TL;DR I put together a Shapeways “store” to make Cast Bronze Kort style propellers and 3D printed rudders available to the hobby. https://www.shapeways.com/shops/rc-warship-tech All, While this was revealed a bit early yesterday I thought I’d go ahead and make a dedicated announcement for it. With the closing of PropShop this past year I couldn’t find a replacement source for cast bronze props suitable for our hobby. (My experiences with the cast “scale” props available hasn’t found them to be effective for our use/requirements.) So I did some experimenting (https://rcwarshipcombat.com/threads/sms-deutschland-build.445111/page-2#post-515211) and created a line of kort style propellers specifically for the hobby. While I was at it I also created a simplified “basic” version of a propeller which is closer to the soldered props available as well as some rudders (with a basic NACA 00XX and a shilling style design) which are IRCWCC legal and matched to the props sizes). All of this is available through Shapeways at https://www.shapeways.com/shops/rc-warship-tech Propellers: The Bronze propellers are solid CAST bronze, not 3D printed laser sintered or anything like that. Shapeways 3D prints a wax part and then uses that to create a traditional lost wax cast part. The upside to this is that it makes one-offs possible for a relatively affordable price, however there are some downsides as well. There will be some very minor variation in the dimensions due to the printing and the casting process, I’ve tried to account for this the best I can with the information provided by shapeways on the process as well as with getting propellers cast and using the results as a guide. However there is the chance the shaft hole in the hub will need to be chased with the proper size drill, which shouldn’t be a big deal. Also they can’t cast in the threads for the set screw so those will have to be threaded once the parts are received. There are plastic (SLS nylon) versions of each propeller as well which are cheaper and I thought they might be helpful for testing and fitting out boat systems before committing to one or two more expensive cast bronze versions. You can try them out in combat if you want, I just don’t have any experience with using that material like that so I don’t know how well they will hold up. Rudders: The rudders are all SLS Nylon and designed to be matched to the class and propeller size of the boat they will be used on. The basic rudders use a NACA 00XX profile, mostly NACA 0028 but a few use other profiles to meet the max thickness rules. In other words they are standard teardrop shaped airfoils. The shilling style rudders are exactly that, shilling style rudders. They have similar thicknesses to the NACA 00XX line of rudders. A 1/8” rudder shaft with a 90º bend will need to be added before use but that should be pretty simple and straight forward as 1/8” brass rod or similar is readily available in many hobby stores. The costs for the rudders came out higher than I was expecting so I’m planning on doing another set that is hollow and would hopefully be a good bit cheaper but require filling with something (foam, caulk, epoxy, etc) before use. Shapeways: For those of you unfamiliar with Shapeways they are a 3D manufacture where you can get 3D designs made in a variety of materials. They allow users to make designs available for the general public to purchase with the creator getting what amounts to a royalty for each item printed. So you’re dealing with a legitimate company that’s been around for over a decade. I’d love to have a mini foundry and be able to cast them myself and all that but realistically it isn’t in the cards, hopefully doing it this way will still be beneficial for the hobby since it doesn’t look like PropShop is coming back. That’s about it, if you have questions please post them or DM me and I’ll try to answer them the best I can. Also if there is desire for configurations that I don’t have up there let me know and we can probably make that happen. (I was trying to hit the majority of cases so I’m sure there is stuff like blade counts and propshaft sizes that may not be optimized for every configuration.) Thanks Chris
I love how this hobby overcomes its obstacles! Nice job! So on the product page for the bronze props it says they are printed bronze. I'm guessing that is really the cast bronze?
Just looked at your page and wanted to say thank you for making all that available to us. Or in the mere mortal language, "HOLY CRAP" how did you do that!!! Thanks Craig
Thanks. Correct, if you read the material info page for Bronze (it is under precious metals, they think i'm making jewelry i guess..) it describes the process, I copied it below. Thanks. How? Lots of work, a bit of research, and some trial and error. I've been bouncing the idea around for a while but I really started working on this whole project about two months ago and it's been taking up a lot of my free time ever since.
Wanted to post some additional pictures up here for everyone. First up is a 1.5” Bronze Kort style propeller. It’s a cast bronze prop, not as polished and shiny as PropShop props were but still well within the realm of acceptable surface finish. Testing with a bit of prop shaft I had on had showed it to be a tight fit but workable, if necessary running a 1/8” bit through it would resolve any issues. I haven’t gotten the set screw hole tapped yet. Same Prop but in the White Strong and Flexible (Nylon) Plastic. The SLS layers are much more obvious and the thin blade edges aren’t well suited for printing. Also while the think blades are fine when cast in bronze they feel pretty weak in plastic. Still the original idea for these was test fitting and spacing during construction which they would be fine for, not so sure about combat. Now a couple of rudders. Class 3 NACA 00XX Class 3 Rudder for a single rudder ship printed in the White Strong and Flexible (Nylon) Plastic. This feels much more solid than the prop did, however the surface finish is on the rougher side, still a coat of paint/epoxy or even a light sanding would probably resolve that. The 1/8” hole for the rudder shaft was a tight fit and a few gentle taps with a hammer were used to seat the shaft properly. Class 3 Shilling Style Class 3 Rudder for a single rudder ship printed in the White Strong and Flexible (Nylon) Plastic with the “Polished” option. It is smoother than the normal White Strong and Flexible but still has a slight noticeable texture.
Those are impressive. I wonder if they could do banana-blade propellers for high-speed submarines and modern warships?
Thanks. You could do banana-blade propellers, not sure how useful they would be in this hobby but for non-combat/scale models that would work.
Thanks for sharing your experience with shapeways. It's pretty awesome that you can get brass parts from your digital designs. To that point, here's a great site that creates props based on fundamental design principles and puts out a beautiful .STL or OBJ file. https://www.wageningen-b-series-propeller.com/ Apologies if someone else has posted this already.
