I am researching Hocking Valley/Chesapeake & Ohio box cars to create a 3d printed model. The cars were built in 1924-25 with wood sides but were converted to steel sides in the early 40's. The ends are marked as being Murphy 7/8 ends, but I am questioning my eyes as to whether they are convex or concave. I am thinking concave or inverted but I am not 100% certain. This particular car has a Murphy Radial roof, but other cars in a similar series had an early C-C Viking roof. My thought is that there are at least 12 variations of these cars with different sides, doors and roofs. 

So what say you? Convex or Concave.

 

The corrugations protrude into the car interior.  

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Tim O'Connor
Sterling, Massachusetts

Dave Wetterstroem  wrote:

On Mon, Jan 16, 2023 at 01:25 PM, Tony Thompson wrote:

And BTW, to me, the word “inverted” means “upside down,” that is, rotated around a horizontal axis. This present case I would interpret as rotated around a vertical axis. I call such a type “reversed,” though I know there is not necessarily agreement on this.

It would appear that Miriam Webster has a broader definition of "inverted":

https://www.merriam-webster.com/dictionary/invert

 
--
Dave Parker
Swall Meadows, CA

"innie" to me as well, but something seems to be going on between the flat panel "squaring up" the end (under the roof) and the first rib.
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Ken Akerboom
http://bmfreightcars.com/

Hi,

  Everyone is saying "innie/concave".  Take another look and especially at the 
upper edge of the tack board ... seems to argue for convex?
                                                                                                      - Jim in the PNW

Dave Parker wrote:

It would appear that Miriam Webster has a broader definition of "inverted":

https://www.merriam-webster.com/dictionary/invert

Mine comes from a long wrestle with crystallography, where you really have to think clearly about rotations etc. And you don’t mix up the terms.

Tony Thompson
tony@...

My take on it is I would like to have a set or two of those ends! O scale! I think I could handle the rest!
Best of luck, oh yea, innies!

I prefer “inverse”.

Thanks!
Brian Ehni
(Sent from my iPhone)

Inward and outward have been used among several Pre-Depression Era modelers. It’s a pretty common steel end for the 1910-1930 decades.

Accurail tooled a very nice rendition on their HO scale 36-foot double-sheathed box cars with steel ends.


Eric Hansmann
Media, PA

Hi Jim - its been a while!  

yes, at the top of the top panel, there is a final, inset shape that looks similar to the lower edge of another corrugation, but runs across the whole of the end (rather than terminating in a point).  It then turns vertical running to the roof fascia.The corner posts of the panel are also bent similarly.   

As I recall, the Westerfield instructions us the term reverse Murphy, and that's what I call them. Reverse means concave instead of convex corrugations. The corrugations are reversed when concave, as the normal corrugation configuration is convex. Not all that difficult.

Nelson Moyer

On Mon, Jan 16, 2023 at 05:04 PM, BRIAN PAUL EHNI wrote:

I prefer “inverse”.

Except that the original iteration of this end had the corrugations protruding INTO the car... So that would be the 'normal' end, and the ones with the corrugations facing outward would be inverse/reverse. I personally prefer to just describe the end, either corrugations facing inward or corrugations facing outward, 'innie' and 'outie' for short.

I just looked up the patent, but it's no help, as the drawings show the corrugations going both ways, the plane of the end sheet being on the neutral axis of the sine wave shaped pressings. I guess you could say the original design could swing both ways :-)

Dennis Storzek

On Mon, Jan 16, 2023 at 04:17 PM, Jim Betz wrote:

Everyone is saying "innie/concave".  Take another look and especially at the 
upper edge of the tack board ... seems to argue for convex?

The easy way to tell the difference is to look at the riveted lap seam between the panels, as that is a straight line between the corners. In this case the tack board is riveted tight against the end sheet just above this lap seam, so the top of the tack board, being riveted to the tip of a corrugation, means the corrugations must protrude inward.

Dennis Storzek

On Mon, Jan 16, 2023 at 06:21 PM, Robert kirkham wrote:

yes, at the top of the top panel, there is a final, inset shape that looks similar to the lower edge of another corrugation, but runs across the whole of the end (rather than terminating in a point).  It then turns vertical running to the roof fascia.The corner posts of the panel are also bent similarly.

Rob has the answer.

Dennis Storzek

On Mon, Jan 16, 2023 at 02:16 PM, Dave Wetterstroem wrote:

I am researching Hocking Valley/Chesapeake & Ohio box cars to create a 3d printed model. The cars were built in 1924-25 with wood sides but were converted to steel sides in the early 40's. The ends are marked as being Murphy 7/8 ends, but I am questioning my eyes as to whether they are convex or concave. I am thinking concave or inverted but I am not 100% certain.

Who built the car? If Pullman or Standard Steel drawings are likely available here: https://www.irm.org/pullmanlibrary/

I probably have as much experience modeling these ends as anybody, having cut tools to make both the 'innie' and 'outie', CNC'd an O scale pattern for someone a number of years ago,  and hand crafted a pattern for my resin kit line back in the dark ages. Incidentally, since it was easier to hand craft the outie pattern, that is what I did, then greased it up and cast another part against it to get the innie I needed. I did all these based on a profile I copied off a prototype car back in the early eighties, the full story of which I wrote up on the 3DSTFC list sometime last year. Go to that group and search on my name and it will come up. Unfortunately the cross section drawing has disappeared. Here is what I wrote about generating the geometry in 3D:

All the 2 1/8" circles are in a straight line 3" apart, and the total 6" is the width of one rib. The ribs meet so the sine wave flows seamlessly from one to the next.

I did not do the horizontal profile, I simply measured from the corner to the tip of the rib, and then the length of the taper. There is no need to concern yourself with the shape of the rib end; it is generated automatically when the surface is modeled. If your CAD software has a way to extrude a solid along a path, you can do so, simply placing the resulting rib on another rectangular solid and subtracting it will result in properly shaped ends on the rib. I could only generate a NURBS surface along a path, then had to trim them to another surface.

Dennis Storzek

--
Tim O'Connor
Sterling, Massachusetts

Yes IRM has drawings for these cars. Pullman 503-F-62 is the general arrangement,503-F-63 is the underframe and brake arrangement. Also has anyone any thoughts as to WHY a particular car used inward or outward Murphy ends? My own thought is it had to do with the 1910 Safety Appliance Act mandated relationship between the safety appliances on the end of the car and the coupler contour. In the case of these ends being applied to an existing design,using an inward facing rib would preserve the existing relationship at the cost of a small loss of inside length,but saving the need and expense to redesign and retool the bolster/ draft arm area of the underframe.Even a small change in dimension in these areas could change the stresses involved.
Larry King