Singer 31-15 Worn Tension Release Lever

[Ogoki]

The machine in question is actually a more obscure 44-79, but the mechanism is same.

I was watching this video on setting up the 31-15, and realized that the tension release lever is actually (or at least according to this video) supposed to release the upper thread tension momentarily as the needle is descending (essentially as the eye of the needle passes through the fabric):
https://www.youtube.com/watch?v=Z1QX4nL65L0

The lever on my 44-79 has a groove worn into it, and it is no longer making contact with the arm that should press against it.  So, I pulled the lever from my 96K, but despite being the same part (according to the parts books and the numbers punched on both parts), it is a little thinner and the arm doesn’t contact it either.

So, before I have somebody braze these levers to build up that area, I am wondering whether this feature is critical for stitch formation.  What purpose does it serve?  I don't think that any of my other machines have this feature, although they are all rotary hook machines; is it particular to oscillating hook machines?

Thanks for any responses.

[Constabulary]

I don't think there should be a tension release while sewing. I do not recall a single machine of my present or past machines in this class that had this "feature". But I´m probably wrong. But to me it makes no sense. Only because it´s shown in a YT video doesn´t it right. FI - often people in YT Videos thread their machines the wrong way so only because they do it on YT makes it not right.

If your release lever it worn and doesn to release tension when lifting the foot you can use a longer tension release pin (the one inside the tension unit) made from bicycle spoke or similar.

[Ken Nelson]

I don't think it is supposed to release the thread with that tension release unless the foot is lifted.  I have a 31-20-same machine, bigger bobbin.  It does NOT release on downward stroke and never misses a stitch.

[Mark842]

I'm with the other responders. I don't have that exact machine but I've had a ton of different ones over the years and don't think I've ever had one that released tension while stitching. Usually the only time you want that feature is when you lift the presser foot so you can pull your work out.

[Ogoki]

Thanks for the responses, guys.  I too was a little skeptical of this "feature."

@Ken Nelson - This machine doesn't skip stitches either.  However, judging by the depth of the groove worn into the tension release lever, it likely would have been releasing the thread tension momentarily on every stroke.

If anybody with a 31- or a 44- would like to pop the cover and verify whether or not the tension lever is pressed by that arm as it passes (or whether there is a gap, as in my attached picture), it would be much appreciated.

[dikman]

I had a 31K20 and that part was missing so I had to fabricate my own (copied from the parts pictures). Mine definitely didn't release the thread tension on the down-stroke and it worked fine. None of my machines do that.

[jimi]

with constabulary. almost 100% sure this is for releasing the tension on the thread when the foot is lifted up, then you can pull your work away and not bend the needle.  

[Bert51]

Your machine appears similar to my 31K47 and it should have a gap like you have. I do not know the size of the gap, but the bloke who used my machine told me he made it bigger so he could turn corners easier with out losing tension.

Stuart.

Edited June 2, 2018 by Bert51
spelling error

[Ogoki]

On 6/1/2018 at 3:55 PM, jimi said:

with constabulary. almost 100% sure this is for releasing the tension on the thread when the foot is lifted up, then you can pull your work away and not bend the needle.  

Yes, there is no question about that.  I'm interested in the statement in the linked video that claims that as the arm to the left of the tension release lever descends, it should contact the lever momentarily, which will in turn press against the tension release pin and push the discs apart (again, just for a split second).  The original lever from this machine (pictured in my hand) is worn in such a way that would support this claim, which has simply made me curious...

On 6/1/2018 at 6:59 PM, Bert51 said:

Your machine appears similar to my 31K47 and it should have a gap like you have. I do not know the size of the gap, but the bloke who used my machine told me he made it bigger so he could turn corners easier with out losing tension.

Stuart.

This machine is OK in that regard.  Lifting with the knee lifter as one would do to pivot around a corner doesn't quite release tension.  It is the gap on the left of the tension release arm that interests me (I assume you are referring to the gap between the lever and the pin on the right).

[RockyAussie]

I did have one machine that did that action and it may have been a Singer post machine I think. The action of that mechanism clearly is nothing to do with releasing the thread for corner turning etc but would appear to be a preparation step for the thread return spring action. As Harry said it comes into play as the needle enters the material and how that would coincide with lifting the foot totally escapes me. I would say that in most leather stitching cases it would not have to come into action but perhaps in some situations Singer thought it would. If it works for you without it I would think that is one bit less of wear and tear to worry about.

[Ogoki]

Yes, exactly, it is a completely different mechanism from the foot-lift-tension-release, although they both release tension via that same lever.  This 44-79 would have been meant for stitching leather gloves, so who knows.  Thanks for that info, @RockyAussie

[RockyAussie]

I just found an interesting bit on Pinterest that shows a bit on this. Link attached. It may contradict what I've said but I still would not be sure. Thought it worth a look anyway-http://www.theprojectlady.com/2016/07/industrial-singer-31-15-sewing-machine_7.html

[Ogoki]

Thanks for the link.  I have seen that article before.  Nice restoration pics.  However, she is still referring to the gap to the right of the lever (between lever and pin), and to the release of tension that coincides with foot lift.

[Wizcrafts]

I own a Singer 31-15. When I raise the foot, either by the hand lever of knee lever, at a certain point the U-shaped crank gets rotated to push the pin that pushes the tension release to separate the disks. That is how it is meant to work. The gap between the crank and pin can be adjusted to fine tune when and how much the disks separate. The disks should not separate during normal sewing operations. If they are doing that, something is wrong with the positions of the parts that affect this action.

Also, don't try to sew more thickness than the machine is designed to handle. My 31-15 is good to a little over 1/4 inch. It can lift higher to clear the material, but not to sew it. This machine uses DBx1/1738/16x257 system needles which are too short for thick sewing operations.

[Darren Brosowski]

People have raised this issue before and for 99.9% of machines it is BS.

I have a PFAFF "basting" machine where the tension is released in sewing but it is designed to move the material pulled through by hand doing a large stitch. The purpose is to hold the fabric together while other processes are done then the basting stitches may be removed