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PostPosted: Tue Jun 24, 2014 3:03 am 
Hi, I'm interested in building the folding Sea Cruiser from I'm new to this, so I'm more or less strictly following the guide. I'm having some problems sourcing the aluminum tubes -- it seems that the .75" x .058" tubes are out of stock most places. However, I found a local source with .75" x .065" tubes. I realize that these tubes would not fit neatly with the .625" OD tubes for the inserts.

My question -- has anyone tried using the .75" x .065" tubes? Or would it be best to wait for the .058" tubes to come back in stock?

PostPosted: Fri Jul 04, 2014 5:22 pm 
I've been wondering about tube thickness and alloy myself. It seems like getting anodized tube would help keep it from oxidizing. I've been looking at:


Yostworks makes the claim that 6061 and 6063 have a tensile strength of 40,000psi but onlinemetals lists 6063 at 27,000psi and 6063 at 45,000psi. McMaster says 22-30 ksi for 6063 and 35-45 for 6061. I must say this is the first time I've see ksi as a unit of measure. 6063 generally seems cheaper, the corrosion resistance and easy availability in clear anodized is a plus. I'm leaning that way but I'm concerned about strength.

I have no answers, but lots of questions. Maybe we should look closely at the specs of commercial folders.


PostPosted: Mon Jul 07, 2014 6:54 pm 
I actually managed to find and order my 6063 tubing. I get that nice sliding fit too! I sourced my tubes from dxengineering -- they were in stock and shipped very quickly.

The reason why I wanted this tubing so urgently was because I'm trying an alternative way to build the boat. I'm attempting to 3D print all the cross-section pieces. So far, I've printed just section 1 of a yostwerks Sea Cruiser:

Since the cross sections are too large to print in one piece, I'm printing them in multiple sections with lap joints, then fusing them with acetone. I have CAD files which I can share once I've verified that this is a valid way to make the cross section pieces!

PostPosted: Tue Jul 08, 2014 6:05 pm 
That's an interesting design. What program are you modeling in? The photo makes them look like miter joints. What material are you printing with? You might look at your joint design and see if you can get the pieces to index a little more accurately. If you're "welding" with acetone be sure to melt a bunch of scrap material into the solvent to help fill gaps. Let me know when you have more photos.

PostPosted: Sat Jul 12, 2014 12:58 am 
I'm modeling everything in OpenSCAD. It's actually very cumbersome initially since it's just code, but it's very nice once everything's in there. I can plug in the offsets for another boat and all the pieces would be auto-generated. I'm currently printing with recycled ABS. I'm printing at 30% hex infill, about 2.4mm outside layers, about 19 mm thick (3/4 inch). That image I posted was section 1 -- I was experimenting with joints at that point, and that one was printed with scarf joints. I wasn't happy with the scarf joints since they tended to slide past each other (the indexing problem you were talking about), so for the rest of the sections I've switched to half-lap joints. They seem to be a good deal stronger too, so I'm pretty happy with that. I had to do a good amount of testing to get the tubes to snap in tightly. I've settled on a 0.7 mm gap for my .75 mm tube.

I've gotten sections 1-3 printed so far. Section 4 is half done. Just two more sections before I can assemble a boat!

PostPosted: Sun Aug 03, 2014 7:25 pm 
knight of the folding kayak realm

Joined: Wed Oct 07, 2009 6:42 pm
Posts: 481
Hi James,
Just catching up on various posts on the forum while I was away. I'm very interested in your experiences with 3d printing the sections for a folder. How is it going? Successes? Failures? Things you'd do differently next time?
Thanks in advance for your thoughts.

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