CNC Router Table Build
Built a full-size CNC router table from OpenBuilds components. Learned more about tramming than I ever wanted to know.
Tools
- › OpenBuilds ACRO 1515 System
- › Makita RT0701C Router
- › GRBL Controller (Arduino Uno)
- › CNC.js (control software)
- › Fusion 360 (CAM)
Materials
- › 80/20 Aluminum Extrusion (1515)
- › NEMA 23 Stepper Motors (3x)
- › DM542T Stepper Drivers
- › MDF Spoilboard (3/4")
- › T-Track Aluminum
Why I Built This
I'd been using a handheld router for years and spending half my time trying to hold a straightedge straight. After one too many blown cuts in expensive walnut, I decided the answer was obviously to build a $1,200 CNC machine instead of just buying a $40 router sled like a normal person.
The squirrel saw the acorns and could not stop.
The Frame
I went with the OpenBuilds ACRO 1515 as the base system. It's a gantry-style router designed for the 1515 extrusion profile. Assembly took a weekend and was surprisingly straightforward — the main challenge was getting everything square before locking it down.
Key step: Use a machinist's square, not a carpenter's square. I made this mistake the first time and spent two hours chasing a squareness problem that turned out to be the square itself being off by 0.3°.
The working area ended up at roughly 500mm × 500mm × 75mm (Z). Good enough for most projects.
Electronics & Wiring
I used a standard GRBL setup:
- Arduino Uno as the controller
- Three DM542T stepper drivers (one per axis)
- 24V 10A power supply
- Mechanical limit switches on all axes
- E-stop button (very important, use one)
The wiring took longer than the mechanical build. I learned that shielded cable for the stepper motors is not optional if you want your limit switches to not false-trigger constantly. Ask me how I know.
Tramming
Getting the router square to the table (tramming) is where I spent most of my time. Tramming is the process of adjusting the router mount so the bit is perfectly perpendicular to the spoilboard.
I used a tramming arm — two dial indicators on opposite ends of a bar — to measure the deviation. Target is under 0.001" across a 6" sweep.
It took about 4 hours of small adjustments to get within 0.003". Good enough.
First Cuts
The first test cut was a simple grid of lines to check for squareness. It looked great. The second test was a text carving — "squirrel built" — in 3/4" MDF.
It worked. I may have done a small victory lap around the garage.
What I'd Do Differently
Use proper cable management from the start. My wiring is functional but not pretty. The cable drag chain was an afterthought and it shows.
Get a better Z-axis. The ACRO's Z-axis has more flex than I'd like for deep cuts in hardwood. I've since added a stiffer router mount which helped, but starting with a ballscrew Z would have been better.
Add dust collection before cutting anything. MDF dust is fine, pervasive, and miserable. I cut about 4 sheets before building the dust shoe. Never again.
Overall though? Best tool I've built. It's changed how I approach projects.
Photo Gallery
