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Michael Duke
(mpd1690) - F
What thickness for a frame sheet? on 12/29/2011 10:32:53 MST Print View

I am looking a building a pack with a frame sheet just to see how it works. I have found HDPE, which I think may be what I need. What thickness would work for it?

John Donewar
(Newton) - MLife

Locale: Southeastern Louisiana
Re: What thickness for a frame sheet? on 12/29/2011 11:17:58 MST Print View

Hi Michael,

What do you want to accomplish with the frame sheet?

Are you looking to maintain shape, provide support a.k.a. internal frame, provide padding or some combination of all of these options?

The framesheet in this picture was made from an approximately .010" - .015" thick plastic placemat from WalMart.

Framesheet made using one dollar plastic placemat

The hoop stay is 6061-T6 .030" wall 1/4" OD aluminum tubing from Online Metals. The sleeves for the hoop stay were sewn to the frame sheet and are made from one inch grosgrain ribbon. The tubing stay was bent with a hand tubing bender from Harbor Freight.

The Tubing Bender

Let's set some design goals and put our heads together. ;-)

Party On,

Newton

Andrew F
(andrew.f) - F - M

Locale: San Francisco Bay Area
Re: framesheet on 12/29/2011 11:32:09 MST Print View

Hey John, that looks pretty slick, what does the whole assembly weigh? I looked around at a bunch of materials last year to make a framesheet (carbon fiber sheet, HDPE, etc.) and couldn't find anything that weighed less than about 8oz. I think a framesheet is much more comfortable than a closed-cell foam pad in a backpack - it keeps the pack body from bulging out when you stuff it and protects you from lumpy items. I have a HDPE framesheet from a commercially made backpack that I used to put in my Ohm when carrying a bear can as it kept the back panel flat instead of bulging out from the cylindrical can.

Andrew

John Donewar
(Newton) - MLife

Locale: Southeastern Louisiana
Re: Re: framesheet on 12/29/2011 11:37:28 MST Print View

Andrew,

Together the frame sheet and stay weigh 3.85 ounces. The tubular hoop stay weighs 1.45 ounces and the frame sheet weighs 2.40 ounces.

Party On,

Newton

Michael Duke
(mpd1690) - F
Re: Re: Re: framesheet on 12/29/2011 12:43:09 MST Print View

I'm looking at making a light frame with a single flat 6601 stay. I an interesting build, and I could see how it compared to a zlite frame. It looks like I may go with a 1/16" HDPE sheet from

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

, pending shipping costs. That translates into .0625" which is about 6 times thicker than your placemat it seems. It seems thin enough though that I will be able to sew a stay holder onto it. What are your thoughts?

Edit: Also going with 1/8 in flat stay I think, or is that too thin?

Edited by mpd1690 on 12/29/2011 12:45:00 MST.

John Donewar
(Newton) - MLife

Locale: Southeastern Louisiana
1/8 inch flat stay on 12/29/2011 13:47:45 MST Print View

Michael,

1/8" is probably OK but how wide of a stay are we talking about?

Party On,

Newton

Michael Duke
(mpd1690) - F
Re: 1/8 inch flat stay on 12/29/2011 14:03:01 MST Print View

I was thinking of getting it here: http://www.metalsdepot.com/products/alum2.phtml?page=flat&LimAcc=$LimAcc

I was thinking 1/2 but I could go any width. I think I may go up 1/16 of an in. to 3/16". Then maybe 3/4 wide. This was my reasoning for 1/8 by 1/2: http://www.mchalepacks.com/sarc/02.htm

John Donewar
(Newton) - MLife

Locale: Southeastern Louisiana
Re: Re: 1/8 inch flat stay on 12/29/2011 15:29:18 MST Print View

Michael,

This is where I shop for my aluminum stock.

http://www.onlinemetals.com/merchant.cfm?pid=19745&step=4&showunits=inches&id=997&top_cat=60

You can take a look there for the sake of price and shipping cost comparison.

My gut tells me to try 1/2" x 3/16" or 3/4" x 1/8" but it is your $$. 3/4" x 3/16" wouldn't be that much heavier but it would be pretty tough and worry free IMO.

Personally I like the round tubing stays because of the perceived higher resistance to bending. In your single stay application tubing presents some design challenges.

I checked on 7075 at Online Metals and they don't stock the right dimensions.

The McHale Packs link has some very interesting information in it.

Party On,

Newton

Michael Duke
(mpd1690) - F
Thanks Newton on 12/29/2011 16:27:38 MST Print View

Thank you Newton. I think I will go with the 3/16 by 3/4. I really appreciate your input.