What is the right bobbin thread tension?

[Gymnast]

I know that most operators of sewing machines newer use instruments to measure the thread tension. They have learned some way of feeling the right tension. But perhaps a few in this forum actually do measure their bobbin thread tension.

I often change thread size in my machines, and I use a spring dynamometer to adjust the bobbin tension every time. I measure it direct from bobbin case or vertical up from the needle plate hole. You can get specialized instrumentation for sewing machines, but it will normally be more expensive than a simple spring dynamometer (Price $3) designed for use in schools.

I have used google to search for information. For domestic sewing machines for garment, I find a recommandations to a tension of 0.2 - 0.5N (0.04 - 0.1 lbsF).

In this leatherworker forum I did find these two links with a tiny amount of information:

Here one person use 11 N or 2.5 lbsF for V138 thread, which in my opinion seems a very high tension. https://leatherworker.net/forum/topic/54237-sewing-machine-set-up-problems-at-witts-end/?tab=comments#comment-347489

And in this link 4.5 N or 1 lbsF for a presumable V277 thread: https://leatherworker.net/forum/topic/31327-boss-is-here/?tab=comments#comment-229798

I normally use 0.5 N or 0.1 lbsF for a V138 thread (Serafil 20). Occationally I increase it to 1.0 N when I like the thread to lay down better and look more nice. For a Serafil 40 or V69 thread I use 0.4 N.

[kgg]

I do change thread size (v69/v92/v138), type (bonded polyester/ bonded nylon) spool size (8oz / 1lb.)and most importantly manufacturer (branded/cheap Chinese). I have noticed variations in stitching even with colour changes, white vs black. I have never done an actual bobbin tension measurement but do the bobbin drop test, adjust bobbin tension as needed and do a test stitch when I make a change to size, type, colour, manufacturer or size of spool. I have found that threading a bobbin from a spool getting down close to about 70 percent will have developed spool coil memory or if has been left on the bobbin for an expended period of time the thread will also develop a bobbin coil memory either is a royal pain.

kgg

[kgg]

9 minutes ago, kgg said:

I have found that threading a bobbin from a spool getting down close to about 70 percent

I meant to say "about 70 percent used".

kgg

[Bert51]

On the subject of tensions, whether Bobbin or Top Thread it does not matter, you have to work out what works for you, for your machine and what your sewing. You use very little tension on thin leather and heavy tension on thick leather.

There is some very helpful post here to guide you to find your ideal tension for this project, hewre is a link to what I found helpful information from one Aussie. Say no more, but the whole thread makes good reading,

 

Bert.

[MikeRock]

Just for the heck of it.....one Newton is roughly the weight of one Apple!!  Four and a bit apples to the pound. 

from the net: Things That Weigh a Newton. In the fruit department, one apple or one orange weighs one Newton. In the sweets department a chocolate candy bar weighs one Newton. While no single currency weighs one Newton, several put together do. One American nickel has a mass of 0.005 kg, so 20 nickels would weigh one Newton.

[RemingtonSteel]

How much does a Fig weight?  Could it be one Newton?

Edited November 29, 2019 by RemingtonSteel

[dikman]

Sorry, MikeRock, but that won't work as their are several variables to take into account - size of apple/orange, type of apple/orange, moisture content, type/size of candy bar etc.

[Frodo]

[MikeRock]

I knew I was leaving the door o-PUN to this......  oh well.  :)))

[dikman]

Groan!