts here in the US, I bought a hundred detail sprues from their PS-1, clipped the runner with the grabs out of them, and sent them out as investment masters. I was warned about the potential for ash to plug the long narrow cavity, and indeed, the reject rate was someplace around 20%, but the properly filled parts were nice.

    Richard Hendrickson did the same to get some durable bracket-mount grabs. I still have a couple dozen of his parts, very nice brass. Don't know what reject rate occurred.

Tony Thompson

tony@...

All-
Why do an interchange freight car prototype that had a hundred or less examples?
Have we completely run out of missed cars with broader multi road application?
I don’t think we have many production single sheathed door and a half box cars and many of them had very long service lives and numbered in the thousands on many lines...and went all over.
Charlie Vlk

Don’t be fooled by the Lionel F3 syndrome- while a great railroad with attractive equipment, nothing else sells like it without Warbonnet paint....ATSF freight units sell about the same as high middle other roads. Even a ATSF layout might not “need” a scarce car that was quickly obsoleted.

CB&Q 110193 Truss Rod boxcar is a Westerfield kit. My modeling date is Oct. 1955 and by then these were probably all gone but I occasionally cheat and so the car has a re-weigh date in 1952. The underframe has not been glued as yet so the body is not yet sitting firmly nested on the U/F. I have also not yet attached the brake wheel. To help keep the turnbuckles taught as well as provide more comfort for someone "riding the rods" a wood plank has been lodged through the four turnbuckles on each side of the underframe. The scratch built Running Board and Latitudinals will receive replacement boards after sandpaper is used to peel some paint up.

Bill Welch

An example of the casting work I have done - O-scale freight truck with functioning equalisation - and genuine American black walnut bolster.  I had expected to find some shrinkage in the axle-boxes because they are a big lump compared to the arch-bars but they were fine, all portions of the sideframes turned out at intended size.

Regards
Paul