Needles designed for sewing thick canvas or heavy leather (e.g. on a traditional sailing ship) have a triangular point, see example 1 and example 2. (These needles are sometimes also called “rigging needles”, but then again not every “rigging needle” is three-edged.)

close-up photography of three-edges needles

Leather: Also known as glovers and as wedge needles, these have a triangular point designed to pierce leather without tearing it; often used on leather-like materials such as vinyl and plastic.

Sailmaker: Similar to leather needles, but the triangular point extends further up the shaft; designed for sewing thick canvas or heavy leather.

Source: Wikipedia s.v. Types of hand sewing needles

The only stated reason I have found is that this design supposedly allows the material to be pierced “without tearing it”.

How would the design of the needle prevent tearing of the material? Is this the (main) reason that needles designed for sewing thick canvas or heavy leather are three-edged?

(Side note: apparently three-edged needles are also used in acupuncture.)

  • 1
    I think this is more a history question, (hand sewing traditions are old) but not sure if it fits the history section of SE.)
    – Willeke
    Jul 22 at 8:50
  • Leather needles are often sharp on the edges of the triangular part while sail needles are not sharp.
    – Willeke
    Jul 22 at 8:56
  • 3
    As I have done a lot of sewing of leather over the years, I can tell you that trying to use a smooth, rounded needle gives more tears along fibres in the leather which can spread much wider than the hole needed, as it widens the hole by stretching. The triangular edges on a leather needle give a controlled cut that doesn't then spread, as the material is not placed under pressure or stretched.
    – Rory Alsop
    Jul 22 at 11:10
  • 1
    I hope this question is acceptable here. One user suggested it and I agreed.
    – Willeke
    Jul 22 at 16:54
  • This question falls under out 'tool-identification' tag: "for questions asking for help figuring out the name or purpose of a known tool".
    – Joachim
    Jul 24 at 9:38

Why are needles designed for sewing thick canvas or heavy leather three-edged?

The answer is quite simple. They are designed this way in order to avoid tearing leather and other thick materials. They also make hand sewing more easy by improving the needles' grip. They are called glovers, because professionals use specially designed gloves when sewing such materials. The gloves have a metal mesh in the palm area to aid hard piercing leathers.

Leather: Also known as glovers and as wedge needles, these have a triangular point designed to pierce leather without tearing it; often used on leather-like materials such as vinyl and plastic.

I have used both on many occasions!

Normal glovers are corded with twine or thread that is slightly thicker than the needle hole in order to prevent movement of the thread once in place. The lack of twine or thread movements once they're in place is the key to preventing any tearing.

One can thus understand why gloves are often employed. Normal needles often break.

Sewing Needle Set - 7 Pieces Hand Repair Upholstery Glover Sail Carpet Leather Curved Canvas Sewing Needles Tool                      Lace Lacing Leather Topgrain Latigo Black 50 Foot Spool
Source: Amazon Source: Amazon

Sewing with leather lace makes so much difference in application with glover needles!
Deerskin moccasins, like the ones shown below, are a great example!

enter image description here
Source: Manitobah.ca

  • 1
    @Joachim Thanks for the editing job!
    – Ken Graham
    Jul 24 at 16:53

My theory is that the triangular shape reduces friction when sewing very heavy canvas, thus making the work easier. Unfortunately, I cannot provide any proof for my claim.

Canvas is a plain weave material. The threads form a net of regular squares. If you try pushing a round needle through it, there will be 4 threads touching the needle on all sides. And since the needle in thicker than the tiny space between the threads, it will push the threads outwards into a circular shape, increasing the surface it has to move through and the friction.

If you push a tringular needle through canvas, less of the surface (mostly the 3 edges) are in touch with the threads. That lowers the overall friction.

Here's a simplified diagram of what I mean:

enter image description here

  • 1
    The diagram shows a big round needle and a small triangular needle. The triangular needles are bigger than the round needles. Once the circumference of the needle is larger than the circumference of the opening in the weave (any needle once more than the tip is in), the threads will be stretched around the needle, in contact with the entire circumference. I suspect the shape of the cross section wouldn't make a significant difference on friction. But I can't provide proof of my theory, either. :-)
    – fixer1234
    Jul 23 at 16:37
  • And with leather, where there is no uniform lattice to speak of, both would act different: triangular shaped needles would mean the material would have to endure a lot more friction along a significantly smaller surface, tearing the material (in a controlled manner), and maybe having less effect on the surface tension and appearance.
    – Joachim
    Jul 24 at 9:48
  • 2
    @Joachim AFAIK leather needles are somewhat sharp at the edges to cleanly cut throught the leather. That's definitely not the case for needles intended to sew canvas. The ones shown in the question have pretty dull edges
    – Elmy
    Jul 24 at 17:44

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