Big Train James
Western Thunderer
In applications such as boiler wrappers, or curved car sides or roofs, is there a commonly accepted rule of thumb/percentage factor for the length of the wrapper versus the length of the curved edge of the former?
The specific implementation I'm considering at the moment is the following US outline "cylindrical" covered hopper (it's not really truly cylindrical), but there are any number of similar cars where the answer would apply.
The length of the former edge should be simple enough to get right, presuming that the proper adjustment is made to overall dimensions to account for the etching process.
What I'm really curious about is the size of the wrapper, and in particular if there is to be a fold line and hard corner at the end of the curved surface. I realize this is splitting hairs when dealing with something like .40 mm sheet, but technically the inside face of the wrapper will be shorter than the outside face, once rolled. It wouldn't be so much of an issue if the curved surface stood on its own, and could be made to fit with some filing. What I'm really concerned about is getting the fold lines positioned properly,
Is this something that can be accounted for in advance? Or is trial and error going to be the ultimate solution? I'd prefer to keep the T&E to a minimum obviously, but especially if I use PPD for the etching, as overseas shipping costs would get out of hand quickly after one or two tries.
In a related situation, what rule(s) apply for sizing a sheet for a tightly rolled edge, like the corner of the hood on the following loco. The prototype is a 4" radius, so .080" ish in O scale.
Lastly, I have a question about using rollers to form curved sheets. I would like to represent the weld seams between panels on the hopper car side. I am considering a half-etched groove at each joint, to be filled with a length of something like .015" phosphor bronze wire. It seems to me that fitting the wires to the side sheet would be simpler when still flat. So the question is, can the side sheet still be rolled effectively once the "weld beads" are soldered into place? Or will they need to be attached after the side sheet is formed?
Or does anybody have a suggestion for a different way to create the welds? I have considered using Archer weld bead resin surface decals. But they are relatively expensive, and there will be something like 24-30 linear inches needed per car.
Thanks,
Jim
The specific implementation I'm considering at the moment is the following US outline "cylindrical" covered hopper (it's not really truly cylindrical), but there are any number of similar cars where the answer would apply.
The length of the former edge should be simple enough to get right, presuming that the proper adjustment is made to overall dimensions to account for the etching process.
What I'm really curious about is the size of the wrapper, and in particular if there is to be a fold line and hard corner at the end of the curved surface. I realize this is splitting hairs when dealing with something like .40 mm sheet, but technically the inside face of the wrapper will be shorter than the outside face, once rolled. It wouldn't be so much of an issue if the curved surface stood on its own, and could be made to fit with some filing. What I'm really concerned about is getting the fold lines positioned properly,
Is this something that can be accounted for in advance? Or is trial and error going to be the ultimate solution? I'd prefer to keep the T&E to a minimum obviously, but especially if I use PPD for the etching, as overseas shipping costs would get out of hand quickly after one or two tries.
In a related situation, what rule(s) apply for sizing a sheet for a tightly rolled edge, like the corner of the hood on the following loco. The prototype is a 4" radius, so .080" ish in O scale.
Lastly, I have a question about using rollers to form curved sheets. I would like to represent the weld seams between panels on the hopper car side. I am considering a half-etched groove at each joint, to be filled with a length of something like .015" phosphor bronze wire. It seems to me that fitting the wires to the side sheet would be simpler when still flat. So the question is, can the side sheet still be rolled effectively once the "weld beads" are soldered into place? Or will they need to be attached after the side sheet is formed?
Or does anybody have a suggestion for a different way to create the welds? I have considered using Archer weld bead resin surface decals. But they are relatively expensive, and there will be something like 24-30 linear inches needed per car.
Thanks,
Jim