How-to: Source BOM for OOMWOO Open-Source Vacuum Robot

I started by drafting a list of parts and deciding which have to be sourced – and which should be 3D printed. I searched each part on AliExpress to see what is available abundantly – and at what price. Find the master Bill of Materials (BoM) here.

Building in the open — notes from the parts hunt.

Driving Wheels

We need a pair driving wheels – the left and the right wheel assemblies. Each driving wheel assembly consists of

• Motor
• Sealed gearbox
• Wheel drop sensor
• Motor’s encoder (to measure travel distance and speed)
• Suspension
• Wheel with a soft tire
• Electrical cables and connector(s)

Aftermarket driving wheel assemblies for – I guess – hundreds of consumer vacuum cleaner robots are widely available on AliExpress – including iRobot Roomba, Roborock, Dreame, Xiaomi, Eufy, Ecovacs, Narwal, Conga, iLife, 360 and so on. I have looked for those both abundantly available and most economical. Two families have stood out:

1. Roborock S5 generation (older) – the round “puck” robots with no mop lift. These fit a large number of vacuums including Roborock S5, S50, S51, S52, S55, S502, and the budget C10, E20, E25 and E35.
2. Roborock S5 Max generation (newer). These fit Roborock S4, S5, S45, S50, S51, S52, S55 Max, S7, S7 Pro, S7 MaxV, E4, E5, E45, E50, E55, G10, T7S, T7S+, S6/S60/S65 Pure/MaxV, S70/75, Q5/7

As of June 2026, both cost basically identical, ranging $24/pair retail when purchasing 3 sets to $33/pair when purchasing a single set. Shipping included, taxes excluded.

According to Google, Roborock vacuums are considered “highly reliable and premium” hardware-wise. The Roborock S5 Max family is newer than the Roborock S5. It stands to reason that Roborock S5 Max parts are likely to be available in the aftermarket for a longer time. Therefore, we should pick Roborock S5 Max parts for sourcing.

As a sidenote, vacuum gearboxes are made of plastic with gears large enough to be 3D printed DIY using, say, a resin printer. I have not tried doing that, though. Gearbox enclosures and wheels are made of plastic as well. Tires can be 3D printed using TPU. Therefore, it may be possible to purchase motors, sensors, suspension spring, gear shafts and cables – and DIY 3D print vacuum gearboxes at home.

That said, 3D printing gearboxes and TPU requires experience, increases build complexity and would hardly save you any money. Therefore, for the sake of keeping OOMWOO beginner-friendly, it seems prudent to source entire drive wheel assemblies.

Here are a few sellers of Roborock S5 Max drive wheel assemblies. I have no relation to any of them.

• https://www.aliexpress.us/item/3256810078830679.html
• https://www.aliexpress.us/item/3256804654874083.html
• https://www.aliexpress.us/item/3256807790516469.html
• https://www.aliexpress.us/item/3256804380606839.html
• https://www.aliexpress.us/item/3256806974926800.html
• https://www.aliexpress.us/item/3256811615892849.html
• https://www.aliexpress.us/item/3256804380606839.html

Caster Wheel

Vacuum robot caster wheels – also known as universal wheel assemblies – can be 3D printed DIY at home and consist of

• Roller
• Roller shaft, steel
• Housing
• Pivot pin, steel

The roller can be 3D printed using the TPU soft rubbery plastic. The pin and shaft can be sourced, or one could just use a machine screw.

That said, I have searched AliExpress for vacuum cleaner caster wheels anyway and found that iRobot Roomba casters are cheapest and most abundant. This is because iRobot has used the same caster part across its every series for around 15 years. Google says Roomba vacuums are “generally reliable”. Sounds good enough.

• iRobot Roomba series 500/600/700/800/900/e/i/j
• Roborock old-style caster — tool-free pull-out, gen1 part covers Roborock S4, S5/S50, S6, T4/T6, Xiaomi gen1/gen2 vacuums and the budget Roborock C10/E20/E25/E35
• Roborock new-style caster – screwed-in, including Roborock S5 Max, S6 Pure, S6 MaxV, S7, S7 MaxV, Q5/Q7/Q Revo, S8 Pro

iRobot casters cost $2.50-$5 depending on how many you order. Roborock old-style casters cost basically same or slightly more. Roborock new-style casters are more expensive and harder to find.

Both iRobot and Roborock old-style casters have a pull-out design that makes cleaning casters from tangled hair easy. The Roborock new-style caster has an integrated bearing and requires a screwdriver to remove.

I have several vacuum cleaner robots and pet hair getting tangled in caster wheels has been one of my little pain points. This hair tangle problem could be solved by using a ball caster or adding a “thread guard” to wheel casters. For now, it seems prudent to reuse/source the cheap and plentiful iRobot caster wheels and try designing a hair-tangle-resistant caster wheel later.

Here is a list of AliExpress iRobot caster sellers. I am not associated with any of them.

• https://www.aliexpress.us/item/3256806123331102.html
• https://www.aliexpress.us/item/2255800999621727.html
• https://www.aliexpress.us/item/3256806525708329.html

Suction Fan

There are at least three deep aftermarket pools for vacuum robot cleaner suction fans – Xiaomi (models before Xiaomi adopted its Roborock brand), Roborock and Dreame. Dreame is Xiaomi’s OEM and some Dreame suction fans fit Xiaomi (pre-Roborock) vacuums.

Here are suction fan options in the order of suction power. This list can have errors – I have not checked it exhaustively.

• 2 kPa – Roborock S50/S51/S55/S6/S65/S5 Max/S6 Pure
• 2.5 kPa – Roborock S7/T7/T7S/S6 MaxV/S5 Max/S7 MaxV
• 5.1-6 kPa – Roborock G20/S80/S85/S80+ /S85+ /S80 Pro Ultra/S85 Pro Ultra Ultron S Plus
• 6 kPa – Dreame L10s Prime/Ultra/Pro, D10s Plus, X10+/20+
• 7 kPa – Dreame S10 / S10 Plus / L20 Ultra / L30 Ultra
• 7 kPa – Roborock P10 Pro Qrevo Maxv P10S Qrevo s Qrevo Pro
• 10-12 kPa – Roborock G20S S8 MaxV P10pro/P10spro/P20, Xiaomi S40 OV81
• 20 kPa – Dreame X50 Ultra X50
• 36 kPa – Roborock Saros 20

These vacuum fans utilize BLDC motors and cost around $10-$30 with Roborock Saros 20 fans reaching $40.