needle size ?

[Aventurine]

Good lord.  I have read the foregoing and I am still baffled.  Please can anyone answer to these specific cases:

1). If I am going to use .6mm wide thread, what John James needles do I need, in whatever sizing system applies in the USA and Amazon in the year 2024 ?
2). If I am to use 1.0mm thick thread, what needles?

https://www.amazon.com/RMLeatherSupply-Saddlers-Harness-Needles-Leather/dp/B07477V1LG

[zuludog]

Here is my general guide to needles & thread, there are also YT Videos -

For thinner leather such as wallets use 0,45mm diameter thread and John James Saddlers Harness Needles item code L3912 size 004

For most leather goods use 0,6mm dia thread and John James Saddlers Harness Needles item code L3912 size 002 - note! make sure they are size 002 and not 2/0 

For thicker leather such as axe covers or if you want a rugged look, use  0,8 to 1,0mm dia thread and Tandy Stitching Needles 10 pack SKU 1195 -00

Briefly, synthetic is stronger than linen and won't rot, but some people prefer linen as it's natural and they like the way it feels/handles

Most people try a few types & makes before they settle on something, so look out for sales & short lengths

You can get John James needles in the USA from Rocky Mountain Leather Supply, I think, and possibly other suppliers as JJ are a well known make internationally; and Tandy are American anyway

But for needles, thread, and any other questions about leather & tools - Don't be afraid of the suppliers! After all they know their business and it it is in their interest to help you, so ask away!

Oh, just a comment - if you are going to use thicker thread and needles, you might need to temporarily enlarge the stitching holes with a round/scratch awl, they're cheap enough. The holes made by chisels & diamond/saddlers awl blades are actually slits, they don't remove any material and will close up around the thread after stitching. You might also need to pull through the needles with pliers, especially when back stitching - pad/wrap the jaws with tape so you don't scratch the needles.