Bobbin wrap on start up

[baileyuph]

Had a problem with my thread wrapping around the bobbin on start up.  Wonder what causes this, I doubt it is only one thing?

What are the potential causes, thread or equipment?  I never had this problem with cotton threads.  I know about holding the ends on start up, but while sewing, a pause, it wrapped.  Kinda frustrating especially when the job must go soon.

I put a new needle in, probably a size 20 or 22, this synthetic thread seems stiff.

Anyone noticing this?  The hook isn't that old, but what do you check on a hook, is it the point for dullness?

Tensions? 

It is doing it on both bottom loaders and top loaders, probably more on top.  Bottom loaders wrap but will break through on their own and go on sewing.

What is the biggest contributor(s) to wrapping?  It doesn't seem to be isolated to a machine brand, maybe more with top loader, but the testing is difficult in a small shop where a bunch of the same type of machines are used.  In a factory, given a lot of machines, that problem would be easier to nail down, I would think.

I could buy a new hook and bobbin case, but for me that would be shooting in the dark.

A note, I have noticed that with these synthetic threads the machines have to be run with tighter tensions.  What can be made of that?

Anyone else going through this?

Doyle

[sofadoc]

It sounds like you're saying 2 different things.

1) You said that it happens on START UP
2) Then you said that it happens after a pause

If it's after a pause, it sounds to me like the bobbin  keeps  spinning after stopping. I had this problem once when I was using metal "M" bobbins that were MEANT for a Juki DNU-1541(bottom load) on my top load 1508.

The 1541 M's are slightly smaller than 1508 M's. So they spin too freely in the hook chamber (and unwind a little upon stopping).
All pre-wound paper shell bobbins are slightly smaller anyway. Some people use anti-spin washers. It looks like a star-shaped lock washer that you drop in the bobbin case before you put the bobbin in. And I've heard of people using any type of thin disc as a "shim".

[baileyuph]

Yes, both but primarily on start up if the two threads were not pulled clear to the back.

That was yesterday, but today didn't happen once.  I did not hold thread on startup today either.  Yesterday, I was sewing some micro fiber, todays sewing was on different type of fabric.

I didn't know about the two sizes for the Juki, I wind my own most of the time.  Meaning I have prewound in black and white only.

Today I did change thread but the thread type was the same.

It has me puzzled.

Doyle

[JDUpholstery]

if you changed the thread you may have had it off in one of the threading points...had trouble like that once and it ended up being that somehow I got the thread behind the tension discs instead of between them...so when you rethreaded it inadvertantly solved your problem....maybe....

[baileyuph]

Vert possible JD, I am keeping an eye on it.  I don't think one can wear these machines out given half care, but I was wondering if there might be a part needed?  I did run my finger over the hook checking for spurs. 

Thanks,

Doyle

[Mojo]

Bob Kovar told me to add a drop of oil the hook everytime I change the bobbin. He said the hooks will wear out fast otherwise.

Of all the parts on the machine to wear, the hook is the worst.

Chris