Hole pattern on GP9 steps

[packer]

Anyone know what the hole pattern used on the GP9s was?

[Mr. Trainiac]

Here's an halfway-decent photo of a BNSF GP9 with a four-tread stepwell. This was a modification BN made. It looks like it has the standard hole perforation pattern that many other EMD units use. The bottom step has four rows of holes while the others have three.

rrpicturearchives.net/showPicture.aspx?id=1292177

Here's a three tread stepwell on an SP locomotive. It looks like all of them are four perforations deep: www.rrpicturearchives.net/showPicture.aspx?id=3572287

[packer]

That’s an interesting detail on the number or rows on them. But how big are the holes and what are the offset of them.

[12bridge]

I can measure one sometime this week.

[12bridge]

[big train james]

As far as I can tell, the common EMD steps either match the common Morton pattern, or they are so close as to be the same.  When I used the Morton pattern for steps for my sw1500 project, I think the pattern spacing and proximity to things like edges or kick plate faces looks correct.  And everything is generally corroborated with field measurements as well.  So I'm sticking with it.

Let's see if this photo will attach.....



The steps posted by 12Bridge don't have the holes along the nose of the tread, that fold over onto the front face of the step.  If you need to add those, they are 7/8" diameter.  The center of the hole is in line with the face of the tread.  It's a tricky thing to 3d model unless you are using a software that can fold a pattern around bend without distorting it.  I'm mostly using Autocad, which doesn't really handle that condition well.  I ended up positioning a sphere of 7/16" diameter, then subtracting it from the step itself.  Not perfect, but it looks okay.  The reality though is that the steps would be better if executed in etched brass or nickel silver, in which case the part will be created like the real thing.  Meaning a 2d pattern of holes punched or stamped into a sheet, which is then folded.  All that may be a moot point when dealing with HO scale steps.  I'm in O scale, so I can maybe do some things that will actually render like the prototype.

I modeled the steps in 3d, because I'm compulsive, and I like to figure out how to solve some of the challenges of making the computer do the math to make something complex.  In reality though, I intend to do 2d artwork for etching and then fold everything up. 

The other missing dimension if doing the steps with the holes along the edge, is the centerline from the face of the step to the center of the first line of large holes. It should be 1-1/2". After that the hole and nub spacings match the drawing.

Hope that helps,
Jim

[big train james]

Yay!!!!! The photo worked, on only the second try.

[big train james]

Just realized, the drawing doesn't indicate hole or nub sizes, just locations.

Large holes are 1-3/8" diameter.
Small holes on leading edge are 7/8" diameter.
Nubs are drawn as 13/32" diameter spheres, but sunken into the tread so that the O.D. at the tread surface is 3/8". I have them drawn with a 1/8" bore in the center of the nub for the 3d model, which is admittedly pointless for any sort of output. But it looks cool in the drawing.

[packer]

Thanks 12bridge and bigtrainjames. I'm wondering how much of that would be visible in HO and if the part I'm working with would become too fragile with all those holes. I had to add material to the sides to get some more strength for the steps. I guess just print it and see? Perhaps photoetch steps is a better option.