AZF8520G-31 - Sewing machine Yamato - Free user manual and instructions

Product Type	Industrial Overlock Sewing Machine
Brand	Yamato
Model	AZF8520G-31
Stitch Type	Safety Stitch (e.g. 518, 504, 401)
Number of Needles	2 or 3 (depending on configuration)
Number of Threads	4 or 5
Max Sewing Speed	Up to 6,500 stitches per minute
Stitch Length	1.0 - 4.5 mm
Differential Feed Ratio	0.7 - 2.0
Power Supply	Single-phase 220V, 50/60 Hz (or 110V)
Motor Power	400 - 550 W (integrated servo motor)
Dimensions (approx.)	500 x 300 x 450 mm (L x W x H)
Weight (approx.)	35 kg
Lubrication	Automatic oil feed system
Needle Thread Tension	Adjustable via dials
Presser Foot Pressure	Adjustable
Cutting Device	Upper and lower knife (adjustable)
Thread Trimmer	Automatic thread trimmer (optional)
Safety Features	Needle guard, emergency stop, safety clutch
Maintenance	Regular cleaning of lint, oil wicks replacement
Accessories Included	Tool kit, oil bottle, screwdrivers, spare needles

Frequently Asked Questions - AZF8520G-31 Yamato

How do I thread the Yamato AZF8520G-31 machine?

Refer to the threading diagram on the machine. Typically, for a 4-thread overlock, pass threads through tension discs, take-up lever, and lower looper. Use the thread path markers for guidance.

What oil should I use for lubrication?

Use sewing machine oil specifically designed for industrial machines (e.g., ISO VG 32). Avoid substitutes like engine oil. Fill the oil reservoir and change wicks periodically.

How to adjust stitch length?

Locate the stitch length dial (usually with numbers 1-4). Turn to desired length; typical range is 1.0 to 4.5 mm. Test on scrap fabric.

Why is the fabric not feeding properly?

Check differential feed ratio. For stretch fabrics, increase ratio >1.0; for stable fabrics, set to 1.0. Also ensure presser foot pressure is correct and feed dogs are not worn.

How to clean and maintain the machine?

Turn off and unplug. Use a soft brush and compressed air to remove lint from feed dogs, hook area, and under the needle plate. Oil as per manual schedule.

What needles are compatible?

Standard industrial needles: DBx1 or DPx5 (size 90/14 to 110/18). Use needle size appropriate for fabric weight.

My machine is skipping stitches. What to do?

Check needle condition (bent/blunt), correct needle type, and timing. Also verify tension settings and that the needle is fully inserted.

How to adjust the knife for cutting width?

The upper and lower knives can be adjusted. Loosen the screw, set the lower knife position, and adjust the upper knife to trim allowance (e.g., 3-6 mm). Tighten securely.

What is the maximum sewing speed?

The Yamato AZF8520G-31 can sew up to 6,500 stitches per minute under optimal conditions. Reduce speed for heavy or delicate fabrics.

How to replace the oil wick?

Remove old wick from oil wick pipe. Insert new wick (e.g., #303) ensuring it reaches the oil sump. Trim to appropriate length. This ensures consistent lubrication to the hook.

USER MANUAL AZF8520G-31 Yamato

HIGH SPEED SAFETY STITCH MACHINE

AZF8520G-31

This instruction manual only includes the different adjustment from AZF8500G.

Before using your AZF8520G-31, please read both instruction manuals for AZF8500G and this model, and understand the contents well.

After reading the instruction manuals, please keep them in a location where it is easily accessible to the operator.

目 次/CONTENTS

1. 縫速度とプーリの回転方向 1

2. ミシンの調整 2

2.1 針の高さ 2

2.2 上ルーパの出量 3

2.3 縁かがり縫いのルーパ糸調子 4

3. 仕様 5

1. Sewing speed and rotating direction of pulley 6

2. Adjustment 7

2.1 Needle height 7

2.2 Distance between needle and upper looper 8

2.3 Looper thread tension for overlock stitch 9

3. Specifications 10

***ILLUSTRATED SPARE PARTS LIST ***

おことわり

The description in this instruction manual is subject to change for improvements of the commodity without notice.

1. 縫速度とプーリの回転方向

图1

2. ミシンの調整

2.1 針の高さ

图2

图3 AZF8520G-31

2.2 上ルーパの出量

图5

图6

注意

图7

各糸道の標準位置

1. 上ルーパ補助糸道①

最も左に寄せる。

1. ルーパ糸道(左)②

A部を水平にする。

1. 上ルーパ糸道③

左端を合マーク④に合わせる。

1. 下ルーパ糸道⑤

B幅の中心を合マーク⑥に合わせる。

1. ルーパ糸繰り⑦

1. Sewing speed and rotating direction of pulley

The maximum sewing speed of this machine is 6,500 rpm. Run a new machine at 15 - 20% lower rotating speed of its maximum sewing speed during the first 200 hours (about one month) so that it will offer a long service life in good condition.

The rotating direction of the motor pulley ① and the machine pulley ② is clockwise as shown in the figure.

CAUTION

If rotating in reverse direction, oil can not be supplied properly, and the machine can be damaged.

Fig. 1

2.1 Needle height

(1) Loosen the screws ① to remove the logo plate ②.
(2) Remove the screw③.
(3) Rotate the machine pulley to raise the needle bar to the highest point.
(4) Loosen the screw④ of needle bar bracket, make adjustment by moving the needle bar up and down.

When the needle bar is at the highest point, make the height from the top surface of the stitch plate to the tip of needle to 10.7 - 11.0 mm.

NOTE

1. Tighten the screw ④ of needle bar bracket with a torque of 1.5 N·m (15 kgf·cm).
2. In case of 2 or 3-needle machine, make sure that the needles are parallel with each other.
3. Apply the liquid packing after reinstalling the screw ③.

Fig. 2

Fig. 3 AZF8520G-31

2.2 Distance between needle and upper looper

Turn the machine pulley clockwise and move the upper looper① to the extreme left. At this point, make the distance between the upper looper tip and the center of the needle to 5.0 - 5.5 mm.

(1)Loosen the screw②.
(2) Keep the lower looper thread eyelet③ away from the auxiliary looper holder cover④.
(3) Remove the screw⑤.
(4) Remove the auxiliary looper holder cover④.
(5)Loosen the screw⑥ to make adjustment.

NOTE

After adjustment, tighten the screw⑥ while pressing it into the machine body.

Information

Distance between needle and lower looper:

3. 3 - 3. 8 mm

Distance between needle and double chain looper:

2. 0 - 2. 2 mm

Fig. 4

Fig. 5

Fig. 6

WARNING

Before making adjustment, ALWAYS turn OFF the motor switch and check that the motor has already stopped.

2.3 Looper thread tension for overlock stitch

Fig. 7

Standard position for each thread eyelet

1. Upper looper supplementary thread eyelet①

Move it to the extreme left.

1. Looper thread eyelet (left) ②

Make the part "A" horizontal.

1. Upper looper thread eyelet ③

Align the left end with the mark④.

1. Lower looper thread eyelet⑤

Align the middle point of line "B" with the mark⑥.

1. Looper thread pull-off⑦

Align the upper right end with the mark⑧ when the lower looper comes to the extreme right.

1. Upper looper thread pull-off⑨

Align the eye of thread pull-off with the mark⑩ when the lower looper comes to the extreme right.

1. Lower looper thread pull-off⑪

Tighten the screw at the center of thread pull-off eye.

For each thread eyelet and thread pull-off

● To tighten the thread tension, move it in the direction "T".

● To loosen the thread tension, move it in the direction “L”.

3. Specifications

Model	AZF8520G-31
Dimensions	380 (L) ×280 (W) ×310 (H) mm
Weight	28 kg
Construction	Dust-proof, Oil-tight and completely sealed
Stitch Type	ISO: (514, 401)
Application	Safety stitch for knitted or woven fabrics
Sewing Speed	up to 6,500 rpm
Stitch LengthNumber of stitchesper inch(25.4 mm)per 30 mm	1.0 - 4.0 mm6.5 - 25 stitches7.5 - 30 stitches
Needle System	DC×27 (for both sides of overlock stitch and double chainstitch)Size#8 - #14(60 - 90)
Needle Storke	24.7 mm
Presser Foot Lift	up to 6.0 mm
Feed Regulation	Push button system
Feeding amount of top feed dog	10.0 mm
Up-and-down movement of top feed dog	5.0-8.0 mm
Lifting amount of top feed dog	8.0-8.5 mm
Differential Ratio	Max. Normal Differential (Gathering) 1:2.3
	Max. Reverse Differential (Stretching) 1:0.7(Available up to 1:0.6 by adjusting the position of the lever pin.)
Differential Feed Regulation	Adjustable by moving external lever even during operation
Knives for Fabric Cutting	Lower Knife : flat type, made of special steelUpper Knife : flat or angled type, made of super hard alloy
Lubricating Oil	YAMATO SF OIL No.28
Capacity or Oil Reservoir	900 cc
Lubication	Forcedly by gear pump
Installation	Semi-submerged type or fully-submerged type

ILLUSTRATED SPARE PARTS LIST

AZF8520G-31

7
AZF8520G-31(1)

Ref.No	Parts No.	Description	品名	Amt. Req
1	0024084	Thread Tension Spring Cap	糸調子パネキャップ(上)	1
2	0024083	Tension Spring Bushing	糸調子ナット回り止メ	1
3	0030255	Tension Spring(Needle Thread)	針糸調子パネ	1
4	0020118	Thread Tension Spring Retainer	糸調子パネキャップ(下)	1
5	000178	Felt(2.5mm)	フェルト	1
6	0031111	Tension Disc	糸調子皿	2
7	000177	Felt(1.0mm)	フェルト	1
8	190016	Tension Post	糸調子棒	1
9	2150164	Tension Disc Eyelet for Needle Thread	針糸調子台糸道	1
10	2150172	Tension Disc Eyelet(Right)	糸調子台糸道(右)	1
11	100001	Nut	ナット	1
12	2109213	Needle Guard(Front)(Overlock Stitch)	オーバ針受ケ(前)	1
13
14	2127623	Presser Foot, Complete Set(AY6, AY8)	押工(組)	1
15	2127602	Presser Foot Hinge	押エヒンジ	1
16	004351	Screw(9/64-40 × 7)	止ネジ	1
17	2127663	Presser Foot(Front/Rear) Unit	押工(前・後)(組)	1
18	0026140	Presser Foot Hinge Pin	押エヒンジピン	1
19	2127604	Presser Foot Spring(Small)	押エパネ(小)	1
20	280002	Screw(3/32-56 × 2.4)	止ネジ	1
21	2159113	Needle Clamp(AY)	針止メ	1
22	001900	Screw(1/8-44 × 2.4)	止ネジ	1
23	2129050	Top Feed Dog	上送り	1
24	2168003	Stitch Plate(AY7)	針板	1
25	2106023	Differential Feed Dog	前送り	1

1jamato

ヤマトミシン製造株式会社

YAMATO SEWING MACHINE MFG. CO., LTD.

4-4-12, NISHITENMA, KITA-KU, OSAKA, JAPAN

TEL:[phone] FAX:[phone]