Stitch Hole Spacing And Nylon Thread Size Logic

[joe h]

When hand sewing with thick leather what do you think from experience is the best stitching chisel size or hole spacing, 2mm, 3mm, etc... to use?

do you find the smaller spacing the stronger? does it even make a difference, say between 2mm to 5mm space and its just about how it looks? what nylon thread size 207, 277, would you use on 2mm to 5mm and why?

[katsass]

When hand sewing with thick leather what do you think from experience is the best stitching chisel size or hole spacing, 2mm, 3mm, etc... to use?

do you find the smaller spacing the stronger? does it even make a difference, say between 2mm to 5mm space and its just about how it looks? what nylon thread size 207, 277, would you use on 2mm to 5mm and why?

From the grumpy old guy; Joe, those stitching chisels are useless, nasty, little things IMO. When using a chisel, your stitching will never come out as good as it will with an awl and an overstitch. Learn to use an awl. It isn't all that difficult, but DOES take practice. I'd advise you to get Al Stohlman's book on "The Art of Hand Sewing Leather" , work at it a while and you'll be much better off, again in my opinion. I hand stitch everything I make, from holsters and knife sheaths to belts, it takes time, but the finished product is worth it. A bit of my stitching, all in 6 stitches per inch (6spi).done with an awl. And, as in the last two pics, you can go through as much leather as needed with an awl -- not so with the chisel. Mike

[joe h]

Let's assume I know what I'm doing. If anyone suggests that chisels are "useless" than they are still making simple craft projects with natural undyed leather. The awl, chisel, hand punch, and sewing machine all have their particular purposes. In my opinion the awl, is the worst and for simple projects with curves and big holes, that is very time consuming. I would always use a hand punch and a 00 tube for curves anyway, it's cleaner, easier, smaller holes, and faster. The awl, even experienced takes forever. Those stohlman suggestions are geared more towards craftwork.

You are not using an awl on fine leather not clampable in a stitching horse even with padding, complicated projects like a large bag with straight lines, a gusset with tight corners, in a commercial application where you have a dead line and not all day stabbing one hole at a time. Another impractical thing is that saddle stitching thing I see some do where you are putting the 2 needles in the hole together. Who stitches thick leather for 3 to 4 hours a day with at least 2mm to 3mm size holes and 277 or 346 thread?

I would really like people's opinion on how and why they choose their hole and spacing sizes? Why 6spi? Is it a strength thing?

For me it's always been an aesthetic thing and like all fashion, copying what other high end leatherwork is selling in the market. Im really trying to get to the science of stitching leather and determine the load capacity for hole, spacing and thread size.

[TwinOaks]

Wow. Great way to respond to someone trying to help you. Also a great way to get other people to chime in and help....

Since we're assuming you know what you're doing, are we also to assume that most commercial applications use sewing machines instead of chisels, and already know why they are stitching at a particular sized thread and spi? Because we're assuming that you know what you're doing, there's really no point in answering the question is there?

[Northmount]

I guess you already know that the closer the holes are, the weaker the leather becomes. Too close and the leather rips when strained. And you already know that with thicker leather, the holes should be further apart.

CTG

[HellfireJack]

I think he's asking people's opinion on where they think the line between strength and aesthetics lies in stitching and not actually looking for advice on how to stitch two pieces of leather together. I personally can't wait to see people's opinions on this one. I've wondered the same thing myself. At what point do people believe spacing and thread size cause a problem rather than add strength. Seems clear to me what his what his original intent was.

You all can keep busting his chops though for having the audacity to clarify his request after recieving an answer pertaining to how to stitch leather together as opposed to an actual answer to his question.

[TwinOaks]

Jack, you do have a point in that, but we'd have to know some particulars such as what type of leather, and particularly what thickness. Then we could make suggestions on which thread to use, and consequently what spacing would look good with it.

We'd probably have to point out that on anything thicker than 8oz vegtan, the chisel is going to get stuck in the leather (provided it even makes it through) and require pulling or even beating the leather off the chisel, which would probably distort the leather a bit and leave some pretty large holes on top. After that we'd need to know how the person doing the stitching wants to fill the large holes left over by the chisel. Personally, for large chisel holes, I think something like 415 fills it nicely, but then the stitches look all bunched up.

We'd probably also point out that hand stitching with waxed linen looks far better than nylon because once you run over it with the overstitch wheel, the stitches all lay down nice and close to the leather, AND you can taper the end of waxed linen and lay it over another thread. That causes the end of the stitch to be pretty much invisible. We might also point out that saddle stitching (regardless of thread size) is by far more durable since a single broken stitch won't unravel... because there's another thread holding the seam together.

But I'm loathe to point any of this out to the OP because I don't want any of my projects to be considered as "crafty", and only done on "natural undyed natural" like those posted by Katsass......oh, wait....his pics show formed, dyed, sealed and finished pieces, some of which have exotic inlays. And we've already been told that hand stitching with an AWL is absolutely the worst way to do these types of projects.

It's kind of humorous, when you think about it, how all these experienced leatherworkers keep suggesting the tried and true methods that just keep working, when there's all these new fangled gizmos available to let you turn out stuff much more quickly.

Oh yeah, I almost forgot......On stitch lines where the spacing doesn't equal out to an exact spi, it's really easy to 'fudge' the spacing over several holes with an awl so that the difference in stitch length is not noticable. And if you were after small holes, you're not going to get much smaller for stitching than a bridle awl.

For most hand stitching, 6-8 spi looks good with 138 - 207 thread. 277 looks better at 5spi. 346 @ 5, maybe even 4 spi, and 416 at 4-5 spi. But all that is of course dependent on how much force the seam will need to withstand, how thick the leather is, and what kind of leather. You could easily do a purse made out of garment leather and use 277 at 5 spi.....but it's overkill and it looks terrible. Something like that looks a lot better with size 92 thread run at 8-10 spi. On the other hand, a pair of saddle jockeys made of vegtan could be sewn at 10 spi with size 69 thread and it'd effectively perforate the seams, resulting in very little strength.

[HellfireJack]

Well no offense TwinOaks but his initial question was open to both awl use and chisels. Note the "the best stitching chisel size or hole spacing". It seems to me he understands there are two methods. It appears someone has just taken offense to his personal preference.

But now you're coming closer to actually discussing the topic.

Do you think the method by which you make the holes will actually change the strength of the stitch. i.e. given the exact same factors in leather type and thickness will a chisel based stitchline be weaker than an awl based stitch line? What about drilling? I have to assume drilling is only used on heavy veg tanned. You wouldn't use one on garment leather that's for sure.

Have you (or anyone here) ever done any force testing on stitching to see where it fails? I understand there are myriad possible scenarios with different leathers and such but all we really need to do is pick some standards like say stitch two pieces of 5/6 oz veg-tanned leather and go from there. Or maybe if we have people who work with other types of leather, like latigo or chrome tanned they can chime in?

Thanks for your answers so far though!

[TwinOaks]

Actually, I'm pretty sure the hole sizing (2mm, 3mm, etc.) is referring to holes punched...that's why using "a 00 on corners" is mentioned.

Chisels move a LOT of leather relative to the actual hole, so all that leather is weakened. And before I get ahead of myself, it should be pointed out that chisels and pricking irons are NOT the same thing.

Drilling? Not even on thick vegtan. Drilling and hole punching both remove leather, and of the two, a punch is better because it cuts the leather where the drill tears the leather (as evidenced by the fuzzies). This can sometimes be a good thing, such as in lacing where you have a (larger than thread) lace filling the hole back up. For stitching, especially where strength is an issue, you want the smallest hole possible. The reason for that is that it keeps more of the grain intact...and the grain is the strongest part of the leather. You've got two things holding a seam together - the thread itself, and the leather between the stitches that's under the thread.

Also worth noting is that a diamond (shaped) awl pierces the leather and pushes open a hole....which WILL close up on its own. When you combine a self closing hole with a small hole size, the result is that there's very little room for dirt and grime to get down into the stitch hole....and dirt, especially sand, is what usually cuts thread. Grime, in all its forms, can hold moisture/bacteria, etc. and cause the thread to rot. Either one results in a broken thread, typically at the most inopportune time.

As to seam strength, well, it's a simple calculation of the tensile strength of the thread being used multiplied by a fraction of the number of stitches (because you're not pulling evenly on all of them). Add in the variable of the leather thickness and tannage, and the number of holes you've made in the leather. Too many holes and the leather between stitches will give way before the thread does....the result is the afore mentioned 'perforating the leather', just like a roll of paper towels.

One more thing to account for is whether the seam was glued before stitching. With a lot of the glues available these days, you can get a bond that is stronger than the leather fibers, so if you go to pull it apart, you're actually pulling the leather fibers apart from each other, not pulling the glued seam apart. Back before industrial adhesives, it was pretty common to have "hide glue" used. So what does the glue do? Well, besides bonding side A to side B and preventing separation, it also prevents slippage between the two pieces. Ever heard leather 'creak' when it's flexed? That's the two pieces rubbing against each other. Enough of that and the only thing holding the leather together is the stitched seam. Proper bonding of two pieces makes it behave like it's a single piece.

[joe h]

Bingo jack, im glad you could see it. "kat" comes right off the bat with his awl advise assuming i don't know how to stitch. Assuming i want to learn how to "Learn to use an awl" Assuming the old Stohlman books contain the great wisdom of leatherwork. And ass-u-me 'ing' every two bit hack that purchases a couple of stamps and strips of scrap from eBay can secure leather together. There is so much bad information on leatherwork, usually from a "craft" perpective so when someone new comes into this field, wrong methods and procedures are made and a lot of crap work exists, that call it "leatherwork'. There is a case to be made if all this crap work is good for the people who make a living with their leatherwork. But then again, the market floods with foreign mass produced inferior products and drives the price to the floor, leaving the customer to wonder why should he should pay $1000 for an American made leather bag when he can pay $200 for a Chinese bag. Leather craftwork, IN MY stupid, nothing, opinion, is like the "Chinese bag" of our industry. (come on you got to laugh at this one). I guess i just wanted to point out to the new comers of leather work that the AWL is not the end "AWL." but who cares, thats my opinion, im sure there are threads where great leatherworkers are are telling people about the virtues of jabbing leather with a spike one hole at a time. be my guest, what do i know.

twin, real good points thanks. if you wax up your diamond chisel tips and press the leather down with your thumb and pull it out you will minimize the "hurt" to the leather. nothing is ideal though. The Awl or a metal chop stick is probably the perfect hand stitching tool for the perfect stitch, but im working with constraints - dead lines, fatigue, and pricing the labor competitively.

Honestly, how long does it take you to stitch say one side of a bag 45", 2 corners, delicate 9/10 leather with 5/6 skived gusset? and no horse clamp because your gona tear up that fine expensive leather. remember, can't have not even 1 scratch or finger nail mark or ding. Now, how many times in a day can you keep up that consistency?

on gluing leather. i don't. i found out 1) it runs when tested with heavy rain and water (i forgot the brand i tested though) 2) MOST important, we all make mistakes and try having to restitch glued leather or repair a customers problem or whatever and work with a $200+ hide.

On linin thread. what is the strength like compared to nylon? Where is it available? how are the color choices?

OK, lets get down to business, forget the nonsense.

My testing:

i build my "stuff" lets say bags of some sort, on aesthetics. sure, like NORTH said, not too close of a stitch will weaken. i dont know about the thicker leather holes should be further apart? how far apart do you mean? i have built "stuff" with 2mm chisel holes at 3mm and 4mm apart with 346 nylon and polester waxed bonded thread into chrome leather 4/5 stitched with heavier 9/10 bridle and harness leather. I have tested these bags, the stitching in particular, with up to 30 pounds of weight. i put them through various vigorous testing methods. 1) hung on side strap dees for 1 week 2) hung on rivit secured handle for 1 week 3) shaken and rotated the bag for about 10 minutes. 4) heavy sun and rain conditions and repeated 1 to 3. the stitching has always held up. the rivits became loose but more because the leather around the holes was stretched and glue started to run in the rain.

What i don't know and would like to know:

i have not tested those heavier leather hides 9/10 stitched together with the same hides just cut down to 5/6. I know chrome leather is stronger, but when you skive that thick leather and stitch it like for a gusset 1) does it lose its strength? 2) now should stitching holes and spacing factor into this?

What I am trying to do:

If anyone has actually tested this that would be great. I would like to move to 5mm spacing with either 207 or 277 nylon waxed bonded thread. less holes = less stitching, but how many pounds am i good for? I and we need real measurements.

[TwinOaks]

Somewhere floating around the internet is a nice little video showing a couple of elderly ladies hand stitching English bridles. Sure they've got experience, and the way they do it is punch two holes feed both needles, repeat. The speed at which they do this is very fast, covering about a linear foot of stitching in just a few minutes (under 5 minutes) and they're working in the 6-8 spi range. Stick, stick, stitch.....

As far as not glueing....well, whatever brand you used wasn't suitable for leather, and if it's glued (bonded) and stitched, it's less likely to come apart....so you won't have to do so much in customer repairs. I use contact cement which is both flexible and waterproof when dry....and it's one of the ones I mentioned as being stronger than the leather fibers. I guess I view it as "Make it so it doesn't come apart" instead of "make it easy to repair when it DOES come apart". That whole 'prevent the problem in the first place' thing. Gluing the the seams also means it isn't going to move while you're stitching it.

Depending on the source of the linen thread, I've had it test anywhere from 15 - 30lbs tensile strength for ~138 sized thread. Nylon is higher. And if you're expecting anyone to be putting that much force on your stitches, you should be using latigo not designer leather. If you're using an analine tanned leather - bag/chap/garment - you aren't going to get fingernail marks in it anyway.

I'd REALLY like to know what kind of leather you're using so I can know what can be considered "delicate" at 9/10oz.....then avoid it.

And one last thing....Katsass, I believe, was offering his opinion (IMO means "In My Opinion), which is based on over 30 years of experience working with leather. To me it wasn't assuming you don't know how to stitch, it was telling you that an awl and saddle stitching is superior to using a chisel. But, you have your way, he has his. Let us know how your way is working out after 30 years.

[joe h]

6spi for 12" at 5min? including the time to move the project in and out of the horse clamp? consistent? for a few hours? without butchering the material or uneven stitch lines?

Where are they because i want to offer them a job, oh but wait, with speeds like that they must be sitting on a leather stitching empire.

There is so much BAD, MISLEADING, and just out right wrong information in this industry. Hence the AWL thing the old timers like to suggest. For craftwork, OK, punching is better - for commercial, wanting to get paid and making designs that truly standout and last forever, please!

Glue - but the little black word thingys on the can said f-o-r L-e-a-t-h-e-r and w-a-t-e-r-p-r-o-o-f - im sure the hot sun and then rain had something to do with destabilizing the chemicals.

Glue will NOT keep stitch from coming apart, at best it keeps the seem closed and looks good. even the most experienced old ladies, during production will make mistakes and have to restitch. if glued, that material is wasted.

what is "designer leather?" can you order that from a tannery like that? i never said "designer leather" or that i use Latigo.

i said i stitch into "chrome leather 4/5 stitched with heavier 9/10 bridle and harness leather" which is already drummed dyed. if you haven't in all these experienced years worked with "delicate" 9/10 USA steer bridle or harness leather that scratches and dents with a finger nail then your advise should not be trusted from the newcomers trying to learn to work with leather and SELL IT TO A CUSTOMER that demands professional work for their payment. This is NOT natural tooling leather where you could hide your clamp marks, scratches finger oils, and other movements of the leather that on some level absorb into the hide. When a customer receives a leather product, its hard enough to get them to understand the natural characteristics of the hide. So when i say "delicate" i don't mean it in a "designer leather", whatever that is, sense. "delicate" to picking up a leather craftsman's touches.

[TwinOaks]

This thread began by asking for advice on stitch size and spacing, and I believe that has been answered. At this point it's turning into an argument, so stick a fork in it......it's done.