Bill of materials (BOM) — KRS version 8-DoF quadruped#

What you need to build Building with Kondo Kagaku KRS servos (RCB-4mini version). Kondo Kagaku parts are priced from Kondo Kagaku’s product pages and its direct-sales site (ROBOSPOT Web Shop) (as of October 2026, tax included).

Buying the parts one by one#

#

Item

Part no.

Unit price

Qty

Subtotal

1

KRS-3302 ICS 6-pack

03147

¥21,780

1

¥21,780

2

KRS-3302 ICS (single)

03146

¥4,180

2

¥8,360

3

RCB-4mini

03120

¥10,780

1

¥10,780

4

Dual USB Adapter HS

02116

¥6,600

1

¥6,600

5

ZH connection cable 2 A type 120mm

02330

¥440

4

¥1,760

6

ZH connection cable 2 A type 160mm

02331

¥440

4

¥1,760

7

Cable with connectors 20cm 40P male–male (jumper wires)

Akizuki 115869

¥160

1

¥160

8

ZH connection cable 2 B type 100mm (optional)

02219

¥440

0–2

—

9

Small-diameter horn B (PCDφ12-M2-offset 0), pack of 12

02158

¥1,650

1

¥1,650

10

Screw Set A (for KXR)

02328

¥1,980

1

¥1,980

Total about ¥54,800 (excluding the optional item 8, the Arduino and the power supply (AC adapter or battery)). The servos are 55% of it.

  • 8 servos. Buying the 6-pack plus two singles is ¥3,300 cheaper than 8 singles (¥33,440). Each servo comes with ZH connection cable 2 (one A type and one B type, 300mm each) and one M3×6 screw.

  • ZH connection cable 2 A type (3 wires, ZH on both ends) connects servo to servo and servo to RCB-4mini. Four each of 120mm and 160mm are used.

  • Jumper wires: tear 4 off a bundle of 40 with male pins on both ends. They go from the servo connector of a ZH connection cable 2 B type to the Arduino: three for TX, RX and GND, and one for VIN.

  • ZH connection cable 2 B type is a cable with ZH on one end and, on the other, a servo connector (female) that fits a 2.54 mm pitch pin header. Two are used: one for the RCB-4mini’s COM port and one to take power from an SIO port to the Arduino. The 300mm ones that come with the servos are enough, so you do not need to buy them. If the extra length inside the body bothers you, buy two 100mm ones.

  • The Dual USB Adapter HS is only used for setting the servo IDs. It is not mounted on the finished robot.

  • The small-diameter horn B does not come with the servos. One per servo, 8 in all (one pack of 12).

  • Screw Set A contains the M2-4, M2-6 and M2-8 low-head screws used on this robot (M2-4 ×16, M2-6 ×24, M2-8 ×8; where they go is in Screws). To buy them separately: M2-4 low-head screw (02086, ¥550), M2-6 low-head screw, pack of 100 (02325, ¥440), M2-8 low-head screw, pack of 100 (02326, ¥440). On the knee’s bottom case side, the case screws already fitted to the servo are taken out and put back, so there is nothing extra to buy.

You also need an Arduino UNO R4 WiFi.

Power#

Power comes from either the AC adapter or the battery. Either one supplies the servos, the RCB-4mini and the Arduino on its own (for how to connect it, see “Power” in Building with Kondo Kagaku KRS servos (RCB-4mini version)).

AC adapter#

For trying things on the desk. It is not included in the Advanced Set B, so buy it separately.

Item

Part no.

Price

Notes

AC adapter (5.9V2A)

04052

¥3,850

DC 5.9 V, 2 A. Comes with an LV conversion DC jack (VH 2-pin), so it plugs into the same place as the battery

5.9 V is slightly below the Arduino’s VIN range (6–24 V), so when using the AC adapter, also keep the USB cable plugged into the Arduino.

Battery (when buying the parts one by one)#

To walk without a cable, use one Kondo Kagaku Ni-MH battery. The Advanced Set B includes the same battery and charger, so if you bought the set you do not need these.

Item

Part no.

Price

Notes

ROBO Power Cell E type 6N-800mAh

02335

¥3,850

Ni-MH 6 cells, 7.2 V nominal, 800 mAh, 78 g. VH 2-pin connector

BX-32MH Ni-MH charger

51207

¥3,740

For 6-cell Ni-MH only. Needs a separate USB AC adapter of 5 V, 1–2 A (2 A recommended). Cannot charge from a PC’s USB port

The E type cannot be charged with a LiFe charger (such as the BX-31LF).

3D-printed parts#

The KRS version’s body and legs are shaped to fit the KRS-3302 and differ from the Feetech version’s STLs. Download the STLs below (in millimetres; exported from the same CAD data as the 3D viewer in Assembly). For rough print settings, see the Feetech version’s Bill of materials (BOM) — 8-DoF quadruped.

Part

File

Size [mm]

Qty

Volume

Body

body_krs.stl

176.0 × 110.0 × 50.0

1

179.2 cm³

Lid

lid_krs.stl

174.0 × 110.0 × 37.0

1

32.3 cm³

Leg bracket

bracket_outline_krs.stl

127.9 × 52.2 × 12.0

4

19.1 cm³

Leg link

leg_link1_krs.stl

84.0 × 43.0 × 26.0

4

33.6 cm³

body_krs.stl (×1)

lid_krs.stl (×1)

bracket_outline_krs.stl (×4)

leg_link1_krs.stl (×4)

Sliced projects (for Bambu Studio)#

Bambu Studio project files with the settings and layout included (all for a 0.4 nozzle and the Textured PEI plate). The body and lid are the version 2 shapes sliced for PLA Matte (white); the two leg plates are sliced for the A1 and PLA. To print on a different printer or filament, open the project and change the printer and filament.

Project

Contents

Printer

Filament

Layer

Supports

body_krs.3mf

Body ×1

Bambu Lab H2D

PLA Matte

0.2mm

Tree (auto)

lid_krs.3mf

Lid ×1 (placed upside down)

Bambu Lab X1 Carbon

PLA Matte

0.2mm

Tree (auto)

leg_links_krs.3mf

Leg link ×4

Bambu Lab A1

PLA

0.2mm

Tree (auto)

leg_brackets_krs.3mf

Leg bracket ×4

Bambu Lab A1

PLA

0.2mm

Tree (auto)

The slicer estimates are 4 h 01 min and 125.3 g for the body, and 3 h 46 min and 68.6 g for the lid (both including supports). The body is 176 × 110 mm, so it also fits on the plate of an A1 mini (180 mm square).

Open in Bambu Studio launches Bambu Studio and opens the project directly (Bambu Studio must be installed). Because the file does not come from MakerWorld, Bambu Studio asks “This file is not from a trusted site”; click Yes to open it.

body_krs.3mf (body)

KRS version body plate

lid_krs.3mf (lid)

KRS version lid plate

leg_links_krs.3mf (leg link ×4)

KRS version plate with 4 leg links

leg_brackets_krs.3mf (leg bracket ×4)

KRS version plate with 4 leg brackets

The left and right legs use the same parts. Print four of each of the leg link and the leg bracket; there are no separate left and right versions (they are assembled facing opposite ways on the left and right).

The leg brackets show opposite faces on the outside on the left and right, so in leg_brackets_krs.3mf two of the four are placed upside down. The face that gets support marks is flipped on two of them, so on the finished robot the marked faces end up on the same side (inside or outside) on both the left and right legs.

Sources#