PDL pack frame.

[George F]

First, I would love to be UL, I really would. But it seems every time I get close a new material comes out or I ad an ounce so I can stay comfortable. Don't get me wrong, I spend a lot of money getting my weight down and every outing at least one person asks where the rest of my gear is. But being PDL at least I don't have to know what my base weight is, just that it is pretty damn light. On to the project:

For quite a while I've had a thought that laminated wood might make for a good light weight pack frame. The goal would be to increase ventilation and get the weight up on my shoulders more, with better transfer to the hips. And maybe a really cool pack frame might help me look more like this:

Though who am I kidding, no matter how sexy the pack I will still look more like this:

I digress, the frame:

The usual starting point for a light weight project, 7' of 5/4 ash.

This is cut into 1/8" wide strips, a lot extra as long as I am at it.

I used a piece of flashing to get the curve of my back. Then I laid it out on particle board, 2 @ 5/8" glued together so it would be as wide as the strips for even pressure. I am only gluing 3 strips together, there are extras on either side to make for even pressure during the glue up. Epoxy, actually. Raka 2 part epoxy, easy to work with and cures semi flexible.

After curing the strip was cut in half for the two side rails, 1/2" x 3/8".

Now the same process for the back cross bars.

These are 3/8" x 3/8".

Starting to assemble the frame using notches in both pieces and thickened epoxy.

This is the basic frame, before the vertical stiffeners.

The verticals are 1/4" x 1/4" that I soaked and then pressed on the main form and let dry for several days.

Lots of clamps come in handy.

After sanding and sealing with a light coat of epoxy. It is 6.8 oz at this point. The mesh should arrive this week, I will post more pictures when I get that on and the harness rigged up.

[BlackHatGuy]

George,

I applaud your ingenuity and your woodworking talent! Looks pretty cool, can't wait to see how it turns out.

[Sam Farrington]

Under 7 oz with conventional materials – Very impressive. It's encouraging to see a frame at that weight without splurging for cutting edge materials that sometimes turn out much weaker than expected.

[Daryl and Daryl]

I'm also impressed with the weight. That's a lot of frame for 7 ounces.

[Sam Haraldson]

George, that thing is absolutely gorgeous! I can't wait to hear whether or not it has the necessary rigidity all while maintaining just the right amount of flex.

[George F]

I am curious myself to see if it is going to be robust enough. If not it is easy enough, if a bit time consuming, to lay up another frame, this time using 4 pieces on the main rails. That would bring them up to 1/2 x 1/2 and a good bit stronger. The rest seems pretty solid. I think the key will be attaching the bag to many points so the load is spread throughout the frame. This frame will be good enough to see if the dimensions are ok or if it needs to be longer or shorter on either end. A good project for this time of year and it beats starting a new character in Skyrim.

[George F]

I still don't have the mesh but the harness is on.

(The flash on my camera seems to be kaput.)
The hipbelt is from my Circuit, not exactly a spare but I can order a replacement. The shoulder straps are Mountainsmith strapettes with some mods, in terms of size and shape very close to what is on the Circuit. I lashed a day pack with 20+ pounds in it to check it out with decent results.

The size and dimensions are good and the load transfer to the hipbelt was just what I was looking for. The frame itself is too whippy and I wouldn't trust the lower portion with putting down a heavy load repeatedly. I have already started laying up a new frame, this time with four instead of three strips on the side rails and the other members the same size. That should do the trick and still come in at an acceptable weight. A bit of a lumbar pad on the hipbelt, load lifters and I should be in pretty good shape. Now it is time to start thinking of a bag.

[Sam Haraldson]

The progress continues!

[Valerie E]

Wow — that is like a gorgeous sculpture! You're really good at woodworking — Could you make me a dining table? ;^)

[George F]

I finished laying up the new frame and have the harness on it.

The same only different. The siderails now have 4 strips instead of 3. The crossbars are also a hair wider, not planned, they just cut that way. I also did a little reinforcing, wooden pins in the main joints and fiberglass strips laid over the back of all the joints. It is much sturdier than the original, now something I would trust on a trip. Of course the weight is up, now the wood frame by itself comes in at 8.1 oz, up from 6.8.

For attaching the back mesh I folded it over a piece of line that runs the length of the back. This provides strength for the lacing so it won't pull out. In the final pack the load lifters will attach to the bag and not the frame but sill be in about the same place. The final weight fully rigged and ready for a bag is 1lb 8.0oz. Thats it for this thread, now time to get going on the bag.

[BlackHatGuy]

Very nice work George. Looks gorgeous. Form and function, can't beat that!

[Daryl and Daryl]

Plus 1 on Doug's comment.

[Rob Daly]

+2 on Doug's comment.

[McHunter Swearingen]

Great idea and follow through with you build George,

I'm a woodworker as well and even last year harvested a big ole Ash windfall that is seasoning in my shop. Oddly enough making an external frame pack out of a log crossed my mind several times, I love hiking with externals and designing a frame with ash goes hand in hand.

Working from the log it is just a matter of splitting out a few "quartersawn" sections. My main worry though was with joint integrity during rapid and extreme moisture changes.

Have you had a chance to test worst case humidity conditions?

And do you happen to know what moisture content the wood was at when you assembled the joints?

Borrowing from the Windsor chair community, wet mortises and dry tenons would help out some.

I'm very interested to see how the epoxy holds up.

That's it, I've decided to build an ash frame too, ha!

[George F]

Thanks for the feedback. I don't know the moisture content but coming from a specialty lumber yard here in Salt Lake is on the dryer side. I did put a tiny strip of fiberglass on the outside of all joints, two on the side rails, for added strength and also rubbed the whole thing with a light coat of epoxy to seal it. It should hold in terms of weather, the same technique is used for canoe components. The flex question is the big one, time will tell. It does carry weight well, I've had a 40lb salt back strapped on for an hour while I puttered in the garage and it was very comfortable. I am working on the bag now, but there are a lot of distractions at home, like broken drain lines in the basement. I will be posting again when it is done.

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