Why Feed and Speed Matter
When running a CNC router, two numbers determine everything about your cut quality: feed rate and spindle speed. These settings control how fast your cutting tool moves through material and how quickly it spins. Finding the right balance keeps your cuts clean, prevents tool wear, and avoids burning or chatter.
Too slow of a feed rate makes the bit rub rather than cut, creating heat and burn marks. Too fast, and the bit can deflect, chatter, or even break. Similarly, spindle speed that’s too high can scorch wood fibers, while too low can lead to rough edges and poor surface finish.
This guide uses verified TwoTrees machining data collected from the H40 500 W spindle to help you dial in safe, effective cutting parameters for wood and other materials. These same principles apply to larger desktop CNC routers like the TTC-450 Pro, TTC-450 Ultra, and TTC-6050.
Key Terms You Should Know
- Feed Rate (mm/min): The speed at which the cutting bit moves across the workpiece. Higher feed rates remove material faster but require more spindle power.
- Spindle Speed (RPM): The rotational speed of the spindle motor, determining how fast the cutting edges move through the material.
- Depth per Pass: How much material the bit removes in one cutting pass. Deeper passes increase material removal rate but also increase tool load.
- Plunge Rate: The vertical speed at which the bit enters the workpiece. Too fast can cause bit breakage.
- Chip Load: The thickness of the material removed by each cutting edge per revolution. This value ties together feed rate, RPM, and the number of flutes.
For beginners, remember this simple relationship:
Feed Rate = Spindle Speed × Number of Flutes × Chip Load
By adjusting any one of these variables, you can fine-tune your cut for smoothness, precision, and speed.
Test-Based Feed and Speed Chart for Hardwood (Oak)
The following table summarizes tested cutting parameters for oak hardwood using the TwoTrees H40 500 W spindle. These values provide a safe baseline for all small desktop CNC routers in the TwoTrees lineup. All cuts were performed with carbide end mills under normal workshop conditions.
| Material | Tool Type | Diameter | Spindle Speed (RPM) | Depth per Pass | Feed Rate | Plunge Rate | Recommended Use |
|---|---|---|---|---|---|---|---|
| Hardwood (Oak) | Single-edged spiral milling cutter | 3.175 mm | 12 000 | 0.6 mm | 1800 mm/min | 1500 mm/min | Fine engraving and lettering |
| Hardwood (Oak) | Double-edged straight-fluted cutter | 3.175 mm | 12 000 | 0.8 mm | 1800 mm/min | 1500 mm/min | Shallow pockets and grooves |
| Hardwood (Oak) | Three-edged spiral cutter | 3.175 mm | 12 000 | 0.95 mm | 1800 mm/min | 1200 mm/min | High-detail contouring |
| Hardwood (Oak) | Single-edged spiral milling cutter | 4 mm | 12 000 | 0.8 mm | 1800 mm/min | 1500 mm/min | General-purpose carving |
| Hardwood (Oak) | Three-edged spiral cutter | 6 mm | 12 000 | 1.5 mm | 1800 mm/min | 1200 mm/min | Efficient stock removal |
Adapting Feed and Speed for Different TwoTrees CNC Models
Although these test results come from the H40 spindle, they apply broadly across the TwoTrees CNC lineup. Each router can handle similar feed rates, with slight adjustments depending on spindle power and frame rigidity.
TTC-450 Pro
The TTC-450 Pro features a 500 W spindle—similar to the H40 test unit. You can safely use the same settings listed above for oak and other hardwoods. For softwoods like pine or MDF, increase the feed rate by roughly 15 – 20 % while keeping the same RPM.
TTC-450 Ultra
The TTC-450 Ultra uses a higher-power 800 W spindle, allowing deeper cuts (up to 1.5 – 2 mm with a 4 mm bit) and slightly higher feed rates. Start 10 % faster than the H40 chart and listen for stable cutting sound. Its reinforced Z-axis helps maintain accuracy in dense hardwoods.
TTC-6050
The TTC-6050 has a larger, more rigid aluminum frame designed for continuous use. This model can safely handle up to 20 % faster feed rates and deeper cuts, especially when using 6 mm end mills. For example, increase feed from 1800 → 2200 mm/min while maintaining spindle speed at 12 000 RPM.
Practical Tips for Optimizing Feed and Speed
- Start conservative: Use the lower end of the recommended feed range and gradually increase until you find smooth, consistent chip formation.
- Watch the chips: Dust indicates rubbing (too slow). Long, curled chips mean your feed and RPM are balanced.
- Listen to the sound: A clean cutting tone is good; a high-pitched squeal means too high RPM or too little feed.
- Check spindle power: If your spindle slows under load, reduce depth per pass instead of lowering feed rate.
- Keep bits sharp: Dull tools increase friction and heat, forcing you to reduce feed rates unnecessarily.
- Clean chips often: Use vacuum or compressed air to remove debris that can interfere with cooling.
Common Mistakes to Avoid
- Too shallow feed rate: Causes burning or tool wear from friction.
- Excessive depth per pass: Strains the spindle and produces chatter.
- Ignoring material differences: Settings that work for oak may be too aggressive for acrylic or aluminum.
- Wrong plunge rate: Rapid plunges can snap small-diameter bits.
- No test cuts: Always run a small test before committing to the full design.
Downloadable Feed & Speed Chart
You can download a printable version of this feed and speed table from the TwoTrees resource center. Keep it near your CNC workstation as a quick reference when changing bits or materials.
Final Thoughts
Mastering feed and speed settings takes some experimentation, but the results are worth it. By following the tested parameters above, you’ll achieve smoother cuts, less tool wear, and shorter machining times. As you gain experience, you’ll naturally recognize the right sound and feel for each material.
All TwoTrees CNC routers—from the compact TTC-450 Pro to the professional-grade TTC-6050—are designed to handle a wide range of feed rates and materials safely. Pairing the right bit with the correct speed settings ensures every project looks as professional as possible.
