Jul 22, 2013 at 6:51 pm #1305690
I've been sketching some ideas for a daypack and want to make one that resembles a slightly larger REI Flash 18. I'm looking for advice on my design and on fabric/materials.
I recently took my Flash 18 on a trip up Long's Peak in CO and it did really well. It was a day trip, not an overnight, so the Flash 18 was just barely big enough for a midweight top, rain jacket, wind jacket, food, 3 liters camelback, food, headlamp, and emergency gear. However, it was packed pretty tight. I made a stiffer backpanel prior to the trip, so that helped carry the load and retain structure, but I'm guessing something around 25 liters would be ideal.
I have my general plans drawn out, but I'm stuck on figuring out which fabrics and materials to buy. I want it to be rugged enough to last for a few years and handle places like the Rockies well. I live on the east coast, but travel frequently. Weight isn't too much of an issue, since this is only a day pack…but I don't want it to be bomb proof and heavy.
Here's my best stab at it:
-XPac VX07 – back panel and bottom
-XPac VX03 – Sides, front panel, and lid
-Oxford Nylon* – reinforcement areas, maybe on the shoulder straps?
-Impetus 1.0* – Inner pockets (probably just a pocket for the foam pad)
-Pocket Mesh – side pockets and maybe a stash pocket on the front panel
-Spacer Mesh – Shoulder straps and maybe for some spots on the backpanel
-Shock cord for side compression (zig-zag pattern)
-plastic hardware for the belt, shoulder straps, sternum strap, and load lifters
*I already own Impetus 1.0 and Oxford Nylon, so I figured I would use it.
How does that look for the body of the pack?
And what kind of webbing should I get for the straps? I don't expect to carry anything more than what I described above.Jul 23, 2013 at 12:12 pm #2008808
I'm working on a similar small pack, I actually just finished one, but the straps are off by a touch so I think I'm going to redo it, I'm using vx materials too, here's what I found:
25 liters is just right for up to 3 days/2 nights, so you got that one correctly.
vx03 is really thin, vx07 is not really strong enough to sew stuff onto unless you reinforce it a bit, I used vx07 for the sides/front and vx21 for the back/bottom, that is just about right if you want the pack to last more than a few trips. There is very little square yardage of the vx07/vx21 total, so the weight just is not really that big a deal, and I'd much rather have a pack that I don't have to worry about literally just touching a branch/twig/chapparel in the wrong way to get a hole, if you want real weight savings and strength, get the $30 a yard hybrid cuben that comes in at around 3.5oz yd and has a 50d polyester exterior, which is stronger than vx03 by far, and only costs about 12 or so a yard more. zpacks sells the hybrid cuben.
A while ago I used a tx03 for side panels on a test pack, and that was literally showing daylight through it via small pin hole breaks in the material before I even had finished the pack, I'd never use that or anything else that thin again for sides/front, maybe for a roll top or something, but even there I'm not sure.
I really like the vx materials because they solve one of the oldest issues with coated nylon, delamination over time, by putting a sheet of plastic inside it, and protecting that from contact with a thin sheet of polyester, a perfect design in my opinion.
Oxford is good, I use it for pockets and strap tops, it's fine, it's basically the top layer of vx21, 200d nylon that is, it's easy to work with and strong enough if you are careful.
there are two main types of mesh, one is much heavier than the other, but look similar, unless you go very fine. I'm referring to the mesh type that is sort of like fishnet material. Be careful of stuff that is too light.
I use regular nylon 3mm cord from I think diygearsupply, shock cord can't be tightened like nylon cord can. I used the same zig zag, with a lineloc 3 for the adjuster part, works well.
1oz / yd nylon is fine for inner pockets, I've used that, it's delicate but fine inside a pack.
The shoulder straps are fine with 3/4" nylon webbing, note there are regular and coarse types of webbing, the regular holds better, but not all companies online tell you which they sell. I believe zpacks and diygearsupply sell the regular more fine type.
zimmerbuilt has excellent hardware, there's a pretty big difference in plastic hardware, his stuff is good, well sourced. Look for more rounded ladderlock strap adjusters if you can find them, there's a sort of basic cheaper kind that is sort of squarish that I don't think is as good.
If you use a hipbelt, a 1" buckle that adjusts on both sides is nice.
With real pockets, not just webbing and some other doodads, this pack weighs 11 oz, and will carry I think 3 days trip as long as my trailhead weight is under 15 pounds. I did not use a hipbelt, nor do I see any particular benefit to using one in this size, I get no detectable side to side movement when walking. If I need to carry more water when starting out I'll use a water bottle holder on my belt to keep that weight off my shoulders.
Hint: if you want your final pack to succeed, get cheap nylon and foam and create the basic body template and strap template and sew it up quickly, including the top and closure system, then walk around in it for 2 hours. I swore after my last pack I would do that next time, and of course I didn't since I'm lazy and now have a very nice looking prototype pack that is a bit uncomfortable under the arm pits because the straps are just a touch off. Don't add any doodads to the prototype, all you are doing is testing your templates and pattern for actual functionality.
I found that a 3" deep front pocket is far better and more versatile than a 2" deep one, and there is almost no extra weight. A rolltop of about 8" height gives you a bit of extra room for fluffy stuff if needed but usually will just be rolled up and also costs almost no extra weight. Y strap over the top attached under shoulder straps can pull the straps back a bit to maintain the pack form, not a huge deal but it's something.Jul 24, 2013 at 10:26 am #2009053
Thank you for the detailed response! I'll try to make a template soon and get my hands on some cheap nylon to try it out. Any chance you have your template drawn out to where you could share it? Here are the dimensions I was thinking of. I'm basing it roughly off the dimensions of REI's Flash 18 and Flash 45.
Back Panel: 11" wide at the top, 10" wide at the bottom, and 20" long
Side Panels: 6" wide at the top, 7" wide at the bottom, 18" long along the outer edge, 20" long at the inner edge (nearest the back panel)
Front Panel: 10" wide, 18" long
Bottom Panel: 10" x 7" square
This isn't including the lid or the pockets. At these measurements, my estimation is ~20L. I might try to expand it a little, and with pockets and a lid, I figure it should round out to around 25L.Jul 24, 2013 at 11:19 am #2009063
Here's my proposed materials list. If someone could comb through it and make sure I'm not short on anything, that would be great! I'm fine if I get too much material, but I don't want to go overboard.
(no waist belt for now)
Back/Bottom – VX21 – 1yd
Sides/Lid – VX07 – 1yd
Shoulder Straps and reinforcements – Oxford Nylon – 1/2 yd (plus I already own a decent amount of scraps)
Inner Pockets – Impetus 1.0 (already own 2 yards)
Guttermann Thread (already own it)
Pocket Mesh – 1 yd
3mm Spacer Mesh – 1/2 yd (shoulder straps)
1/8" Nylon Cord – 10' (side compression)
1/8" Microcell Foam – 20" (back panel)
3/4" Nylon Webbing – 8' (shoulder straps)
5/8" Nylong Webbing – 8' (load liters and roll-top closure)
Grosgrain – 10 yards (finishing seams)
Hardware (from http://www.zimmerbuilt.com/hardware.html):
Pack Hooks – 8 (side compression)
Line Loc 3 – 2 (side compression)
Sternum Strap Set – 1
5/8"" Apex Dual Buckle – 2 (roll-top closure)
3/4" LadderLocs – 2 (shoulder straps)
5/8" LadderLocs – 2 (load lifters)Jul 24, 2013 at 11:37 am #2009069
My templates are in thick card stock, pattern paper from sewing store. I just made the pack a box, though for a daypack your angling in towards the top makes good sense to me.
I failed to consider the change in angle would pull the s shoulder strap in closer to the armpit on a shorter pack, coupled with an existing error of having the straps too far apart (4", should be 3" from what I can see, maybe even 2.5") which is of course why we should always make new template/prototypes for new dimensions, heh.
My pockets are complicated, multipanel, but have true depth all the way too the bottom, not maybe the best thing to start out with.
Because I wanted an UL type few night pack, I made mine a touch larger than yours, your dimensions sound fine for a daypack that will hold a fair amount of stuff, I did 20×12, 20×6 panels, with of course 1" total seam allowance, plus a 1" deep bathtub bottom which is hard to make and I don't recommend it for a first pack type project, and for a daypack not really needed anyway. 8" rolltop, which gives a practical 3" or so of extension, give or take.
I may redo a prototype today of 22"x5.5"/22"12" with the bathtub bottom, if I'm not too lazy, then I'll know if the templates and straps work.
This is about 26 liters give or take, I don't include the rolltop volume or pocket volume in the volume, so if your body is 20 liters that's basically big enough for an overnighter with very light gear, ie, a perfect daypack. I was tempted also to just make a daypack that could double as an overnighter, but opted for the multi overnighter since it's more useful to me.Jul 24, 2013 at 11:40 am #2009072
James MarcoBPL Member
@jamesdmarcoLocale: Finger Lakes
I would examine the straps and buckles closely. On the first batch of Murmurs from GG, they used high quality nylon and good buckles, but there was a mismatch. The nylon worked fine for a few uses, then as the buckles wore slightly, they allowed the strapping to slip. This happened on the waist, and shoulder harness. When wet, this was even more pronounced since nylon absorbs moisture…it's dyable.
On the new pack, they substituted lower quality poly straps. They are roughly about twice the thickness. These have the added benefit of being highly waterproof. The somewhat thicker strap, is a little stiffer and grabs well in the buckles, preventing the slipping.Jul 24, 2013 at 11:56 am #2009079
consider those, you can attach them with 1/2 grossgain to pack sides, and the cord slips nicely through them, they weigh almost nothing. Since you're already ordering from zimmerbuilt just toss 10 or 20 of those, I don't think you'll regret that decision. Remember to tape down the d rings after the panels are finished so you don't sew them into the seam when you sew together the panels. Don't ask me why I suggest this…
Your amounts seem about right, though remember for a prototype you are not going to be reusing that much stuff in terms of the materials, you can cut out the hardware though, but you can also make the pack just good enough so you can actually use it for something, which makes making the prototype a bit less tedious, heh.
If I say this enough times maybe I'll actually really do it.
By the way, think I talked myself into trying the hybrid cuben for a pack, only 1 yd is needed, but I think I would not recommend a material that expensive and odd for a first pack.
I'm curious if the load lifters will work or help, I suggest adding those to the prototype then fill the pack as you really would use it and go for a 2 hour hike, try it with and without them, ie, loosen them all the way, then adjust them, walk for a while with each way.
I'm curious what you will find there, let me know, I didn't use them, though clearly they can pull the top of the pack closer to the straps, but I'm curious if you can actually feel the difference, and what that difference is, you'd need to be doing real hiking to notice I think, ie, hills, up, down, flats.Jul 24, 2013 at 12:11 pm #2009086
this shows what the parts and materials you'd use look like. Note, I use 1/2" webbing for the y strap, and 1/2 grossgrain for most cord/d ring/lineloc 3 connections.
I don't really like the zimmerbuilt type clunky sternum strap stuff, I prefer the simpler 3/4" 3/4" type but most people only sell the 1"/3/4" one, I actually want only 3/4" / 1/2" but nobody makes those so I adapt the sternum strap with a bit of 3/4 webbing so I can use the half inch.
Note that for a sternum strap you probably want elastic with a sort of U of webbing over it so it can expand / contract with your movements, that's a bit tricky to make. I used doubled 1/2" elastic because at 1/2", one layer isn't enough, with 3'4" you'd probably be fine with a single layer of 3/4" elastic.
By the way, you can buy, but I cannot find who sells them now, the simple sternum strap hardware in 3/4" 3/4" with the slotted middle of 3 bars that let you put it on and take it off, I have to see where I got those and get more, nobody seems to have them in stock now.Jul 24, 2013 at 12:28 pm #2009090
quest sternum strap 3/4" they still have them, whew!
These are easy to assemble and very light and do exactly what is needed.Jul 25, 2013 at 1:09 pm #2009422
Thanks! This is great info. I'm in no rush to build it, but I hope to finalize my plans soon.
You mentioned something above about the shape of the pack affecting the straps. With a day pack at ~20-23 liters, would it be wise to have it's circumference expand as it goes down? My REI Flash 18 has a wider bottom than top, but only on the back panel. That's the design I am going for…let me know if you have other thoughts.
Or maybe this is a better question – is there a general consensus on pack design in regards to shape? ie changes in pack circumference over different planes (x,y,z)?Jul 27, 2013 at 5:40 am #2009935
I made a pack a bit like what you are trying to do last year, and put a post of it on my blog here. There is a PDF at the start of the post that goes over the materials that I used. I added designs for a roll-top version of the pack at the end of the PDF.
I was able to make the pack about 24L with only 1 yard of fabric, because I used the same fabric for the entire body and formed it a specific way. If you are trying to avoid having leftovers, it may be worth using just the one fabric for the body, since buying in less than 1 yard increments is uncommon. Otherwise, your materials look about right.
I haven't designed a pack with varying dimensions before, but for a very light daypack, it could allow a little more flexibility in movement at the slight cost of volume.Jul 27, 2013 at 1:01 pm #2010013
Thank you Chris! This is excellent. I appreciate your attention to detail.
What do you think of your style of bag compared to a bag with multiple shaped panels in terms of comfort and load carrying?Jul 27, 2013 at 8:25 pm #2010123
This pack was given to a family member who uses it several times a week for short hikes and trips around town. He doesn't seem to notice anything odd with the carry so far. I was able to take it on a couple of day hikes and try it out as well. In contrast, my current weekend pack uses multiple panels. I couldn't tell a real difference between the carry of the two.
With a pack staying below about 25L, and light loads, I don't know if you ever really will. Since the amount of fabric you are using is relatively low, making your whole pack out of VX21 really wouldn't be a weight issue if you wanted to give this a go. Plus a couple less seams can increase the life of a pack.
I don't own one, but I believe that the Zpacks Zero follow a style similar to what I used. I have only ever noted a single seam down the center of the back panel in their pictures at least.
In the end, it might just come down to what you are trying to add on the pack. My current weekend pack has compression loops and a big front pocket, and I generally like to tuck those away into a seam. So I have multiple panels. I believe the design you want is similar to that, so the simplified panels may not work as well for you now that I think about it.
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