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3D printable 2x4 cross connector: joins two 2x4s on edge crossing like a plus, one stacked on the other (STL, STEP)
Is there a 3D printable block that holds two 2x4s crossing at 90 degrees, both on edge, without cutting the wood? · Hardware · basis: 2x4 dressed (dry) size 1-1/2 × 3-1/2 in (38.1 × 88.9 mm) per DOC PS 20 American Softwood Lumber Standard; 1.4 mm sliding clearance is Xem's FDM default for this part.
Also called: 3d printed 2x4 connector stl, 2x4 cross bracket, printable lumber connector, 2x4 plus connector, 2x4 stacking block, perpendicular 2x4 connector, 2x4 on edge connector, cross lap block 2x4
Exact dimensions. Every file is drawn at true size with no tolerance added. The holes and pins that meet another part are listed below under Mating features, with the fit each joint needs; open those by your process's clearance before making the part. Mating features
- length
- 55.5 mm
- width
- 55.5 mm
- height
- 90.0 mm
Notes
- Both boards stand on edge (the 1-1/2 in side is the width). The block slides down over the lower board and the upper board drops into the top slot at 90°, so the stack is about 7 in to the top of the upper board.
- No cutting or notching of the lumber. Add a screw through a wall into each board if the joint must not lift apart.
- Slots are 39.5 mm for a 38.1 mm board. Rough-sawn, wet or swollen 2x4s can run thicker: test-fit one block first.
- Print upright as modelled, 4 or more walls, 20 % or more infill, PETG or ABS outdoors. No supports: the lower slot's 39.5 mm ceiling bridges.
3D printable 2x4 cross connector: joins two 2x4s on edge crossing… size chart
| feature | size mm | fits |
|---|---|---|
| block | 55.5 × 55.5 × 90 | — |
| lower slot (opens down, along X) | 39.5 wide × 40 deep | 2x4 on edge, 38.1 thick |
| upper slot (opens up, along Y) | 39.5 wide × 40 deep | 2x4 on edge, 38.1 thick |
| walls / web | 8 / 10 | — |
| lead-in chamfer | 1.5 | — |
Mating features
Drawn at the exact size. Open press, slide, run and socket features by your process's clearance (tolerances by process); leave designed gaps and clamp fits as drawn.
| feature | exact | mates with | fit | files |
|---|---|---|---|---|
| lower slot | 39.5 mm wide, 40 mm deep | 2x4 on edge (38.1 mm) | slide | all |
| upper slot | 39.5 mm wide, 40 mm deep | 2x4 on edge (38.1 mm) | slide | all |
Where the files are
Other publishers' files are linked, not hosted. "verify" = check the license at the link before commercial use.
| NIST / ALSC | Voluntary Product Standard PS 20-25, American Softwood Lumber Standard | web | Publisher's page; dimensions are facts |
| American Wood Council | Weights and Measurement: nominal vs actual lumber sizes | web | Publisher's page; dimensions are facts |
Free files
★ Free files 1 parts. Xem Studio design: free to use, print and sell things from; not to be republished as files. Xem Studio Design License. index.json
Use this part in your AI. Your AI gets the exact sizes and files straight from Xem and can design a mount, case or adapter around it. Direct downloads here are limited to one file every 10 minutes; through your AI they are unlimited.
Connect Xem to your AI (free, no account, about a minute)
https://xemstudio.com/mcp- Claude: add Xem from the Claude directory (one click).
- ChatGPT (Plus or higher): open Connectors → Advanced → turn on Developer mode → Create → paste the address, no authentication → Create.
- Cursor: install with one click. VS Code: install with one click.
| 2x4-cross-block | 2x4 cross connector: 55.5 × 55.5 × 90 mm block, two 39.5 mm slots 40 mm deep at 90°, one down, one up; prints upright with no supports | STEP · STL |
https://xemstudio.com/mcp to Claude, ChatGPT, Cursor or any MCP client (free, no account, one minute) and it can look up exact sizes, mating fits and free STEP/STL from every chat.Plain text: sheet.txt · JSON: /api/geometry?object=2x4-cross-block-connector
Fits with
Questions
What size is a 2x4 really?
1-1/2 × 3-1/2 in (38.1 × 88.9 mm) dry and dressed. The slots here are 39.5 mm so the 38.1 mm side slides in.
Do the boards need to be cut or notched?
No. The block slides over one board and the other drops into the top slot; the wood stays full length.
Does it work with the boards lying flat?
No. Both slots fit the 1-1/2 in side, so both boards stand on edge.
How do I print it without supports?
Print it upright as modelled. The lower slot's 39.5 mm ceiling bridges on any tuned FDM printer.
Will it hold if I lift the top board?
It locates the boards but does not lock them. Drive a screw through a wall into each board if it must not come apart.