Stitch length

5mm is the best length straight stitch to use for outdoor gear it puts less stress on the fabric it keeps it from tearing.
But most home machines only have 4mm straight stitch length setting.
Terry

Thanks Terry,

It looks like I am at just about 4mm right now. My machine (Pfaff 130) could definitely do 5mm so I will try that out. It does look like Henry's are closer to 4 to me. I will have to take another look though to be sure.

Most of the stuff I sew I use a 4mm stitch length. 5mm's a little longer than I'd like

Take note that commercial manufacturers prefer stitch lengths as long as possible because it makes the sewing faster. Long stitches are however weaker: fewer threads per metre.

Also note that using longer stitch length means a higher stress on each hole, which means the holes get stretched open more under load. More leaks.

I find 4 mm on silnylon a shade long in high-stress regions, and prefer 3 mm. (Yes, my machines are fully variable.) YMMV.

Cheers

Roger, Commercial manufacturers will choose long stitch lengths because it is faster a small percentage of the time. The time difference is not huge. Generally quality stitching wins out. Now if they would use quality thread!

Each project will dictate a specific stitch length! I generally shoot for 3.5mm-5mm depending on the material & will baste with a large (6-7mm) stitch.

> Generally quality stitching wins out.
You are an optimist. Me, I go on what I have seen in gear. But it probably depends on the actual manufacturer. They vary.

> Now if they would use quality thread!
Ah well, here we are in some agreement for sure!

Cheers

"…Basically I have been sewing most everything at the same length henry Shires uses on the tarptents. Is this bad form?"

Generally, in custom made products, yes. Bad form means you will be coppying the manufacturor's production length. For sewing large volumes of fabrics together with a rolled seam, most manufacturors use one length, it is easier. Doing the same with rolling a mesh into a silnylon seam is OK, but alters the strength of the seam. It is not the same, nor should be treated the same while sewing. Adding a zipper? Or sewing a dor over mesh and canopy? One layer, two layers, rolled/felled seams, will require different stitch lengths. Attaching webbing loops to fabric requires a different stitch length, often a different needle, thread and tension.

Stitch length, needle size, thread size and tension are all related for a perticular bit you are working on. Some companies prefer cotton wrapped polyester threads. Some prefer extra strong nylon threads. Some use 100% polyester threads. This will effect the size and shape of the needle. The size of the needle will effect the strength of the substrate (along with stitch length.) Different materials do require different stitch lengths. Differnt construction methodes require different stitch lengths. A glued seam will require not only enough to hold everything firmly together, but will also reinforce the glue making thread, material and glue work together…a balance between several components, not only stitch length.

Sewing burlap is much different than sewing silk. Stiching leather will not work well with the same seaming used for sewing silk. Sewing cuben can be a disaster when compared with glueing the same seam. PU fabrics loose waterproofness and strength with the same seam as used for silnylon. Just a few rather drastic examples of how thread size, stitch length, glueing, tension, needle holes can influance seams. This is besides the obvious number of perforations that the needly puts in the fabric.

I don't believe there is a chart of these things, except for generally. There are simply too many variables. This is part of what makes fine custom sewing so different from factory made stuff. More art than science. Watch a good taylor at work. He will often do almost incomprehensible steps that take time. Neat and consistent make strong seams, generally. Long stitch lengths have their place. Short stich lengths have theirs. When do you use them? Well, it depends…

Do Henry's shelters hold up? Hard to go wrong copying his methods if you are building
a somewhat similar item.