Feeds and Speeds for Wood

CNC Feeds and Speeds Cookbook

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Here's your comprehensive guide to Feeds and Speeds for Wood, together with Tips and Techniques that are specific to cutting wood on a CNC Machine.

Wood Types

When calculating feeds and speeds for wood, we generally look at 4 different famillies. You can see them in our G-Wizard Feed and Speed Calculator's Material menu:

Just 4 wood types? Why not more?

To access the full variety of woods under each family, use the "More..." button on G-Wizard.

People wonder why we don’t have a lot more categories and sub-categories. After all, there are so many categories for steel, why not for wood too? The answer has to do with the size of the “sweet spot” that relates feeds and speeds to good results in a material, together with the relative hardness of the woods (or other materials) versus the cutters (HSS or Carbide). The Sweet Spot determines how the relationship between speed (spindle rpm) and feedrate need to come together for good cutting results. A typical Sweet Spot looks like this schematically:

The green areas reflect ideal Sweet Spot matches for a material and cutting conditions. You can optimize MRR (Material Removal Rate), Surface Finish, and to an extent a blend of all three. Red reflects danger zones. It’s important to note you can get into just as much trouble running too slowly (due to rubbing) as running too quickly.

Tools usually fail for a couple of main reasons:

– They get too hot, which softens the tool and results in a dull edge. Tools have a certain maximum speed, called the “Surface Speed” that governs how fast they can run against a given material. Running too slowly relative to feeds also generates a lot of heat due to Rubbing. This destroys a tool gradually, though gradual can mean a matter of minutes if the tool is hot enough.

– Tools can break because the flutes get too full, the chips have no place to go, and the tool jams and snaps off. This destroys a tool suddenly and is more commonly what beginners see.

A lot else can shorten a tools life–chipped edges in some materials, materials like stainless steel can “work harden” and suddenly become much harder during the cutting process, and some materials like aluminum try to weld themselves to the cutting edge if lubricant or appropriate tool coatings are not used. But, over heating and chip loading are the two main tool life enemies that are directly feeds and speeds related.

You can learn all this and much more from our free Feeds and Speeds Tutorial, but for now, let’s stay with this idea of a Sweet Spot. In general, the sweet spots for woods are much larger than for metals. For harder steels and difficult materials like Titanium, the sweet spot gets very small indeed. Imagine there are actual numbers on our Sweet Spot diagram. “Size” of Sweet Spot refers to how wide a range of numbers are safe.

What determines the “Size” of a Sweet Spot?

A lot of this is all up to that relative difference in hardness between material and cutter. Even Carbide is not all that much harder than hardened steel whereas it is phenomenally harder than even the hardest woods. Red Oak, for example, has a Brinell Hardness of about 3.7. Mild steel is 120, hardened steel is 900, and tungsten carbide is 4000!

It turns out that the characteristics that affect the feeds and speeds for wood are different than hardness. They have to do for example with the behavior of the sap relative to the sawdust and how the chips are made. Plastics, similarly, can behave differently–hard plastics as a name is a bit of a misnomer (though it is the industry standard in tooling catalogs). It refers to the chipping characteristics of the plastic. Hard Plastic turns to dust–it shatters. Soft Plastics allow a nice clean chip to be sliced off, almost like you slice cheese with a knife. Of course, the same is true for woods. “Hard” Wood versus “Soft” Wood has more to do with the seeds of the Wood than the actual hardness. Balsa seems soft but is technically a Hardwood. Hardwood seeds have a covering–shell or fruit, while Softwood does not.

Another factor influencing all this has to do with manufacturing process for the material. In the case of materials like MDF and Plywood, their manufacture can result in abrasive grit being embedded in the layers and that grit matters more than the wood in feeds and speeds. This is why so much router work prefers Carbide tooling even though wood is relatively soft. HSS just doesn’t stand up to that kind of grit very well.

With all that said, there are still differencs in hardness for various woods, and there is a standard scale, called the "Janka" scale that is used to rate the relative hardness of various woods.

Softwoods

Here are the various softwoods, sorted by Janka hardness, that one might attempt to CNC:

Common Name	Scientific Name	Janka Metric Hardness   K-N	Janka Imperial Hardness lb-feet
balsa	Ochroma pyramidale	0.4	90
ceiba	Ceiba pentandra	1.1	240
cottonwood - balsam poplar	Populus balsamifera	1.3	300
white-cedar, northern	Thuja occidentalis	1.4	320
aspen, quaking	Populus tremuloides	1.6	350
buckeye, yellow	Aesculus octandra	1.6	350
cedar, atlantic white	Chamaecyparis thyoides	1.6	350
cottonwood, black	Populus trichocarpa	1.6	350
fir, subalpine	Abies lasiocarpa	1.6	350
red cedar, western	Thuja plicata	1.6	350
willow, black	Salix nigra	1.6	360
cuangare	Dialyanthera spp.	1.7	380
okoume	Aucoumea klaineana	1.7	380
pine, eastern white	Pinus strobus	1.7	380
pine, sugar	Pinus lambertiana	1.7	380
jelutong	Dyera costulata	1.7	390
spruce, Engelmann	Picea engelmanni	1.7	390
fir, balsam	Abies balsamea	1.8	400
basswood, American	Tilia americana	1.8	410
basswood, Carolina	Tilia caroliniana	1.8	410
fir, noble	Abies procera	1.8	410
aspen, bigtooth	Populus grandidentata	1.9	420
pine, western white	Pinus monticola	1.9	420
redwood, second growth	Sequoia sempervirens	1.9	420
sajo	Campnosperma panamensis	1.9	425
cottonwood, eastern	Populus deltoides	1.9	430
fir, pacific silver	Abies amabilis	1.9	430
obeche	Triplochiton scleroxylon	1.9	430
pine, limber	Pinus flexilis	1.9	430
cypress, Mexican	Cupressus lustianica	2	460
pine, ponderosa	Pinus ponderosa	2	460
shorea, light red meranti	Shorea spp., lauan-meranti group	2	460
incense-cedar	Libocedrus decurrens	2.1	470
fir, white	Abies concolor	2.1	480
pine, lodgepole	Pinus contorta	2.1	480
redwood, old growth	Sequoia sempervirens	2.1	480
spruce, white	Picea glauca	2.1	480
chalviande	Virola spp.	2.1	481
butternut	Juglans cinerea	2.2	490
fir, grand	Abies grandis	2.2	490
limba	Terminalia superba	2.2	490
spruce, red	Picea rubra	2.2	490
fir, California red	Abies magnifica	2.2	500
hemlock, eastern	Tsuga canadensis	2.2	500
pine, Jeffrey	Pinus jeffreyi	2.2	500
banak	Virola spp.	2.3	510
Douglas-fir, interior south	Pseudotsuga menziesii	2.3	510
spruce, Sitka	Picea sitchensis	2.3	510
tulapueta	Osteophloeum platyspermum	2.3	512
spruce, black	Picea mariana	2.3	520
chestnut, American	Castenea dentata	2.4	540
hemlock, western	Tsuga heterophylla	2.4	540
poplar	Liriodendron tulipifera	2.4	540
yellow poplar	Liriodendron tulipifera	2.4	540
catalpa, northern	Catalpa speciosa	2.4	550
catalpa, southern	Catalpa bignonioides	2.4	550
hura	Hura crepitans	2.4	550
pine. red	Pinus resinosa	2.5	560
baldcypress	Taxcodium distichum	2.3	570
pine, jack	Pinus banksiana	2.5	570
cedar, Alaska	Chamaecyparis nootkatensis	2.6	580
cedar, yellow	Cupressus nootkatensis	2.6	580
alder, red	Alnus rubra	2.6	590
silverbell, Carolina	Halesia carolina	2.6	590
tamarack	Larix laricina	2.6	590
Douglas-fir, interior north	Pseudotsuga menziesii	2.7	600
Spanish-cedar	Cedrela spp.	2.7	600
ilomba	Pycnanthus angolensis Exell	2.7	610
red cedar, southern	Juniperus silicicola	2.7	610
pine, pitch	Pinus rigida	2.8	620
cativo	Prioria copaifera	2.8	630
sassafras	Sassafras albidum	2.8	630
alder, European	Alnus glutinosa	2.9	650
determa	Ocotea rubra	2.9	660
Douglas-fir, interior west	Pseudotsuga menziesii	2.9	660
pine, spruce	Pinus glabra	2.9	660
pine, Table Mountain	Pinus pungens	2.9	660
primavera	Tabebula donnell-smithii	2.9	660
pulgande	Dacryodes spp.	3	666
hemlock, mountain	Tsuga mertensiana	3	680
sumac, staghorn	Rhus typhina	3	680
pine, loblolly	Pinus taeda	3.1	690
pine, shortleaf	Pinus echinata	3.1	690
magnolia, cucumber tree	Magnolia acuminata	3.1	700
maple, silver	Acer saccharimum	3.1	700
Douglas-fir, coast	Pseudotsuga menziesii	3.2	710
boxelder	Acer negundo	3.2	720
cedar, Port Orford	Chamaecyparis lawsoniana	3.2	720
chinkapin, giant	Castanopsis chrysophylla	3.2	730
pine, sand	Pinus clausa	3.3	730
pine, pond	Pinus serotina	3.3	740
pine, virginia	Pinus virginiana	3.3	740
birch, gray	Betula populifolia	3.4	760
pine, slash	Pinus elliotti	3.4	760
shorea, yellow meranti	Shorea spp., lauan-meranti group	3.4	770
sycamore, american	Platanus occidentalis	3.4	770
parana-pine	Araucaria augustifolia	3.5	780
shorea, dark red meranti	Shorea spp., lauan-meranti group	3.5	780
mahogany, true	Swietenia macrophylla	3.6	800
magnolia, sweetbay	Magnolia virginiana	3.6	810
tupelo, black	Nyssa sylvatica	3.6	810
elm, american	Ulmus americana	3.7	830
larch, western	Larix occidentalis	3.7	830
mahogany, African	Khaya spp.	3.7	830
elder, blue	Sambucus cerulea	3.7	840
ash, black	Fraxinus nigra	3.8	850
maple, bigleaf	Acer macrophyllum	3.8	850
sweetgum	Liquidambar styraciflua	3.8	850
elm, slippery	Ulmus rubra	3.8	860
pine, pinyon	Pinus edulis	3.8	860
pine, longleaf	Pinus palustris	3.9	870
hackberry	Celtis occidentalis	3.9	880
tupelo. water	Nyssa aquatica	3.9	880
red cedar, eastern	Juniperus virginiana	4	900
sande	Brosimum spp., utile group	4	900
birch, paper	Betula papyrifera	4	910
ekop	Tetraberlinia tubmaniana	4.1	910
pine, ocote	Pinus oocarpa	4	910
anime	Protium spp.	4.1	920
sourwood	Oxydendrum arboreum	4.2	940
cherry, black, American	Prunus serotina	4.2	950
maple, red	Acer rubrum	4.2	950
robe	Tabebul spp., roble group	4.3	960
ash, pumpkin	Fraxinus profunda	4.4	990

 

Hardwoods

Here are the various hardwoods, sorted by Janka hardness, that one might attempt to CNC:

Common Name	Scientific Name	Janka Metric Hardness   K-N	Janka Imperial Hardness lb-feet
teak	Tectona grandis	4.4	1000
walnut, black	Juglans nigra	4.5	1010
albarco	Cariniana spp.	4.5	1020
holly, American	Ilex opaca	4.5	1020
magnolia, southern	Magnolia grandiflora	4.5	1020
buckthorn, cascara	Rhamnus purshiana	4.6	1040
oak, southern red	Quercus falcata	4.7	1060
avodire	Turraeanthus africanus	4.8	1080
manni	Symphonia globulifera	5	1120
andiroba	Carapa guianensis	5	1130
oak, chestnut	Quercus prinus	5	1130
shorea, white meranti	Shorea javanica, lauan-meranti group	5.7	1140
cherry, wild, European	Prunus avium	5.1	1150
santa maria	Calophyllum brasiliense	5.1	1150
ash, oregon	Fraxinus latifolia	5.2	1160
juniper, alligator	Juniperus deppeana	5.2	1160
maple, black	Acer nigrum	5.2	1180
oak, overcup	Quercus lyrata	5.3	1190
oak, water	Quercus nigra	5.3	1190
ash, green	Fraxinus pennsylvanica	5.3	1200
oak, black	Quercus velutina	5.4	1210
oak, laurel	Quercus laurifolia	5.4	1210
pine, heart	Pinus resinosa	5.5	1225
kapur	Dryobalanops spp.	5.5	1230
oak, swamp chestnut	Quercus michauxii	5.5	1240
pine, Caribbean	Pinus caribaea	5.5	1240
birch, river	Betula nigra	5.6	1260
birch, yellow	Betula alleghaniensis	5.6	1260
iroko	Chlorophora spp.	5.6	1260
keruing	Dipterocarpus spp.	5.6	1270
laurel, California	Umbellularia californica	5.6	1270
myrtlewood	Umbellularia californica	5.65	1270
angelique	Dicorynia guianensis	5.7	1290
mersawa	Anisoptera spp.	5.7	1290
oak, northern red	Quercus rubra	5.7	1290
oak, shumard	Quercus shumardii	5.8	1290
beech, American	Fagus grandifolia	5.8	1300
ramin	Gonystylus bancanus	5.8	1300
alder, white	Alnus rhombifolia	5.9	1320
ash, white	Fraxinus americana	5.9	1320
elm, cedar	Ulmus crassifolia	5.9	1320
elm, rock	Ulmus thomasii	5.9	1320
ovangkol	Guibourtia ehie	5.9	1330
oak, post	Quercus stellata	6	1360
oak, white	Quercus alba	6	1360
oak, bur	Quercus macrocarpa	6.1	1370
cypress, Australian	Callitris glaucophylla	6	1375
coffeetree, Kentucky	Gymnocladus dioicus	6,2	1390
oak, scarlet	Quercus coccinea	6.2	1400
sepetir	Pseudosindora palustris	6.3	1410
tanoak	Lithocarpus densiflorus	6.3	1420
maple, sugar (hard)	Acer saccharum	6.4	1450
madrone, Pacific	Arbutus menziesii	6.5	1460
oak, willow	Quercus phellos	6.5	1460
birch, sweet	Betula lenta	6.5	1470
oak, cherrybark	Quercus falcata varpagodifolia	6.6	1480
hickory, bitternut	Carya cordiformis	6.7	1500
merbau	Intsia spp.	6.7	1500
pau marfim, Patagonian maple	Balfourodendron riedelianum	6.7	1500
oak, pin	Quercus palustris	6.7	1510
sapele	Entandrophragma cylindricum	6.7	1510
witch hazel	Hamamelis virginica	6.8	1530
elm, winged	Ulmus alata	6.8	1540
hickory, water	Carya aquatica	6.9	1550
afrormosia	Pericopsis elata	6.9	1560
honeylocust	Gleditsia triacanthos	7	1580
peroba de campos	Paratecoma peroba	7.1	1600
yew, Pacific	Taxus brevifolia	7.1	1600
oak, swamp white	Quercus bicolor	7.2	1620
opepe	Nauclea diderrichii	7.3	1630
alder, Nepalese	Alnus nepalensis	7.4	1690
locust, black	Robinia pseudoacacia	7.6	1700
pilon	Hyeronima spp.	7.6	1700
kempas	Koompassia malaccensis	7.6	1710
para-angelim	Hymenolobium excelsum	7.7	1720
piquia	Caryocar spp.	7.7	1720
apple	Malus sylvestris	7.7	1730
peroba rosa	Aspidosperma spp., peroba group	7.7	1730
tree-of-heaven	Ailanthus altissima	7.7	1731
angelin	Andira inermis	7.8	1750
benge	Guibourtia arnoldiana	7.8	1750
hornbeam, American	Carpinus caroliniana	7.9	1780
shorea	Shorea spp., baulau group	7.9	1780
ebony, black and white, pale moon	Diospyros malabarica	7.9	1790
laurel, mountain	Kalmia latifolia	8	1790
serviceberry	Amelanchier spp.	8	1800
hickory, shellbark	Carya lacinosa	8.1	1810
hickory, pecan	Carya illinoensis	8.1	1820
hophornbeam, eastern	Ostrya virginiana	8.3	1860
purpleheart	Peltogyne spp.	8.3	1860
hickory, shagbark	Carya ovata	8.4	1880
jarrah	Eucalyptus marginata	8.5	1910
wenge	Millettia laurentii	8.4	1930
degame	Calycophyllum candidissimum	8.6	1940
hickory. mockernut	Carya tomentosa	8.8	1970
pedauk - African	Pterocarpus soyauxii	8.6	1970
ash, blue	Fraxinus quadrangulata	9	2030
karri	Eucalyptus diversicolor	9.1	2040
wallaba	Eperua spp.	9.1	2040
hickory, pignut	Carya glabra	9.5	2140
sucupira	Diplotropis purpurea	9.5	2140
dogwood, flowering	Cornus florida	9.6	2150
goncalo alves	Astronium graveolens	9.6	2160
mahogany, Santos, Cabreuva	Myroxylon balsamum	9.8	2200
tornillo	Cedrelinga cateniformis	10.2	2299
ebony, persimmon, white	Diospyros virginiana	10.2	2300
mora	Mora spp.	10.2	2300
persimmon, common	Diospyros virginiana	10.2	2300
mesquite	Prosopis spp.	10.4	2345
cherry, Brazilian	Castenea dentata	10.4	2350
courbaril	Hymenaea courbaril	10.5	2350
greenheart	Chlorocardium rodiei	10.5	2350
ebony, Ceylon, East Indian	Diospyros cebenum	10.8	2430
granadillo	Platymiscium yucatanum	10.9	2450
oak, live	Quercus virginiana	12.9	2680
bubinga	Guibourtia spp.	12	2690
olive	Olea europaea, O. capensis		2700
rosewood, Brazilian	Dalbergia nigra	12.1	2720
sucupira	Bowdichia brasiliensis	12.2	2750
osage orange, horse apple	Maclura pomifera	12.3	2760
bloodwood, conduru, cardinal wood	Brosimum rubescens	14	2900
kaneelhart	Licaria spp.	12.9	2900
ebony, mun	Diospyros mun	13.4	3000
macawood	Platymiscium spp.	14	3150
rosewood, Indian	Dalbergia latifolia	14.1	3170
bulletwood	Manilkara bidentata	14.2	3190
ebony, African, Gaboon, Nigerian	Diospyros crassiflora	14.1	3220
ebony, Macassar, striped	Diospyros celebica	14.1	3220
azobe	Lophira alata	14.9	3350
manbarklak	Eschweilera spp.	15.5	3480
ipe	Handroanthus spp. (lapacho group), Brazilian walnut	15.6	3510
marishballi	Lincania spp.	15.9	3570
lignumvitae	Guaiacum spp.	20	4500

 

Tips and Techniques for Cutting Wood on a CNC Machine

Carbide or HSS Cutters?

In most cases, you'll want to purchase carbide cutters. First, a lot of wood products such as plywood and MDF can contain considerable amounts of highly abrasive grit due to the way they are manufactured. That grit radically shortens the life of HSS tools and you'll need carbide to stand up to it. Second, the spindle speeds used in most CNC woodwork are very fast, and this is also advantageous for Carbide because it tolerates the higher temperatures associated with the fast speeds better. Lastly, carbide is much stiffer than HSS, and so tool deflection is less likely to be a problem. Here is a great article: What Every CNCer Ought to Know About Tool Deflection.

Avoid Splintering the Surface with Special Router Bits

Specialize bits are available to help reduce the likelihood of splintering the surface of your wood (or laminated materials too):

- Upcut: This is the normal end mill style. The spiral flute carries chips up and out of the hole as it cuts. These are probably the worst about splintering, though with serious fine tuning and slower feeds and speeds you may be able to tame it a bit.

- Downcut: With downcut geometry, the spiral is reversed so it pushes down instead of pulling up. This is great for reducing splintering of the top surface, but you do want to be careful the chips can go somewhere. Cutting deep tight slots can be problematic for this type of cutter sometimes.

- Compression: A compression cut is a combination of upcut and downcut. It has the spiral set to pull up at the bottom of the material, then it reverses direction at the top. It's name comes because it is pushing the chips to the center of the cutter, or "comrpessing" them, in other words. Compression cutters can avoid splintering both top and bottom, so are ideal for many applications where you're making one pass to cut all the way through the material.

- Straight Flute: Straight flutes have no twist. This reduces their likelihood of splintering, and it also makes the cutters cheaper. However, their performance is not so hot in terms of ultimate feeds and speeds.

For much more on Cutters for CNC Routers, see our specific article.

More Splintering and Tear-Out Tips

- The more porous the wood, the more likely it is to splinter.

- Slower, shallower cuts will reduce the splintering.

- Climb Cutting can make tear-out less like than Conventional Milling.

CNC Router or VMC?

Would you believe that for many CNC woodworking applications, a VMC (Vertical Machining Center) can make more sense than a CNC Router? All sorts of companies like Taylor Guitars and Fender are using VMC's on a daily basis for woodwork. That link has the details, but here are some of the reasons why:

- Cost: When high levels of precision are needed (guitar making is very precise), the VMC can achieve precision at a lower price point.

- Floor Space: Most of the gantries are set up to take 4×8 sheets.  These custom shops are doing smaller runs and they’re not machining plywood sheets.  The desire to include climate control to keep the wood stable also means shop floor square footage is at a premium.  Smaller machine footprints help keep this cost under control.

- Dust Control:  The full enclosure of a VMC really helps keep the dust down in the shop.

- Tool Changer:  While they’re certainly available for CNC Routers, they’re standard on VMC’s.  Fender needs 21 tools for their application and keeps 20 in the changer and the 21st sits in a dedicated space on the table where the spindle can fetch it as needed.

Vacuum Table Tips

Vacuum Tables are often the preferred method of workholding for wood, and we have a huge page chock full of great information on how to use Vacuum Tables.

Check out our Total Guide to Vacuum Tables...

Calculating Feeds and Speeds for Wood

Feeds and Speeds Calculator for Wood and CNC Routers

For CNC Woodworking applications, a good Feeds and Speeds Calculator needs the following features:

- A detailed wood database to fine tune Feeds and Speeds by wood species.

- Support for the special cutters used by CNC Routers such as downcut, compression, and straight flute.

- If you have a hobby-class machine, it isn't as sturdy or rigid as a commercial machine. Feeds and Speeds will need to be adjusted.

- Support to help you limit feeds and speeds to levels that won't pop the parts of your vacuum table.

Our G-Wizard Calculator is the world's first feeds and speeds calculator specifically designed for CNC Router use, and it does all that and more.

G-Wizard's Material Database has hundreds of wood species built-in...

My Cutter Gets Really Hot or the Wood is Being Burnt

If the cutter is getting hot to the touch (careful!), and especially if there is any discoloration or the wood is being burnt, your feedrate relative to the proper feedrate is too slow, and the cutter is rubbing. For a full explanation of rubbing, see this article from our Feeds and Speeds Tutorials.

Geometry causes rubbing when we feed cutters too slowly. It heats everything up and will burn wood...

More CNC Wood Resources

Machining Wood in a Vertical Machining Center

CNC Machining Fuels Guitar Innovations

They Build Dreams: The Fender Custom Shop

Onsrud CNC Production Routing Guide

How to Survive Your First CNC Router Fire

Lumber Size Information

Try the Free Trial Version of G-Wizard Speeds and Feeds Calculator...

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