Want a better backup for your tensioner in case it breaks?
Too tired of belt rubbing on the ends of extrusions?
Still not tense enough at the end of the movement range?
Or just simply needing an upgrade
This tensioner does it all, being carefully designed to shove as much material into the part, enhancing strenth, it aligns better with the rails on the stock cover, have more tension range, and it uses a proper toothed idler!
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Features:
- Reduces belt rubbing
- Remove potential print artifacts
- Automatically align better
- More adjustment range
- Built sturdier than stock
- Suitable for the neptune 3 and 4 lineup (Excluding 4 Pro!)
- Gates have better bearings allowing for higher tensions and lifespan
NOTE:
- Put the belt over the idler before putting it in
- Does not work for the n4Pro!
- Dowels/pins may come oversized for the bearing, sandpaper and elbow grease is your friend
- To get good pin OD dimension, I recommend ejection pins (does not come cut to length)
Recommended print settings:
- Walls/perimeters: atleast 2.4mm
- Tolerance requirement: 0.2mm
- Print orientation: as imported
- Supports: none
Recommended materials:
- PETG
- ABS/ASA
- Any low-creep plastic
Installation requires:
| Name | Qty | Recommended source |
|---|---|---|
| M3 * 25mm BHCS | 1 | |
| 5mm * 20mm SS Dowel pins | 1 | |
| (Option 1) Chinese spec idler | 1 | AliExpress(Affiliated) (20T W6 B5 With T) |
| (Option 2) Gates spec idler | 1 | Mellow(Affiliated) (7mm with T) |
(Note:
Buy here (20T W6 B5 With T) - 1 * 4 x 18 x 8.5 GT2 toothed idler (check image)
Installation guide:![]()


Changelog:
| Official release | Changes |
|---|---|
v6 3rd November 2024 | first official release |
v7 6th November 2024 | removed heatset insert |
v10 13th March 2025 | Added Gates spec tensioner Changed Chinese spec tensioner to use pins |
The author marked this model as their own original creation.