Confidential G Series Disc Grinder User Manual

Confidential G Series Disc Grinder

WARNING: Before attempting disassembly, be sure to turn off the power switch and disconnect the power cord plug from the outlet.

Precautions on disassembly and reassembly

[Bold] numbers in the description below correspond to the item numbers in the parts list and exploded assembly diagram for the Models G 12SA4 and G 12SA4(S), and <Bold> numbers to those for the Models G 13SB4 and G 13SB4(S).

Disassembly

1. Removal of the armature and stator
   1. Loosen the Tapping Screw (W/Flange) D4 x 20 [51]<51> and pull out the Tail Cover [50]<50>. Remove the Carbon Brushes (1 Pair) [38]<38> from the Brush Holders [36]<36>.
   2. Loosen the four Seal Lock Screws (W/Sp. Washer) M4 x 14 [7]<7> and remove the Packing Gland [6]<6> ass’y and Lever Holder [8]<8>.
   3. Loosen the four Tapping Screws (W/Flange) D4 x 25 [1]<1> that fix the Gear Cover [2]<2> to remove the Armature [24]<24> from the Housing [34]<34> together with the Diffuser [23]<23>. At this time, check that the Rubber Bushing [33]<33> is fitted in the housing ball bearing chamber.
   4. Carefully wrap the Armature [24]<24> with a soft, clean rag to protect it from being damaged, and clamp it securely in a vise. Then remove the Special Nut M7 [18]<18> and extract the Gear and Pinion Set [25]<25>.
   5. Disconnect the four internal wires of the Stator [30]<30> from the Pushing Button Switch [40]<40> and Brush Holders [36]<36>.
   6. Remove the Fan Guide [29]<29> and Stator [30]<30> from the Housing [34]<34>.
      NOTE: If the Stator [30]<30> is hard to be removed from the Housing [34]<34>, heat the Housing [34]<34> up to about 60°C to facilitate removal. Then pull out the Rubber Bushing [33]<33>.
      • Each internal wire of the Stator [30]<30> is covered with a glass tube. Do not bend the internal wires repeatedly and do not peel off the glass tubes when removing the Stator [30]<30> from the Housing [34]<34>. Otherwise, the internal wires may be disconnected.
      • Do not apply excessive force to the terminals of the Stator [30]<30> when removing them from the Pushing Button Switch [40]<40> and Brush Holders [36]<36>. Otherwise, the terminals of the Stator [30]<30> may be broken.
2. Removal of the rubber bushing
   Insert the special repair tool J-201 spring hook (Code No. 970977) between the Rubber Bushing [33]<33> assembled in the Housing [34]<34> and the housing ball bearing chamber, and then pull out the Rubber Bushing [33]<33>.
3. Removal of the dust seal
   1. Insert the hooks of the J-204 bearing puller between the Ball Bearing 698SS [32]<32> and the Dust Seal [31]<31> and fix the hooks with the wing bolts.
      NOTE: Be careful not to insert the hooks excessively.
   2. Put the bearing puller on an appropriate stand. Press down on the armature shaft with a hand press and pull out the Ball Bearing 698SS [32]<32>.
   3. Pull out the Dust Seal [31]<31> from the armature shaft.
4. Removal of the gear and spindle
   1. Loosen the four Seal Lock Screws (W/Sp. Washer) M4 x 14 [7]<7> and remove the Packing Gland [6]<6> from the Gear Cover [2]<2>.
   2. Remove the Retaining Ring for D12 Shaft [4]<4> that secures the gear to the Spindle [12]<12>.
   3. When it is necessary to remove the gear from the Spindle [12]<12>, it is highly recommended that the special repair tool J-245-3 sleeve (Code No. 307720) described below is utilized. Place the assembly on a sleeve that matches the dimension of the Packing Gland [6]<6> and press down on the top of the Spindle [12]<12> with a hand press to remove the gear as shown in Fig. 1.
      
   4. Removal of the pushing button switch
      1. Disconnect the two internal wires of the Stator [30]<30> and two internal wires of the Noise Suppressor [43]<43> from the Pushing Button Switch [40]<40>.
      2. Remove the Cord [52]<52> from the side rib of the Housing [34]<34>.
      3. Push the Slide Bar [49]<49> and Slide Knob [47]<47>. Leave a 6- mm gap between the Slide Bar [49]<49> and Housing [34]<34>.
         Pull the Pushing Button Switch [40]<40> as shown in Fig. 2.
         
      4. Remove the Cord [52]<52> from the Pushing Button Switch [40]<40>.

Reassembly

Reverse the disassembly procedure to reassemble. Note the following points.

1. Rub grease into the teeth of the Gear and Pinion Set [25]<25> with your fingers so that the grease reaches each tooth bottom. Note that under-lubricated Gear and Pinion Set [25]<25> may wear at a faster rate.
2. When replacing the Armature [24]<24> and the Ball Bearing 698SS [32]<32> on the commutator side, press the Dust Seal [31]<31> in while carefully noting its direction until the end face of the Dust Seal [31]<31> contacts the butting surface of the Armature [24]<24>, and check that the Dust Seal [31]<31> cannot turn freely. (See Fig. 3.) The Dust Seal [31]<31> is an important element for improved dust protection of the Ball Bearing 698SS [32]<32>. Be sure to replace the Dust Seal [31]<31> with new one at every disassembly work. Fit the Rubber Bushing [33]<33> into the housing ball bearing chamber before installing the Armature [24]<24>. (See Fig. 4.)
3. When installing the Stator [30]<30> into the Housing [34]<34>, insert it while being careful about correctly placing the internal wires of the Stator [30]<30> as shown in Fig. 5. Connect the four internal wires of the Stator [30]<30> correctly as shown in Fig. 6.
   NOTE:
   • Be careful not to put the internal wire of the Carbon Brush (1 Pair) [38]<38> on the top of the Brush Holders [36]<36> when connecting the internal wires of the Stator [30]<30> or when connecting the Carbon Brush (1 Pair) [38]<38>.
   • Each internal wire of the Stator [30]<30> is covered with a glass tube. Do not bend the internal wires repeatedly and do not peel off the glass tubes when mounting the Stator [30]<30> to the Housing [34]<34>. Otherwise, the internal wires may be disconnected.
   • Do not apply excessive force to the terminals of the Stator [30]<30> when inserting them into the Pushing Button Switch [40]<40> and Brush Holders [36]<36>. Otherwise, the terminals of the Stator [30]<30> may be broken.
     
4. Be sure to soak the inner diameter of the Felt Packing [9]<9> with machine oil. Otherwise, its dust sealing function will fail to work properly, resulting in premature damage to the ball bearing of the Packing Gland [6]<6>. Wipe the Felt Packing [9]<9> lightly with a rag before assembling.
5. Mount the Fan Guide [29]<29> in proper direction by matching the gate mark of the Fan Guide [29]<29> with the “N” mark of the Housing [34]<34> as show in Fig. 7.
   
6.  Do not catch the pigtail of the Carbon Brush (1 Pair) [38]<38> in the Tail Cover [50]<50> when mounting the Tail Cover [50]<50>. Check that the pigtail is in its proper position as shown in Fig. 8 before mounting the Tail Cover [50]<50>.
   
7. Tighten three of the four Seal Lock Screws (W/Sp. Washer) M4 x 14 [7]<7> except the one for securing the Lever Holder [8]<8>. Mount the Lever [27]<27> and Retaining Ring D4 [28]<28> to the Lever Holder [8]<8>. Hook the Spring [26]<26> on the Lever [27]<27>. Then tighten the remaining Seal Lock Screw (W/Sp. Washer) M4 x 14 [7]<7>.
8. Mount the Pushing Button Switch [40]<40> according to the following steps.
   • Attach the Cord [52]<52> to the Pushing Button Switch [40]<40>.
   • Mount the Pushing Button Switch [40]<40> while pressing the pressing point of the Pushing Button Switch [40]<40> as shown in Fig. 9.
   • Mount the Ferrite Core [42]<42> and Cord [52]<52> as shown in Fig. 10.
     

Lubrication point and type of lubricant

NOTE: Use a brush when rubbing grease.

1. When replacing the Gear Cover [2]<2>, lubricate the inner circumference of the needle bearing with 0.3 g of Cosmo Molybdenum No. 1 grease.
2. Rub 18 g of Cosmo Molybdenum No. 1 grease into the pinion chamber of the Gear Cover [2]<2>.
3. Rub 2 g of Cosmo Molybdenum No. 1 grease into the teeth of the gear.
4. Rub 0.7 g of Cosmo Molybdenum No. 1 grease into the teeth of the pinion.

Tightening torque

Insulation test

Measure the insulation resistance and dielectric strength after reassembly.

• Insulation resistance: 7 MΩ or higher (as measured with a 500 VDC megaohm tester)
• Dielectric strength: 4,000 VAC/minute, with no abnormalities ————– 230 V to 240 V
  2,500 VAC/minute, with no abnormalities ————– 120 V

No-load current value
After no-load operation for 30 minutes, the no-load current values should be as follows.

Wiring diagram

STANDARD REPAIR TIME (UNIT) SCHEDULES