Since - Randall UNION Lockstitch Instruction Manual

Trouble Shooting
SKIPPING StItCheS
Skipping stitches may be caused by one of several reasons and is usually a matter of adjustment.
1. Damaged needle
2. height of the needle is improperly set
3. The hook of the needle is turned and not properly catching the thread
4. Thread Tension not set
5. Thread-Guide out of alignment and is not delivering the thread into the eye of the needle
6. Thread-Arm is misaligned, therefore allowing the thread to drop before the needle eye enters work
7. Awl and needle too small for work, especially in work of heavy construction
8. Shuttle point out of alignment and is not dividing loop. (note: Use a new needle when checking)
9. needle and awl out of alignment
10. The needle holds the thread for too long or too short. Adjust shuttle timing.
11. excessive wear on the Thread-Guide, Thread-Arm, or needle mechanisms
IrreGULAr StItChS
1.
Small knots at random intervals under work (generally without breaking the thread) can be caused by uneven bobbin
tension. This can be caused by the bobbin not being wound evenly, poor quality thread, or use of an old waxed bob-
bin that dry. with older macines the bobbin tension mechanism can be worn and needs servicing. wear on the shuttle
mechanism cuases periodic snags.
2.
Irregular stitches or knots on top of work caused Take-Up Spring UL-157 being out of adjustment or bent out of
shape. The take-up spring should hold in such a manner that there is no slack between the take-up spring and the thread
guide.
StrANDING or BreAKING threAD
1.
needle damaged or bent
2.
needle barb is out square and causes stranding or breaking of thread by catching only part of the thread
3.
Thread of wrong twist or poor quality. Avoid knotty natural threads. Thread is knotting in the topside caused by exces-
sive twist. common with poor quality natural threads or synthetic threads that have too much stretch or excessive coiling
especially near the end of a spool.
4.
needle not casting off thread after shuttle picks up loop. check needle timing and its position in relation to the shuttle
point.
5.
After adjustment or changing from a high throat plate to a lower one the thread lock pulls tighter into material, causing
breakage. normally leaver 2 to 2-1/2" of thread under the material. reset thread lock lower.
6.
poor condition of wax or Thread lubricator. Always use fresh waxes and lubricants.
7.
bobbin thread tension too stiff, cuasing the thread to catch on the bobbin door spring.
8.
Shuttle tension too weak, causing the thread loop to catch inside the boobin
9.
Sharp edges on the presser-foot, needle plates, shuttle, looper or thread guide. Smooth sharp edges with emery cloth or
abrasive cord. Test by running thread through the hole and forcing it over the edges, pulling back and forth. needle plates
or presser-feet may have sharp edges as a result of awl or needle damage from improper handling. Thread guide and
looper may have sharp points if they are rubbing together when sewing.
10.
Thread Guide UL-165 incorrectly adjusted causeing needle hook to split the thread or hits the needle
11.
Too much take-up. normally leaves broken thread on top of work. reset machine timming on upper section bach one
tooth.
12.
check that the alignment of needle is on center with shuttle point. In older machines there can be excessive play in the
shuttle mechanism, or where on the thread groove on the shuttle is deep enough to cause the thread to snag.
BreAKING NeeDLeS
1.
Needle is deflected or bent while sewing thick, hard or difficult work. Use larger Needle and Awl.
2.
needle is too small for the thread
3.
needle comes in contact with the hardware or strikes exisitng hole at a bad angle.
4.
needle sets too high and hits shuttle point, possibly because bad shuttle timing or dirt in needle bar hole.
5.
needle alignment incorrect, causing needle to punch its own hole
6.
Awl is bent
7.
feed timing off, with foot not lifting in time for needle feed
8.
Presser-Foot Lifting mechanism worn or out of adjustment, not lifting for needle feed
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technical Support
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a n da l l
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Since 1858

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