AR4 (MK5) parts list
The AR4 manual gives conflicting motor part numbers (BOM vs DIP switch table). Check the motor list in Mistakes builders make before ordering.
Desktop six axis arm with machined aluminum links, geared closed loop steppers and a Teensy controller, built from kits or self-sourced parts.
Robot armsadvanced by Annin Robotics (Chris Annin)
Total parts cost: $1,200 to $2,300 (cheapest listed sellers add up to about $1,452)
Kit route: combo kit from $1,189 plus the StepperOnline package at $699 plus filament, about $1,950; adding the $299.98 ready-printed cover set and a $74.50 servo gripper kit gives the high end. Low end is a rough guess for a 3D printed structure with self-sourced hardware and electrics plus the $699 motor package. Excludes grippers unless noted, a PC, tools, tax and shipping.
Exploded view
Tap any part to see where to buy it. Diagram is schematic, not to scale.
Every part you need
| Part | Qty | Spec | Where to buy |
|---|---|---|---|
| StepperOnline 17HS15-1684D-EG10-AR4 geared stepper motor | 1 | NEMA 17, 10:1 precision planetary gearbox, 1000 PPR magnetic encoder; driver set to 1.82 A, 800 microsteps Joint 1 (base) | StepperOnline: $91.71 (unverified) StepperOnline: check price (unverified) full AR4-MK4/5 motor, driver and power package ($699, see Kits) |
| StepperOnline 23HS22-2804D-YGS50-AR4 geared stepper motor | 1 | NEMA 23, 2.8 A, 50:1 YGS planetary gearbox, 1000 PPR encoder; driver set to 2.29 A Joint 2 (shoulder), the highest load joint | StepperOnline: $152.52 (unverified) StepperOnline: check price (unverified) full AR4-MK4/5 motor, driver and power package ($699, see Kits) |
| StepperOnline 17HS15-1684D-EG50-AR4 geared stepper motor | 1 | NEMA 17, 50:1 precision planetary gearbox, 1000 PPR encoder; driver set to 1.82 A Joint 3 (elbow) | StepperOnline: $101.68 (unverified) StepperOnline: check price (unverified) full AR4-MK4/5 motor, driver and power package ($699, see Kits) |
| StepperOnline 11HS20-0674D-EGS16-AR4 geared stepper motor | 1 | NEMA 11, 16:1 planetary gearbox, 1000 PPR encoder; driver set to 0.50 A Joint 4 (forearm roll) | StepperOnline: $106.65 (unverified) StepperOnline: check price (unverified) full AR4-MK4/5 motor, driver and power package ($699, see Kits) |
| StepperOnline linear stepper for J5 (17E19S1684MB4-200RS-AR4 in the current package) motor | 1 | NEMA 17 external lead screw linear motor, 1.68 A, 200 mm screw, 1000 PPR encoder; manual names 17LS19-1684E-200G; driver set to 1.56 A, 1600 microsteps Joint 5 (wrist pitch) via a lead screw | StepperOnline: $65.40 (unverified) StepperOnline: check price (unverified) full AR4-MK4/5 motor, driver and power package ($699, see Kits) |
| StepperOnline 14HS11-1004D-EGS20-AR4 geared stepper motor | 1 | NEMA 14, 20:1 precision planetary gearbox, 1000 PPR encoder; driver set to 0.92 A Joint 6 (tool flange) | StepperOnline: $98.76 (unverified) StepperOnline: check price (unverified) full AR4-MK4/5 motor, driver and power package ($699, see Kits) |
| StepperOnline DM332T digital stepper driver driver | 3 | 1.0 to 3.2 A, 18 to 30 VDC Drives joints 1, 2 and 3 | StepperOnline: $16.05 (unverified) StepperOnline: check price (unverified) full AR4-MK4/5 motor, driver and power package ($699, see Kits) |
| StepperOnline DM320T digital stepper driver driver | 3 | 0.3 to 2.2 A, 10 to 30 VDC Drives joints 4, 5 and 6 | StepperOnline: $13.75 (unverified) StepperOnline: check price (unverified) full AR4-MK4/5 motor, driver and power package ($699, see Kits) |
| StepperOnline LYD2409000 24V 230W power adapter power | 1 | 24 VDC, 7 to 9 A, 100 to 240 VAC input Powers the drivers and the arm | StepperOnline: $76.12 (unverified) StepperOnline: check price (unverified) full AR4-MK4/5 motor, driver and power package ($699, see Kits) |
| StepperOnline ST-M3 motor bracket motor bracket | 1 | Bracket for the J4 motor Mounts the NEMA 11 J4 motor | StepperOnline: check price (unverified) manual lists it under StepperOnline; confirm it ships in the package |
| AR4 MK5 structural parts (26 aluminum parts) structure | 1 | Base plate, turrets, spindles, arm, motor mounts, J5 and J6 housings; can be 3D printed instead The arm's frame | Annin Robotics: $699.00 set of 26 |
| 1 in OD aluminum tube, 0.035 in wall, cut to 116.3 mm structure | 1 | McMaster-Carr 1968T17; cut and drill per the manual drawing J4 main shaft; only needed for a fully 3D printed arm | McMaster-Carr: check price (unverified) length; cut to 116.3 mm |
| 32009 taper roller bearing bearing | 2 | 45x75x20 mm Listed in the manual's hardware BOM | Annin Robotics: check price (unverified) full AR4 MK5 hardware kit ($319, see Kits) |
| 30206 taper roller bearing bearing | 2 | 30x62x17.25 mm Listed in the manual's hardware BOM | Annin Robotics: check price (unverified) full AR4 MK5 hardware kit ($319, see Kits) |
| 30204 taper roller bearing bearing | 1 | 20x47x15.25 mm Listed in the manual's hardware BOM | Annin Robotics: check price (unverified) full AR4 MK5 hardware kit ($319, see Kits) |
| 30203 taper roller bearing bearing | 1 | 17x40x13.25 mm Listed in the manual's hardware BOM | Annin Robotics: check price (unverified) full AR4 MK5 hardware kit ($319, see Kits) |
| AXK3552 / AS3552 thrust bearing with washers bearing | 1 | 35x52x4 mm Listed in the manual's hardware BOM | Annin Robotics: check price (unverified) full AR4 MK5 hardware kit ($319, see Kits) |
| NTA1625 needle thrust bearing bearing | 3 | 1.00x1.5625x0.0781 in Listed in the manual's hardware BOM | Annin Robotics: check price (unverified) full AR4 MK5 hardware kit ($319, see Kits) |
| TRA1625 thrust washer bearing | 4 | 1.000x1.5625x0.0312 in Listed in the manual's hardware BOM | Annin Robotics: check price (unverified) full AR4 MK5 hardware kit ($319, see Kits) |
| TRD1625 thrust washer bearing | 2 | 1.000x1.5625x0.125 in Listed in the manual's hardware BOM | Annin Robotics: check price (unverified) full AR4 MK5 hardware kit ($319, see Kits) |
| B1616 needle roller bearing bearing | 2 | 1x1-1/4x1 in Listed in the manual's hardware BOM | Annin Robotics: check price (unverified) full AR4 MK5 hardware kit ($319, see Kits) |
| HK1612 needle roller bearing bearing | 1 | 16x22x12 mm Listed in the manual's hardware BOM | Annin Robotics: check price (unverified) full AR4 MK5 hardware kit ($319, see Kits) |
| 688Z deep groove ball bearing bearing | 1 | 8x16x5 mm Listed in the manual's hardware BOM | Annin Robotics: check price (unverified) full AR4 MK5 hardware kit ($319, see Kits) |
| Brass bushing 3 mm ID x 7 mm OD x 20 mm bushing | 2 | 3x7x20 mm Listed in the manual's hardware BOM | Annin Robotics: check price (unverified) full AR4 MK5 hardware kit ($319, see Kits) |
| 3 mm shaft, 85 mm long shaft | 2 | Usually sold at 100 mm; cut to 85 mm Listed in the manual's hardware BOM | Annin Robotics: check price (unverified) full AR4 MK5 hardware kit ($319, see Kits) |
| 8 mm keyed rotary shaft, 50 mm long shaft | 1 | 8 mm with keyway Listed in the manual's hardware BOM | Annin Robotics: check price (unverified) full AR4 MK5 hardware kit ($319, see Kits) |
| 2x2 mm key stock, 50 mm long shaft | 1 | 2 mm square Listed in the manual's hardware BOM | Annin Robotics: check price (unverified) full AR4 MK5 hardware kit ($319, see Kits) |
| 60 tooth XL timing pulley pulley | 1 | Phenolic version works; a print file also exists Listed in the manual's hardware BOM | Annin Robotics: check price (unverified) full AR4 MK5 hardware kit ($319, see Kits) |
| HTD 5M 20 tooth pulley (one long, one short) pulley | 2 | Pair for the joint 3 HTD drive Listed in the manual's hardware BOM | Annin Robotics: check price (unverified) full AR4 MK5 hardware kit ($319, see Kits) |
| XL 15 tooth pulley, 8 mm bore pulley | 2 | One needs a 3 mm keyway broached Listed in the manual's hardware BOM | Annin Robotics: check price (unverified) full AR4 MK5 hardware kit ($319, see Kits) |
| XL 10 tooth pulley, 6 mm bore pulley | 1 | XL pitch Listed in the manual's hardware BOM | Annin Robotics: check price (unverified) full AR4 MK5 hardware kit ($319, see Kits) |
| HTD 550-5M belt belt | 1 | 550 mm, 5 mm pitch Listed in the manual's hardware BOM | Annin Robotics: check price (unverified) full AR4 MK5 hardware kit ($319, see Kits) |
| 180XL037 timing belt belt | 1 | XL pitch, 3/8 in wide Listed in the manual's hardware BOM | Annin Robotics: check price (unverified) full AR4 MK5 hardware kit ($319, see Kits) |
| 150XL037 timing belt belt | 1 | XL pitch, 3/8 in wide Listed in the manual's hardware BOM | Annin Robotics: check price (unverified) full AR4 MK5 hardware kit ($319, see Kits) |
| 84XL037 timing belt belt | 1 | XL pitch, 3/8 in wide Listed in the manual's hardware BOM | Annin Robotics: check price (unverified) full AR4 MK5 hardware kit ($319, see Kits) |
| #6 x .375 thread forming screw fastener | 26 | Thread forming screw for plastic Assembly | Annin Robotics: check price (unverified) full AR4 MK5 hardware kit ($319, see Kits) |
| M1.6x4 pan head screw fastener | 6 | Per the manual's fastener list Assembly | Annin Robotics: check price (unverified) full AR4 MK5 hardware kit ($319, see Kits) |
| M2.5x6 pan head screw fastener | 6 | Per the manual's fastener list Assembly | Annin Robotics: check price (unverified) full AR4 MK5 hardware kit ($319, see Kits) |
| M2.5x8 pan head screw fastener | 6 | Per the manual's fastener list Assembly | Annin Robotics: check price (unverified) full AR4 MK5 hardware kit ($319, see Kits) |
| M3x6 button head screw fastener | 2 | The fastener table lists M3x6 button head twice (1 + 1) Assembly | Annin Robotics: check price (unverified) full AR4 MK5 hardware kit ($319, see Kits) Fastenere: check price (unverified) choose length and pack size |
| M3x30 pan head screw fastener | 16 | Per the manual's fastener list Assembly | Annin Robotics: check price (unverified) full AR4 MK5 hardware kit ($319, see Kits) |
| M3x10 flat head screw fastener | 13 | Per the manual's fastener list Assembly | Annin Robotics: check price (unverified) full AR4 MK5 hardware kit ($319, see Kits) Fastenere: check price (unverified) choose length and pack size |
| M3x10 set screw fastener | 4 | Per the manual's fastener list Assembly | Annin Robotics: check price (unverified) full AR4 MK5 hardware kit ($319, see Kits) Fastenere: check price (unverified) choose length and pack size |
| M3x10 pan head screw fastener | 8 | Per the manual's fastener list Assembly | Annin Robotics: check price (unverified) full AR4 MK5 hardware kit ($319, see Kits) |
| M3x14 pan head screw fastener | 8 | Per the manual's fastener list Assembly | Annin Robotics: check price (unverified) full AR4 MK5 hardware kit ($319, see Kits) |
| M3x14 socket head screw fastener | 6 | Per the manual's fastener list Assembly | Annin Robotics: check price (unverified) full AR4 MK5 hardware kit ($319, see Kits) Fastenere: check price (unverified) choose length and pack size |
| M3x16 socket head screw fastener | 4 | Per the manual's fastener list Assembly | Annin Robotics: check price (unverified) full AR4 MK5 hardware kit ($319, see Kits) Fastenere: check price (unverified) choose length and pack size |
| M3x20 flat head screw fastener | 8 | Per the manual's fastener list Assembly | Annin Robotics: check price (unverified) full AR4 MK5 hardware kit ($319, see Kits) Fastenere: check price (unverified) choose length and pack size |
| M3x20 pan head screw fastener | 6 | Per the manual's fastener list Assembly | Annin Robotics: check price (unverified) full AR4 MK5 hardware kit ($319, see Kits) |
| M3x25 pan head screw fastener | 8 | Per the manual's fastener list Assembly | Annin Robotics: check price (unverified) full AR4 MK5 hardware kit ($319, see Kits) |
| M3x3 set screw fastener | 5 | Per the manual's fastener list Assembly | Annin Robotics: check price (unverified) full AR4 MK5 hardware kit ($319, see Kits) Fastenere: check price (unverified) choose length and pack size |
| M3x4 set screw fastener | 9 | Per the manual's fastener list Assembly | Annin Robotics: check price (unverified) full AR4 MK5 hardware kit ($319, see Kits) Fastenere: check price (unverified) choose length and pack size |
| M3x5 set screw fastener | 20 | Per the manual's fastener list Assembly | Annin Robotics: check price (unverified) full AR4 MK5 hardware kit ($319, see Kits) Fastenere: check price (unverified) choose length and pack size |
| M3x5 socket head screw fastener | 5 | Per the manual's fastener list Assembly | Annin Robotics: check price (unverified) full AR4 MK5 hardware kit ($319, see Kits) Fastenere: check price (unverified) choose length and pack size |
| M3x6 set screw fastener | 7 | Per the manual's fastener list Assembly | Annin Robotics: check price (unverified) full AR4 MK5 hardware kit ($319, see Kits) Fastenere: check price (unverified) choose length and pack size |
| M3x8 socket head screw fastener | 5 | Per the manual's fastener list Assembly | Annin Robotics: check price (unverified) full AR4 MK5 hardware kit ($319, see Kits) Fastenere: check price (unverified) choose length and pack size |
| M4 nut fastener | 4 | Per the manual's fastener list Assembly | Annin Robotics: check price (unverified) full AR4 MK5 hardware kit ($319, see Kits) Fastenere: check price (unverified) choose length and pack size |
| M4 washer fastener | 12 | Per the manual's fastener list Assembly | Annin Robotics: check price (unverified) full AR4 MK5 hardware kit ($319, see Kits) |
| M4x10 flat head screw fastener | 16 | Per the manual's fastener list Assembly | Annin Robotics: check price (unverified) full AR4 MK5 hardware kit ($319, see Kits) Fastenere: check price (unverified) choose length and pack size |
| M4x10 set screw fastener | 12 | Per the manual's fastener list Assembly | Annin Robotics: check price (unverified) full AR4 MK5 hardware kit ($319, see Kits) Fastenere: check price (unverified) choose length and pack size |
| M4x8 pan head screw fastener | 3 | Per the manual's fastener list Assembly | Annin Robotics: check price (unverified) full AR4 MK5 hardware kit ($319, see Kits) |
| M4x10 socket head screw fastener | 16 | Per the manual's fastener list Assembly | Annin Robotics: check price (unverified) full AR4 MK5 hardware kit ($319, see Kits) Fastenere: check price (unverified) choose length and pack size |
| M4x14 flat head screw fastener | 2 | Per the manual's fastener list Assembly | Annin Robotics: check price (unverified) full AR4 MK5 hardware kit ($319, see Kits) Fastenere: check price (unverified) choose length and pack size |
| M4x14 socket head screw fastener | 1 | Per the manual's fastener list Assembly | Annin Robotics: check price (unverified) full AR4 MK5 hardware kit ($319, see Kits) Fastenere: check price (unverified) choose length and pack size |
| M4x18 flat head screw fastener | 6 | Per the manual's fastener list Assembly | Annin Robotics: check price (unverified) full AR4 MK5 hardware kit ($319, see Kits) Fastenere: check price (unverified) choose length and pack size |
| M4x20 pan head screw fastener | 2 | Per the manual's fastener list Assembly | Annin Robotics: check price (unverified) full AR4 MK5 hardware kit ($319, see Kits) |
| M4x20 socket head screw fastener | 8 | Per the manual's fastener list Assembly | Annin Robotics: check price (unverified) full AR4 MK5 hardware kit ($319, see Kits) Fastenere: check price (unverified) choose length and pack size |
| M4x45 pan head screw fastener | 4 | Per the manual's fastener list Assembly | Annin Robotics: check price (unverified) full AR4 MK5 hardware kit ($319, see Kits) |
| M4x5 set screw fastener | 20 | Per the manual's fastener list Assembly | Annin Robotics: check price (unverified) full AR4 MK5 hardware kit ($319, see Kits) Fastenere: check price (unverified) choose length and pack size |
| M6x14 socket head screw fastener | 13 | Per the manual's fastener list Assembly | Annin Robotics: check price (unverified) full AR4 MK5 hardware kit ($319, see Kits) Fastenere: check price (unverified) choose length and pack size |
| M6x18 flat head screw fastener | 9 | Per the manual's fastener list Assembly | Annin Robotics: check price (unverified) full AR4 MK5 hardware kit ($319, see Kits) Fastenere: check price (unverified) choose length and pack size |
| M6x20 socket head screw fastener | 3 | Per the manual's fastener list Assembly | Annin Robotics: check price (unverified) full AR4 MK5 hardware kit ($319, see Kits) Fastenere: check price (unverified) choose length and pack size |
| M8x14 socket head screw fastener | 2 | Per the manual's fastener list Assembly | Annin Robotics: check price (unverified) full AR4 MK5 hardware kit ($319, see Kits) Fastenere: check price (unverified) choose length and pack size |
| 20 AWG flexible silicone wire, black, red, blue and green wire | 3.2 m each color | Per the manual's electrical BOM Motor and power wiring | Annin Robotics: check price (unverified) full AR4 MK5 electrical kit ($229, see Kits) |
| Continuous flex CAT5 (or better) cable, 26 AWG shielded, stranded wire | 6.6 m | Per the manual's electrical BOM Encoder and signal runs through the arm | Annin Robotics: check price (unverified) full AR4 MK5 electrical kit ($229, see Kits) |
| Standard CAT5 (or better) cable wire | 50 cm | Per the manual's electrical BOM Short runs in the base; solid core is fine | Annin Robotics: check price (unverified) full AR4 MK5 electrical kit ($229, see Kits) |
| 20 AWG 2 conductor red and black wire wire | 37 cm | Per the manual's electrical BOM Power lead | Annin Robotics: check price (unverified) full AR4 MK5 electrical kit ($229, see Kits) |
| 1/4 in braided sleeve wire | 3 m | Per the manual's electrical BOM Wire bundling | Annin Robotics: check price (unverified) full AR4 MK5 electrical kit ($229, see Kits) |
| 3/4 in braided sleeve wire | 1.65 m | Per the manual's electrical BOM Main harness sleeve | Annin Robotics: check price (unverified) full AR4 MK5 electrical kit ($229, see Kits) |
| PG-21 cable gland nut connector | 2 | Per the manual's electrical BOM Harness pass-through | Annin Robotics: check price (unverified) full AR4 MK5 electrical kit ($229, see Kits) |
| EMI shielding tape, 2.5 cm wide shielding | 66 cm | Per the manual's electrical BOM Shields signal wiring | Annin Robotics: check price (unverified) full AR4 MK5 electrical kit ($229, see Kits) |
| USB-C 90 degree keystone jack connector | 1 | Per the manual's electrical BOM PC connection on the base | Annin Robotics: check price (unverified) full AR4 MK5 electrical kit ($229, see Kits) |
| Micro USB to USB-C cable, 20 cm cable | 1 | Per the manual's electrical BOM Teensy to keystone jack | Annin Robotics: check price (unverified) full AR4 MK5 electrical kit ($229, see Kits) |
| 3144 Hall effect sensor, 3.3V sensor | 3 | Per the manual's electrical BOM Homing for joints 1 to 3 | Annin Robotics: check price (unverified) full AR4 MK5 electrical kit ($229, see Kits) |
| 10T85 limit switch sensor | 3 | Per the manual's electrical BOM Homing for the wrist joints | Annin Robotics: check price (unverified) full AR4 MK5 electrical kit ($229, see Kits) |
| Round magnet 4x4 mm magnet | 3 | Per the manual's electrical BOM Triggers the Hall sensors | Annin Robotics: check price (unverified) full AR4 MK5 electrical kit ($229, see Kits) |
| Dupont 2.54 mm female 3 pin lead connector | 5 | Per the manual's electrical BOM Sensor connections | Annin Robotics: check price (unverified) full AR4 MK5 electrical kit ($229, see Kits) |
| 5.5 mm DC power jack socket power | 1 | Per the manual's electrical BOM 24V input on the base | Annin Robotics: check price (unverified) full AR4 MK5 electrical kit ($229, see Kits) |
| KCD1 SPST rocker switch switch | 1 | Per the manual's electrical BOM Main power | Annin Robotics: check price (unverified) full AR4 MK5 electrical kit ($229, see Kits) |
| 40 mm 24 VDC brushless fan fan | 1 | Per the manual's electrical BOM Cools the driver enclosure | Annin Robotics: check price (unverified) full AR4 MK5 electrical kit ($229, see Kits) |
| PBS-110 push button switch switch | 1 | Per the manual's electrical BOM Base push button | Annin Robotics: check price (unverified) full AR4 MK5 electrical kit ($229, see Kits) |
| Teensy 4.1 with pins controller | 1 | Per the manual's electrical BOM Main controller (3.3V logic) | PJRC: check price (unverified) with pins Adafruit: $29.95 no headers; out of stock 2026-10-25 Annin Robotics: check price (unverified) full AR4 MK5 electrical kit ($229, see Kits) |
| Terminal block breakout board for Teensy 4.1 controller | 1 | Per the manual's electrical BOM Screw terminals for the Teensy | Annin Robotics: check price (unverified) full AR4 MK5 electrical kit ($229, see Kits) |
| 2x12 power distribution terminal block power | 1 | Per the manual's electrical BOM Distributes 24V and ground; qty not printed in the BOM, one board is shown | Annin Robotics: check price (unverified) full AR4 MK5 electrical kit ($229, see Kits) |
Quantities follow the official AR4 (MK5) docs: https://www.anninrobotics.com/downloads. "Unverified" prices come from search listings or older BOMs that we could not confirm on the seller's product page.
Kits (fewer orders, check what they leave out)
| Kit | Price | Includes | Leaves out | Buy |
|---|---|---|---|---|
| AR4 MK5 Robot Combo Kit Annin Robotics | $1,189.00 | 26 machined aluminum parts, bearings, belts, pulleys, shafts, pins, screws and the primary electrical parts | Motors, drivers, power supply, printed covers, gripper | Annin Robotics: $1,189.00 |
| Upgraded AR4 Robot Complete Electric Package AR4-MK4/5 StepperOnline | $699.00 | Six geared encoder motors, 3x DM332T, 3x DM320T, LYD2409000 24V supply; fits MK3, MK4 and MK5 | Everything else; EU warehouse orders ship with EU plugs only | StepperOnline: $699.00 |
| AR4 MK5 Aluminum Parts Kit Annin Robotics | $699.00 | 26 machined aluminum structural parts | Hardware, electrics, motors | Annin Robotics: $699.00 |
| AR4 MK5 Hardware Kit Annin Robotics | $319.00 | Bearings, belts, pulleys, shafts, pins, machine screws and set screws | Structure, electrics, motors | Annin Robotics: $319.00 |
| AR4 MK5 Electrical Parts Kit Annin Robotics | $229.00 | Teensy 4.1 path, wiring and base electronics | Motors, drivers, power supply | Annin Robotics: $229.00 |
| AR4 3D printed parts set (red; gray and black also offered) C.I. Printing | $299.98 | Ready-printed PETG covers and spacers (price as listed on Annin's kit page) | Everything else | C.I. Printing: $299.98 |
| Servo Gripper Parts Kit Annin Robotics | $74.50 | Servo, Arduino Nano and breakout, current sensor, power supply, cables, hardware | Printed fingers and housings | Annin Robotics: $74.50 |
| Pneumatic Gripper Parts Kit Annin Robotics | $139.00 | Primary pneumatic gripper parts and mounting hardware | 24 VDC power brick, air supply | Annin Robotics: $139.00 |
3D printed parts
Needed. Covers, spacers, sensor and magnet mounts are always printed; PETG is recommended. Manual settings: covers about 15 to 20% infill, structural spacers 50% with 4 walls. A fully printed structure is possible (at least 50% infill, 90%+ for J2 and J3 spindles and tension rings, about 2 spools) but needs epoxy for split parts, tapped holes and an aluminum J4 tube. Files: https://raw.githubusercontent.com/Annin-Robotics/downloads/main/2026/06/AR4-MK5-3D-Print-Files.zip
Mistakes builders make
- Motor part numbers disagree inside the manual: the BOM shows J2 YGS50 and J6 14HS11 EGS20 motors, while the DIP switch table lists HG50 and 14HS13-0804D-PG19. The J5 motor in the current StepperOnline package (17E19S1684MB4-200RS) also differs from the manual's 17LS19 part. Buy the current package or match its SKUs.
- The J2 motor ships with a loose motor-to-gearbox coupler. Remove the side plug and tighten it with a hex key before installing.
- Remove the POM nut from the J5 lead screw before assembly, and peel the decal off the J6 gearbox.
- Bearings are a light press fit. Press them square with an arbor press or vise, or warm the aluminum; never hammer them in.
- If self-sourcing: the 3 mm shafts come in 100 mm lengths and must be cut to 85 mm, and one 15 tooth XL pulley needs a 3 mm keyway broached.
- The Teensy sketch must match the HMI software version, and the Nano or Mega aux sketch must match that pair.
- "Collision or Motor Error" with encoders enabled usually means encoder noise or wiring. Use the shielded continuous flex CAT5 the BOM calls for and check counts with motors on and off.
- DIP switch settings changed with control software 6.1; the ROS 2 driver warns about using the right settings for your version.
- The ROS 2 driver build can fail on example_files on a clean Jazzy install; adding a COLCON_IGNORE file there lets the rest build (issue 18).
- StepperOnline packages shipped from the German warehouse come with EU plugs only.
FAQ
How much does it cost to build the AR4 (MK5)?
About $1,200 to $2,300 in parts at current prices, Kit route: combo kit from $1,189 plus the StepperOnline package at $699 plus filament, about $1,950; adding the $299.98 ready-printed cover set and a $74.50 servo gripper kit gives the high end. Low end is a rough guess for a 3D printed structure with self-sourced hardware and electrics plus the $699 motor package. Excludes grippers unless noted, a PC, tools, tax and shipping..
Do I need a 3D printer for the AR4 (MK5)?
Yes. Covers, spacers, sensor and magnet mounts are always printed; PETG is recommended. Manual settings: covers about 15 to 20% infill, structural spacers 50% with 4 walls. A fully printed structure is possible (at least 50% infill, 90%+ for J2 and J3 spindles and tension rings, about 2 spools) but needs epoxy for split parts, tapped holes and an aluminum J4 tube.
Is there a kit for the AR4 (MK5)?
Yes: Annin Robotics, StepperOnline, Annin Robotics, Annin Robotics, Annin Robotics, C.I. Printing, Annin Robotics, Annin Robotics. Check what each kit leaves out before ordering.
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beginner · $232 to $330
The original LeRobot leader and follower arm pair; now deprecated in favor of SO-101 but uses the same servos.
Last checked 2026-10-25. Sources: raw.githubusercontent.com · www.anninrobotics.com · www.anninrobotics.com · www.anninrobotics.com · www.anninrobotics.com · www.anninrobotics.com · www.omc-stepperonline.com · www.omc-stepperonline.com · github.com · github.com · www.adafruit.com