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Navigating Rough Waters with Markforged

Editor’s Note: Our friend and customer Rob, owner of Superstition Machine Works sent us this awesome story of how he helped his friend Eric fix a critical component on the rudder of his kayak with a Markforged 3D printed part after the original crumbled and failed. We love to hear customer successes like this — share your own story with us by dropping us a line at!

Markforged: Hi Eric and Rob, we’re intrigued — tell us what’s going on in these pictures!

Eric: So the story goes, I bought a used kayak last year and a plastic part that holds the stainless steel rod [that the rudder uses] to pivot on was crumbling apart due to age. I had just got done paddling a flat water river [editor’s note: a flat water river is an extremely smooth flowing river — you can find them in your area with this really handy website!]. I had just pulled my kayak up on the dock with the rudder hanging out over the water when all of a sudden, the pivot rod out of nowhere just drops into the river and was never seen again.

Rob machined a replacement of the pivot rod that was lost, as well as 3D printing a fiberglass-reinforced connection to the rudder

M: Oh no — that sounds unrecoverable!

E: Haha yeah, it made my rudder useless. My kayak is 15 years old and the manufacturer does not make it anymore nor does it sell replacement parts.

The replacement pivot rod and bracket fully assembled — note the rudder engagement line passing through the part

M: While we’re talking about the rudder, can you give us some background on why it’s important? We’ve done some kayaking here but we’ve never seen one with a rudder before.

E: I paddle in rivers and the rudder helps with maneuverability on fast moving rivers and makes my turns much sharper. My kayak is 14 feet long. So think of it as an old Cadillac [with a huge turn radius] when turning without a rudder and then as a high performance sports car with the rudder engaged.

M: So what did you do next?

E: I’m big time on radio control (RC) trucks. That’s really my first hobby with kayaking as #2. When my part broke I didn’t know who to turn to. Rob has been making awesome complex parts for RC’s through his company Superstition Machine Works and I figured it was worth a shot asking him [if he could help]. Really glad he was able to pull it off and breathe new life into my old boat!

The rudder assembly removed from the kayak

M: Rob — this part looks awesome, can you give us a little more detail about it?

Rob: Sure thing — the initial request from Eric was to machine the replacement part from Acetal. I talked him into trying the fiberglass-reinforced 3D printed version. I designed the part in Autodesk Inventor based on what was left of the plastic piece that was crumbling. I initially tried slicing it for the Mark One but couldn’t get the reinforcement that I was looking for. Then I got the Mark Two and was able to reinforce it in an ideal orientation to resist the stresses it would see in service. You can see, in Eric’s photos, that the part is clamped between two steel plates. Because of this, the part was printed on it side to place the layers into compression once it was bolted between the two plates.

M: So how’d it turn out?

The 3D printed replacement part during a test fit on the kayak

E: I haven’t had a chance to use it out on the water just yet. But so far it fits, looks, and functions great! Its been raining in Central Texas flooding the area and all of our lakes and rivers have been closed due the volume of water and having all the dams open. It’s starting to calm back down though and I should be able to get back on the water soon. I will get some pics soon I can when I’m on the water!

M: Thanks guys this is awesome!

Have a success story yourself? Share your it with us by dropping us a line at!

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