Example 2A: Calculate the speed and feed for a 1″ diameter, 4 flute HSS endmill in aluminum using a manual milling machine in lab.

Note that these speed and feed values are guidelines assuming proper (flooded) lubrication, workpiece stiffness and depth of cut.  When learning how to use the CNC, always start lower (around 60% on the spindle speed and feedrate override buttons) and work your way up as you gain confidence or purchase your own tools (lol).

TIP: Plunging should generally be performed at 75% of the speed and 25% of the feedrate of the calculated peripheral cutting parameters.

First, lookup the recommended surface speed in Table 1 for a 1” HSS endmill cutting aluminum (V ≈ 250 ft/min) and calculate the spindle speed from Equation 2 using the aforementioned 75% speed reduction:

Please begin by reviewing the comprehensive course document on this topic, as it clearly explains the process of calculating these parameters for drilling and milling operations.  The governing equations are summarized below.

Drilling speeds and feeds formulafor steel

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Note that these speed and feed values are guidelines assuming adequate (flooded) lubrication, workpiece stiffness and drill depth less than 3 drill diameters (0.75″).  When applying oil manually (as in the lab), scale the feed and speed back to 60%, so N = 450 rpm and f = 3.6 in/min (final answer).

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TIP: IF this was being performed on a CNC lathe, typical parting feed rates vary between 0.001 in/rev (for steels) and 0.005 in/rev (for plastics).  But remember, do NOT use the power feed when parting on a manual lathe unless you own the machine!

Drill speed calculator

TIP: Countersinking should generally be performed at 25% of the speed and the same feed per revolution as the equivalent sized drill.

TIP2: When drilling deeper holes (> 3xD) without high pressure TSC (thru spindle coolant), reduce spindle speed an additional 50%.

Drilling speeds and feeds formulacalculator

First, lookup the recommended surface speed in Table 1 (V ≈ 100 ft/min) and calculate the spindle speed from Equation 2:

Next, lookup the recommended feed per tooth (chipload) in Table 3 (ft ≈ 0.008 in/tooth) and calculate the feed rate using Equation 3:

Next, lookup the recommended feed per tooth (chipload) in Table 3 (ft ≈ 0.004 in/tooth) and calculate the feed rate using Equation 3:

TIP: Reamers should generally be run at half the spindle speed and twice the feed per revolution of the equivalent sized drill bit.

Example 4: Calculate the speed and feed for a 1″ diameter, 6 flute HSS annular cutter in ¼” thick aluminum on a manual milling machine in the lab.

* multiply feed values in table by 0.5 for difficult to machine materials, flexible toolholding or workpieces, or lighter-duty machines*

All of the information that you need to build our plans can be found in the standard plan. However, if you want even more granular detail to make your job easier, you should consider our premium plans. These come with additional shop diagrams that we drew when creating the prototypes. Shop drawings are not available for every plan.

The table below contains a recommended surface speeds for common materials when using DML equipment.  These values are conservative because our primary goal is fostering a safe learning environment (for our users and our tools!), not trying to squeeze every second out of each operation.

HSS drillspeeds and feedscalculator

TIP1: Since annular cutting is a plunging operation, it should generally be performed at 75% of the speed and 25% of the feedrate of the calculated peripheral cutting parameters (as with endmill plunging).

The International System of Units (SI), more commonly referred to as the metric system, is the alternative set of units that we have available for some of our plans. It uses millimeters, centimeters, and meters for measurement. This is the one you probably want if you are outside the United States. These plans are provided by our business partner, Australian Woodsmith, and are based on the original Woodsmith plan. However, dimensions and other elements of the plan may vary between the metric and standard versions. Be sure to double-check the plan before building.

Example 3: Calculate the speed and feed for a HSS countersink used to countersink a #10 clearance hole in aluminum using a manual milling machine.

Drilling speeds and feeds formulametric

The United States Customary System of Units (USCS or USC), more commonly referred to as the English or Imperial system, is the standard set of units for our plans. It uses inches and feet for measurement. This is the one you probably want if you are in the United States, and it is the one we have traditionally offered on this website.

First, lookup the recommended surface speed in Table 1 (V ≈ 250 ft/min) and calculate the spindle speed from Equation 2:

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HSS drillspeeds and feedsmetric

Note that these speed and feed values are guidelines assuming proper (flooded) lubrication, workpiece stiffness and depth of cut.  When applying oil manually (as in the lab), scale the feed and speed back to 60%, so N = 570 rpm and f ≈ 18 in/min (final answer).  Note also this problem assumes we peripheral milling versus plunge milling (since we never teach the students the latter in lab).

First, lookup the recommended surface speed in Table 1 (V ≈ 250 ft/min) and calculate the spindle speed from Equation 2:

TIP: When working with plastics with good machinability, use the cutting parameters for aluminum up until the point that the plastic melts.

TIP2: Do not plunge an annular cutter at a feedrate less than 0.001 ipt (inch per tooth) in strain hardening materials like 304 stainless or titanium.

First, lookup the recommended surface speeds in Table 1 (VALUM ≈ 625 ft/min, VSTEEL ≈ 250 ft/min (notice the 2.5 multiplier))

A general rule of thumb for materials which are strong enough to support the drilling process is that fr is between 1 - 3% of the drill diameter, depending on the material strength.

Note that these speed and feed values are guidelines assuming adequate (flooded) lubrication, workpiece stiffness and drill depth less than 3 drill diameters (0.75″).  When applying oil manually (as in the lab), scale the feed and speed back to 60%, so N = 900 rpm and f = 3.6 in/min (final answer).

HSS drillspeeds and feedschart pdf

Next lookup the recommended feed per revolution for the equivalent size drill bit in Table 2 (fr ≈ 0.006 in/rev) and calculate the feed rate using Equation 3:

Note: when applying oil manually, scale the feed and speed back to 60%, so N ≈ 420 rpm and f ≈ 4.8 in/min (final answer).  This is close enough to 500 rpm that I would first try this tool at the low end of high range with good oil application and see how it goes.

First, lookup the recommended surface speed in Table 1 (V ≈ 625 ft/min) and calculate the spindle speed from Equation 2:

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Note: since applying oil manually, scale the speeds back to 60%, so NALUM ≈ 1425 rpm and NSTEEL ≈ 570 rpm (final answer).  Note these are MAXIMUM values and lathe chuck safety must take precedence; spinning the lathe chuck at 570 rpm is about the upper limit of what we safely do in the lab, so for smaller or easier to machine workpieces, DO NOT EXCEED 600 RPM regardless of the calculation results, unless you are running a collet chuck.

Next lookup the recommended feed per revolution for the drill bit in Table 2 (fr ≈ 0.004 in/rev) and calculate the feed rate using Equation 3:

Every metal cutting operation requires selection of proper cutting parameters for success.  As a DML TA, you need to understand basic calculations that will allow the tools you use to work as intended.

Example 2B: Calculate the speed and feed for a 1/2″ diameter, 3 flute carbide endmill if peripheral and plunge cutting in aluminum using a CNC milling machine in lab.

Next, calculate the feed rate used for plunging.  Remember annular cutters should be fed at approximately 25% of the feedrate for an equivalent sized endmill.  From Table 3, lookup the recommended feed per tooth for a 1″ HSS endmill (ft ≈ 0.008 in/tooth) and calculate the plunge feed rate using Equation 3:

As you can see Acetal (Delrin) is one of the most machinable plastics and nylon is four times less machinable (which is why it should usually be avoided!).

Drilling speeds and feeds formulapdf

Note that these speed and feed values are guidelines assuming adequate (flooded) lubrication and workpiece stiffness.  When applying oil manually (as in the lab), scale the feed and speed back to 60%, so N = 330 rpm and f = 2.0 in/min (final answer).

TIP1: Recommended peck depth when drilling less than 3xD (e.g. 3 drill diameters) with flooded coolant is one drill diameter, or when applying oil manually, or under low pressure, is 50% of drill diameter.

Example 5: Calculate the speeds for parting off 1” diameter aluminum and 1” diameter mild steel workpieces on the lathe using the standard carbide part-off inserts.