Your extruder skips on retractions. You hear that click-click-click and see underextruded layers. You’ve cleaned the nozzle, dried the filament, and calibrated e-steps three times — and it still skips. The problem isn’t your settings. The problem is your single-gear extruder can’t generate enough grip force to push filament through the hotend at print speeds above 60mm/s. A dual-gear extruder fixes it — but which one, and how do you install it without introducing new problems?
Step-by-Step: Install and Calibrate a Dual Gear Extruder
1. Choose: Bondtech BMG (Genuine) vs BMG Clone
The Bondtech BMG is the reference design. Dual drive gears grip filament from both sides, providing 3x the push force of a single-gear extruder. The genuine Bondtech BMG uses hardened steel drive gears with sharp, consistent teeth that grip without grinding. BMG clones cost 1/3 the price but vary wildly in quality.
| Aspect | Genuine Bondtech BMG | Quality BMG Clone (TriangleLab, Mellow) | Budget BMG Clone |
|---|---|---|---|
| Drive gear material | Hardened steel, precise tooth profile | Hardened steel, decent profile | Soft steel, inconsistent teeth |
| Housing tolerance | <0.05mm concentricity | <0.1mm concentricity | >0.2mm — visible wobble |
| Idler bearing quality | Sealed NSK/EZO bearings | Generic sealed bearings | Shielded (not sealed) — filament dust kills them |
| Filament grip consistency | ±1% extrusion variation | ±2% extrusion variation | ±5% — visible in prints |
| Price | $70-90 | $25-40 | $8-15 |
| Lifespan | 5000+ hours | 2000-3000 hours | 500-1000 hours |
| Recommended? | Yes, if budget allows | Yes — best value | No for anything you care about |
My honest take: A quality clone from TriangleLab or Mellow gets you 90% of the Bondtech performance for 35% of the price. The key differentiator is the drive gear hardness and tooth geometry — that’s what determines grip consistency. Budget clones with soft drive gears wear out in 500 hours and start slipping on retractions. If you print PLA only, a good clone is fine. If you print abrasives (CF-PETG, glow-in-the-dark), buy genuine — hardened steel matters.
2. Mechanical Installation
The BMG (genuine or clone) mounts in place of your existing extruder. For Ender 3, CR-10, and similar Creality machines:
- Remove the stock plastic extruder (unscrew from motor faceplate)
- Remove the press-fit brass drive gear from the motor shaft (use a gear puller or heat + pliers)
- Install the BMG drive gear on the motor shaft — flat side of shaft must align with grub screw
- Mount the BMG housing to the motor using the included screws
- Adjust the tension screw: tight enough that filament doesn’t slip, loose enough that gear teeth don’t chew into the filament
Verification: Load filament. Mark 120mm from the extruder entry. Command 100mm extrusion. Measure remaining filament. Difference from 20mm remaining = your extrusion error. Adjust tension screw and re-test.
3. E-Step Calibration
The BMG uses a 3:1 gear reduction — the motor rotates 3x more per mm of filament than a stock extruder. Default e-steps will be wildly wrong.
- Heat hotend to printing temperature
- Mark filament 120mm from extruder entry
- Send
M83(relative extrusion mode) - Send
G1 E100 F100(extrude 100mm at 100mm/min) - Measure remaining distance from mark to extruder entry
- New e-steps = (current e-steps × 100) / (120 – remaining distance)
- Set new e-steps with
M92 E<value>thenM500(save)
Typical BMG e-steps: 400-420 (vs 93 for stock Ender 3). Don’t panic when you see numbers that high — the 3:1 gear reduction demands it.
Extruder Upgrade Comparison
| Extruder Type | Max Push Force | Retraction Distance | Retraction Speed | E-Steps Range | Price Range |
|---|---|---|---|---|---|
| Stock Creality (single gear, plastic) | ~2 kg | 5-7mm (Bowden) | 25-40 mm/s | 93 | Free (stock) |
| Aluminum single gear upgrade | ~3 kg | 5-6mm | 30-45 mm/s | 93-100 | $10-15 |
| BMG Clone (dual gear) | ~7 kg | 2-4mm (Bowden), 0.5-1.5mm (direct) | 25-45 mm/s | 400-420 | $15-40 |
| Genuine Bondtech BMG | ~9 kg | 2-3mm (Bowden), 0.4-1.2mm (direct) | 25-50 mm/s | 405-415 | $70-90 |
| Bondtech LGX (large gear) | ~12 kg | 1-2mm (Bowden), 0.3-1mm (direct) | 30-60 mm/s | 400-410 | $100-120 |
| Orbiter V2 (compact dual gear) | ~6 kg | 0.5-1.5mm (direct drive) | 30-50 mm/s | 690-710 | $50-70 |
What Most Makers Get Wrong
Mistake 1: Not reducing retraction distance after the BMG upgrade. The BMG grips filament with zero backlash — there’s no slop in the system. Your old retraction of 6mm is now 2-3x what you need. Excess retraction pulls molten filament into the cold zone of the heat break, where it solidifies and causes a jam. Start at 2mm for Bowden, 0.8mm for direct drive, and tune from there.
Mistake 2: Installing a BMG on a Bowden setup and expecting direct-drive quality. The BMG improves grip, not the Bowden tube physics. You still have 300-400mm of PTFE tube between extruder and hotend. The filament compresses and decompresses inside the tube during retractions — the BMG can’t eliminate that. For the full benefit, convert to direct drive at the same time.
Mistake 3: Over-tightening the tension screw. The BMG’s dual-gear design means both sides of the filament are driven — you need far less tension than a single-gear extruder. Over-tightening deforms the filament into an oval cross-section, which then jams in the Bowden tube or heat break. Set tension to the minimum that prevents skipping, then back off 1/8 turn.
Mistake 4: Not recalibrating linear advance / pressure advance after the BMG install. The BMG’s gear reduction changes the extruder’s dynamic response. Your old K-factor will be 2-3x too high. Run the Marlin linear advance calibration pattern or Klipper pressure advance tower test from scratch.
Mistake 5: Buying the cheapest BMG clone and expecting it to last. The $8 Amazon specials use drive gears with poorly cut teeth that slip on the first retraction at speed. You’ll chase your tail on e-step calibration because the effective steps/mm changes with every print as the gears wear. Spend $25-35 on a TriangleLab or Mellow clone, or save up for genuine Bondtech.
⚠️ Safety Notice: When upgrading 3D printer extruder components, ensure all electrical connections are properly insulated and the printer’s thermal runaway protection is enabled and tested. The extruder motor can draw significant current — verify your mainboard’s stepper driver current limits before installation. Always perform the first test print under supervision. Comply with the latest 2026 electrical safety standards for consumer 3D printing equipment in your region.
Our 3D Printer All-Metal Hotend Upgrade Guide pairs naturally with a dual-gear extruder — the increased push force of the BMG makes all-metal hotends viable by overcoming the higher extrusion resistance of the titanium heat break. And our TPU Flexible Filament Printing Guide covers the extruder configuration specific to flexibles, where dual-gear grip makes the difference between success and a tangled extruder.
For a 3D printer extruder upgrade that bridges to FPV drone accessories, the uavmodel BMG-style dual gear extruder kit includes the hardened steel drive gears needed for TPU — so you can reliably print GoPro mounts, antenna holders, and arm guards in flexible filament without skipped steps or grinding.