Juki 5550N experiencing problem in the bobbin area

[Wizcrafts]

1 hour ago, friquant said:

I'm enjoying learning hidden qualities of the thread check spring. Which of these screws do I loosen on my 341 to effect #1 and #2?

The bottom travel stopper is set by the bottom screw inside the open channel in the bracket. The slack adjustment is the little screw in the curved slot that's above the main shaft and nut.

[thobgood]

1 hour ago, AlZilla said:

Have you looked at everything the thread touches and slides across to be sure there's not a burr somewhere? Come to think of it, have you looked to be sure the thread is feeding smoothly from the spool?

Thread is coming off the cone smoothly, that was my first thought too! Someone suggested rubbing a cotton ball over the bobbin area where the thread passes to check for burrs. I'm going to try that next. Thanks!

1 hour ago, friquant said:

I'm enjoying learning hidden qualities of the thread check spring. Which of these screws do I loosen on my 341 to effect #1 and #2?

After reading Wizcrafts' note about the thread check spring, I found this video that helped me understand it more. You might enjoy it as well.

https://www.youtube.com/watch?v=4758pErWmY8

 

[thobgood]

38 minutes ago, friquant said:

What jumps out at me is that the latch opens abruptly.

Which part is the latch? Apologies for my ignorance.

38 minutes ago, friquant said:

I don't see the bobbin case opener..maybe it's internal? 

Is the opener the part that releases the bobbin case so you can remove it? There's a little hinged latch on the bobbin case that lets you remove it.

[Wizcrafts]

19 minutes ago, thobgood said:

Is the opener the part that releases the bobbin case so you can remove it? There's a little hinged latch on the bobbin case that lets you remove it.

No, that isn't the opener. On some machines there is a lever with a bent arm that pulls back on the bobbin case to let the thread slip through without getting hung up. If your machine has a latch opener, it is quite abrupt in comparison to those found on our typical walking foot machines. Without the opener lever, the only thing making room for the thread to the hook is the thread itself. That works if the top thread is taut, but can fail if it has too much slack.

[friquant]

27 minutes ago, thobgood said:

Which part is the latch?

The latch is the area between these two red arrows. It's also what keeps the bobbin case from spinning as the hook spins. The latch has to open at least once during the stitch cycle to let the thread pass. 

[thobgood]

14 minutes ago, friquant said:

The latch is the area between these two red arrows. It's also what keeps the bobbin case from spinning as the hook spins. The latch has to open at least once during the stitch cycle to let the thread pass. 

Aha! Thank you. I've learned something!

[thobgood]

Update: I checked my hook timing and the hook was touching the needle and moving it slightly instead of passing close to the needle like it should've been. I found a video that helped me adjust the hook timing to be correct. That felt good! I'm still having the issue I described initially, feeling resistance when handwheeling as the takeup lever reaches its lowest position and then feeling two pops in the bobbin area as I add a slight bit more force. I'll do a thorough check for burrs tomorrow. I'm happy I fixed the timing issue though! 😃

[thobgood]

I forgot to say, if anybody else finds this thread in the future and wonders about hook timing, I found this video quite helpful: https://www.youtube.com/watch?v=GxMT3UfE_tk&t=6s

 

[Wizcrafts]

43 minutes ago, thobgood said:

Update: I checked my hook timing and the hook was touching the needle and moving it slightly instead of passing close to the needle like it should've been.

Some hooks have a deflector shield that will prevent the needle from touching the needle. They are thin steel and bendable. Yours may or may not have one. If not, just move the hook away from the needle slightly. This may alter the timing, so recheck it afterward and advance or retard the hook as necessary.

[friquant]

 

1 hour ago, thobgood said:

feeling two pops in the bobbin area as I add a slight bit more force

When I feel two pops it's when the thread has not cleared the latch by virtue of the latch opening but rather by the thread being yanked past it. Maybe you can find out what opens the latch. Removing the bobbin case may help you see additional mechanisms at work.