Materials
Primary consideration is how fast the flutes of the cutter move against the material. A secondary consideration is the direction of rotation of the cutting tool (typically clockwise) and the interplay between the movement of the spindle and material, Climb vs. Conventional Milling.
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Feed and Speed Calculators
Several online tools exist for calculating linear movement (feeds) and spindle RPM (speeds):
In addition, one needs to decide upon a cutting depth advancment, and the amount of stepover (how much each toolpath overlaps, see the Glossary).
Metals
Aluminium
6061 plate
Forum discussions here:
- Feed: 160 mm/min
- Plunge: .2 mm
- Speed: 20,000 RPM (DW 660)
Shapeoko cutting metal — aluminum, includes specifics for bit, depth, stepover, feed and use of a cooling solution.
- Bit: 2 flute 1/8" endmill.
- Feed: 12ipm
- Speed: generic dremel turned on high (30k RPM?)
- Cut Depth: .0125"
- Stepover: .0625" (50% of bit diameter)
- Cooling/Lubricant: liberally applying WD40 as the job was being cut
Milling Aluminum - First Results
Re: Belt on outside (about milling parts for same)
Re: Shapeoko cutting metal (post with link to[1]
10mm 6160 aluminum plate
Carbon Fiber Plates and Aluminum Bearing Blocks
400 mm/min feed 20000 RPM 1/8" four flute solid carbide endmill. Spiral plunge lots of tap magic cutting oil throughout the milling. 0.25 mm pass depth.
Steel
Mild Steel
Stainless Steel
Forum post discussing this:
Brass
Plastics
UHMW
- Bit: single or double flute 1/8" end mill (with center point for drilling!)
- Feed: 30-60ipm
- Speed: generic dremel turned up to 11
- Cut Depth: 1/16" @50-60ipm or 1/8" @30-40ipm
- Stepover: ???
- Material Thickness: Varies (Tested 1/8" - 3/4")
- [Wikipedia Link]
Info:
When milling UHMW you want "chips" to come off the bit. If you find that you are instead getting "threads" of material you need to either increase your speed or increase your depth (preferably not both). You will notice a difference depending on the direction your mill is going. If you get a lot of "chatter" (bit seems to hop) while milling uphill (where bit is turning into the material) you'll want to slow your job down slightly.
There is a heat issue with all plastics, the idea is to remove as much material in one rotation of the spindle as possible then move on. If you dwell in one place too long your bit will heat up and the material will heat up, leading to distortion, bad smells, and dull bits.
There's a really good page on spindles and milling here: http://www.cncathome.com/spindles.html (site has been off-line for a while now --- is there an alternative?)
HDPE
Plastic that can easily be found in your local supermarket as a white cutting board (but also available in other colors). Only limitation is they are typically quite thin, usually not greater than 1/4"(6mm) thickness. Thicker material is available (9mm or so is sold as "half-inch" cutting boards) from specialty suppliers or online.
Forum posts discussing (very conservative) specifics of cutting it here.
- Bit: double flute 1/8" end mill
- Feed: 355mm/m
- Speed:11,000 RPM (Dremel 4000 set to 11)
- Cut Depth: 0.5mm (this value is probably too small --- tended towards strings instead of chips)
- Stepover: 1.5mm
One datapoint, Improbable Construct notes ``2 flute 1/8" endmill, 40% step over, 1/16" cut depth, 27000 RPM, at a feed speed of 1200 mm with good results. Of course that was with dual Y motors and the double x mod.
Polycarbonate (Lexan)
- Bit: double flute 1/8" end mill
- Feed: 1000mm/m
- Speed:20,000 RPM
- Cut Depth: 1mm
- Stepover: 2mm
Acrylic
Notes from IC for cutting his dust shoe:
- Bit: double flute 1/8" end mill
- Feed: 400mm/min
- Speed:20,000 RPM
- Cut Depth: 0.08"
- Stepover: n/a (through cut)
- Plunge Rate: 75mm/min.
Wood
Hard Maple
Forum post showing a cut in hard maple using a Dewalt DW660 here.
Forum user cchristianson posted the following numbers in Re: First real project! dimensional letter shop sign: 24 in/m for feed with 5 in/m plunge @ 1/16" passes (1/8" 4 flute end mill). The same values were used for a very hard mahogany as well.
Pine
Forum post showing small, detailed cuts in pine (including a Harley Davidson logo) here.
MDF
MDF (medium-density fibreboard) is a relatively easy material to cut. It's soft and evenly composed, so the bit should have no trouble working through it at a consistent pace. The main concern when cutting MDF is that cutting will yield a lot of airborne sawdust (which, due to how MDF is made, can be harmful to to inhale). Wearing a dust mask is certainly not a bad idea.
You should also be aware of burning issues while cutting MDF. If your cuts are making the wood darker and/or producing a smell, try using a faster feed rate or a better bit (a 2-flute carbide endmill works very well). Faster feed rates prevent the bit from staying in one place for too long, which is a factor in overheating.
Projects
- Three inch MDF Box Forum post with speed and bit specifics here.
- Bit: 2 flute 1/8" endmill.
- Feed: 100ipm
- Speed: ???
- Cut Depth: ???
- Stepover: ???
- Simple triangles (Blog post)
- Bit: 2 flute 1/8" carbide endmill
- Feed: 400mm/min (conservative)
- Speed: 30,000rpm (DW660 standard)
- Cut Depth: 7.5mm (entire 1/4" sheet)
- Stepover: ???
- 2D wing shape (Blog post) (Video)
- Bit: 2 flute 1/8" carbide endmill
- Feed: 400mm/min (conservative)
- Speed: 30,000rpm (DW660 standard)
- Cut Depth: 1.5mm (very conservative)
- Stepover: ???
- Signs carved out of MDF: here
Plywood
AngusF noted in Re: How to mount DW660?, “1/8" end mill cutting Baltic birch plywood at a 0.7mm depth per pass, I will miss steps at 800mm/min, but not at 700. I'm still using the stock spindle...”
With a DW660, double X, Y drive shaft, this gives a fairly clean edge.
- Material: 1/4" nominal (4.8mm - 5.2mm actual) Birch Ply from Home Depot
- Bit: 2 flute 1/8" Carbide
- Feed: 1000mm/m
- Speed: 30,000 RPM
- Cut Depth: 2mm
- Stepover: 2mm
Other
Corrugated cardboard
I cut this as a test first cut before moving onto heavier materials. I used a conical shape cutter that came with my rotary tool. It's coated with some sort of rough particles. The edges of the cuts are rather messy, which would be tricky to clean up (e.g. with sandpaper), especially in areas where little "islands" have been cut (inside the "a" and "e") as there's not much left below to hold them in place.
PCB
Copper circuit board cut on the forums here/
Rubber
(I have in mind to make rubber stamps, e.g. for a mini production run of home-made Christmas cards...)
Foam
Forum user Cwalster noted in post Re: Foam cutting?, "EPS and EPP ... the trick is to use HSS, flat end mills and to conventionally cut it. If you don't you get a fuzzy surface."
Forum user PsyKo noted the following settings in Re: Foam tool organizer:
33kg/m^3 Foam
- Bit: 6, 8 or 12mm wood end mill (such as these http://www.bois.com/media/192315/360x300-fraises.jpg)
- Feed: 1200 mm/min (can probably go higher, but I'm in no rush)
- Speed: ?
- Cut Depth: 5 to 10 mm
- Stepover: 50% of bit diameter
