Question 1

What parts do I need to build an AR4?

Accepted Answer

The combo kit is the arm: aluminum, hardware, and the primary electronics. Motors and drivers ship factory-direct from StepperOnline. Covers and spacers are 3D printed in any color. A gripper or tool holder (pneumatic, servo, or your own) bolts to the flange.

Question 2

Why a Teensy 4.1 and an Arduino Nano?

Accepted Answer

The Teensy 4.1 has just enough pins for the arm drivers and encoders, and it runs at 600 MHz, which is required for the kinematics. Grippers, solenoids, and small 180° servos do not need that speed and typically want 5 V. The Nano or Mega is a 5 V board; the Teensy is 3.3 V. The control software talks to both at once so the arm and the tooling move together.

Question 3

Can I buy the motors and drivers from Annin Robotics?

Accepted Answer

No, by design. Chris has partnered with StepperOnline for years so the motors ship factory-direct with no markup, faster freight, and genuine factory support. Stocking, boxing, and reshipping heavy motors would raise the cost of the project for everyone. Two purchases: Combo Kit from Annin, electric package from StepperOnline.

Question 4

Can I buy the robot fully assembled?

Accepted Answer

Not from Annin Robotics. Assembly labor would add a lot of cost, and building the arm yourself is the point: you learn how it is wired and how to troubleshoot it. For now the project stays a kit so the price stays as low as possible.

Question 5

Are the AR3 and AR4 robots on AliExpress sold by Annin Robotics?

Accepted Answer

No. Those are illegal counterfeits. They often cannot run the latest software, use open-loop encoders, weak drivers, and gearboxes with backlash that are not the precision units from StepperOnline. Chris gets a great many complaints about them.

Question 6

What are the key specs?

Accepted Answer

Reach 24.75 in (62.9 cm). Payload 4.15 lb (1.9 kg). Repeatability 0.25 mm. Aluminum robot mass 27 lb (12.25 kg). Max power 8.25 A / 198 W. Full drawings and wiring live in the free MK5 build manual.

Question 7

I don’t have a 3D printer. Can I buy the covers?

Accepted Answer

Yes. C.I. Printing sells complete printed-part sets and clear acrylic side panels. Chris still recommends owning a printer. An entry-level machine often costs less than outsourcing every cover, and you will want it for custom grippers anyway.

Question 8

What grippers can I use?

Accepted Answer

Any gripper you can mount. The manual shows an SMC MHF2-8D pneumatic and a servo gripper design. Chapter 5 covers wiring and control; both boards (Teensy + Nano) can drive tooling together.

Question 9

Can I build and sell the AR4?

Accepted Answer

The design is free for education, hobby, and automating your own work. Do not manufacture the robot or its parts strictly to resell and profiteer off the project. That violates the intent of the shared-source platform.

Question 10

Is MK5 the last hardware revision?

Accepted Answer

Yes, for the foreseeable future. Hall-effect sensors on J1–J3 were the last item on the hardware list. Software, manuals, and accessories will keep moving. If you have an MK4, there is a documented upgrade path.

Frequently asked questions