PRR Cinder (pyramidal) Bumpers now available at Keystone Details!

[Lemosteam]

Keystone Details has now added a PRR Cinder (pyramidal) Bumper based on plan 70100-B to its linup as a 4 pack:



The product is intended to be coated with your favorite ballast/cinder product after installation.  A score line allows for Atlas Code 55 track height with the un-cut product designed to fit Unitrak. Sanding off 0.3mm will work for Atlas Code 80 track.  Some trimming may be necessary around your track underlayment product (cork, etc.) at the track opening.  The wall inside is designed to butt against the end of your track for prototypical proportions.

[wcfn100]

Is the scale on those correct.  11x10 cm for the four pack at $31 seems off to me.   


Jason

[Lemosteam]

Is the scale on those correct.  11x10 cm for the four pack at $31 seems off to me.   


Jason

The scale is dead on, in fact I modeled the design to the smallest sizes permissible on the PRR plan.  Some of these parts are seemingly very expensive when I upload them, and of course they are hollow to minimize the volume of the plastic as well.

http://prr.railfan.net/standards/standards.cgi?plan=70100-B&frame=YES&sortby=1

[wcfn100]

Okay, I didn't see the part about fitting Unitrack .   


From the drawings, it looks like these go down to the bottoms of the ties which for Atlas c55 would result in a pyramid about .64 cm tall.  If that's your 1.09 cm dimension because of the Unitrack, you may want to make a non-Unitrack version.

Jason

[Lemosteam]

The pyramid does not rest on the ties. The design must rest on the substrate of the layout because it is much wider than the track.  I drew cross sections of code 55 and 80 with cork roadbed, and Unitrak.  The line on the model is a cut line for code 55 to sit flat on the layout.  I don't want to risk customers buying the wrong product.

[Chris333]

Not that it matters to me, but...

Since you are covering these with ballast and detail doesn't matter, why not offer them in that cheaper WSF nylon stuff?

[wcfn100]

  I drew cross sections of code 55 and 80 with cork roadbed, and Unitrak.

I understand that, I'm just saying that in the drawing it sits on top of the cork.  And when drawn that way, it cuts the price in half for the 4 pack and matches the prototype size better.  I just thought that could be a good option to offer.

Not trying to make waves, the price just struck at first me for how big/small I thought they were, but I understand now why it's that way.

Jason

[Lemosteam]

I understand that, I'm just saying that in the drawing it sits on top of the cork.  And when drawn that way, it cuts the price in half for the 4 pack and matches the prototype size better.  I just thought that could be a good option to offer.

Not trying to make waves, the price just struck at first me for how big/small I thought they were, but I understand now why it's that way.

Jason

@wcfn100 It doesn't sit on the cork either.  It is much wider and would sit on the foam, plywood, etc.

@Chris333 I can look into that, but I wold have to makes the walls much thicker. I can test that on Shapeways.

[wcfn100]

@wcfn100 It doesn't sit on the cork either.  It is much wider and would sit on the foam, plywood, etc.

Then you and I read the drawing differently.

Jason

[Lemosteam]

Then you and I read the drawing differently.

Jason

@wcfn100 Not sure how you can? Note the roadbed under the track in  Section A-A- this is the cork essentially.  Here is a cross section through the design (gray) and various track and cork measured directly from each type of track.  At the angle of the sides of the mound (there is no way the edges can sit on the cork and be dimensionally accurate:

[wcfn100]

@wcfn100 Not sure how you can? Note the roadbed under the track in  Section A-A- this is the cork essentially.

Right, and I don't read it as going into the 'cork' that but sitting on top of it.

This is what I see:



But whatever, I'm not trying argue about the design.  Again, the price just made something seem off for 4 bumpers, but that was solved many replies ago.   

Jason

[Lemosteam]

@Chris333 The product is now also available in Black Strong & Flexible for reduced cost.

@wcfn100 Your model does not account for the tie thickness which also sits on the cork.

I guess my section doesn't make sense then?  The cork simply isn't wide enough on a single track for the part to actually sit on looking along the track.  I am either not following your line of reasoning or have made a mistake in my design?

I really would like to understand if there is a flaw in the design, so I am not trying to be argumentative either.

If I shorten the model to the top surface of the cork, what will hold the part up at the far end?  it will only be resting on the rail head at the front end, no?

Unless you are thinking of cork that covers an area larger that the width of a single cork Midwest cork strip?

Here is a solid of the track exiting the bumper.  the cut line is stricly for C55/cork users (I would simply cut away the corkinstead of cutting the part to clear the cork):

[wcfn100]

I guess my section doesn't make sense then?

Well it makes sense and is well thought out, it's just not how I read what the drawing is showing.  But that could just be me.  Wouldn't be the first time. 

Unless you are thinking of cork that covers an entire area?

People handle sidings different ways, some do lay them right onto a larger corked area so the siding doesn't looked raised.  Otherwise you typically know where a siding ends and could just add some extra cork where the bumper would go.


Jason

[peteski]

How about either adding a 2nd score line or designing a 2nd type of bumper for those modelers who have their tracks on a solid flat piece of cork (or lay their yard tracks directly on the layout's surface)?

[towl1996]

Not to drift this too far...but since we have two bumper styles, does any one know the situation in which the PRR chose one type over the other. I suspect the cinder type was used in more rural settings, but what standard did the Standard Railroad of the World use?