dado1965

I send you some pictures of some objects I sewed using Vergez Blanchard # 9 (in these cases, a portmanteau) linen thread Cable 632 and the total thickness leather (2 layers) 2.4 mm to 2.6 mm. What I would ask is: is there a formula to determine the relationship between the number of spi of iron pricking, thickness of leather and linen thread diameter? For example, the seam having a thickness of 2.8 mm to 3.2 mm is preferable to use a mark No. 8 (8 spi) with wire 532, or a mark No. 9 (9spi) with wire 532 (it is preferable to increase the thickness of the wire or the distance between points?), and so to get up to a thickness of 3.2 mm to 3, 8 mm (maximum thickness that I sew some side cases) is better to use a wire 332 or 432 with a Claw No. 7 (7spi)? While more points and higher and the strength and elasticity of the seam?