Thor parts list

Open source 3D printed six axis arm driven by NEMA 17 steppers and GT2 belts, controlled with G-code like a 3D printer.

Robot armsadvanced by Ángel LM (AngelLM)

Exploded view

Tap any part to see where to buy it. Diagram is schematic, not to scale.

Every part you need

Quantities follow the official Thor docs: http://thor.angel-lm.com/documentation/. "Unverified" prices come from search listings or older BOMs that we could not confirm on the seller's product page.

3D printed parts

Needed. 3 to 4 kg of PLA or PETG plus about 0.5 kg of ABS for the small parts that touch motors (gears, motor holders). A 200x200 mm bed works if you use the split Art2 parts in mods/; one-piece Art2 needs 200x300 mm. Docs suggest 0.3 mm layers, 3 to 4 walls, 20% infill, supports over 50 degrees. Total print time is around 200 hours. Files: https://github.com/AngelLM/Thor/tree/main/stl

Mistakes builders make

• The BOM has a DC jack but no power supply. The fans are 12V and the board has 12V aux pins, so plan a 12V supply sized for seven steppers.
• StepperOnline lists a 6 mm D-cut output shaft on the 17HS13-0404S-PG5, while the BOM pulleys are 5 mm bore. One builder could not fit them; the author suggests filing or drilling the pulley bore (issue 84).
• The 6 mm balls from the BOM link measured about 5.98 mm, leaving play in the articulation 4 bearing ring that made the motor skip. A 5.96 mm ring mod is in the mods folder (issue 99).
• The 102 mm and 128 mm rods are not sold at those lengths. Buy longer 5 mm rod and cut it (issue 105).
• Some 40 tooth GT2 pulleys have an M4 set screw hole that does not line up with the printed Art56 gear (issue 53).
• Steppers can get hot enough to soften printed gears. Print motor-contact parts in ABS and fit the fans (issue 29).
• On the ControlPCB, the servo signal pin PDIG1 must be rewired to Arduino pin 7 instead of pin 41, or the gripper servo gets no PWM (electronics docs, issue 80).
• Paint the optodisks (primer or nail polish) so light does not pass through the thin walls, leaving the slot clear.
• AliExpress short links in the BOM sometimes redirect to a different product. Check each item before paying.
• The GitHub wiki BOM is outdated; the website BOM is the current one (issue 105).

FAQ

How much does it cost to build the Thor?

About $300 to $450 in parts at current prices, The project FAQ puts components at about 350 EUR. Seven steppers come to about $116 at StepperOnline; the rest is mostly low cost AliExpress parts. Excludes a 3D printer, 3.5 to 4.5 kg of filament, a 12V power supply (not in the BOM), tools and shipping..

Do I need a 3D printer for the Thor?

Yes. 3 to 4 kg of PLA or PETG plus about 0.5 kg of ABS for the small parts that touch motors (gears, motor holders). A 200x200 mm bed works if you use the split Art2 parts in mods/; one-piece Art2 needs 200x300 mm. Docs suggest 0.3 mm layers, 3 to 4 walls, 20% infill, supports over 50 degrees. Total print time is around 200 hours.

Buying guides for this build

• Best 6 axis robot arm kit to build yourself
• Best stepper motor driver for a robot arm
• Cheapest robot arm to build

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Last checked 2026-10-25. Sources: thor.angel-lm.com · thor.angel-lm.com · thor.angel-lm.com · thor.angel-lm.com · github.com · github.com · github.com · github.com · github.com · github.com · github.com · www.omc-stepperonline.com · www.omc-stepperonline.com · www.omc-stepperonline.com · store.arduino.cc