Model Railroading > BNSF 72’ Frostline Reefer (CAD 8) – Turnbuckles

This is CAD 8 of a series on generating the CAD geometry for the BNSF 72’ Frostline Reefer project.
 
CAD 1 thru 7 of this series was posted earlier.
 
Work continues on the Plug Door…
 
As the Handle is rotated, the gear train will pull/push horizontal Turnbuckles that come out the sides of the Gearbox Cover.  The end of the Turnbuckle is attached to the backside of the Lock Rod.  When the Plug Door is opened, the Turnbuckles are pulled towards the Gearbox Cover, rotating the Lock Rods a ¼ turn. This brings the Plug Door away from the door frame.  Reverse the Handle rotation, and the Plug Door is shoved into the door frame, creating a positive seal.
 
Turnbuckle
The main component is a long hollow cylinder, with hex nuts welded to each end.  (One nut has left-handed threads, so rotating the Turnbuckle’s cylindrical body will push or pull the threaded shafts, to fine-tune the length.)  
 



Edited 5 time(s). Last edit at 03/17/23 11:03 by tmotor.

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Too Close For Comfort
On the prototype the Turnbuckle is close to, but NOT in contact with the face of the Plug Door.  When the geometry matches this design, the model will have the Turnbuckle supported only by the ends, kinda’ like a grab iron.  Will this be too fragile?  There’s one way to find out…
 
Some 3D prints will be tested for just how much abuse they can take.  Because they are recessed into the Plug Door, it is less likely they will encounter enough force to break them.  However, after 3D printing some Plug Doors, they will be tested to confirm their durability.
 
Lost In Space
When the geometry is “floating” away from the main components, moving these parts around to get them aligned (with each other, or the rest of the Plug Door) can be a bit of a chore.  One thing that helps is to group components on their own plane.  This way the plane can be moved, and the components come along for the ride as a unit.
 
Dave

 



Edited 1 time(s). Last edit at 03/17/23 00:02 by tmotor.

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