Adjustable Cross Bar-Carbon Frame

daryl,
think i can see a picture of this attached to the backpack and frontpack? id love to see how this thing carries

Alex,

Here’s a photo of me wearing the pack before I gave it to him. I am 5′ 8″, however, and he is 6′ 5″ so I’m not sure what conclusions can be drawn from the photo.

This pack is a modified version of the pack I made for him and he has been using for several years. I’m sure we have some trial and error ahead of us. Several parts of the pack are untested.

Here’s a thread about previous versions of the pack without the adjustable cross bar.

here

A nylon irrigation T connector? I never thought of that! Very clever!

Cheers

Daryl,
Are those tees the ones form McMaster-Carr you have posted about, or have you found something new? Would appreciate knowing. Thanks. Sam

Samuel,

The 1/2″ X 1/2″ X 3/8″ T fitting might have come from Grainger. Not sure but I just tried finding it at McMaster-Carr and couldn’t. I do find what I think is it at Grainger.

TEE

So I guess you could say Mcmaster-Carr is teed off. (Making jokes like this makes me laugh….tee, hee, hee).

Daryl,
Thanks. I have a pack project coming up, and will check both M-C and Graingers before making a decision. Sometimes I have to do mini orders just to compare the quality of what they are selling.

Basic 3/8"3/8"x3/8" and 1/2"x1/2"x1/2" tubing tees can be found at Home Depot:

http://www.homedepot.com/p/SharkBite-3-8-in-Plastic-Barb-Tee-UP360A/202721877#.UhbhShYqdz8

$1.84

I didn't see 3/8" x 3/8" x 1/2" tees online (tees are described A x B x C where A-B is the straight-through direction and C is the side port, the one though which fluid must turn 90 degrees), but I suspect the store has them. Certainly an irrigation supply place or MJ grow supply would.

Cheaper, heavier, but stronger, 3/8" x 3/8" x 1/2" tees are available in brass at Home Depot for $1.72:

http://www.homedepot.com/p/SharkBite-3-8-in-x-3-8-in-x-1-2-in-Brass-Reducing-Tee-UC364LFA/202721865?MERCH=REC-_-product-2-_-202721877-_-202721865-_-N#.UhbiIBYqdz8

I'm imagining an even lighter-than-plastic-fitting option that would however, be stronger. Sort of a gusset, a 45-45-90 triangle of aluminum flashing material on each side, stiffening short sections of arrow shafts, chunks of aluminum tent poles, that served as receivers.

Or just a small 45-45-90 triangle of plywood, drilled out for each diameter strut. Maybe reinforced with a single layer of fiberglass cloth and epoxy on its outer surface. Or epoxy a 45-45-90 triangle of aluminum on each side of the plywood, and it could be a pretty thin piece of plywood.

Hi David

> I'm imagining an even lighter-than-plastic-fitting option that would however, be
> stronger. Sort of a gusset, a 45-45-90 triangle of aluminum flashing material on
> each side, stiffening short sections of arrow shafts,
Works well, but I used 0.8 mm aluminium sheet formed in a custom press tool I made up. There are pics of my pack frame and the packs at
http://www.bushwalking.org.au/FAQ/DIY_RNCPacks.htm

Easton arrow shafts, some curved to go around my back. Bending them cleanly is another story. CF shafts for the sides should work OK.

Cheers

Roger and David,

Thanks for the additional thoughts/info. They triggered these thoughts from me, in no particular order:

(1) Thanks for the Roger's pack info link. Read it before but will go back over it again. Lot of good info there and I had lost track of where it was.

(2) Lighter fittings are always desirable but these things are already pretty light and can easily be made even lighter by truncating them and drilling holes in them. A truncated 3/8" barbed nylon tee, for example, only weighs about 3 grams. Here are some photos of ones I've butchered.

(3) Stronger would be desirable for some pack designs. These are plenty strong for my packs, however. They fit loosely where they connect to the spars and the whole pack frame flexes. I've been watching a crudely bored out 3/8" fitting on my wife's pack for years. It is so thin I can see through it. There are some small cracks in it but it has never failed and I doubt that it will. In fact none of these nylon fittings have ever failed on any of my packs and I've subjected them to at least a couple thousand hours of abuse.
(4) These things are really handy for the myog folks. A functional backpack frame can be assembled in less than an hour, weighs only a few ounces, costs less than $20 and lasts indefinitely (haven't had one fail yet).

Alex,

"id love to see how this thing carries"

Alex,

To further address your question I threw together a replica of the pack I just made for my friend and have included some photos below. I wear my pack to the gym every day then stop by Safeway for groceries and head home so I'm able to give my packs about a half hour test run every day. For these photos I have about 35 lbs of sweaty gym clothes and groceries (including a 30 pack of Natty Light).

If I was to use this pack for myself on a regular basis I would shorten the vertical spars. My tall friend might need them but at 5'8" I don't. (unless I incorporate them into a tent frame) The up/down adjustability of the front and back bags and the up/down adjustability of the cross bar shoulder strap placement allows me to adjust the overall pack so it works on me, however.

Thanks daryl, thats awesome

Daryl: Great ideas, great pics, as always.

I hear you on not chasing a few grams if you have a good solution already. That you're using nylon fittings helps a lot. Other thermoplastics aren't nearly as tough.

But I need to take you out for a beer – a better beer.

The aluminum gussets could be used to fab or repair a joint using a rock as an anvil, a stick as a peen, duct tape to secure it, and a beer can as a source of aluminum. Even Bud could be used for that.

David,

I hear you and will start stock piling my Natty Lite cans for future use.

By the way….just to show you how slow I am…..I couldn't figure out how you knew what type of beer I drink until it dawned on me that I just posted a photo of my Safeway beer run.

I wouldn't last a week as a criminal. I'd probably forget that I was wearing a name tag while robbing a bank or send a ransom note and photo of the hostage with me showing in the mirror.