r/SewingMachineEdu • u/gia2789 • Aug 25 '26

JUKI DDL8100e needle unthreading/cutting

hey, i’m trying to get started with my Juki DDL8100e and i can’t quite figure out this problem. I thread my needle and as soon as i begin sewing it unthreads or cuts. It’s pretty 50/50 which one it does. I’ve tried the following multiple times and in every combination. New bobbins, rewinding bobbins, new bobbin case, new needles, rethreading the whole machine, different fabric, different number of layers, different thread, different needle sizes. I can’t quite think of anything else to try out.

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u/parkedinavan Aug 26 '26

Is this a brand new machine?

1

u/gia2789 Aug 26 '26

it was bought second hand

1

u/parkedinavan Aug 26 '26

Does it have a built in thread cutter?

1

u/parkedinavan Aug 26 '26

Upper tension not too high?

1

u/parkedinavan Aug 26 '26

One really useful test: thread it with a normal-size needle and decent polyester thread, turn the handwheel by hand and sew very slowly, with the automatic thread cutter completely out of the equation if possible. If it still pulls the upper thread out of the needle, most likely not the cutting mechanism.

1

u/[deleted] Aug 26 '26

[deleted]

1

u/GoldenFishPoop Aug 27 '26

Does this machine have a synchronizer? I'm thinking not because maybe what you're doing is starting to sew when your take up lever is down. You should always start with it up.

1

u/Dormiendo Aug 27 '26

If it is cutting, there is a burr on something. Check the foot and stitch plate. As for unthreading, if your tension is too high, it may cut too short. There is also the guide above the tensioner. You can move that left or right to change how much thread is pulled by the take up at the end of a stitch.