Lighter Carbon Back Stay - version 2
Display Avatars Sort By:
Kevin Egelhoff
(kegelhoff) - F

Locale: Southern Cal
Lighter Carbon Back Stay - version 2 on 02/13/2009 14:08:19 MST Print View

Latest version using less carbon and honeycomb ... Might still be a little too stiff and the weight is now down to 7.94 oz. (225 grams) I'm going to make one more light weight and less stiff version to test out. THinking I will send the lighter one to Bill F for testing ??? Bill, think you can easily figure out a way to incorporate this into you pack design for testing out ?

Vesion 2 carbon stay

Thanks
Kevin

Matthew Roberts
(matthewjamesroberts) - F

Locale: San Fernando Valley
diggin it on 02/13/2009 20:02:04 MST Print View

I'm digg'n it.

Steven Evans
(Steve_Evans) - MLife

Locale: Canada
Re: Lighter Carbon Back Stay - version 2 on 02/13/2009 22:03:59 MST Print View

Hey Kevin, very nice work. Any chance you can enlighten us on the process to make something like this? did you have to make a negative to wrap the carbon fibers on...and then cut it off? I think you know why I am interested. ;)

Edited by Steve_Evans on 02/13/2009 22:32:18 MST.

Kevin Egelhoff
(kegelhoff) - F

Locale: Southern Cal
Re: Re: Lighter Carbon Back Stay - version 2 on 02/13/2009 22:27:48 MST Print View

Steven,
No, I'm just using sheets of "prepreg" that I cut to the shape I'm looking for and lay them up on a tool that I formed from plaster on someones back and then turned into a carbon fiber tool. I can shoot some pictures of the tool next week and show you what the patterns look like. The entire part then gets bagged and goes into a autoclave to cure under heat and vac.
Not sure what new part you are thinking of ... you are working on so many new things !!!
Tubes are MUCH easier to make !! I can whip out carbon tubing in a day. These back stays take a few days each to make when we have free time.
Kevin

Steven Evans
(Steve_Evans) - MLife

Locale: Canada
Re: Re: Re: Lighter Carbon Back Stay - version 2 on 02/13/2009 22:38:01 MST Print View

Ahh, I see. From the picture, I thought the structure was hollow. So it is solid then, how thick is it?

Seems like were both working on new things...good fun, isn't it?!

Kevin Egelhoff
(kegelhoff) - F

Locale: Southern Cal
Re: Re: Re: Re: Lighter Carbon Back Stay - version 2 on 02/13/2009 23:16:21 MST Print View

Actually, to keep the part as light and stiff as possible I'm using some honeycomb in-between the carbon plies running down the center section of the spine. Kind of like making a hollow core but WAY lighter and stiffer.
Stuff used in aerospace that we had laying around.
The thinest honeycomb we have is 3/8" thick so the mid section is about 1/2" thick with the carbon. The edges with just the carbon are only 1/8" thick.
Yes, it is always fun. I just wish I had more time to finally start on a new quilt, I want to make a new cuben shelter for two this year, and finish this carbon stay and then look at making a cuben pack that works with it.
Looking forward to seeing some of your projects this year !! Still hoping you have some time to work on the titanium stove so I don't have to figure out how to make one!!
Kevin

Edited by kegelhoff on 02/13/2009 23:17:38 MST.

Steven Evans
(Steve_Evans) - MLife

Locale: Canada
Re: Re: Lighter Carbon Back Stay - version 2 on 02/16/2009 21:00:00 MST Print View

Stuff used in aerospace that we had laying around

ahhh, old aerospace stuff, I hear you :)

So, the honeycomb is made from carbon aswell? Some sort of standard product that you can wrap the carbon around? Forgive the questions, I haven't worked with carbon before (short of the ice axe experience) so I'm pretty interested in this stuff.

Edited by Steve_Evans on 02/16/2009 21:11:07 MST.

Kevin Egelhoff
(kegelhoff) - F

Locale: Southern Cal
Re: Re: Re: Lighter Carbon Back Stay - version 2 on 02/16/2009 21:08:17 MST Print View

Steven,
Here is the description of Honeycomb. It comes in large sheets that you can cut to the desired shape. Think of it more as super strong foam that you box in with the carbon fiber on each side but this is about 1/2 the weight and about three times stronger. Boxed with the carbon you can make parts super stiff and super light. This is how aricraft wings, bulkheads, and other large parts are built in aircraft. Not cheap but works awesome !!

Aluminum Honeycomb Cores
PCGA-XR1 3003 Aluminum Honeycomb
PCGA-XR1 3003 commercial grade aluminum honeycomb is a lightweight core material offering excellent strength and corrosion resistance for industrial applications at low cost. PCGA-XR1 3003 honeycomb is made from 3003 aluminum alloy foil. more... PAMG-XR1 5052 Aluminum Honeycomb
PAMG-XR1 5052 aerospace grade aluminum honeycomb is a lightweight core material which offers superior strength and corrosion resistance over commercial grade aluminum honeycomb. PAMG-XR1 5052 honeycomb is made from 5052 aluminum alloy foil and meets all the requirements of MIL-C-7438. more... PAMG-XR1 5056 Aluminum Honeycomb
PAMG-XR1 5056 aerospace grade aluminum honeycomb is a lightweight core material which offers superior strength and corrosion resistance over 5052 and 3003 aluminum honeycomb. PAMG-XR1 5056 honeycomb is made from 5056 aluminum alloy foil and meets all the requirements of MIL-C-7438.
Picture of honeycomb

Steven Evans
(Steve_Evans) - MLife

Locale: Canada
Re: Lighter Carbon Back Stay - version 2 on 02/16/2009 21:15:33 MST Print View

OK, it all makes sense now (sometimes it takes me a while :) )..thanks for the answers.

Matthew Roberts
(matthewjamesroberts) - F

Locale: San Fernando Valley
agreed on 02/17/2009 00:10:37 MST Print View

Yes, thank you. I've been wondering with the exact same question. ...too bashful to ask though.

Roger Caffin
(rcaffin) - BPL Staff - MLife

Locale: Wollemi & Kosciusko NPs, Europe
Re: Re: Re: Re: Lighter Carbon Back Stay - version 2 on 02/17/2009 01:53:07 MST Print View

Hi kevin

> Here is the description of Honeycomb.

I hate to think what the stuff costs though! Any idea?

Cheers

Joe Clement
(skinewmexico) - MLife

Locale: Southwest
Lighter Carbon Back Stay on 02/17/2009 07:27:10 MST Print View

Reminds me of the old Hexcel skiis.

Kevin Egelhoff
(kegelhoff) - F

Locale: Southern Cal
Re: Re: Re: Re: Re: Lighter Carbon Back Stay - version 2 on 02/17/2009 16:49:47 MST Print View

Roger,
I don't know the actual cost as we got it in a big shipment. We used to make Hockey parts out of it but don't make the parts anymore. They make several different grades, different thicknesses, and it comes in a lot of different materials from paper based, to Stainless steel based, to the most popular aluminum based material. COOL stuff.
The piece I used for back plate only weighed 4.5 grams and was about 1/2" wide and 20.5" long !!!!

Joe, you are correct !!! Ski manufactures, hockey blade, and others use this in the core to keep parts super light and super stiff.

Kevin

Kevin Egelhoff
(kegelhoff) - F

Locale: Southern Cal
New Version 3 carbon stay !! on 02/25/2009 17:03:23 MST Print View

This one is narrower and lighter, now down to 6.4 oz but may still be too stiff and can still be reduced in width to decrease the weight!!! Figuring out how to make these quicker and MUCH nicer looking now! I think I can take this down to the 5 oz. range and still have the stay stiff enough to support a 35 lb. load. I did two, 1 hour hikes this last week with the pack loaded up with about 32 lbs. and I think the stay really helps the pack carry the load well, transfers the weight to the hips, and keeps my back cool and dry with the only contact points above the hips being at the base of my neck and where the should straps touch. Seems like this really helps with heavy loads !!!
I just need to find some time to try it out now with a 15 to 20 lb load to see how that feels. I might have to make one more carbon stay designed to carry a 15 lb. load that mabye weighs 2 to 3 oz. Along with a 5 oz Cuben pack the complete pack would weigh in well less then 10 oz.

But ... it doesn't appear that too many poeple on this site seem to interested in a carbon stay to help support the load ??? Weight still to high or don't you see the benefits of having the carbon stay attached to the pack ?? Let me know what you are thinking .....

Version 3 stay
New stay next to pack

Devin Montgomery
(dsmontgomery) - MLife

Locale: one snowball away from big trouble
Re: New Version 3 carbon stay !! on 02/25/2009 18:39:48 MST Print View

Kevin,

I have to start out by saying that I am really impressed with your fabrication - carbon fiber pre-preg, honeycomb sandwich - you should be making crew racing shells!

I personally haven't been looking for a way to carry very heavy loads, but if I were, I would more interested if I could see this integrated into a pack as you suggest. For use as a lightweight curved stay, I think its competition (for effectiveness, price and weight) is certainly GG's 3.4 oz curved aluminum stay.

Steven Evans
(Steve_Evans) - MLife

Locale: Canada
Re: New Version 3 carbon stay !! on 02/25/2009 19:06:13 MST Print View

Kevin, that one looks awesome. In the picture, do you have one of the supports inserted into the backpack? If it is, what pack is that?
As for interest, I am! But it is probably a little out of our league to give input on the design/manufacture. I'll just sit back and enjoy the finished product :)

OK, well it looks like it would be great for my winter pack. My summer gear is too light to require a frame, but I use a Arctic Drypack for winter and need the rigid support for the loads (15-18 lbs of gear plus fuel and food - adds up quickly). Being able to integrate it into existing packs would be great, but if you offered the cuben version at under 10oz, I'd be willing to buy the whole package.

As for the weight, if GG has one at 3.4 oz, surely the carbon version can be lighter, unless of course the GG version is not rigid enough and additional material is req'd to create the stiffness.

One more question, is there some flex to the hip wings? Are they required to transfer the weight? Just asking because I thought some people just used carbon shafts inserted into a CCF pad as a frame...however, I have not tried either so I have no idea if it works well.

Did I mention that looks awesome?!

William Puckett
(Beep) - F

Locale: Land of 11, 842 lakes
Re: Carbon Back Stay V.2 on 02/25/2009 19:24:37 MST Print View

This is looking better and better with each iteration. I don't think the weight is the issue as much as finding the sweet spot for stay support vs. weight trade off. If the pack carries well because of the stay design, then a "penalty" of a few ounces doesn't seem too steep.

I'm more "concerned" that the stay length may be specific to the individual and the pack with no wiggle room for adjustment.

Edited by Beep on 02/25/2009 19:25:16 MST.

Matthew Roberts
(matthewjamesroberts) - F

Locale: San Fernando Valley
ZPack Blast on 02/25/2009 19:39:40 MST Print View

I have a ZPack Blast. After 5 hours with it, I was pretty well sold on finding a way to transfer the weight to my hips.

You're design is inspiring. I'm thinking about taking a shot at something similar.

Kevin Egelhoff
(kegelhoff) - F

Locale: Southern Cal
Re: Re: New Version 3 carbon stay !! on 02/25/2009 21:59:35 MST Print View

Hi Steven,
Thanks. Always nice when we get better at making the products. I'm getting a little better with each one.
Yes, in the bottom photo the one on the left is the Gossamer Gear new Mariposa Plus pack with the version 1 stay incorporated into it. I got GG to send me another waist belt that I'm now taking appart and going to mod to make a real belt that will easily work with the new stay incorporated into it. Pretty easy mod.
Yes, the GG alum stays are the current ones I'm using and really like they way they worked in my pack. And THAT is the reason why I started down this path ... thinking that the carbon stay could do a few more things like keep the pack off your back for more air flow, and with the wings going around the waist being able to transfer the load from the pack directly to the waist line. Of course this thought came to me after looking at BILL'S great work !!!
Yes, the wings are flexable and they flex more as you get closer to the tips. Still need to make them a little more flexable so they can;t even be felt. Even being a little too rigid, I have had people with a waist size of 32" try on the pack and say it felt good and people with a waist of 44" were able to flex the waist portion and still not complain. Has more flexablility then I thought although it hasn't been tested on different size waists for more then 10 minutes.
I'm in the process of making a few more that are all really different to try and do some real world testing.
Should be a fun test !!

Kevin Egelhoff
(kegelhoff) - F

Locale: Southern Cal
Re: Re: Carbon Back Stay V.2 on 02/25/2009 22:03:56 MST Print View

William,
I have been playing with the lengths and can easily trim the length a few inches if required. A small foam piece is easily glued to the top part that rest just below the neck. So far .... it hasn't created a hot spot but STILL needs more testing on different length torsos to see how much it can be modified and still feel good.

Matthew,
My thoughts exactly with that pack being super light and large capacity on the bigger models. Would be an easy mod to be able to add this stay!

Edited by kegelhoff on 02/25/2009 22:06:09 MST.