light but stiff sheeting materials for increasing pack firmness?

[Kodiak Firesmith]

Hey Folks, got a small project where I'm cleaning up a stock REI Stoke 29. Right now it has some horribly bent up 1/8" CCF for the backing plate which I need to replace or at least strengthen with something to give shape back to the pack – any ideas for what materials I could use?

Thanks!

[Ryan Smith]

HDPE plastic sheet is commonly used by pack makers.

http://www.usplastic.com/catalog/item.aspx?itemid=23869

Ryan

[Kodiak Firesmith]

Thanks Ryan – thoughts on thickness?

[James Marco]

HDPE works OK. My only objection is the weight. High Density is the correct name. Two carbon arrow shafts (at around 1oz) would weigh considerably less than the ~6-8oz the HDPE weighs and provide more stiffness in the vertical 18" or so that it would cover. Your sleeping pad will also provide additional firmness if you use the 1/4" pads commonly available. Or just lay it flat against your back if it is too large to fit.

I did much the same with my old Trek. I removed the 1/4" foam pad and sewed the bottom closed. I added a second piece of fabric around the upper and lower corners after slitting the rear open. I slipped in two arrow shafts on either side and stitched along them, pretty much making them permanent (though the foot would only get within about an 1/8" of the shafts.) This enabled me to carry about 30-40 pounds comfortably with no pack collapse. Once I added my pad (1/2"x20x10 in 5 layers,) this was really comfortable.

Alternatively, you can add some external pad keepers (1/3 length pockets made from some mesh) that lets you add your pad to the pack. A 5 layer, 11" wide sleeping pad will work for warmer months with your pack under your feet and a stuff sack for a pillow. 5 payers will support about 25-30 pounds depending on weather you use dimpled pads, plain pads or inflatables. Just check to make sure your hip belt still works since it does change with/without the pad. You can use the existing pocket for other things.

[Ryan Smith]

Kodiak,

I did some checking around and looks like 1/8" is the most common size. James is right though, it will weigh about 6oz.

Ryan

[Russell Lawson]

try to use a garden seedtray bottom sheet. I have green ones that are checkered plastic that is nice and thick. weighs 3.5ounces once the sides are snipped off and can be utilized to increase ventilation. im designing a backpack based on one 24" tray sheet with aluminum stays on the sides

[Sam Haraldson]

Are you looking to gain stiffness or just shape? If shape is your only concern then use foam. If you want a bit of stiffness then HDPE is the way to go.

[Dan Yeruski]

Good stuff at ebay

http://www.ebay.com/itm/4mm-White-24-x-36-4-pack-Corrugated-Plastic-Coroplast-Sheets-/171533868113?pt=LH_DefaultDomain_0&hash=item27f0371c51

Corrugated Plastic Coroplast Sheets

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