Best Of Scratchbuild Project - CC&F Twin Trailer Flat Car

[Angus Shops]

Tim, it looks like the attachment of the coupler pocket to the body of the car may be a weak point. May I suggest you add a ‘flange’ to each side of the coupler pocket so that the coupler pocket can be secured to the adjacent deck pieces (the pieces marked “A” in the photos). A compromise, but but a more solid solution. With regards to the bulk of the fabricated coupler pockets, a fabricator of your skills could probably fabricate a replacement for the MT box out of styrene and dispose of the MT box altogether and have a box that can be securely glue to the car structure.
Geoff

[BCR 570]

Hi Geoff:

My original build plan has the end sills connecting the coupler pocket to the end of the side sills and runways resulting in a fairly strong assembly.  The adjacent runways are only .010" thick so not a lot of strength there.

Given my chequered experience with 3D printed coupler boxes and the poor performance of MT draft gear inside them, I have ruled out building replacement boxes.

Thank you for the suggestions; I am working on a new design today.  i had hoped to get hte end sills on today but this requires some more thought.


Tim

[Angus Shops]

Ah, end sills. I didn’t consider that. Makes perfect sense.
G

[BCR 570]

I appreciate the input.  I spent much of this morning trying to devise a lower profile box to no avail.  It just doesn't have the structural integrity required.  At the end of the day the car has to operate well on my layout.  Couplers are one of the areas on our models where we often have to make sacrifices in appearance for functionality.

My original design plugs nicely into the end of the car, locates the coupler box centrally and at the right height, and locks everything together, so will go with that.


Tim

[peteski]

My original design plugs nicely into the end of the car, locates the coupler box centrally and at the right height, and locks everything together, so will go with that.


Tim

I just offered a suggestion - in the end you are the designer and the builder, and know what works the best.

[BCR 570]

Yep, but as stated above I am always open to suggestions.  There is always more than one way to do things.

Tim

[BCR 570]

Side Sills (Part 4)
The addition of the side sill assemblies is a major step forward for these models.  I spent some time planning exactly how to do this as the parts are over 6 actual inches in length, which is a long glue joint.  The photograph below shows a cross-section of the test sections I built, which illustrate the orientation of the side sills on the model:




You can see that the bottom edge of the side sills is more or less level with the ends of the diaphragms and cross-members, and the top edge of the side sills is about .040" above the runways.  I determined that it was probably best to install the side sills with the models and parts upside down on a flat surface.  To achieve this, the cars would have to be shimmed up .040" to mate correctly with the side sills.

I hauled out my magnetic gluing tray again, which was used earlier in the project.  Against the wall of the tray, I placed an aluminum track alignment tool which gave me a perfectly flat surface to push the car up against.  I cut lengths of .040" thick styrene to place underneath the car and shim it up to the correct height, and placed the car on top upside down.  At one end I placed an angle block to help align the side sills with the runways.  I then pushed this entire assembly up against the length of aluminum.

The plan was to push against the side sill with magnets, but this resulted in the side sill tipping over, and I needed it to be perpendicular to the car.  I cut lengths of .125" x .125" styrene which were thicker than the side sill, and used these as blocks to push against.  These kept the side sills perfectly upright.  After checking everything to ensure all was well, I removed the car, applied glue to the ends of the bolsters and diaphragms, placed the side sill back against the car, and then moved the magnets into position so that they were pushing against the blocks next to the side sill.  I used a second angle block at the other end to ensure that the side sill was aligned perfectly with the runway.  I then applied glue to the joint between the runway and side sill at each end.  The addition of the first side sill looked like this:




After letting the initial joints dry for two hours, I removed the car from the tray, applied glue to the sections in between the bolsters and diaphragms, and returned the car to the tray for another hour or so.  After removing the car from the tray for a second time, I checked the glue joint to ensure that it was solid all the way along, and applied additional glue where needed.  I have found this to be a better method than applying lots of glue all at once as several applications of smaller quantities of glue helps to avoid the heat build-up and resulting deformation which can sometimes occur.

The car was now turned around for installation of the second side sill.  I had to cut a second set of .125" x .125" spacers to go between the length of aluminum and the previously installed side sill as the chain pockets protruded out past the sills (probably should have installed those later  ).  I then repeated the process described above to add the second side sill, which looked like this:




With the side sills now attached to the car, I was able to complete those end cut-outs.  I estimated them to be 8" long and 8" high.  I had already cut away the top flange for these.  The next step was to slice down through the web of the side sills to the runways.  For this I used a new #17 Xacto blade:




The same blade was then used to slice horizontally through the web of the side sills at the level of the runways to meet the first cut.  The corner square of styrene was thus removed, and hte cut-outs were cleaned up with files:




And here are the two cars after installation of the side sill assemblies, and completion of the end cut-outs:




And a photograph of a car on its trucks after installation of the side sill assemblies:




This is a good place to stop for a while and take a break from the plastic cement fumes.  When I resume, my attention will turn to the end sill assemblies and coupler pockets, after which I will be able to take the cars for their first test run.


Tim

[Lemosteam]

Second nomination for a "Best OF" here.

@BCR 570 , the precision with which you trim styrene, is one reason I will not scratch build like this.  I can see from every piece you show that the ends are perfectly square to the axis of extrusion in every plane and that is something I have tried but cannot achieve.

It's really amazing and I admire your accuracy, not to mention how you have made repeatable cuts on multiple parts.

[peteski]

Second nomination for a "Best OF" here.

2 earlier nominations were made in replies # 61 and 62 (previsous page). Not sure what one has to do to make this happen.

And as far as your modeling skills go, even if you can't make a square cut in a piece of styrene, your are a CAD magician, able to come up with some amazing N scale models.  Don't CUT yourself short. 

[Lemosteam]

2 earlier nominations were made in replies # 61 and 62 (previsous page). Not sure what one has to do to make this happen.

And as far as your modeling skills go, even if you can't make a square cut in a piece of styrene, your are a CAD magician, able to come up with some amazing N scale models.  Don't CUT yourself short. 

Yes, I suppose it would have taken me a couple days to model this and even provide cavities for his weights!  But there is no comparison for building something from the ground-up.

[peteski]

Yes, I suppose it would have taken me a couple days to model this and even provide cavities for his weights!  But there is no comparison for building something from the ground-up.

But you are no slouch either.    We all excel at one thing or another, and often complement each other's skills, even joining forces on a project. Sharing knowledge and techniques is what this forum is great for.

[BCR 570]

Coupler Pockets & End Sills (Part 1)
I have spent some time deliberating over the best approach for the coupler boxes and end sills.  My original test end section included a styrene box fully enclosing the #1023 coupler, end sills built from three separate pieces of strip styrene, and corner gussets.  After deciding to switch to #1016 couplers I adapted the coupler box as required.  Here is my original test end section with one set of component parts for the coupler box and end sill:



The pieces for the end sills were attached to the outer end of the coupler box on either side:






This resulted in an assembly which would then plug onto the end of the car, leaving just the tiny corner gussets to be added:




However, I was not satisfied with the results of this approach.  I was not able to keep the end sills as straight and perpendicular as I would like, and the modified coupler box was now quite large.  I opted to build a second set of coupler boxes omitting with the bottom plate underneath the coupler which was not really necessary, thus reducing the overall thickness of the box.  I also opted to install the coupler boxes onto the cars and then the end sills.  This approach yielded better results.

The first component of each half of the end sills is a strip of .020" x .060" styrene which is actually a support for the ends of the running plates.  These are only .010" thick and there needs to be something more for the end sill pieces to attach to.  With the cars upside down on planks of .040" thick styrene, the running plate supports were glued in place:




Here are the modified coupler boxes and the two pieces for each section of end sill:




The inside ends of the running plate supports were then trimmed with files to allow the coupler boxes to slide into place between them.  The coupler boxes were slid into place and glued to the ends of the centre sills and the ends of the running plate supports:




This provides three points of attachment for the coupler boxes and after installation they seem to be fairly secure.  The addition of the end sill pieces will provide additional attachment and support.


Tim

[peteski]

Looks good!

[BCR 570]

Thank you; you should know that my decision to reduce the profile of the coupler box by eliminating the bottom plate was in response to your earlier suggestion.  I have kept the full height sides as they are needed for the end sills to join onto.

Tim

[peteski]

Thank you; you should know that my decision to reduce the profile of the coupler box by eliminating the bottom plate was in response to your earlier suggestion.  I have kept the full height sides as they are needed for the end sills to join onto.

Tim

I'm glad that you found my commend useful - the coupler area looks less bulky now.