Melco EP 1 - 7. Troubleshooting Guide; Thread Breakage Issues

7-1
5. Troubleshooting Guide
Thread breakage
11034 Rev. A 7. Troubleshooting
PROBLEM
POSSIBLE CAUSES
SOLUTIONS
Design
Stitches are too short and/or too
dense
Check the design for short and/or
dense stitches, and edit the
design to remove them
Needles
Incorrect needle for thread size
being used
Replace with a compatible needle
Needle is bent, damaged, or dull
Replace needle
Needle position is incorrect
Install the needle correctly (see
needle installation)
Needle scarf and/or needle eye is
burred
Replace needle
Thread
Incorrect thread size for the
needle being used
Replace with a compatible needle
Poor quality thread
Replace with a high quality
thread or spray silicone on thread
cone
S-twist (right twist) thread being
used
Replace with a Z-twist (left twist)
thread
Improper threading
Thread correctly (refer to
threading section)
Upper/bobbin
tension
Upper/bobbin tension too tight
Loosen upper/bobbin tension
Ratio of upper thread to bobbin
thread incorrect
Adjust upper and/or bobbin
tension (see tension section)
Incorrect check spring
tension/stroke
Adjust/replace check spring (refer
to the technical manual)
Fabric and hoops
Fabric is hooped loosely
Tighten fabric in the hoop (see
hooping section)
Inadequate backing allows fabric
to pull into needle plate hole
Increase number of backing
pieces
Rotary hook
Hook timing is incorrect
Adjust hook timing (refer to the
technical manual)
Rotary hook does not rotate
smoothly
Clean, oil, or replace
Gap between the UTC retaining
tab and the rotary hook is too
narrow
Widen the gap (refer to the
technical manual)
Bobbin
Bobbin is damaged
Replace bobbin
Bobbin thread feeds poorly
Repair or replace bobbin
Thread path
Scratches or burrs on thread path
Remove scratches with emery
cloth
Needle depth
Needle depth is incorrect
Adjust needle depth (refer to the
technical manual)