SMS Deutschland Build

Thanks.

Yes it feels like brass, i have no reason to think it isn't.

 

Yeah. Brass/bronze, whats a little tin/zinc between friends, it's mostly copper either way. I'm sure I can't tell them apart by feel.

Gees...It's not like it came with a Metallurgical Report, I dont have material properties on it or anything.

 

Bronze typically has better corrosion resistance in marine environments. ie Salt water which we don't normally deal with, but we do fight in some pretty chemical laden ponds from time to time. For our use case I'd be surprised if there is a significant difference between them. Bronze is a little harder and more brittle, Brass is softer and more malleable so I guess you stand a better chance of bending a brass blade than a bronze one.

They are lost wax investment cast like Nick said. They aren't sintered or anything like that. When I do the machining to bore the shaft hole and cut off the nub I'll get some pictures to show of the inside, if it isn't solid bronze I'll be writing a strongly worded letter.

edit: I'm bad at english....

 

I cut the nub off the end after brazing it onto the propshaft. As expected it is solid bronze, I cleaned up the cut off nub a little to get a halfway decent picture of it. (The silver portion in the middle is prop shaft material/SS that also got cut off.) Not the best picture but I dont have a true macro setup so good enough for me.



And a rather boring picture of the prop brazed onto the shaft.

 

Prop Cost (Not including shipping):

Old Pricing: $37.41

New Pricing: $33.99

 

Slowly making some progress, I got the hull epoxied and strategically fiber-glassed. Motor mount is going in tonight so should get to test out this drive belt setup in the near future and the rudder will get designed/built/installed after that.

 

Minor progress tonight. I sorted out the first crack at a rudder in Fusion360 and got the G-Code for it produced. Hopefully tomorrow I'll have time to test it/cut the rudders. I'll mill the long section shown and then section it into two halves (and some extra) before gluing the halves together for a nice symmetric rudder, that method worked pretty well on the VDT rudders. (way easier than trying to sand symmetrical rudders by hand) I also did a very quick test of the belt drive system now that the motor mount is secured. Everything moved as it was supposed to when power was applied, so far so good but lots more testing is needed.

 

I made some more progress on the rudder over the past couple of days, also decided that I'm not sure that first rudder shape I put together is what I really wanted so ended up building that and a slightly different one. (and spent a bunch of time tweaking the G-Code so I could spend a little less time sanding...30 min tweaking G-Code to save 5 min of sanding is a good trade right? #lazy?)

"Action" shot of the mill finding the rudder hidden in a piece of wood.


The two rudders I'm starting out with, they need a little more clean-up once I add the post and glue them together, I might end up giving them a thin skin of carbon fiber for a little extra strength. With the increased rudder area they are actually pretty huge compared to the hull and will stick out the back some.


Located and drilled the hole for the rudder shaft/tube assembly as well, I need to make some room inside the hull to get everything to fit. (I purposely made this way harder to do than I typically would but that should let me test some different things out which will be fun. I'll probably end up with some sort of belt/chain drive for the rudder, typically I use gears. Trying new stuff is good. )

 

Not sure if I'm going to use the original prop that I designed for this boat and shown above or the 1/5" Kort style (https://www.shapeways.com/product/N36GRSQJV/1-50-quot-bksp-rh?optionId=65276201), wont know which until I get it one the water (haha,) and do some testing. Anyway here is the new prop option:


Servo mount plate, brass soldered together in the reflow oven to maintain the alignments:


With mini high torque servo, need to waterproof it but that's not a big deal:



Had to modify the pulley a bit in order to embed a servo horn in it but it turned out well I think, atleast I'm happy with it so far. Also this shows the adjustment/tension system for the belt. That's there mostly to easy installation and swapping parts if needed as well as to account for if I need to use a different pulley ratio.



I built a bunch of rudders matched to the original prop, no finished pics of those yet. This is the shapeways rudder that is matched to the prop in this post. Shown is the rudder/stuffing tube/pulley setup. It's probably the shortest one I've worked on which made it a little tricky but it was fun. I've seen them built with O-ring before and figured I'd give it a shot, not sure how much it matters or not. Just something new/different for me to try. The pulley hub ended up getting trimmed down a little after this picture to fit better, also it got drilled/tapped for the setscrew, exciting stuff.



One of the rear of the boat with the new prop/rudder dry-fit into place. The differences between this prop/rudder and the original prop/rudder combo mean the new prop sits about 1/8" to far forward hench the little brass spacer I made so the propeller sits where I want it. Also that makes switching between the prop/rudder sets a lot easier.


And a shot inside the hull showing how everything will be situated.


Next is probably epoxying stuff in place and then bench testing the drive system.