Dec 19, 2012 at 7:57 pm #1297213
This is another thread about materials, after finally realizing in the last couple years that the quality of materials, or lack of it, has been the bane of my MYOG existence; and surprisingly, a much bigger challenge than design or construction.
After spending too much time ordering and trying kite fittings, it dawned that there must be something better. Thanks to Daryl Clark for pointing in the direction of the plumbing department.
The little plastic barbed ones are a harder plastic material compared to rubbery kite Tees, and appear to come at least in nylon and polyethelene, immediately raising some preliminary questions: Which is stronger? Which is more bondable to annodized ALU? What are the best adhesives to bond with? Any answers from those in the know will be very much appreciated.
There are the hose/tubing barb Tees, and the Pex ones (the plastic, not the brass). The barbs are not important, because it is the inner diameter of the T that connects to the tube. (See Daryl's photos of his pack frame on this forum) The tubing ones are available in both nylon and polyethylene, but could not find at sharkbite.com the name of the plastic used on the black Pex ones.
All of them can be readily adapted to work as T fittings on ultra light pack frames or the like. The half-inch size polyethylene are available with an ID of 3/8", and the nylon with a little smaller ID that tightens as the tube insert approaches the T joint, and thus require a little drilling out to get a consistent ID. The Pex half-inch size come with a consistent ID around .312" that fits Easton fly tube, for example.
Particularly on the nonPex ones, the Tees can be cut back a bit. All of them are much lighter in weight than the heavier, rubbery kite Tees, and at least appear to be much stronger. Drilling or boring out greatly weakened the kite Tees, and will be avoided as much as possible with the plumbing ones.
The kite Tees will still be useful for angling the tubing, with 30, 45 and 60 degree fittings available. But the small 60 degree ones often split, and were unreliable. Only the heavier ones were at all reliable. But for 90 degree applications, the plumbing Tees will be used unless and until they prove no stronger than the heavier, rubbery kite Tees, which I doubt very much will be the case.
Another small step on the way to a much lighter pack frame. YES!Dec 19, 2012 at 11:24 pm #1936817
@rcaffinLocale: Wollemi & Kosciusko NPs, Europe
Nylon – good stuff, can be glued with the right glue
Polyethylene – interesting but not very strong stuff, largely ungluable
CheersDec 20, 2012 at 8:22 am #1936887
Daryl and DarylBPL Member
@lyrad1Locale: Pacific Northwest, USA, Earth
My favorite source for the nylon barbed fittings that Samuel describes is here:
There are endless project possibilities with these little critters. I have barely tapped their potential. Here are some tips to get you thinking:
*The Y shaped ones look like they would work for creating A frame poles that could then be inserted into a hole, loop or grommet of a tarp or tent.
*The straight connecting pieces that reduce in size from one end to the other can be used for spar end caps. Pick a size that is larger (id) than your spar on one end but smaller than the spar on the other end. The nylon fitting can then be tied to pack or tent.
*The Ts make tent pole bottoms that won't sink into soft ground.
*Fittings with ids larger than your spars allows you to run webbing or cord through the fitting to connect things and to snug up the spar/fitting connection.
*I typically insert the spar into the fitting. I have experimented with inserting the very small fittings into the spars and made and used a backpack frame made in this way. It worked but it seemed just a matter of time before the spar would split. I could have reinfoced the spar end with a metal ring but then I'm getting closer to the weight of the larger (spar-into-fitting) fitting so why bother. Spar-into-fitting is way stronger looking.
*You'll have to experiment a bit because, as Samuel mentions, the id is not specified and will vary from brand to brand. Only the od is specified because they are meant to be inserted into tubing.
If I was sent to prison I would ask for some spars and fittings to keep me busy while I served my time. They are like tinker toys to me.Dec 20, 2012 at 2:48 pm #1937011
M-C is a great site for hard to find stuff. That's where we went for a while when the Cuben/Hysol thing started.
But Home Depot had the nylon ones like those in the photos of your pack. You might want to compare prices. Yah, forgot to mention that the plumbing fittings do cost more than the kite ones. Price of progress.
OK, nylon it is. Since bubbles and expansion are not a problem in this application, will probably try urethane glue first – Elmer's Glue-All Max is the one I have.
If that fails to satisfy, then it is on to the Hysol 2-part from Fastenal. And if that fails, somewhere lying around is info on the best quality epoxy from boat-building days. Any other ideas?
Thanks for the steer on the nylon. Still wish I knew what the Pex ones are made of.
They are the best designed and come with a smaller ID.Dec 20, 2012 at 5:43 pm #1937055
Daryl and DarylBPL Member
@lyrad1Locale: Pacific Northwest, USA, Earth
The selection at my local HD is pitiful. There are only a few white nylon Ts….almost nothing else.
I've purchased and experimented with dozens of sizes and shapes purchased from various sources but Mcmaster Carr has the best selection by far.
DarylDec 21, 2012 at 4:22 pm #1937283
Yes, but they are cheap, and two legs will fit the Easton 340 tube, and the third fits Easton 312. And the 312 leg can be used as is, or drilled out for 340, the same ID as the others. Quite a bit of versatility for a little bit of nylon plastic, and it should hold my pack frame spars together just peachy.
Don't ask me why they would make one half of the top T bar with one ID, and the other half with another ID. Strange, but for me, useful.
Sorry if I sent you on a wild goose chase. Maybe that's why they call it 'Home Desperate.' (Almost the same stuff is at Lowes) In any event, they also have the black PEX tees with 312 ID that look pretty sturdy. Not enough types to play with, but adequate, I'm hoping, to hold a pack frame together against all the stresses of packing. Certainly better than the kite tees for this purpose, but maybe you knew that, since you switched away from them also.
Should I need something more specialized, or perhaps stronger, will definitely order from M-C as you suggest. Thank you.
BTW, in looking at dozens of types, did you ever run across a T with an angled post, like kite tees ('leading edge connectors') come with? As earlier noted, the kite tees are not very sturdy, unless you use the thickest heavy ones, and even then not so much. I am looking for something in 60 degrees that could be trusted to hold a spar to which shoulder or lift straps are attached. Kites and Fun Things had a photo of some heavy 60 degree Tees, but when I ordered them, they sent and had only regular right-angled ones. Just a mistake, but the existence of the photo suggests that heavy 60 degree ones do exist. I can make the equivalent of Tees out of sewn twill or grosgrain tape, but an actual fitting will look a heck of a lot nicer; but only if it will hold the blankety-blank spar to the frame.
Into the backcountry we go!
P.S. (Later that evening): Checked out the McMaster-Carr site again and found some Y-fittings that with a little modication, may provide a 60 degree connection. Won't know until I obtain and can examine them. Thanks again, Daryl. Great suggestion.
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