Upper thread gets stuck in the bobbin case. Any ideas?

[Nico619]

Hello, I recently bought a Necchi 910-159 sewing machine (should be a pfaff 191 copy), and for some reason sometimes when i start sewing, slowly pressing the pedal, it doesn't start, and you can hear the motor becoming louder and louder, almost as if it's too hard for it to go through the leather. But the thing is that the needle hasn't even moved from the top position, so it's not because of that...

I'll post two videos, one in which the sewing machine works normally, and another one in which it gets stuck. After hearing the motor becoming louder it suddenly starts sewing at full speed, which is the problem i want to solve..

NO PROBLEM: https://imgur.com/a/0YczOWe

PROBLEM: https://imgur.com/a/RJD4sCs

 

I've analized the sewing machine in the past few hours and i think i might have found what causes the problem.

I first noticed that it was not a motor problem: the increasing sound is caused by the bobbin being jammed by the thread.
Now, at first i thought it was the bobbin thread, being not properly winded or something along those lines. However after a few tests and rewindings i started noticing that it probably was the upper thread..

I then used two threads of different colors, and as i assumed, it was the upper thread which for some reason winds around the bobbin case, causing this jamming which causes that sound by the motor, since it can't freely move the lower thread.
The super fast sewing right after that happens because, i assume, the motor is finally able to break the jammed thread and sews at full speed...


So now i'm pretty sure this is the explanation, however i have no idea how to solve this upper thread jamming around the bobbin case.

here is a video of the upper thread getting stuck: https://imgur.com/a/WU6zqsl

[Burkhardt]

Post on YouTube and give the links for there. The links given don't work then with YouTube the links will have a archive for future viewers.

[Nico619]

NO PROBLEM: https://imgur.com/a/0YczOWe

PROBLEM: https://imgur.com/a/RJD4sCs

 

here is a video of the upper thread getting stuck: https://imgur.com/a/WU6zqsl

 

 

now they should work.

[CowboyBob]

Are you holding onto the needle thread for the first 3 stitches?

[Nico619]

@CowboyBob yes, I'm holding the thread at the start.

 

I think I have finally solved the problem!

I'm not sure what exactly was causing it, but I mainly did two things:

-I rethreaded the whole machine. I had already threaded it in the past with no problem, but maybe this time something was wrong with it and rethreading it solved a tension problem.

-I had noticed that the roller foot was slightly in the way of the needle, causing it to infinitesimally bent. So i added a washer to have the roller foot move slightly to the left, to avoid being in the way of the needle.

-I also added some oil in the machine. It was supposed to be already oiled, and it probably was, however I added some more in case that was the problem.

 

I ran a few tests with various thicknesses of leather and so far i haven't gotten this problem again.

 

Thank you anyway for taking the time to read it this far!

[CowboyBob]

Great,maybe it was threaded wrong?

[Nico619]

that might have contributed to it. As a matter of fact i have followed the same video before and after, but maybe the thread got off the tension disk and that exacerbated the problem

[Wizcrafts]

7 hours ago, Nico619 said:

that might have contributed to it. As a matter of fact i have followed the same video before and after, but maybe the thread got off the tension disk and that exacerbated the problem

You ain't the Lone Ranger! Today, I was hurrying to sew a wallet for a customer on his way to pick it up. I had to re thread from #277 to #207 thread. I changed the bobbin and needle, then ran a test in a piece of bridle leather. Strangely, the knots were all on the bottom, where they were perfectly balanced earlier with one size larger thread and needle. I decided to add some top tension and looked at the tension disks as I went to turn the nut. That's when I noticed that the top thread was NOT inside the disks! Doh! It even happens to seasoned sewers.

[jrdunn]

On 12/15/2023 at 5:36 AM, Nico619 said:

infinitesimally

 

16 hours ago, Nico619 said:

exacerbated

@Nico619,  I like your vocabulary.  It's a welcome change from my collection of mostly four letter words.

[Nico619]

11 hours ago, Wizcrafts said:

You ain't the Lone Ranger! Today, I was hurrying to sew a wallet for a customer on his way to pick it up. I had to re thread from #277 to #207 thread. I changed the bobbin and needle, then ran a test in a piece of bridle leather. Strangely, the knots were all on the bottom, where they were perfectly balanced earlier with one size larger thread and needle. I decided to add some top tension and looked at the tension disks as I went to turn the nut. That's when I noticed that the top thread was NOT inside the disks! Doh! It even happens to seasoned sewers.

Well, I'm glad that's a common problem, it makes me feel less stupid haha

2 hours ago, jrdunn said:

I like your vocabulary.  It's a welcome change from my collection of mostly four letter words.

I tend to use pretty common words as well, however every once in a while my mind kicks in and gives me some rarer and more specific words, that was the case :D