● 17 min readShowdown: Uno R4 vs Uno R3 vs Nano
Welcome to Vol. 12 of The Probots Showdown. Three boards. Three price points. Three very different futures for your project.Should you stick with the
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| 50+ | ₹783.02 ₹ 663.58 + 119.44 GST | |
| 75+ | ₹759.05 ₹ 643.26 + 115.79 GST | |
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Premium black anodised 5-hole T-shaped joining plate for 2020 aluminium extrusions. Engineered for high-rigidity T-junctions and structural cross-members in CNC and 3D printer frames.
Achieve the perfect "pluck" on your timing belts for flawless print layers. The Black Aluminium 2020 Belt Tensioner (Toothed Short Arm) is designed for makers who demand industrial-level precision from their desktop machines. Featuring an 11mm internal clearance and a precision-toothed pulley, this component eliminates belt slippage and "ghosting" artifacts by providing consistent, adjustable tension.
Probots™ ProSpec Grade Engineering Unlike plastic-bodied tensioners that flex under load, this unit is Probots™ ProSpec Grade, milled from a solid aluminium alloy block. The "Short Arm" design (85mm total length) is specifically engineered to save space on your X or Y axis without sacrificing the tensioning stroke. The integrated 20-tooth pulley ensures that the belt teeth remain perfectly engaged, significantly reducing wear compared to smooth-bore tensioners.
Material: 6061 Aluminium Alloy (Anodised Matte Black)
Arm Configuration: Short Arm (Total Length: 85mm)
Internal Width: 11mm (Supports 6mm and 10mm GT2 Belts)
Pulley Type: Precision 20-Tooth GT2 Idler (Dual Ball Bearings)
Profile Compatibility: Standard 2020 (20mm) V-Slot & T-Slot Profiles
Tensioning Distance: ~8mm to 16mm adjustable range
Adjustment: Hand-turn thumbscrew (Tool-less tuning)
Weight: 75g
Ender 3 / CR-10 Upgrades: The ultimate drop-in replacement for X-axis and Y-axis (on compatible frames) to improve print clarity.
Custom CoreXY Builds: Ideal for compact belt paths in Voron V0 or RatRig style machines.
Precision Camera Sliders: Ensures smooth, jitter-free motion for time-lapse and cinematography rigs.
Desktop CNC Routers: Provides stable tensioning for light-duty linear rail belt drives.
Unlock New Capabilities (Project Evolution)
Past Projects: If you’ve previously relied on "pulling by hand and tightening a screw," you know how difficult it is to get perfectly balanced tension across two belts.
Feature Upgrade: This tensioner allows for micrometre-level tuning while the machine is live. You can "dial in" the perfect tension while watching a calibration cube print, instantly eliminating ghosting artifacts.
Effort Level: Beginner. Pre-assembled body; only requires mounting to the profile end.
Virtual Technician & Tips
Probots™ Secure-Transit : Small pulleys and bearings are sensitive to impact. We ship every unit in Probots™ Secure-Transit padded packaging to ensure the pre-installed bearings arrive smooth and silent.
Pro Tip: For the best results, turn the knob until the belt sounds like a low bass note when plucked. Do not over-tighten, as this can put excessive radial load on your stepper motor bearings.
1 x Aluminium Tensioner Main Body (Black Anodised)
1 x 20-Tooth GT2 Pulley (Pre-installed with dual bearings)
1 x Large Adjustment Thumbscrew
2 x M4/M5 Mounting Screws (Standard for 2020 profile mounting)
2 x T-Nuts (Hammer-head style for easy slot entry)
Will this fit the original Ender 3? Yes, it is a popular direct upgrade for the 2020 X-axis profile of the Ender 3 and Ender 3 Pro.
Does it support 10mm wide belts? Yes, the internal 11mm clearance allows for both 6mm and 10mm GT2 belts.
Why a toothed pulley instead of a smooth one? Teeth prevent the belt from sliding or "walking" horizontally, which protects the belt edges from fraying against the aluminum walls.
Is it made of plastic? No, the body, arm, and pulley are all made from high-strength aluminum alloy.
How much space does it add to my profile? The short-arm version adds approximately 85mm to the end of your extrusion.
Can I use this on a 2040 profile? This specific model is designed for 2020; a 2040 profile is too wide for this bracket to sit flush.
Do I need to take my printer apart to install this? You only need to remove the existing pulley holder and thread the belt through the new tensioner.
Does it come pre-assembled? Yes, the main tensioner mechanism and pulley are pre-assembled for your convenience.
What is the "Short Arm" advantage? It is more compact, making it less likely to hit your printer's enclosure or wiring.
How do I know if it's too tight? If your stepper motor starts "clicking" or getting very hot, the belt is likely over-tensioned.
Are the bearings replaceable? Yes, the pulley uses standard dual ball bearings that can be replaced if they eventually wear out.
Is it compatible with T-slot profiles? Yes, as long as the profile is 20mm wide.
Will the black finish wear off? The anodized finish is highly durable and designed to resist scratches from the adjustment screw.
What is the thread size of the adjustment screw? It typically uses an M4 or M5 adjustment bolt depending on the production batch.
Can I use this for the Y-axis? Only if your Y-axis uses a 2020 profile (like the Ender 3 V2). The standard Ender 3 uses a 4040 Y-axis.
Does it include the belt? No, timing belts are sold separately.
How does it improve print quality? It eliminates "backlash" (slop) in the belt, making corners sharper and layers more consistent.
Can I adjust it while printing? Yes, the tool-less knob makes it safe and easy to perform fine-tuning during a print.
What is the mounting hole spacing? The mounting holes are 15mm apart, designed for standard 20mm profiles.
Is it corrosion resistant? Yes, the anodized aluminum and stainless hardware are resistant to humidity and rust.




Probots sells every Electronics Part for your next Project. You can order 10,000+ Electronic Parts Online - Arduino, Raspberry Pi, NodeMCU Development Boards, Sensors, Motors, Motor Drivers, SMPS, Plastic Enclosures etc in India directly on probots.co.in
We delivery electronics components and parts throughout India using standard couriers like Bluedart, Delhivery & India Post.
For order related queries contact -
Probots sells every Electronics Part for your next Project. You can order 10,000+ Electronic Parts Online - Arduino, Raspberry Pi, NodeMCU Development Boards, Sensors, Motors, Motor Drivers, SMPS, Plastic Enclosures etc in India directly on probots.co.in
We offer specialized services for Bulk, Wholesale & B2B Customers like discounted prices, additional shipping options, customised products, etc . Customer with large quantity & regular orders qualify for the specialised discounted rates.
We also offer dedicated sales team to assist you with the order process by providing sales quotations, PI, technical support for choosing products, etc.
Note: Business Orders are processed manually and usually take 1-3 days to process compared to placing the order directly on our website. Please plan your purchases accordingly.
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Probots Electronics is highly regarded for its great selection of components and professional service. Customers frequently praise the awesome care and timely delivery provided by the team to ensure all products arrive safely.
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