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!

[Tejas]

Here are two links on using a spring scale to measure tension:

http://jukiindia.com/Item-List/Adjustment_Procedue.pdf

http://sew24.blogspot.com/2012/11/how-to-measure-thread-tension-with.html

 

[Gymnast]

12 hours ago, Bert51 said:

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,

Yes, I think you always need to test on test pieces of real fabric or leather to adjust your tensions to the result you want. However, when you have used your machine for something else, and you go back to the same kind of work again, you can limit your amount of trials by using an instrument to set your tensions.

I did read your refered thread about tensions and results and i just read it fast again. I think it covers many interesting subjects, and many issues of mostly top thread tension. I believe that the bobbin tension in most cases do not vary that much. However the top tension can vary a lot due to how heavy the fabric you are sewing and your aim at getting a ballanced stitch.

14 hours ago, kgg said:

but do the bobbin drop test, adjust bobbin tension as needed and do a test stitch

The weight of the filled bobbin and bobbin case of my class 15 type is about 0.18 N. So a drop test ensures a force somewhat above this value - typically 0.25 N for me. The weight of a larger bobbin case and bobbin will of cause increase this value. When you try to measure the tension by holding a boobin case by hand and pull the thread of by the dynamometer, I can get rather big variations in figures. The force is dependent of the direction of your pull from the bobbin case and if you tuch the rolling bobbin.

In my expierience, you get more dependable tension figures by measuring the thread tension of the bobbin thread comming up through the needle plate. For some machines it is hard to remove the bobbin case, and then you need to use this method anyway. I have not seen any significant difference in bobbin tension from a near empty bobbin and a near filled bobbin. I do not use bonded thread, and I get your point, that the coil memory in bonded thread have issues.

I do not want to make this a physics class, so I will just say that the weight of 1 Pound on the earths surface is 4.45 Newton [N].

[Constabulary]

Really - NM for bobbin cases? There is always someone who needs numbers for everything. Bobbin tension is no science and no one needs a table for this - there is just a freaking screw - turn it back and forth - done! Even as a novice it took me just e few trials to figure out how top and bottom tension works. its explained in all manuals I recall - even with pictures. Bottom tension as low as possible the rest is top tension and if you need a tighter stitch increase both by a 1/4 turn at a time until the know is balanced - done. You have to try it anyway so what is a NM number good for?

[Gunnarsson]

The Husqvarna 2000 series domestic machines were adjusted for 22 grams tension on the bobbin thread from factory. (Just for reference, not machines for leather obviously.) The pattern cams for those machines happens to weigh about 22 grams, so the manual suggest using one of those hanging from the thread to rough adjust the bobbin tension. A simple method anyone can use without any special tools, just find a suitable weight. 100g = 1N.

[Gymnast]

1 hour ago, Gunnarsson said:

The Husqvarna 2000 series domestic machines were adjusted for 22 grams tension on the bobbin thread from factory. (Just for reference, not machines for leather obviously.) The pattern cams for those machines happens to weigh about 22 grams, so the manual suggest using one of those hanging from the thread to rough adjust the bobbin tension. A simple method anyone can use without any special tools, just find a suitable weight. 100g = 1N.

Thanks for this reference. I got another reference that recommend 21 gram-force. I think most domestic machines use a V23 thread for garment. I tried to measure the force from a bobbin case a similar way using a digital kitchen scale, where I look for the weight loss on the scale:
 

However I do see some variation in the measurement depending on how I hold the bobbin case. With some care I think this kind of measurement is useable. Many households got a digital kitchen weight today. But it seems to me that measurement by a spring dynamometer on the thread from the needle plate is a more accurate measurement.

I do not agree, that a spring dynamometer is a special tool. It is not that commen in a home, but most people have used them in primary school, and they are cheep and easy to understand and fast to use.

2 hours ago, Constabulary said:

Really - NM for bobbin cases? There is always someone who needs numbers for everything. Bobbin tension is no science and no one needs a table for this - there is just a freaking screw - turn it back and forth - done! Even as a novice it took me just e few trials to figure out how top and bottom tension works. its explained in all manuals I recall - even with pictures. Bottom tension as low as possible the rest is top tension and if you need a tighter stitch increase both by a 1/4 turn at a time until the know is balanced - done. You have to try it anyway so what is a NM number good for?

Thanks for your comment, Constabulary. I like to get some opposition, and it helps to bring forward a good debate and arguments. In my view it is very fast to use a spring dynamometer and bring back the tensions to a privious desided tension. When I do the test sewing, it will normally be spot on again. Without use of the dynamometer I would typically need 5 tests and itterations by test sewing. So I think the use of the dynamometer is a faster way. And yes I like numbers

PS: My mother had a Husqvarna 2000, and I learned to sew on it as a child, but I did not know this about the cams.

[dikman]

An interesting exercise but I agree with Constabulary on this one. We have to be careful not to over-think things sometimes.

[Tejas]

7 minutes ago, dikman said:

An interesting exercise but I agree with Constabulary on this one. We have to be careful not to over-think things sometimes.

Contraire -- what what works for some folks might not work for other folks. The OP seems to offer a repeatable solution for varying situations.that might appeal to some users.

[dikman]

It's "au contraire", to be precise and yes, your are right, of course, but I think it's safe to say that most on here who use industrial sewing machines soon learn how to judge bobbin tension and also, in most cases, tend to leave the bobbin alone and tweak the upper tension when adjustment is needed. Except in dire cases.

This is precisely what I just did with my Chinese patcher. I could not get it to sew consistently and eventually backed the bobbin tension right off and use the upper feed to balance the stitching. That finally worked.

[Gymnast]

Well, now people that like to share these bobbin tension values can do it.

I use these spring dynamometers, and I think the most significant benefits have been to diagnose tension problems faster and fix them. It it is much faster than a lot of test sewing. I have had problems with tensioners giving variation in tension including once with a shuttle tensioner. When you search this forum and look for problems with tension or helpers suggesting wrong tension - I think you get over 1000 posts.

[KathyBrown]

Has anyone used a TOWA bobbin gauge?  Pretty slick.  I have a longarm quilting machine (in addition to my other machines, one of which is a Consew 206rb5) and it is helpful, as I change types and weights all the time.  I was looking for gauge settings recommended for my Consew but all I can find is the drop test, of which I have found at least three ways to do it.  I have just been working on moosehide slippers and have been fighting the tension which feels really tight.  Being a retired physician, I like precision - reproducible numbers rather than hammers or "it just feels right".  I was hoping that someone might have a suggestion for a starting point for an industrial walking-foot machine sewing leather???  It appears to be very different than for my longarm.

[Pintodeluxe]

I like low tension sewing, so I set my bobbin tension fairly light.  Like pulling dental floss from its container, or maybe a little more tension than that.  

That way you won't have to use tons of upper tension to balance the stitch.  

[DonInReno]

3 hours ago, KathyBrown said:

  I was hoping that someone might have a suggestion for a starting point for an industrial walking-foot machine sewing leather???

A drop test/tension adjustment, with an industrial large bobbin case produces about 28g of tension - around the weight of five US quarters.

Unlike fabric which allows little resistance to the take up of thread , leather requires a large enough needle to make a path for the thread to pull up into the leather.    If the needle is on the small side and upper thread meets too much resistance, it can appear that the lower tension is too tight when it’s actually correct.

Upper tensions can be quite high and it’s not uncommon to have an industrial originally set up for fabric sewing to require a heavier/thicker tension spring.

[Gymnast]

23 hours ago, KathyBrown said:

Has anyone used a TOWA bobbin gauge?  Pretty slick.  I have a longarm quilting machine (in addition to my other machines, one of which is a Consew 206rb5) and it is helpful, as I change types and weights all the time.  I was looking for gauge settings recommended for my Consew but all I can find is the drop test, of which I have found at least three ways to do it.  I have just been working on moosehide slippers and have been fighting the tension which feels really tight.  Being a retired physician, I like precision - reproducible numbers rather than hammers or "it just feels right".  I was hoping that someone might have a suggestion for a starting point for an industrial walking-foot machine sewing leather???  It appears to be very different than for my longarm.

I think the Towa bobbin gauge is too expensive and over complicated. Its simpler and cheaper to use spring dynamometers, and they can measure the thread tension in more ways and be used to measure needle thread tension as well. Last time I looked for these dynamometers you could get them for about $1.5 each via Aliexpress from China. I would choose to get three types, 0-1 N, 0-5 N and 0-25 N. I prefer them over digital types, because you can get a better idea of the tension variation. This a short video that shows how these gauges look like:

 

[Gymnast]

I just saw two beginners having problems with thread tension in this forum. And it can be hard to help them when many things can be wrong. But thread tension can be quite easy to measure for a beginner and then this problem will be almost fixed. All the old guys in this business can just feel that the thread tension is right and adjust it according to that.

Lately I did a video about ways to adjust bobbin thread tension:

 

[kgg]

3 hours ago, Gymnast said:

But thread tension can be quite easy to measure for a beginner

I particularly liked the video at about the 4:30 mark showing a excellent visual of the drop method of adjusting the bobbin tension.

kgg