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Aluminum for folder

Posted: Sun Mar 18, 2018 8:36 am
by brillythekid
Hi everyone,

I'm hoping to make my first folder. Probably a Baidarka type since I want it for expedition use. On the Yostwerks site the recommended aluminum poles are 3/4" with 5/8" inserts. I live in a country where metric is used and the poles recommended to me were:

* 20/2 (20mm diameter with 2mm wall thickness) with 15/1 for the inserts, or

* 16/1.5 with 12.8/1.9 inserts.

Both are 6063-T5

A few questions:

1. Is there a big difference between 6063-T832 (recommended on Yostwerks) and the 6063-T5 I can purchase here?

2. The inserts for the 16mm seemed to fit beautifully (with the 0.2mm clearance). Of course the inserts for the 20mm would be looser (with the 1mm clearance). On Yostwerks looks like the two options are 0.6mm and 0.16mm clearance. Can anyone suggest which sounds like the better clearance for the inserts of the two options I got?

3. As far as pole thickness the 16mm sounds nicer because it would be lighter. Would it be strong enough? On Yostwerks the 19mm (3/4") is 1.25mm or 1.47mm thick, so maybe the 16mm with 1.5mm thickness is sufficient? The 20mm (closer to 3/4") is 2mm thick - maybe an overkill?

4. Is the insert thickness significant, since the 15mm insert for the 20mm poles are only 1mm thick?

I think those are my questions for now.

Thank you very much!

Re: Aluminum for folder

Posted: Thu Mar 22, 2018 8:12 am
by gbellware

You are asking questions that involve metallurgy and physics that could command more than one Masters thesis (and I am a pure amateur!). There are so many variables at play with telescoping tubing that every answer brings with it a "however"...


T-835 is by far the better choice. It is almost twice as strong as T-5, especially where it counts in the dynamic environment you will use it in your folder, namely, fatigue strength.
I wouldn't fret over weight difference between the larger and smaller tubing you are considering, it can't amount to more than a few ounces for the amount of tubing you will use.
Don't know if the metric tubing you are sourcing is available with anodization, but that would be a huge plus and would be a big factor is selection. Regardless use T-9 (Boeshield) every time you put the tubes together.
Use the closest tolerance between ID and OD that will allow tubes to telescope. Any play between telescoping tubes will render the joint weaker by a huge margin, especially for the thinner wall tubing you are considering. Conventional wisdom is to allow .015 inches for safe clearance, but you may get away with .011 clearance depending on how accurately the tubing has been drawn. You can use +/- .005 inches as the typical variance in actual vs. spec wall thickness on whichever tubing you use in order to estimate what will work and what will bind or be too sloppy.

Hope that is of some help, looking forward to seeing your results,


Re: Aluminum for folder

Posted: Sun Apr 08, 2018 11:47 am
by RangerTim
Thanks to billythekid for asking the questions and to gbellware for his response. My questions regarding replacement tubing for a Folbot have mostly been answered.

Another question please: While I can source anodized T-835 in 0.75" OD, 0.058" wall, I cannot find the insert tubing (0.625 OD) anodized. Should I keep looking for anodized? I do apply Boeshield before assembly. The boat can remain assembled for two weeks or so in a salt water environment.

Re: Aluminum for folder

Posted: Mon Apr 09, 2018 6:59 am
by gbellware
Re: anodized insert tubing

I would not worry about anodized inserts. For my money I would be more concerned about fit and finish and religious use of Boeshield. I would be careful about putting a neat edge on the insert tubing and polishing it to a smooth finish before treating with Boeshield, then let the tubing set dry for a day before assembling for the first time. Just my $.02.


Re: Aluminum for folder

Posted: Sun Apr 29, 2018 11:34 am
by brillythekid
Thank you G for your reply and suggestions. And RangerTim, I'm glad it helped you too.

What I ended up doing, since this is my first attempt at my own folder, as far as I know there's no real serious conditions in my area that I'd paddle in, and I wanted to get the show on the road... is to decide to get the available lower grade aluminum (T5) - part the 20/2 and part the 16/1.5. The 20/2 seemed much sturdier, and the 16/1.5 somehow significantly lighter, so the idea was to combine the two...

If this kayak works out nicely, the next, if relevant for more serious travels abroad (hopefully), I'd probably order the better grade (T832) from abroad.

An interesting point I'd like to share is I ended up getting extra 16\1.5 as inserts for the 20\2 (and not the 15)! Seems it shouldn't fit, but it does, very nice and snug. For the permanent side of the insert it's perfect, and for the detachable side I grinded very slightly just to be on the safe side, though I'm not sure it was even necessary since it goes in only 3 inches, and it doesn't seem it would get stuck over those few inches (at the factory it did get stuck, but only over a longer distance -- so I had to buy those two pieces of course, which was fine). I found that interesting, and hopefully helpful. Though maybe not recommended sight unseen?

I posted another question on "what boat for me" I'd love help with.

Thank you!

Re: Aluminum for folder

Posted: Thu Sep 06, 2018 6:56 am
by brillythekid
An important note (I think) after some experience with my new folder -

The nice snug fit of the 16mm into the 20/2 connections (as I wrote in my previous post on this thread a few months ago) become TOO snug, and sometimes stuck, so I don't recommend it... Probably the pressure from the waves, and the sand that comes in with the water; and that it's a lower grade aluminum and not as resistant to the above probably doesn't help either.

So far took it only with the car, so that it didn't fold well wasn't a problem, but to take it on public transportation would be risky the way it is. So some changes have to be made to the 20/2 - 16 connections. The 12.8 - 16/1.5 connections seem fine and basically easy to deal with.

Side note: made the Cruiser from Yostwerks as my learning kayak - for building and paddling (downsized all dimensions to about 95% of original). I'm far from an experienced paddler, but extremely impressed with the stability of the boat. Can't wait to get to the water again.