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Penrhos1920

Material selection for buffers

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Is Shapeways fine detail plastic (FDP) a good material for buffers?  Traditionally they are either polystyrene, white metal or brass often with steel heads.  Is FDP strong enough and not too brittle for the body?  Has anyone successfully printed brass buffer bodies?

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Posted (edited)

In 4mm I've only ever had one FDP buffer shank fail on me, and that was from a 4 foot drop that landed right on that buffer. None of the other materials offer fine enough walls that you can make the clearance hole through for metal heads and keep a reasonably prototypical outer diameter. 

 

These are my Cambrian ones with MJT sprung heads:

P1040223.jpg.e7d931e4cc98202802eaff17281afcf9.jpg

Edited by Quarryscapes
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7 hours ago, Quarryscapes said:

In 4mm I've only ever had one FDP buffer shank fail on me, and that was from a 4 foot drop that landed right on that buffer. ....

 

 

That’s no worse than whitemetal which would have bent beyond use and polystyrene would have probably bent as well.

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If you were to do away with springing and glued steel heads in it'd be even stronger of course.

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Posted (edited)

I bought a block of Mike Trice's 4mm scale buffer housings off Shapeways and find them quite acceptable, likewise the buffer housings in Bill Bedford's (Mousa Models) resin wagon kits.  Yes they are brittle and need to be handled with care, and there are more robust alternatives e.g. MJT in whitemetal with embedded steel buffers, but once in place, no more care than any other finescale model.  Both Bill's and Mike's 3D printed units are intended to be used with turned steel buffer heads and integral coil springs (that should be  springs  actually).  Mike's work first time, Bill's I found I needed a bit of clearing out with a 0.5mm drill through to the rear and a 0.9mm to 1mm drill for the shank - by hand in a pin chuck.  I used Wizard Models buffer heads and springs - you need about 12 prings for each wagon as they follow similar trajectories to particles in the CERN accelerator.

 

Bill also provides 3D printed couplings in these kits, but they are less satisfactory, mainly because couplings get handled a lot, but also because they are difficult to secure in the solebar without gumming up.  Their pulling strength seems ok, but they are very prone to falling apart under lateral pressure on the links - no doubt due to weak bonding of the filament between layers.  Given the scale thinness of the links, this is probably not the best material for couplings.

Edited by DayReturn
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