Machine & Technics - Sewing wool fabrics with thick linen threads

[Wizcrafts]

On 9/2/2025 at 5:50 PM, Ferreol said:

I'm starting to think about a project that consists of sewing wool fabric (approx. 400gsm) with thick linen thread (diameter: 3mm).

Many years ago, I had a Union Lockstitch machine that was made to sew horse tack. The ULS is a needle and awl machine. The needles are barbed like hand sewing needles are. I explored all of the available thread options, then bought needles and awls that would punch the proper size holes for that size of linen thread. In my searches, I found that the thickest linen thread sold in the USA at that point in time was Barbour's Irish Linen in 8 cords. This is equivalent to .828 mm diameter. It called for a gigantic needle, size 30, which nobody had in stock. The largest needle I could get was a #250. It was able to hook and sew with 6 cord linen thread.

I later discovered that these thicker sizes of thread were meant for the shoe repair trade, not saddlers. Some shoe sole sewing machines were apparently capable of handling up to 10 cord linen thread, which is about 1 mm diameter. They are specialized machines that can weigh 500 pounds or more. I would recommend that the OP searches for an old time shoe repair shop that uses old sole stitchers and see if they can sew his or her projects for a nominal fee.