Patrick Matthews

Yes, that's what it is.
 
But two topics here:
 
1. For any CNC machine, one starts with a 3D CAD model of a part. This is fed into some sort of tool path generating software, wherein you define the part's orientation and the size of the rough blank. Using the s/w, you then define what the rough and finishing cuts look like, based on the cutting tools used... the s/w generates the path that the cutting tool will follow. For simple 3-axis mills (including router tables with an adjustable Z-axis), I believe there is even free s/w available.
 
2. Going beyond the basic 3-axis machines, you have 5-axis and even more complicated machines available. Something like a half hull can be machined on a simple 3-axis; a complicated carving, like a 3D sculpture, a figurehead, etc., could make use of 5-axis. It gives the machine the ability to twist and turn the part under the cutting tool... search Youtube with "5-axis CNC" and you'll find plenty of fascinating videos of this. 
But 5-axis machines are very specialized, expensive, and take very skilled programmers to set up... so your machine-carved figurehead will likely be very important to you, for you to take this path!

In functional boat and ship models, many modelers use brass props made of stamped blades soldered to machined hubs. Nicer props, having a more realistic shape, are made by casting in brass or bronze. The process used for these is lost wax, or investment, casting. Usually, the waxes are made by injecting wax into a rubber mold; the rubber molds can be made from a carved or machined master.
 
Should you need a unique prop design, you’ll need to commission a master and a mold; don’t forget to allow for casting shrink when you specify the master! Need a left and a right? Twice the masters and molds.
 
Another option? 3D print the waxes- no need for masters, no rubber molds, and complete freedom to scale and mirror the design.
BTW: You can also machine the waxes on a 5-axis mill… but that’s another challenge.
 
But if you can create a 3D CAD model of the prop, and don’t mind machining the bore yourself, you can use very convenient 3D printing services like Shapeways to source your own custom props.
 
In this example, I made some props for Monterey Clipper fishing boats, using the Yuba-Hicks “weed cutter” design that many of these boats carried. While it’s possible to draw a convincing prop from scratch with some basic knowledge of prop blade shape, I had the benefit of the original factory drawing to work from:

 
CAD rendering of the design:

 
Raw cast bronze prop from Shapeways-  2.5” diameter:

 
From the same CAD model, a 2.25” opposite hand prop (on left):

 
Machining the bore and threads on my lathe:

 
Prop with a 3D printed Hicks engine model:

 
The 2.25” prop went on this 1:8 scale model Monterey:

Even easier... look for larger stranded wire made up of fine uncoated strands. Done.
 
But not quite... straighten the wire: clamp one end in vise, and firmly pull the wire until you feel it yield just a bit... let loose, and the wire will be straight!

Place blobs of wet tissue paper on previously soldered areas, then use a hot iron to solder the next. 
Pretinning can help, and use flux.

Thanks. More at: 
 

Old thread alert!
But I'll repeat something I just mentioned in another soldering thread: soggy globs of toilet paper (umm, use fresh water...) as heat sinks.
 
I soldered a whole mess of brass rails to brass stanchions, pre-situated in drilled holes on a painted plastic deck... with the soldering taking place as close as 1/4 inch from the deck. The soggy blobs did the trick, no damage at all.
 
 

Old thread alert!
But I'll repeat something I just mentioned in another soldering thread: soggy globs of toilet paper (umm, use fresh water...) as heat sinks.
 
I soldered a whole mess of brass rails to brass stanchions, pre-situated in drilled holes on a painted plastic deck... with the soldering taking place as close as 1/4 inch from the deck. The soggy blobs did the trick, no damage at all.
 
 

Place blobs of wet tissue paper on previously soldered areas, then use a hot iron to solder the next. 
Pretinning can help, and use flux.

Thanks. More at: 
 

Old thread alert!
But I'll repeat something I just mentioned in another soldering thread: soggy globs of toilet paper (umm, use fresh water...) as heat sinks.
 
I soldered a whole mess of brass rails to brass stanchions, pre-situated in drilled holes on a painted plastic deck... with the soldering taking place as close as 1/4 inch from the deck. The soggy blobs did the trick, no damage at all.
 
 

In functional boat and ship models, many modelers use brass props made of stamped blades soldered to machined hubs. Nicer props, having a more realistic shape, are made by casting in brass or bronze. The process used for these is lost wax, or investment, casting. Usually, the waxes are made by injecting wax into a rubber mold; the rubber molds can be made from a carved or machined master.
 
Should you need a unique prop design, you’ll need to commission a master and a mold; don’t forget to allow for casting shrink when you specify the master! Need a left and a right? Twice the masters and molds.
 
Another option? 3D print the waxes- no need for masters, no rubber molds, and complete freedom to scale and mirror the design.
BTW: You can also machine the waxes on a 5-axis mill… but that’s another challenge.
 
But if you can create a 3D CAD model of the prop, and don’t mind machining the bore yourself, you can use very convenient 3D printing services like Shapeways to source your own custom props.
 
In this example, I made some props for Monterey Clipper fishing boats, using the Yuba-Hicks “weed cutter” design that many of these boats carried. While it’s possible to draw a convincing prop from scratch with some basic knowledge of prop blade shape, I had the benefit of the original factory drawing to work from:

 
CAD rendering of the design:

 
Raw cast bronze prop from Shapeways-  2.5” diameter:

 
From the same CAD model, a 2.25” opposite hand prop (on left):

 
Machining the bore and threads on my lathe:

 
Prop with a 3D printed Hicks engine model:

 
The 2.25” prop went on this 1:8 scale model Monterey:

Old thread alert!
But I'll repeat something I just mentioned in another soldering thread: soggy globs of toilet paper (umm, use fresh water...) as heat sinks.
 
I soldered a whole mess of brass rails to brass stanchions, pre-situated in drilled holes on a painted plastic deck... with the soldering taking place as close as 1/4 inch from the deck. The soggy blobs did the trick, no damage at all.
 
 

Old thread alert!
But I'll repeat something I just mentioned in another soldering thread: soggy globs of toilet paper (umm, use fresh water...) as heat sinks.
 
I soldered a whole mess of brass rails to brass stanchions, pre-situated in drilled holes on a painted plastic deck... with the soldering taking place as close as 1/4 inch from the deck. The soggy blobs did the trick, no damage at all.
 
 

Old thread alert!
But I'll repeat something I just mentioned in another soldering thread: soggy globs of toilet paper (umm, use fresh water...) as heat sinks.
 
I soldered a whole mess of brass rails to brass stanchions, pre-situated in drilled holes on a painted plastic deck... with the soldering taking place as close as 1/4 inch from the deck. The soggy blobs did the trick, no damage at all.
 
 

And ANOTHER thing... these outfits (like Shapeways) have set up so that you can sell your own designs in your own shop... they handle the web work, order taking and fulfillment, and send you a check every month. Sweet.
I got started in it just to make my range of cowl vents available... those nasty little vents, about the hardest part to make on any ship model!
 
The examples below are on a 1:32 ocean salvage tug.
 
 

Kurt-
Sorry I couldn't make it to Manitowoc to give that talk!
 
My advice to any fine modeler: Do NOT waste money on "affordable" home 3D printers... they are frustrating to use, and produce poor quality parts. Instead, take your designs to a commercial house like Shapeways or iMaterialise, where they have spent MILLIONS on top quality equipment... parts will come out quickly and much nicer than anything a home machine can produce.
 
Here is my latest 3DP project, an animated Hicks marine engine in 1:8 scale. Mostly 3D printed, with a little PE and traditional machining. Even the brass parts, including the prop, were 3D printed. Well actually, the waxes were printed, and then fed into the traditional investment casting process. 
 
 
 

Old thread alert!
But I'll repeat something I just mentioned in another soldering thread: soggy globs of toilet paper (umm, use fresh water...) as heat sinks.
 
I soldered a whole mess of brass rails to brass stanchions, pre-situated in drilled holes on a painted plastic deck... with the soldering taking place as close as 1/4 inch from the deck. The soggy blobs did the trick, no damage at all.
 
 

In functional boat and ship models, many modelers use brass props made of stamped blades soldered to machined hubs. Nicer props, having a more realistic shape, are made by casting in brass or bronze. The process used for these is lost wax, or investment, casting. Usually, the waxes are made by injecting wax into a rubber mold; the rubber molds can be made from a carved or machined master.
 
Should you need a unique prop design, you’ll need to commission a master and a mold; don’t forget to allow for casting shrink when you specify the master! Need a left and a right? Twice the masters and molds.
 
Another option? 3D print the waxes- no need for masters, no rubber molds, and complete freedom to scale and mirror the design.
BTW: You can also machine the waxes on a 5-axis mill… but that’s another challenge.
 
But if you can create a 3D CAD model of the prop, and don’t mind machining the bore yourself, you can use very convenient 3D printing services like Shapeways to source your own custom props.
 
In this example, I made some props for Monterey Clipper fishing boats, using the Yuba-Hicks “weed cutter” design that many of these boats carried. While it’s possible to draw a convincing prop from scratch with some basic knowledge of prop blade shape, I had the benefit of the original factory drawing to work from:

 
CAD rendering of the design:

 
Raw cast bronze prop from Shapeways-  2.5” diameter:

 
From the same CAD model, a 2.25” opposite hand prop (on left):

 
Machining the bore and threads on my lathe:

 
Prop with a 3D printed Hicks engine model:

 
The 2.25” prop went on this 1:8 scale model Monterey:

Yes, that's what it is.
 
But two topics here:
 
1. For any CNC machine, one starts with a 3D CAD model of a part. This is fed into some sort of tool path generating software, wherein you define the part's orientation and the size of the rough blank. Using the s/w, you then define what the rough and finishing cuts look like, based on the cutting tools used... the s/w generates the path that the cutting tool will follow. For simple 3-axis mills (including router tables with an adjustable Z-axis), I believe there is even free s/w available.
 
2. Going beyond the basic 3-axis machines, you have 5-axis and even more complicated machines available. Something like a half hull can be machined on a simple 3-axis; a complicated carving, like a 3D sculpture, a figurehead, etc., could make use of 5-axis. It gives the machine the ability to twist and turn the part under the cutting tool... search Youtube with "5-axis CNC" and you'll find plenty of fascinating videos of this. 
But 5-axis machines are very specialized, expensive, and take very skilled programmers to set up... so your machine-carved figurehead will likely be very important to you, for you to take this path!

3-axes are plenty for most machinable-from-wood jobs... what would need 5?
 
But all you need is the appropriate software to generate tool paths, and away you go!

Kurt-
Sorry I couldn't make it to Manitowoc to give that talk!
 
My advice to any fine modeler: Do NOT waste money on "affordable" home 3D printers... they are frustrating to use, and produce poor quality parts. Instead, take your designs to a commercial house like Shapeways or iMaterialise, where they have spent MILLIONS on top quality equipment... parts will come out quickly and much nicer than anything a home machine can produce.
 
Here is my latest 3DP project, an animated Hicks marine engine in 1:8 scale. Mostly 3D printed, with a little PE and traditional machining. Even the brass parts, including the prop, were 3D printed. Well actually, the waxes were printed, and then fed into the traditional investment casting process. 
 
 
 

3-axes are plenty for most machinable-from-wood jobs... what would need 5?
 
But all you need is the appropriate software to generate tool paths, and away you go!

And ANOTHER thing... these outfits (like Shapeways) have set up so that you can sell your own designs in your own shop... they handle the web work, order taking and fulfillment, and send you a check every month. Sweet.
I got started in it just to make my range of cowl vents available... those nasty little vents, about the hardest part to make on any ship model!
 
The examples below are on a 1:32 ocean salvage tug.
 
 

Kurt-
Sorry I couldn't make it to Manitowoc to give that talk!
 
My advice to any fine modeler: Do NOT waste money on "affordable" home 3D printers... they are frustrating to use, and produce poor quality parts. Instead, take your designs to a commercial house like Shapeways or iMaterialise, where they have spent MILLIONS on top quality equipment... parts will come out quickly and much nicer than anything a home machine can produce.
 
Here is my latest 3DP project, an animated Hicks marine engine in 1:8 scale. Mostly 3D printed, with a little PE and traditional machining. Even the brass parts, including the prop, were 3D printed. Well actually, the waxes were printed, and then fed into the traditional investment casting process. 
 
 
 

Kurt-
Sorry I couldn't make it to Manitowoc to give that talk!
 
My advice to any fine modeler: Do NOT waste money on "affordable" home 3D printers... they are frustrating to use, and produce poor quality parts. Instead, take your designs to a commercial house like Shapeways or iMaterialise, where they have spent MILLIONS on top quality equipment... parts will come out quickly and much nicer than anything a home machine can produce.
 
Here is my latest 3DP project, an animated Hicks marine engine in 1:8 scale. Mostly 3D printed, with a little PE and traditional machining. Even the brass parts, including the prop, were 3D printed. Well actually, the waxes were printed, and then fed into the traditional investment casting process.