Juki 1541S Inconsistent Tension

[ultimind]

Picked up a new-to-me Juki 1541S and initially it sewed wonderfully. Machine was very dirty from being used in a factory environment. I'm afraid my good intentions of cleaning and oiling everything has caused some serious inconsistent tension issues. Oiled all indicated points per the manual, removed needle plate cover and evacuated all the old factory lint. Cleaned out bobbin case area with compressed air and a brush.

For this project I'm sewing nylon with Tex70 bonded nylon thread. Visually, it appears that the top thread goes from having too much tension, to too little tension. This happens at all sewing speeds. Whether I'm crawling slowly or ripping through at max speed. Bottom side fares a bit better but is also not entirely inconsistent. Any thoughts or recommendations would be helpful. I've ripped my hair out all day over this!

• I have checked all the thread paths and they are clean and clear, no snags.

• Needle is fresh - Size 21.

• Bobbin case holder is not Juki OEM - it's made by Haya (problem?)

• Bobbins were cheap $0.50/ea from Amazon in a 20pk (problem?)

• Hook timing appears to be correct

• Check spring path is clean and clear

• Tension disks are clean and clear

  

[brmax]

Not that the textile weave wont close up! But the needle size is to big, in that the recommendation from mfg.’s is size 16-18 for tex 70, size #69 threads. 

Sometimes its easiest to back off bobbin case thread tension screw. Adjusting this where its very lite! tension. Then working with the top more easily. Your stitch can waver a bit I think first with the needles hole making ability. Then followup with tension checks.

Carefully notice any case tension screw. In their ability to be consistant in applying or reducing. I've had one with threads very very screwy, from new. Uncommon i think. 

I do feel we all consider, or maybe i should just say me. I feel the big brands we know of do in fact have better consistancies in their products. This sometimes bothers me afterward, when i have these very same issues. But hey, I many times relearn 

Something I heard and started is keeping a few different bobbin cases extra. Also more importantly is keeping some separate if you can for different thread sizes. This I find criticaly handy in using threads of same size, but different types. In examples, high heat or solarfix marine. 

In closing I wouldnt do anything without changing the needle size first, to at least close as possible to 18.

Good day

Floyd

 

 

[kgg]

Could be as simple as a bad spool of thread with the thread on the spool temporarily binding or uneven unravelling from spool. I think the size of needle may also being playing a factor, 18 or 20 g depending on thickness of material). I have had the problem when I over loaded the bobbin combined with incorrectly threading the bobbin. I needed to adjust the stop on the bobbin winder and re thread a fresh bobbin correctly ( in through the hole of the bobbin disc bracket from the spool, around the disc, out through the same hole then to the bobbin case on the winder. A couple photos of your top threading may help to spot something.

[kgg]

Just to add to my previous post. How I check the tension on my Juki 1541S is with the bobbin in the case I pull out about 6 inches and hold the end of the tread and let the bobbin / case rest flat in my other hand. I then try to lift the works up by the thread. If the bobbin case and bobbin doesn't stand up vertically and the works remain flat in my hand with the bobbin spinning easily  I tighten the thread tension spring screw. If it lifts off my hand with no thread coming off the bobbin, I loosen the thread tension spring screw. I like the bobbin case to stand up and the bobbin spin with a little resistance in the case. I only thread the bobbin to about 80 percent.

kgg

[ultimind]

45 minutes ago, brmax said:

In closing I wouldnt do anything without changing the needle size first, to at least close as possible to 18.

 

Changing down to a Size 18 did help with consistency to some degree. 

There's still a few spots where it it gets tight for a single stitch. 

[ultimind]

57 minutes ago, kgg said:

A couple photos of your top threading may help to spot something.

Here's the top threading. The guard in the last photo was removed to better see the thread path.

[brmax]

The thread path is looking good from my point of view.  Whats a priority for myself is keeping a consistant pattern of how I thread through all the guides and holes. 

Everyone can do it in any method by the book, but as everything having a known consistant pattern helps.  Especially in any situation of multiples and or monitoring these for troubleshooting. 

Your onto the issue for sure, if its possible look or video the spools usage or thread coming off during this issue.

When you notice an irregular stitch, you may count until the next. Maybe its a visible moment off the spool where you see something. Narrowing further I have made marks on the thread just off the spool to help in different situations.

Its crazy how a lite! thread issue coming off the spool makes it a pain for a bit. 

 

Good work there

Floyd

[kgg]

In your last photo there is a thread retaining screw, spring and flat plate that is missing in the last large guide before the needle (where there are two threads). This holds the thread flat against the guide before the thread goes through the guide hole just above the needle. I think this is to keep the thread in a consistent position during up and down stroke of the needle so it don't flap around.

[kgg]

In my last posts I said ' (where there are two threads) " it should have said (the large guide just below where there are two threads in the guide).

kgg

[ultimind]

33 minutes ago, kgg said:

In your last photo there is a thread retaining screw, spring and flat plate that is missing in the last large guide before the needle (where there are two threads). This holds the thread flat against the guide before the thread goes through the guide hole just above the needle. I think this is to keep the thread in a consistent position during up and down stroke of the needle so it don't flap around.

It was interesting I noted this part missing from nearly all the machines in the factory where I got this from. Perhaps removed for a reason or it's easily damaged in production. Looks like it's ~$25 in parts to get that piece replaced. Certainly won't be seeing the daily grind in my home shop that this machine saw for the first few years of its life.