3D Printed NACRA parts

upper and lower castings
tiller arms
goose neck
rudders
centerboards
fem-bot crew

Beam end caps. Rudder adjustment screws.

Yea beam end caps with like a 1/4" hole with a beveled radius so people can pass a downhaul line through the beam.

End caps with wing seat attachment points or holes.

I 3D print all the time for work (medical implants), mostly PLA or 17-4 SS. I have heard of carbon becoming printable. Is is normally a robust material. What brand printer do you use? Thanks, John

Hi John,

I've been printing with Kevlar, Fiberglass, Nylon, and Carbon Fiber for some time now, (with an Ultimaker 2+ Extended (with Olsson Ruby) and a MarkForged Mark One Professional) and they are extremely strong. The Ultimaker 2+ is my current printer I use and has been upgraded to an all-metal hot-end, and a special nozzle that can print abrasive materials, such as Nylon and Carbon Fiber. I've had quite a bit of success printing parts for my boat so far, and highly recommend that you look into it. PLA won't be up for the task in most of the things you need, but it's relatively inexpensive to upgrade to other materials!

The end caps and rudder adjustment screws are a great idea guys and should be pretty easy to make...I'll print myself some, and then put up some photos of the end result, and give you all some feedback on testing!

Example of the mast ball for post 1983 NACRA's...

http://www.tempestaerospacelimited.com/apps/webstore/products/show/7475581

Edited by sea_flyer on May 17, 2017 - 04:03 PM.

FWIW, the standard ball will last forever if you bed it in the casting with Marine-tex.

Wax the ball with a couple of coats of your favorite polishing wax. Mix up some Marine-tex, put a blob in the casting and press the ball in, and tape it into place. Before it hardens, scrape out the excess marina-tex that has oozed around the ball. You only need a smooth bearing surface on the top of the ball. After it has cured, pop out the ball, screw it onto the stud, and go sailing. Do this with a new ball, and you'll never have to replace it again.

I have an stl file for a Wave end cap for back rests. You could probably sell lots of those. I will forward it if you want to try to build one.

Hi John,

Sure that would be great! If you want, you can email it to me: tempestaerospace@gmail.com

I just made one for my NACRA 5.7, and it is printing right now, so I will let you all know how it turns out!

do you have the ability to scan stuff - then duplicate with the 3d printer?

If you made rudder cams, I think there are 2 sizes. One for the 14/16 and one for the others you'd probably sell a bunch. The hole is always wallowing out from grounding. Probably the most replaced part. If you did that same nylon carbon mix or just something strong it would be legit. Don't make them hollow on one side like the current ones. Just beefcake

sea_flyer is any of the print medium UV resistant? I had someone print up a bracket to hold my wind vane, and 8 months stored on the tramp broke it down. I had to make a replacement from UV stabilized Delrin, using the table saw and drill press.

Hi,

I have been meaning to sort out making some end caps for a long time, I would really appreciate it if you could please share the design?

Thanks

Anthony

Hey guys,

I've actually had success printing the beam end caps, rudder set screws, and am working on some other components...I'll post some photos of my progress later today.

Klozhald, as far as UV resistance goes, I'll be doing some extensive testing on this...NylonX is a new material, and there really isn't a ton of data for it, with regards to UV resistance...My boat is outside all the time, and is in Florida, so I should be able to give you some good feedback with time. I think that with the combination of both Nylon, and Carbon Fiber, it will probably do better than most, but how it compares with Delrin, remains to be seen...I'll keep you posted!

MN3 wrote: do you have the ability to scan stuff - then duplicate with the 3d printer?

That rarely works out. Converting a point cloud to solid model that can be printed is time consuming work. I suspect the software and the scanning system will get better as time goes on so in even 2 years from now my comments could be out of date, but for most of the parts we are talking about a pair of calipers and some engineering paper work wonders.

What about printing big stuff like rudder castings. Might have to beef up some areas or just design your own style that fits existing rudder mounts. They are pretty expensive on all boats and over time the supply is only getting smaller.

That rarely works out. Converting a point cloud to solid model that can be printed is time consuming work. I suspect the software and the scanning system will get better as time goes on so in even 2 years from now my comments could be out of date, but for most of the parts we are talking about a pair of calipers and some engineering paper work wonders.

Please 3d print a time machine - go to the future - bring back a REAL scanner so i can scan my boat parts for 3d printing - while you are there please grab me a Star Trek lunch computer so i can have lasagna or pizza within a few seconds at any time

your assistance is appreciated - feel free to 3d print up some money as thanks from me!

What about printing big stuff like rudder castings

I just purchased a new set of uppers from Mystere (1 of them was poorly cast and i asked for replacement)

funny - at the same exact date this thread was posted our friend Paul (guy who was camping with us last fall on the P18-2) sent me a text with images of his new 3d printer. I asked about castings - he said "no" lol

Rudder castings are exactly as stated, cast parts done in aluminum. There are many issues with this (no casting is ever 100% the same as the next, and some contain defects), but its a relatively cheap method to fabricate parts in volume with reasonable consistency. As CNC machining has come down in cost, some manufacturers (Goodall) have switched to that, which leads to higher consistency in the parts as you start with a pure base metal. The reality is these parts are not that expensive. Go and price some custom machined parts, or even volume machined parts, with similar specs:

Multiple holes located on different faces to under 0.005" location
6061-T651 aluminum or equivalent
Type II anodized finish

Good luck at matching casting price from a dealer. Even a carbon filled plastic 3D printed part would fail in a new york minute the first time you tried sailing with one. You need titanium or maybe aluminum 3D printing and that is expensive with long print times. Even on a home printer you are looking at overnight runs.

I used to work next to a company that had one of the metal printers that would laser a metal dust bed and essentially weld together the model. Something like that could probably make a product as strong as a cast. Even with the carbon printer if enough material was used it seems like a reasonable strength thing to make. Maybe use stainless sleeves where the mounting points are and I'd think it could hold

Samc99us,

Believe it or not, Matterhackers, the company that created the NylonX filament, states that it is a potential replacement for aluminum using 3D printing instead of CNC. This stuff is unbelievably strong, especially when it is printed dense, and I'd be willing to bet that if designed properly, it could hold up to more abuse than a cast part...there is definitely a lot more flex in the material, despite its density (which prevents the shearing or breaking we see in cast parts). If you're into the sort of thing, I have provided you a link with a spec sheet on the filament, just to give you an idea of its properties:

https://www.matterhackers.com/downloads/AMIfv94tLUD_jrZbAj3B7inzYBrnO2aELoGjOYPkCLLC2P4Ea9DTSEokWa45V-JegGpkcc0slkRj50SHFaRcjJRBTt5z4UbOjDNRNvuYKAG3zoaAk6fmWj60wqpakaWfZg8S9NZsxboUqmPNvLIEBSyP9WCOxxdQUun1GXGpdZ4UyfYAkvnAKdI

As for scanning, it is possible to scan and print something extremely accurate, but the problem is the cost of the scanner...at that level of precision, you can start at $9,000, and go up to north of $100,000 for a handheld scanner...

Tamumpower1,

I am actually working on creating a set of rudder castings with NylonX, to see if it is viable...I have a design already created, but I will obviously have to print, and then test them to see how they perform...I definitely don't mind field testing stuff, so I'll give you all the feed back...

As promised...end caps and mast ball...

I used calipers to measure existing parts, and then used Autodesk's Fusion 360 software to design the parts...then sent them to the printer...these are made with the NylonX material we have been discussing...

Let me know when you have yours - i am ready 🙂

As for scanning, it is possible to scan and print something extremely accurate, but the problem is the cost of the scanner...at that level of precision, you can start at $9,000, and go up to north of $100,000 for a handheld scanner...

Edited by MN3 on May 24, 2017 - 04:50 PM.

Thanks for the data sheet sea_flyer. FYI, That tensile strength number for the Nylon X is 3.1 times weaker than 6061-T651, and the tensile modulus is 10 times lower with corresponding increase in flex. This flex translates directly into helm feel and thus speed. Not a good thing in this particular application; please note this is why EPO rudders blades are all the rage on H16's/H18's and the plastic ones are considered mediocre especially for racing. Your Nacra 5.7 has fiberglass rudders blades that are of comparable stiffness to the aluminum castings, which means well balances strain rates. Using a plastic casting is thus transferring some load back to the rudder head and you could be asking for trouble when that shears off.

Also please note your concerns about flex and shearing in a cast part translates directly to a 3D printed part, if not more so. These parts rely on fusing between layers, and often that is the failure point, not the material itself.

I have limited access to a >$100k SLS 3D printer and it can come close to machined nylon in final part specification, but again this is nowhere near the properties of even lower grade cast aluminum alloys ( https://en.wikipedia.org/wiki/Aluminium_alloy#Cast_alloys). If you do go ahead with this, I would print the part such that the sides are flat against the build table, thereby putting the grain at 90 degrees to the shear loading on the casting and reducing that failure mode. Good luck.

P.S: I do think this is useful tech for a lot of parts like the mast ball, end caps, some adjustment screws, possibly the bearing surfaces in newer Nacra rudder parts, stopper balls, lightly loaded latch mechanisms etc. Home 3D printing just won't replace aluminum parts today, but I can see it getting there in another 10 years (some patents have expired that may alloy this). Home CNC machining is there today however 🙂

Edited by samc99us on May 24, 2017 - 04:18 PM.

Samc99us,

Definitely some very valid points/concerns. My original plan was to just print smaller replacement parts for the items already made in delrin, plastic, or nylon, but since the rudder castings were suggested by some other members' posts, I figured I would try it to see if it can be done.

I liked your suggestion about printing it flat against the build table, and plan to do just that. I also plan to use a random/tetrahedral infill pattern, which will definitely help with the strength and any tendency for shear to occur. I have seen some other cats use carbon fiber castings, with carbon fiber rudders, and I wonder that if I print these, perhaps I should switch to a lighter set of rudders? I'm mainly looking for something with a better performance/weight ratio.

I'm definitely not afraid to try out stuff for the sake of science and learning, so I'll be sure to give you guys some more feedback as I progress. If you have any suggestions, please continue sharing...I'm definitely open to those!

sea_flyer wrote: As promised...end caps and mast ball...

I used calipers to measure existing parts, and then used Autodesk's Fusion 360 software to design the parts...then sent them to the printer...these are made with the NylonX material we have been discussing...

They look great! Would you be willing to share those designs with us please? I appreciate that you spent time and energy creating the designs so I absolutley understand if you dont wish to do so.

Thanks, Anthony

sea_flyer,

Switching to a lighter set of rudder blades (carbon) isn't going to help the situation. Carbon is significantly stiffer than glass or nylon (its close to that of steel, and can exceed it if it's a high quality aerospace pre-preg built with expensive high modulus fibers) and will transfer all the rudder load through your castings to your pintails to the transom of the boat. Personally I wouldn't waste my time trying to print a set of castings. Maybe if you use your Marked Forge and did it in 3D printed full carbon you would get someone reasonable.

You would have to build something on the order of double the thickness of the original castings to even get close to aluminum using your NylonX material, even at 100% infill. FYI, I've printed with most of the materials you are playing with, and have run print jobs in excess of 36 hours on a consumer FDM machine-we were on a deadline to get to a test event and it was the only way to get some fairing parts done in time. They are not the same, even the carbon impregnated variety, as the SLS nylon prints I do somewhat regularly. None of these compare with aluminum in terms of stiffness or strength. I'm not sure how the Marked Forge prints compare, but they have some big name sponsors and users and I suspect some MIT grads working for them, so I suspect their Oynx parts are up there.

Out of curiosity, what kind of price-point would the end-caps have to make it worthwhile printing some?

We could just take the 3D printed part, cut it in half and use it to make a sand mold then slap a little molten aluminum in there. Everyone's got a backyard foundry right...? Would only need about 1300 degrees F

Samc99us,

Definitely great info, and thank you for sharing your experiences...I think the biggest problem I would have printing the rudder castings is the sheer build size...neither one of my printers has the build volume necessary to print one in one piece. I did successfully design a set in Fusion 360, but I just don't have the volume to print them. Some of the newer MarkForged printers could do it though...I'd be especially interested in the Onyx...I've looked at upgrading my printer to the version capable of doing Onyx, but there is a wait time, and considerable price attached, so I don't think I'll be able to try that until later this year, when I have a month to spare sending it in.

Aquaddict,

I'd be happy to share the .stl file with you...if you'd like to shoot me a PM with your email, I can email it to you.

Tominpa,

I'm able to print a set of these end caps (2) for about $10...extremely reasonable...they take about 2-3 hours to print. Definitely worth the effort, IMHO.