JUKI LU-2810 - 33. TROUBLES IN SEWING AND CORRECTIVE MEASURES

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33. TROUBLES IN SEWING AND CORRECTIVE MEASURES
Troubles Causes Corrective measures
1. Threadbreakage
 (Threadfraysorisworn
out.)
 (Needlethreadtrails2to
3cmfromthewrongside
ofthefabric.)
①
 Threadpath,needlepoint,hookbladepointor
bobbincaserestinggrooveonthethroatplate
hassharpedgesorburrs.
②
 Needlethreadtensionistoohigh.
③
 Bobbincaseopeningleverprovidesan
excessiveclearanceatthebobbincase.
④
 Needlecomesincontactwiththebladepoint
ofhook.
⑤
 Amountofoilinthehookistoosmall.
⑥
 Needlethreadtensionistoolow.
⑦
 Threadtake-upspringworksexcessivelyor
thestrokeofthespringistoosmall.
⑧
 Timingbetweentheneedleandthehookis
excessivelyadvancedorretarded.
○
 Removethesharpedgesorburrsontheblade
pointofhookusinganeemerypaper.Buffupthe
bobbincaserestinggrooveonthethroatplate.
○
 Decreasetheneedlethreadtension.
○
 Decreasetheclearanceprovidedbetweenthe
bobbincaseopeningleverandthebobbin.
Refer to "22. ADJUSTING THE BOBBIN CASE
OPENING LEVER" p.22.
○
Refer to
"20. NEEDLE-TO-HOOK RELATION"
p.20.
○
 Adjusttheamountofoilinthehookproperly.Refer
to "8. LUBRICATION" p.9.
○
 Increasetheneedlethreadtension.
○
 Decreasethetensionofthespringandincrease
thestrokeofthespring.
○
Refer to
"20. NEEDLE-TO-HOOK RELATION"
p.20.
2. Stitchskipping
①
 Timingbetweentheneedleandthehookis
excessivelyadvancedorretarded.
②
 Pressureofthepresserfootistoolow.
③
 Theclearanceprovidedbetweenthetopend
oftheneedleeyeletandthebladepointof
hookisnotcorrect.
④
 Hookneedleguardisnotfunctional.
⑤
 Impropertypeofneedleisused.
○
Refer to
"20. NEEDLE-TO-HOOK RELATION"
p.20.
○
 Tightenthepresserspringregulator.
○
Refer to
"20. NEEDLE-TO-HOOK RELATION"
p.20.
○
Refer to
"21. ADJUSTING THE HOOK NEEDLE
GUARD" p.21.
○
 Replacetheneedlewithonewhichisthickerthan
thecurrentneedlebyonecount.
3. Loosestitches
①
 Bobbinthreaddoesnotpassthroughthe
tensionspringoftheinnerhook.
②
 Threadpathhasbeenpoorlynished.
③
 Bobbinfailstomovesmoothly.
④
 Bobbincaseopeningleverprovidestoomuch
clearanceatthebobbin.
⑤
 Bobbinthreadtensionistoolow.
⑥
 Bobbinhasbeenwoundtootightly.
○
 Threadthebobbinthreadcorrectly.
○
 Removeroughpartswithaneemerypaperor
buffitup.
○
 Replacethebobbinorhookwithanewone.
○
Refer to
"22. ADJUSTING THE BOBBIN CASE
OPENING LEVER" p.22.
○
 Increasethebobbinthreadtension.
○
 Decreasethetensionappliedtothebobbinwinder.
4. Threadslipsofftheneedle
eyeletsimultaneouslywith
threadtrimming.
①
 Threadtensiongivenbythetensioncontroller
No.1istoohigh.
○
 Decreasethethreadtensiongivenbythetension
controllerNo.1.
5. Threadslipsoffthe
needleeyeletatthestart
ofsewing.
①
 Threadtensiongivenbythetensioncontroller
No.1istoohigh.
②
 Clampspringhasimpropershape.
③
 Bobbinthreadtensionistoolow.
○
 Decreasethethreadtensiongivenbythetension
controllerNo.1.
○
 Replacetheclampspringwithanewoneor
correctthecurrentone.
○
 Increasethebobbinthreadtension.
6. Threadisnotcutsharply.
①
 Thebladesofmovingknifeandcounterknife
havebeenimproperlyadjusted.
②
 Thekniveshavebluntblades.
③
 Bobbinthreadtensionistoolow.
○
Refer to
"23. POSITION OF THE COUNTER
KNIFE AND ADJUSTMENT OF THE KNIFE
PRESSURE" p.23.
○
 Replacethemovingknifeandcounterknifewith
newones,orcorrectthecurrentones.
○
 Increasethebobbinthreadtension.
7. Threadremainsuncut
afterthreadtrimming.
 (Bobbinthreadtrimming
failurewhenstitchlength
iscomparativelyshort.)
①
 Initialpositionofthemovingknifehasbeen
improperlyadjusted.
②
 Bobbinthreadtensionistoolow.
○
 RefertotheEngineer’sManual.
○
 Increasethebobbinthreadtension.
8. Threadbreaksatthestart
ofsewingafterthread
trimming.
①
 Theneedlethreadiscaughtinthehook.
○
 Shortenthelengthofthreadremainingonthe
needleafterthreadtrimming.
Refer to
"16. THREAD TENSION" p.17.
9. Whenaheave-weight
materialissewn,the
materialwarps.
①
 Thefeedamountofthetopfeedisinadequate.
○
 Decreasethefeeddogheightandreducethe
feedamountofthebottomfeed.(Refertothe
Engineer'sManualfortheadjustmentprocedure.)