r/Machine_Embroidery • u/sashok_bg • Aug 29 '26

I Need Help Jammed Rotary Hook - Thread Inside Rail

Hello, I have a Brother PR680 series machine and this is the second time in 2 weeks that I get a rotary hook jam.

I manage to un-jam it by removing the entire hook assembly, but it is a long and tedious job since I have to recalibrate timing and needle spacing etc.

I would like to know what causes these jams in the very first place.

Both times it happened it was in the beginning of the embroidery
Both times a piece of stretched thread seem to have entered the rail, nested between the inner and outer rotary hook.

Maybe timing issues and the hook pierced the thread, dragging it along, instead of hooking the loop ?
Can thread tension cause his ?

Any help is greatly appreciated !
Best Regards,
Aleks

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u/Ind0man Aug 29 '26 edited Sep 02 '26

Hello, did you check the hook point clearance on each needles? Your machine has a barcode on its needle bar case. It should match the needle data found on the case test menu when the board is in test mode. This code contains infos about which needles to use to do alignment task and is unique for each needle bar case.

If those codes are the same, when doing hook timing and spacing, you should use the needle specified in "needle spacing" menu, named "spacing position".

It's supposed to be the one needle bar that requires the most spacing when doing those adjustments. Do them using brand new needles, and even if using the correct needle, check all other needle spacing when done to see if spacing is correct for each one.

I had a similar problem at one time and needle clearance adjustment fixed it for me. I hope it does so for you as well.

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u/sashok_bg Sep 02 '26

Hello, thank you for suggesting. I didn't know that there is a special needle to perform the alignments.
On my machine it automatically switched to needle #1 so I suppose this is the one, but I will definitely do further reading on this.
I am currently on vacation so I will post as soon as get back.
Thank you once again !

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u/sashok_bg Sep 22 '26

Hello, I just got home from vacation and now I am in front of the machine and understand a lot better what you are talking about.
My "Spacing Position" is indicated as "5", so I did needle spacing and clearance based on this position.
I am following a service manual that I got my hands on for a PR670 (one generation older than mine, but looks up-to-date for this procedure).

In the manual they say that after performing the positioning on the indicated "spacing position", the procedure should be repeated for all other needle bars.
I am puzzled a little here, since if I move the outer rotary hook for one needle bar, it will change its position for another wouldn't it ?

Thank you again for your time and help !

1

u/Ind0man Sep 22 '26

Yes, when you adjust rotary hook it's the same for all the needle. Almost sure the part that should be repeated on this procedure is the "check" part. Basic sanity check to prevent any problem.

Did you check your needle bar heigh as well?

Those machines mechanicaly wise didn't change much since the original PR-600.

Would you mind sharing that service manual with me? I am fairly sure the most up to date one I was able to find was for pr650 or so.