260 Brass Metal Spinning Project

[Ed T]

OK, one last "spin" on this. Since the segments are being spun why not just have a step to a smaller diameter spun onto the small end of each part that would fit into the ID of the adjacent part arond 1/4 to 3/8". This would stiffen up the edge a lot, provide auto alignment to some extent and should be simple to do during the spinning operation (as long as you do it on the small end). Since the hull shape is decorative and not a pressure vessel of any kind, you might want to consider soft solder. It would be easier to do, lots less costly, far fewer issues associated with temperature, less chance of melting a hole in something and, most important, it is far easier to undo than silver solder should the need arise. With "telescoping parts" the joint would be very strong.

 

[sunworksco]

Spinning a lip on the hull sections would necessitate some complicated multi-piece mandrels.
Can I find a low-temp silver solder that is 260 brass colored?
Thanks,
Giovanni

 

[Ed T]

I'm not an expert on metal spinning, but I can certainly see that putting a step on the big end of a tapered part would be a problem requiring some collapsing cores etc. . I am not sure I understand why putting a step on the small end would be any big deal . Even cheap metal kitchenware at the dollar store and metal lampshades often have this kind of feature. WRT the color matching, I doubt you're going to find anything that matches perfectly, but you might have better luck in the bronze brazing rod department than in the silver solder department. Looking at photos of the prototype, the seams were fairly apparent any how. Out of curiousity, any idea how the prototype was built/assembled?

 

[sunworksco]

No prototype has been built.
My metal spinner does not recommend spinning the lip. It is too difficult to get a precise lip spun in brass.
Spinning aluminum is what most people see or very shallow vessals but we are doing sections of around 10" depths.
Thanks,
Giovanni

View attachment Metal Spinning Tutorial.doc

 

[Ed T]

I meant the prototype built in the 19th century. Your metal spinner hopefully knows more about the process than I do (wouldn't be too hard).

 

[sunworksco]

Here is the USS Holland.
Regards,
Giovanni

 

[Jasonb]

I would have thought that was built with rivits.

Regarding colour matching even silversolder(braze) will tarnish black over time due to the silver content, Bronze braze will be a better colout but the heat needed will be higher so the risk of distortion even higher.

Jason

 

[Ken I]

Jason B has a point about rivets.

Why not spin inner rings for the joints and rivet the assembly together - paticularly if this is the flooded section of the hull and not required to be watertight.

I would also look cool.

Ken

 

[sunworksco]

My metal spinner told me that he could spin the inner rings.
I'm thinking that he could use the same hull mandrels then cut a small section out of the rings to get a slightly smaller diameter.
I think that I could use gold silver solder paste on the seams then file them smooth.
The original hull does not have rivets.
Thanks,
Giovanni

 

[Jasonb]

The original hull does not have rivets.

Can I ask what was used instead to join the plates and hold them to the ribs? I thought they would have used countersunk rivits.

Silver solder paste is no different to the stick form, its just the same material ground into a fine powder and then mixed with flux paste, it also has a limited shelf life and costs a lot more and will still tarnish to black unless sealed from teh air with a lacquer.

Spinning the joint rings will be ideal, you could tack them on with a few CSK brass rivits to hold it together whilst soldering then when the rivits are filed flush they wil be invisible

Jason

EDIT
Just found this
"Thankfully we 'grew up' sooner than later and built 6 Holland type submarines under licence here in the UK. They were considerably different again externally (an example being the USS Holland had mainly flush rivets, ours the normal 'domed' rivets. Was John Holland even then thinking of reducing drag? I would like to think so."

 

[sunworksco]

I was planning to use gold/silver solder that will not tarnish.
I think the hull was originally welded with some flush riveting.
Rivets might be the best method and like you say, can be machined flush after soldering.
I'm going to fixture the hull onto a 5-axis laser cutting machine after soldering the hull sections together then have the access door cut out of the bottom. All of the drain and vent holes can be cut,too. I can also have the longitudinal plate lines cut into the hull.
The rib sections image is of the later 1903 version, which is more hydro-dynamically designed.
Good idea!
Thanks,
Giovanni

 

[sunworksco]

Here is a CG of the USS Holland Submarine.
Regards,
Giovanni

View attachment USS Holland 3D CAD Drawing.tif