JUKI DDL-8700-7 Engineer's Manual

6. BOBBIN CASE WITH AN IDLING PREVENTION SPRING
The DDL-8700-7 use bobbin cases with an idling prevention springs. Adjust the tension of the an idling
prevention spring as follows:
If the bobbin races Increase the spring tension.
If excessively tight stitches are
produced at low sewing speed:
Increase the bobbin thread tension and
the an idling prevention spring tension.
If loose stitches are produced
at low sewing speed:
Decrease the bobbin thread tension and
the an idling prevention spring tension.
If loose stitches result Decrease the spring tension.
(1) How to adjust the tension of the an idling prevention spring
(2) When using a bobbin case
When using a bobbin case with an idling prevention spring, be sure to orient the bobbin as shown below:
1) Remove the spring as illustrated below, using an old sewing machine needle. (At this time, hold the
spring with your thumb to prevent it from jumping out.)
2) Adjust the spring pressure by changing the height of the arch of the spring.
3) Set ear ❶ first, and insert the sewing machine needle to push the central part of the spring, then set ear
❷. (Bobbin case spring : Part No. D1837-555-B0B)
1) 2) 3)
(3) How to correct irregular stitches produced at high/low speed
(Caution) If the bobbin races or if irregular stitches are produced at high/low sewing speed,
it is advisable to use a bobbin case with an idling prevention spring.
Change this height
Ears
Rotation of bobbin
Rotation of bobbin
For a bobbin case with no anti-racing spring
0.3 ± 0.2
mm
− 61 −

JUKI DDL-8700-7 Specifications

General

Max Stitch Length	5 mm
Needle Bar Stroke	30.7 mm
Lift of the Presser Foot	By hand: 5.5 mm, By knee: 13 mm
Lubrication	Automatic
Needle	DB×1
Hook	Full rotary hook
Power Requirement	Single-phase 100~120V, 200~240V
Motor	Direct-drive servo motor
Weight	45 kg