Concrete Tie strip for N Scale and Code 40 Rail

[ednadolski]

I'm starting this thread to see if anyone is interested in collaborating on an N scale tie strip for modern concrete tie track (North American prototype) using code 40 rail.  I'm not really sure where this will lead, for me at this point it's basically a feasibility study.  My motivations are (a) the (apparently perpetual) supply & availability problems that continue to plague the ME N-scale concrete tie products; and (b) to see if it is possible to make something 'just a little bit better' (tm) than any existing product. 

I had dabbled with this some time ago, to the point of making a file and printing it out on Shapeways using the WSF (White Strong Flexible) material. The results were (not surprisingly) quite poor, and at the time there really wasn't much else in terms of options for better resolution materials.  So I thought I would post the .skp file here and ask if anyone would care to look it over and comment about what kind of printing options might be worth trying, and if you have any comments or changes to suggest.  Here is the file download link on sabercathost.com:

https://sabercathost.com/medP/ConcreteTie.020.skp

It's been a long while since I've used SketchUp and I've forgotten nearly all of it.  I don't remember any printing or scaling options that I used with this file, tho there were a few hoops to jump thru to produce a file format that Shapeways wanted.  Hopefully current printing capabilities have made that part easier.

Thanks, and I'm looking forward to hearing all your thoughts!

Ed

[C855B]

Ed - Is there any chance you can export this to a DXF or DWG format? My CAD app sorta-kinda reads the .skp file, but it's rendering the image in a way that doesn't give a lot of confidence in whether it's right.

This dovetails with a project that @GaryHinshaw and I have been tossing about, so I'd like to see what we can do with you have here.

[ednadolski]

@C855B  I will try... I no longer have the computer where I had the SketchUp installed (it'd been that long, that the machine died!) so let me see what I can do.

Ed

[ednadolski]

All I could get (so far) was to export as a .dae, does that help?

https://sabercathost.com/medR/ConcreteTie.020.dae

[Norris04]

I think it does.

[C855B]

All I could get (so far) was to export as a .dae, does that help?

https://sabercathost.com/medR/ConcreteTie.020.dae

I was able to convert the DAE to DXF using MeshLab, but even better, after knowing what to tweak I'm now looking at a converted .skp file.

HOWever... the gauge in the artwork measures to be 0.390"; it should be 0.354". How long and wide should the ties be? If I can get the expected length to correspond with the gauge error, maybe we can determine if there was some unexpected "growth" in the conversion and I can adjust accordingly.

EDIT: The ties in the file correspond to 8.5' long, exactly. So now I'm confused, because if I correct the placement of the cleats to the proper gauge, they'll be right on the edge of the "valley". I don't think that's right, is it? Do you have any prototype dimension information for or photos of this particular tie?

[narrowminded]

I was able to convert the DAE to DXF using MeshLab, but even better, after knowing what to tweak I'm now looking at a converted .skp file.

HOWever... the gauge in the artwork measures to be 0.390"; it should be 0.354". How long and wide should the ties be? If I can get the expected length to correspond with the gauge error, maybe we can determine if there was some unexpected "growth" in the conversion and I can adjust accordingly.

EDIT: The ties in the file correspond to 8.5' long, exactly. So now I'm confused, because if I correct the placement of the cleats to the proper gauge, they'll be right on the edge of the "valley". I don't think that's right, is it? Do you have any prototype dimension information for or photos of this particular tie?

I got .040" between the guides which would be for code 40.  I got .3726 inside to inside span, add back the difference between the rail foot and head, .022" and that says the drawing would have a .3946" gauge.  That's not correct but is also different than what @C855B got. 

NMRA standard calls for .359"/ .353" (.355" target +.004"/ -.002").  I have measured as much as .364" on Atlas flex track and code 55 turnout as well as .359" at a different leg on the same turnout. 

I'd be inclined to use .356" for the target and allow +/-.002".  My experience with my Nn3 track is that the target is almost always on the money and the few excursions have never exceeded .002" so I'm comfortable with those numbers.  Wheels at max NMRA tolerance shouldn't exceed .343" so there's plenty to work with.  And what's cool is, all of this with NO track gauges!  Just lay it down in the guides, done and on the money.

Same question for me.  Do you have prototype dimensions?  Also, are those rail guides the shape/appearance you would want? I have never seen concrete ties other than from a good distance.  And I can definitely do this.  

[narrowminded]

I'll add a few tie manufacturer's catalog sites here.  Start with LB Foster CXT division.  There are different choices for mainline vs: lighter duty.  Many choices.   But the dimensions don't change that much.

https://www.lbfoster.com/en/market-segments/rail-technologies/solutions/concrete-ties

Rail One

https://www.railone.com/products-solutions/long-distance-and-freight-transport/ballasted-track-systems/concrete-sleepers-b70

One thing I'm seeing from searches is the guides can be a little more robust, more like what I've done on my Nn3 track.

[ednadolski]

I'll measure the C40 rail again, but IIRC offhand I used 0.039-0.040" for the base and 0.020" for the rail head width.  (The rail height is irrelevant wrt gauge spacing)

Likewise for the ties I think I used 7x9x102 scale inches, but again let me dig thru my files and make sure. (There used to be a reference somewhere on the UPRR web page, but it gets trick as there are a number of distinctly different prototypes for concrete ties).

Ed

[ednadolski]

https://www.railone.com/products-solutions/long-distance-and-freight-transport/ballasted-track-systems/concrete-sleepers-b70

Mmmm definitely not that one....

[ednadolski]

Aha found it:

https://www.up.com/cs/groups/public/@uprr/@customers/@industrialdevelopment/@operationsspecs/@specifications/documents/up_pdf_nativedocs/pdf_up_std_0204.pdf

I don't think I tried to replicate the scalloping or the rail seat canting.

Ed

[narrowminded]

Ed, I've got a drawing started.  I used your drawing for the basic dimensions rounding the odd .008" to the nearest even fraction.  The results were the same dimensions discovered in the LB Foster Catalog, the mainline tie as well as others in their line.  The rail canting could be done but I'm honestly not sure it would show, might aggravate gluing and weighting, and also not sure if the wheels would like it with the cant getting close to matching the wheel angle.  I'm not going to do that for the test piece.  If it was determined after test piece inspection that it had benefit we could kick that around later.  Also the triangle details although I'm not sure if they'd even show when ballasted.

The dimensions are:

Length           102"
Width at foot  11"
Height            9"
Center thick    7" (my best guess)
Tie spacing     24"

I'm working on the guides and tie bridging next applying what I've learned from my Nn3 experience.  I may get a test print later today.  If not, tomorrow is hernia operation day so it may delay things a day or three or five.

[C855B]

You have a lot more direct experience here, so I'll stand by. We agree on the gauge measurement; I initially measured the same but should have said "~0.390" since I was away from the studio and was eyeballing C40 rail dimensions; rounding down seemed prudent.

My conversions have a little pyramidal "tooth" at the center of the base of each side of the tie. It was very small and would be buried by ballast, so I didn't think much of it. However, it's not on the 1:1 info, so was that intentional (centering marker, perhaps?), or is it a conversion artifact?

Good luck with your procedure, Mark. I was in those particular shoes last year.

[narrowminded]

My conversions have a little pyramidal "tooth" at the center of the base of each side of the tie. It was very small and would be buried by ballast, so I didn't think much of it. However, it's not on the 1:1 info, so was that intentional (centering marker, perhaps?), or is it a conversion artifact?

Good luck with your procedure, Mark. I was in those particular shoes last year.

This is my second go around with this one.  We're cutting for real this time!   The nurse said she's bringing the beer.

I saw those pointers and didn't include them on this go.  They could be added but I found that when laying this track it was just as easy to draw an arc on the inside radius for the tie end or the tie spacing piece under the rail and insert guide pins in the corner of the tie bridge and tie.  It's better seen in practice but is actually quite easy.

I may get a print this afternoon.  History says there's always something that could use a tweek.  We'll see.

[ednadolski]

This is my second go around with this one.  We're cutting for real this time!   The nurse said she's bringing the beer.

Best wishes, hoping all goes well!

I saw those pointers and didn't include them on this go.  They could be added but I found that when laying this track it was just as easy to draw an arc on the inside radius for the tie end or the tie spacing piece under the rail and insert guide pins in the corner of the tie bridge and tie.  It's better seen in practice but is actually quite easy.

I may get a print this afternoon.  History says there's always something that could use a tweek.  We'll see.

@narrowminded I'm floored at how quickly you've moved forward with this!   Thanks a ton!

The little pointers were intended for alignment to the centerline of a cork roadbed, but I really have no idea how well they would print.  (Maybe some kind of little notch instead?)

I did get a chance to measure the C40 rail, here with equivalent scale size for AREA 136 lb. rail [1]:

   0.042" height  (scale eq.: 0.0457")
   0.039" - 0.040" base   (scale eq.:  0.0375")
   0.0195" - 0.020" rail head  (scale eq.:  0.018")

So the C40 is about 8% undersize in height, which actually is rather less undersized than I had thought [2].

Ed

[1] http://www.akrailroad.com/products/136-lb-area-rail

[2] The Code 55 rail by comparison is about 20% oversized on height, and more than 60% oversized on rail head width. (Not too surprising, considering that it's actually an HO scale representation of 75 lb. rail.)