Bag Construction-Puckers, Folds, Darts

[jrprottas]

Here are photos of a couple of my favorite maker's messenger bags, used as examples of my bag construction questions.

Newbie who has so far only made prototypes out of thin pleather. I'm still trying to figure out my design for a "turned" construction, 6 oz  vegtan, small (8"w x 14" tall) sling bag.

Can you see how these were constructed from these pics? I see a front and back, with a single side piece???  Perhaps a second side piece that only creeps up from the bottom 6" creating the side pocket with the banded, riveted edge and reinforcing the bottom.

My main question, since I have no actual experience:  These bags appear to have the same design but in the first photo it was necessary to have the puckered folds; and in the last photo it was unnecessary. WHY??? 

What design principle would eliminate the need for puckers, folds and/or darts?

Does the first design have a larger, rounded corner. Would that explain the need for the folds?  How would one "anchor" the folds so that they look the same on both sides?

Stuck, Jeff

 

[blue duck]

Jeff without actually seeing it or talking with the maker, my guess it is just designers choice. The top bag appears to have a rounder bottom corners, the bottom much more square. But that does not affect the use of the fold/dart. The darts/folds are created by making the leather wider along the bottom of the front piece and tucking it in. Again just a design choice, not necessary. I would bet the back piece of the top bag does not have those folds.  If you don't want that look, just create your pattern as a flat piece and then measure your gusset around that. If you wanted the dart/fold you would create the dart to take up that excess material and then you would measure for the gusset. I believe the gusset is three pieces, perhaps more without seeing the bottom. It doesn't take nearly as big a piece of leather that way. If you want to create that fold look I would skive down the thickness at the edge, so the leather will lay down better. To make them even you need to measure out the same distance from each edge to start the fold and take up the same amount of material on both folds. Tack or glue it down and then sew.

[jrprottas]

5 hours ago, blue duck said:

Jeff without actually seeing it or talking with the maker, my guess it is just designers choice. The top bag appears to have a rounder bottom corners, the bottom much more square. But that does not affect the use of the fold/dart. The darts/folds are created by making the leather wider along the bottom of the front piece and tucking it in. Again just a design choice, not necessary. I would bet the back piece of the top bag does not have those folds.  If you don't want that look, just create your pattern as a flat piece and then measure your gusset around that. If you wanted the dart/fold you would create the dart to take up that excess material and then you would measure for the gusset. I believe the gusset is three pieces, perhaps more without seeing the bottom. It doesn't take nearly as big a piece of leather that way. If you want to create that fold look I would skive down the thickness at the edge, so the leather will lay down better. To make them even you need to measure out the same distance from each edge to start the fold and take up the same amount of material on both folds. Tack or glue it down and then sew.

wow. thanks blue duck for your time in explaining this. 

So if I understand, the folds are a design element accomplished by making the front width a little greater and gathering the extra length at matching anchor points. BTW, you're right, the back doesnt have the folds.

Further, the rivetted bands on the sides may, or may not have a pocket behind them, as they may simply be a design for attaching different sections of the gusset?

Honestly, you have cured the many obsessed sleepless hours with your single post, and I'm indebted to you. 

Lacking the actual construction experience it's difficult to conceptualize some of the bags I see, and would want to emulate. And obviously, most bags do not show photos of the bottom.

Would you consider solving my only other riddle causing my lack of sleep?  I'll post the question and photos after my old man nap. thanks again mr duck.  Jeff

 

[blue duck]

39 minutes ago, jrprottas said:

if I understand, the folds are a design element accomplished by making the front width a little greater and gathering the extra length at matching anchor points.

You are quite right. If you do want to do this technique, make sure and lay it out on paper, put the actual fold in. You will find it is not a straight line across the bottom. You will need to add a bit extra to compensate for the fold. It is hard to describe, but if you would like to do it, I will draw (very poorly) what I am trying to explain.

42 minutes ago, jrprottas said:

the rivetted bands on the sides may, or may not have a pocket behind them, as they may simply be a design for attaching different sections of the gusset

I am pretty sure it is just a design element. No pocket included, but you could change it to that if you like. See how the upper part of the gusset goes over the bottom? That would also help keep weather/water/etc. from sliding down into the seam. (Well that is why I would do it)

51 minutes ago, jrprottas said:

most bags do not show photos of the bottom

For this bag I think you would want to add feet just to protect your leather. But you can accomplish this with many different options. Metal feet, 4, 5, 6 whatever keeps it off the ground. Metal or wood bars. Even use of 'spots' or other hardware that sits proud of the leather. Depending on your bottom leather, you may want or need to reinforce the bottom.

46 minutes ago, jrprottas said:

Would you consider solving my only other riddle causing my lack of sleep?

I will certainly try. However,  melatonin might really be the answer.  

 

 

[jrprottas]

Below are a couple of photos of a Saddleback Mtn. backpack that is said to be made from only 2pcs of leather. The flap, back and bottom in one piece; and the front and sides from a second piece of leather.

A friend created the template on a CAD  program the dimensions of which don't work. Does the template design reflect the correct approach?

Is there a formula for creating the darts?  viz width and depth measurements? Or a straightforward explanation of how to tinker with pattern to make the pcs fit together?

[Tugadude]

Blue Duck is correct.  The first bag was based upon the traditional U.S. Mail Bag design and they sometimes featured the folds.  I presume it was to allow the bag to bulge out a bit more and create extra capacity, however small it might be.

So it is mainly an aesthetic choice.  Regarding the template, I would just cut and fold until it resembles what you want it to be.  Looks like the paper is pliable enough that you can accomplish that.  I'm not big on making exact copies of marketed items, so I would change "something" about it, just to personalize the design.  YMMV.

Edited August 19, 2019 by Tugadude

[blue duck]

My opinion on that SBM, well we won't get into that too much, just don't buy into all of their 'reasoning' behind design etc. Much of it is just marketing, which they are really good at. But I would maybe steer clear of that type design to begin with for practical reasons as well. That will be a real bugger to sew, unless you have access to a sewing machine. I guess a patcher. It could be hand stitched, but don't think that would be any fun. For a beginner project, those are some really big pieces of leather to buy, work with, or perhaps mess up.

Mr. Tuga has the right idea. Just cut out of paper to begin with and adjust to suit. The one you have looks like a good start on how you would create darts. After you make the paper look right, I would suggest making the pattern out of something cheap. Felt will have a bit of body and give you an idea how the design will work. When satisfied,  you might even do it with cheap leather before using the good stuff. It will also help with the construction sequence.

As a gee whiz, when making a pattern don't forget to add your seam allowance where needed. Another lesson learned the hard way.

 

[chrisash]

Tandy has some free e-books at present the 3 x Al Stohlman "leather cases vol 1-3" may be of assistance to you

[jrprottas]

3 hours ago, chrisash said:

Tandy has some free e-books at present the 3 x Al Stohlman "leather cases vol 1-3" may be of assistance to you

great lead. thanks. I'll check them out tonight

[jrprottas]

I'm not finding the free ebooks on tandy's site. do you have the url?  thank you so much

On 8/2/2019 at 10:40 PM, thunter9 said:

i have a cb 4500 the complete package would  like to sell . even have the foam the head was shipped in 

do to my health 

 

On 8/10/2019 at 7:04 AM, mikesc said:

"Sustain oil" ?
btw..If you are on a phone ( your mention of "app" suggest that you probably are ) the consensus , amongst those who post from phones, is that the easiest way to reduce the data size of an image is to email it to yourself.
re the mark I tend to think that even if you dyed the whole thing very dark, you'd still see it, and if it is oil ( what kind of oil ) the oily areas would probably not take up the dye as much as the rest, leaving you with a very dark bag, with a very visible stain.Camouflaging it might well work better if you cannot get it out.

 

18 hours ago, kgg said:

The main question is what do you want to make. Is it going to be mostly wallets, bags or holsters. Then decide what your budget is and from those decisions you can narrow down your machine choices, new /used, brand name / clone, flatbed / cylinder / post / patcher. Remember that no machine can do it all.

kgg

 

2 hours ago, jrprottas said:

great lead. thanks. I'll check them out tonight