# Drop-in T-nuts for 20, 30, 40 and 10-series (1 in) extrusion

> What are drop-in T-nut dimensions for 2020 extrusion?

- Category: Hardware › Framing
- Kind: Hardware
- Basis: Drop-in nut: width = slot opening so it passes the opening, length = cavity − 1 so it turns 90° (designed), tap-drill thread hole
- Page: https://xemstudio.com/objects/drop-in-t-nuts/ · JSON: https://xemstudio.com/api/geometry?object=drop-in-t-nuts · Plain text: https://xemstudio.com/objects/drop-in-t-nuts/sheet.txt
- License: dimension sheet CC BY 4.0 (Xem Studio); linked files under their publishers' licenses

**Exact dimensions.** Every file is drawn at true size with no printing tolerance. The holes and pins that meet another part are listed below under Mating features, with the fit each joint needs; open those by your printer's or process's clearance before making the part.

## Notes

- The nut is as wide as the slot opening, so it drops in through the face, and 1 mm shorter than the cavity width, so it turns 90° to lock behind the lips (designed).
- 20-series: 10 × 6 × 4.2 body with a 6 × 6 × 1.8 boss, M3 / M4 / M5. 30-series: 15.5 × 8 × 6, boss 8 × 8 × 2.5, M5 / M6 / M8. 40-series: 19 × 8 × 6.5, boss 8 × 8 × 3, M6 / M8. 10-series: 13.4 × 6.5 × 4.8, boss 6.5 × 6.5 × 2.3, 1/4-20 / 10-32.
- Thread holes are the standard tap drills (M3 2.5, M4 3.3, M5 4.2, M6 5.0, M8 6.8, 1/4-20 5.1, 10-32 4.0); body edges carry a 1.2 mm chamfer.
- Use a drop-in nut where the profile end is already closed.

## Mating features (exact size; open press / slide / run / socket by your process clearance, leave designed and clamp as drawn)

| feature | exact | mates with | fit | files |
|---|---|---|---|---|
| T-nut tongue | slot opening × lip (6.0 × 1.8 on 20-series; 8.0 on 30/40; 6.5 on 10-series) | slot opening | slide | tnut-* |
| drop-in T-nut width | slot opening | passes through the opening | slide | tnut-dropin-* |
| drop-in T-nut length | cavity − 1 | turns 90° in the cavity | designed | tnut-dropin-* |
| T-nut thread hole | tap drill (M3 2.5 … M8 6.8, 1/4-20 5.1, 10-32 4.0) | screw thread | designed | tnut-* |
| bracket / gusset / plate screw holes | Ø5.5 / 6.6 / 9.0 / 7.14 | M5 / M6 / M8 / 1/4-20 clearance | designed | all |

## Sizes

| series | body_mm | boss_mm | threads |
|---|---|---|---|
| 20 | 10 × 6 × 4.2 | 6 × 6 × 1.8 | M3, M4, M5 |
| 30 | 15.5 × 8 × 6 | 8 × 8 × 2.5 | M5, M6, M8 |
| 40 | 19 × 8 × 6.5 | 8 × 8 × 3 | M6, M8 |
| 10 (1 in) | 13.4 × 6.5 × 4.8 | 6.5 × 6.5 × 2.3 | 1/4-20, 10-32 |

## Where the files are

- Wikipedia: [T-slot nut](https://en.wikipedia.org/wiki/T-slot_nut) — web — CC BY-SA 4.0 (text)
- OpenBuilds: [Tee nuts and brackets for V-slot](https://openbuildspartstore.com/) — web, STEP — OpenBuilds site (verify at link)
- Long Earth Society: [Engine and rig builds on extrusion frames](https://longearthsociety.com/engineering/) — web, video — LES site

## Free STEP/STL (10 parts, CC BY 4.0, Xem Studio)

Index: https://xemstudio.com/files/hardware/drop-in-t-nuts/index.json

- tnut-dropin-20-m3: [STEP](https://xemstudio.com/files/hardware/t-slot-brackets-and-nuts/tnut-dropin-20-m3.step) · [STL](https://xemstudio.com/files/hardware/t-slot-brackets-and-nuts/tnut-dropin-20-m3.stl) — drop-in T-nut, 20-series slot: 10 × 6 × 4.2 body, 6 tongue (exact to the opening), M3 tap-drill hole Ø2.5
- tnut-dropin-20-m4: [STEP](https://xemstudio.com/files/hardware/t-slot-brackets-and-nuts/tnut-dropin-20-m4.step) · [STL](https://xemstudio.com/files/hardware/t-slot-brackets-and-nuts/tnut-dropin-20-m4.stl) — drop-in T-nut, 20-series slot: 10 × 6 × 4.2 body, 6 tongue (exact to the opening), M4 tap-drill hole Ø3.3
- tnut-dropin-20-m5: [STEP](https://xemstudio.com/files/hardware/t-slot-brackets-and-nuts/tnut-dropin-20-m5.step) · [STL](https://xemstudio.com/files/hardware/t-slot-brackets-and-nuts/tnut-dropin-20-m5.stl) — drop-in T-nut, 20-series slot: 10 × 6 × 4.2 body, 6 tongue (exact to the opening), M5 tap-drill hole Ø4.2
- tnut-dropin-30-m5: [STEP](https://xemstudio.com/files/hardware/t-slot-brackets-and-nuts/tnut-dropin-30-m5.step) · [STL](https://xemstudio.com/files/hardware/t-slot-brackets-and-nuts/tnut-dropin-30-m5.stl) — drop-in T-nut, 30-series slot: 15.5 × 8 × 6 body, 8 tongue (exact to the opening), M5 tap-drill hole Ø4.2
- tnut-dropin-30-m6: [STEP](https://xemstudio.com/files/hardware/t-slot-brackets-and-nuts/tnut-dropin-30-m6.step) · [STL](https://xemstudio.com/files/hardware/t-slot-brackets-and-nuts/tnut-dropin-30-m6.stl) — drop-in T-nut, 30-series slot: 15.5 × 8 × 6 body, 8 tongue (exact to the opening), M6 tap-drill hole Ø5
- tnut-dropin-30-m8: [STEP](https://xemstudio.com/files/hardware/t-slot-brackets-and-nuts/tnut-dropin-30-m8.step) · [STL](https://xemstudio.com/files/hardware/t-slot-brackets-and-nuts/tnut-dropin-30-m8.stl) — drop-in T-nut, 30-series slot: 15.5 × 8 × 6 body, 8 tongue (exact to the opening), M8 tap-drill hole Ø6.8
- tnut-dropin-40-m6: [STEP](https://xemstudio.com/files/hardware/t-slot-brackets-and-nuts/tnut-dropin-40-m6.step) · [STL](https://xemstudio.com/files/hardware/t-slot-brackets-and-nuts/tnut-dropin-40-m6.stl) — drop-in T-nut, 40-series slot: 19 × 8 × 6.5 body, 8 tongue (exact to the opening), M6 tap-drill hole Ø5
- tnut-dropin-40-m8: [STEP](https://xemstudio.com/files/hardware/t-slot-brackets-and-nuts/tnut-dropin-40-m8.step) · [STL](https://xemstudio.com/files/hardware/t-slot-brackets-and-nuts/tnut-dropin-40-m8.stl) — drop-in T-nut, 40-series slot: 19 × 8 × 6.5 body, 8 tongue (exact to the opening), M8 tap-drill hole Ø6.8
- tnut-dropin-10in-1-4-20: [STEP](https://xemstudio.com/files/hardware/t-slot-brackets-and-nuts/tnut-dropin-10in-1-4-20.step) · [STL](https://xemstudio.com/files/hardware/t-slot-brackets-and-nuts/tnut-dropin-10in-1-4-20.stl) — drop-in T-nut, 10in-series slot: 13.4 × 6.5 × 4.8 body, 6.5 tongue (exact to the opening), 1/4-20 tap-drill hole Ø5.1
- tnut-dropin-10in-10-32: [STEP](https://xemstudio.com/files/hardware/t-slot-brackets-and-nuts/tnut-dropin-10in-10-32.step) · [STL](https://xemstudio.com/files/hardware/t-slot-brackets-and-nuts/tnut-dropin-10in-10-32.stl) — drop-in T-nut, 10in-series slot: 13.4 × 6.5 × 4.8 body, 6.5 tongue (exact to the opening), 10-32 tap-drill hole Ø4

## How it fits

### Goes in or on
- [Aluminium T-slot extrusion: 2020, 2040, 2060, 2080, V-slot, 3030, 3060, 4040, 4080, 1010, 1515](https://xemstudio.com/objects/t-slot-extrusions/): passes the slot opening, turns 90° in the cavity

### Connects to
- [Button head socket screws, M2–M8 (ISO 7380)](https://xemstudio.com/objects/button-head-screws-metric/): screw into the tap-drill hole

### Alternatives
- [Slide-in T-nuts for 20, 30, 40 and 10-series (1 in) extrusion](https://xemstudio.com/objects/slide-in-t-nuts/): full-width nut slid in from the end

## Questions

**What is a drop-in T-nut for 2020?**

A 10 × 6 × 4.2 mm nut that passes the 6 mm opening and turns 90° in the 11 mm cavity.

**Why is the drop-in nut 1 mm shorter than the cavity?**

So it can rotate 90° inside the slot; it is a designed gap.

## Fits with

- [Slide-in T-nuts for 20, 30, 40 and 10-series (1 in) extrusion](https://xemstudio.com/objects/slide-in-t-nuts/)
- [L corner brackets for 20, 30, 40 and 10-series extrusion](https://xemstudio.com/objects/t-slot-corner-brackets/)
- [Aluminium T-slot extrusion: 2020, 2040, 2060, 2080, V-slot, 3030, 3060, 4040, 4080, 1010, 1515](https://xemstudio.com/objects/t-slot-extrusions/)
- [2020 aluminum extrusion](https://xemstudio.com/objects/2020-extrusion/)
- [Button head socket screws, M2–M8 (ISO 7380)](https://xemstudio.com/objects/button-head-screws-metric/)