Douglas Fir vs SPF
Natural Material · grade comparison
Douglas Fir and SPF are both natural material grades. Douglas Fir is the stronger of the two: tensile strength 105 MPa (15.2 ksi) against 22 MPa (3.19 ksi) for SPF, about 4.8 times as much. SPF is lighter (0.42 g/cm³ vs 0.48 g/cm³ for Douglas Fir) and Douglas Fir is stiffer (13.4 GPa vs 9.7 GPa). On the shop floor, SPF machines more easily (excellent vs very good).
Douglas FirChoose it when strength drives the design.
SPFChoose it when weight is the constraint, or when the part is machined in volume.
Douglas Fir vs SPF: propertiesHow to read these bars
- One bar per material. A full bar is the highest value among all natural material grades in the FabDigit library; each bar is drawn as a share of that.
- The better value (by the usual engineering direction) is in bold. Rows with no direction — density, thermal conductivity — have no bold.
- Values are typical room-temperature figures for the condition named on each card.
- Confirm against the certified mill or resin datasheet before design release.
How to read these bars
- One bar per material. A full bar is the highest value among all natural material grades in the FabDigit library; each bar is drawn as a share of that.
- The better value (by the usual engineering direction) is in bold. Rows with no direction — density, thermal conductivity — have no bold.
- Values are typical room-temperature figures for the condition named on each card.
- Confirm against the certified mill or resin datasheet before design release.
Mechanical
Strength, stiffness, ductility and hardness at room temperature.
Elastic (Young's) Modulus
Shear Modulus
Poisson's Ratio
Tensile Strength (Ultimate)
Compressive Strength
Flexural Strength
Shear Strength
Hardness, Mohs
Same in both: Elongation at Break 1% · Fracture Toughness (K_IC) 0.4 MPa·√m0.36 ksi·√in
Physical
Density and transition temperatures.
Density
Porosity
Thermal
How each material carries heat and how hot it can run.
Specific Heat Capacity
Thermal Expansion (CTE, 20–100 °C)
Same in both: Thermal Conductivity 0.12 W/m·K0.07 BTU/hr·ft·°F · Max Service Temperature (continuous) 65°C149 °F · Min Service Temperature -60°C-76 °F
Electrical
Conductivity and insulation.
Electrical Resistivity
Dielectric Strength
Chemical & Environmental
Corrosion and environmental resistance (0–100 scores).
Corrosion Resistance
Manufacturability
FabDigit workshop ratings (0–100 scores) — how each material behaves on the machine.
Machinability
Same in both: Polishability 45 / 100
Sustainability
Primary-production footprint per kilogram.
Embodied Energy (primary production)
Embodied Carbon (primary production)
Embodied Water
Typical Recycled Content
Common Calculations
Ratios derived from the values above.
Specific Strength (UTS / density)
Specific Stiffness (E / density)
Thermal Diffusivity
Same in both: Thermal Shock Resistance Index 0
Strength versus weight
Yield strength against density for every natural material grade in the FabDigit library; the compared grades are highlighted. Up and left is stronger for its weight.
Manufacturing and finishing
| Capability | Douglas Fir | SPF |
|---|---|---|
| Default condition | — | — |
| Relative cost | $ Budget | $ Budget |
| Min. machined wall | — | — |
| Best machined surface | — | — |
Douglas Fir vs SPF — frequently asked
Is Douglas Fir stronger than SPF?
Yes. Douglas Fir has a typical tensile strength of 105 MPa (15.2 ksi) against 22 MPa (3.19 ksi) for SPF — about 4.8 times as much.
Which is cheaper, Douglas Fir or SPF?
Both sit in the same relative cost tier ($, budget); the part price will be decided by machining time, tolerance and quantity rather than by the material.
Which is easier to machine, Douglas Fir or SPF?
SPF. Its machinability rates excellent (95/100) against very good (80/100) for Douglas Fir.
Ready to make it?
Upload a CAD file and FabDigit prices the part in Douglas Fir and SPF side by side — material, machining time, tolerance and finish in one quote. Certified material data ships with the order on request.
Typical handbook values for the conditions named above, normalised for comparison. Hardness on non-Brinell scales is converted approximately for charting only. Request certified data with your order for design-critical properties.