KEVOS® MAKEOS · Manufacturing
Reaming Plan (Drilled Size, Stock, Speeds, Cycle Time, Holes per Reamer)
To ream a batch of holes to size, what size should the pilot hole be drilled, how much stock is left, what spindle speeds and cycle time result, and how many holes will a reamer do?
Plan for drilling and reaming holes: the pilot drill size from the finished size and your reaming allowance, the radial stock per side against your range, the drilling and reaming spindle speeds and feed rates (drilling as the drilling cycle planner tool), the feed per reamer tooth, the time per hole including the reamer's retract, the total time for the batch, and the holes per reamer and reamers needed from the reamer's life in metres of hole.
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How this tool works
Inputs, units and where to find them
| Input | Unit | Typical source |
|---|---|---|
| Finished hole diameter | mm | Finished diameter of the reamed hole. |
| Reaming allowance on diameter | mm | Material left on the diameter for the reamer, from the reamer maker or a cutting data handbook for this size and material. |
| Hole depth | mm | Depth of the hole. |
| Number of holes | Number of holes in the batch. | |
| Drilling the pilot | ||
| Drilling cutting speed | m/min | Cutting speed for the pilot drill in this material, from the tool maker or cutting data. |
| Drilling feed | mm/rev | Feed per revolution for the pilot drill. |
| Drill point angle | ° | Point angle of the drill (118° is common for general-purpose drills). |
| Reaming | ||
| Reaming cutting speed | m/min | Cutting speed for the reamer, usually well below the drilling speed; from the reamer maker or cutting data. |
| Reaming feed | mm/rev | Feed per revolution for the reamer, usually higher than the drilling feed. |
| Reamer teeth | Number of teeth on the reamer. | |
| Reamer retract | choice | Reamers are often withdrawn at feed to avoid marking the hole; choose rapid if your process allows. |
| Times and limits | ||
| Approach and breakthrough clearance | mm | Extra travel before and after the cut. |
| Positioning or tool change time per hole | s | Time to move between holes or change tools, per hole. |
| Reamer life in metres of reamed hole | m | Reamed length one reamer gives before regrinding or replacement, from your records or the maker. |
| Smallest radial stock you accept | mm | Least stock per side you allow (too little and the reamer rubs). |
| Largest radial stock you accept | mm | Most stock per side you allow (too much and the reamer is overloaded). |
| Highest spindle speed available | rpm | Highest spindle speed of the machine. |
What each input means
Open an input to see what it is, its units, the worked example and the common mistakes, with a small diagram.
What this means: Finished hole diameter
- What it is
- The finished diameter of the hole after reaming, the nominal size of the reamer.
- Units and format
- Enter a number in mm: millimetres. The form accepts 0.000001 mm to 500 mm. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 10 mm as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- Sets the reaming spindle speed and, with the allowance, the pilot drill size.
- Get it right
- Use the reamer size, which is usually made to give the hole tolerance on the drawing.
What this means: Reaming allowance on diameter
- What it is
- The material left on the diameter for the reamer to remove, the difference between the finished size and the pilot drill size.
- Units and format
- Enter a number in mm: millimetres. The form accepts 0.000001 mm to 10 mm. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 0.25 mm as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- Sets the pilot drill size and the radial stock that is checked against your range.
- Get it right
- Take it from the reamer maker or a cutting data handbook for the hole size and material; drills cut a little oversize, which reduces the real stock.
What this means: Hole depth
- What it is
- The depth of the hole to be drilled and reamed, measured from the face where the tool enters.
- Units and format
- Enter a number in mm: millimetres. The form accepts 0.000001 mm to 2000 mm. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 20 mm as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- Drilling and reaming times and reamer use rise in proportion.
- Get it right
- For a through hole use the material thickness; the clearance input adds the run-out.
What this means: Number of holes
- What it is
- The number of holes of this size and depth in the batch, used to total the time and the reamers needed.
- Units and format
- Enter a plain number with no unit. The form accepts 1 to 1000000. Use a whole number. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 50 as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- Total time and reamers needed rise in proportion.
- Get it right
- Count every hole that will be drilled and reamed with the same tools and settings.
Drilling the pilot
What this means: Drilling cutting speed
- What it is
- The surface speed at the outside of the pilot drill, which with the drill diameter sets the drilling spindle speed.
- Units and format
- Enter a number in m/min: metres per minute. The form accepts 0.000001 m/min to 1000 m/min. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 25 m/min as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- A higher speed shortens the drilling time.
- Get it right
- Take it from the drill maker for the drill type and work material.
What this means: Drilling feed
- What it is
- How far the pilot drill advances for each revolution of the spindle.
- Units and format
- Enter a number in mm/rev: millimetres per revolution. The form accepts 0.000001 mm/rev to 5 mm/rev. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 0.15 mm/rev as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- A higher feed shortens the drilling time.
- Get it right
- Use the drill maker’s feed for the diameter and material.
What this means: Drill point angle
- What it is
- The included angle of the drill’s point, which sets how far the point must travel past the depth before the full diameter is cutting.
- Units and format
- Enter a number in °: degrees of angle. The form accepts 60° to 180°. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 118° as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- A smaller angle lengthens the point and adds a little drilling travel.
- Get it right
- 118° is common on general-purpose drills; 135° and 140° are used for harder materials and carbide drills.
Reaming
What this means: Reaming cutting speed
- What it is
- The surface speed at the cutting edges of the reamer, usually well below the drilling speed to give size and finish.
- Units and format
- Enter a number in m/min: metres per minute. The form accepts 0.000001 m/min to 1000 m/min. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 10 m/min as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- A higher speed shortens the reaming time.
- Get it right
- Take it from the reamer maker or cutting data for the material; too high a speed spoils the finish and shortens reamer life.
What this means: Reaming feed
- What it is
- How far the reamer advances for each revolution; reamers usually run at a higher feed per revolution than drills of the same size.
- Units and format
- Enter a number in mm/rev: millimetres per revolution. The form accepts 0.000001 mm/rev to 10 mm/rev. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 0.4 mm/rev as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- A higher feed shortens the reaming time and raises the feed per tooth.
- Get it right
- Use the reamer maker’s feed; too low a feed makes the reamer rub, too high a feed tears the surface.
What this means: Reamer teeth
- What it is
- The number of cutting teeth (flutes) on the reamer, which divides the feed per revolution into the feed per tooth.
- Units and format
- Enter a plain number with no unit. The form accepts 1 to 40. Use a whole number. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 6 as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- More teeth lower the feed per tooth at the same feed per revolution.
- Get it right
- Count the flutes on the reamer to be used.
What this means: Reamer retract
- What it is
- Whether the reamer is withdrawn from the hole at the cutting feed or at rapid traverse after reaching depth.
- Units and format
- Choose one of 2 options from the list: At feed rate (common for a good finish); At rapid traverse.
- Example
- The form opens with “At feed rate (common for a good finish)” selected as a worked example. Choose the option that matches your case.
- Effect on the result
- Retracting at feed doubles the time the reamer spends in each hole.
- Get it right
- Withdrawing at feed is common because a rapid retract can mark the reamed surface; check your process.
Times and limits
What this means: Approach and breakthrough clearance
- What it is
- The extra travel added before the tool reaches the work and after it breaks through, so that it starts and finishes cutting at full feed safely.
- Units and format
- Enter a number in mm: millimetres. The form accepts 0 mm to 100 mm. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 2 mm as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- Adds to the travel of both tools and so to the time per hole.
- Get it right
- A couple of millimetres is usual for a programmed approach; more for uneven surfaces.
What this means: Positioning or tool change time per hole
- What it is
- The time to move between holes or index the work, counted once for drilling and once for reaming at each hole.
- Units and format
- Enter a number in s: seconds. The form accepts 0 s to 600 s. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 3 s as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- Adds directly to the time per hole.
- Get it right
- Measure it from a trial run or the machine’s rapid rates; tool changes between the drill and reamer can be spread across the holes.
What this means: Reamer life in metres of reamed hole
- What it is
- The total length of hole one reamer can ream before it needs regrinding or replacing, expressed in metres.
- Units and format
- Enter a number in m: metres. The form accepts 0.000001 m to 100000 m. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 30 m as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- A longer life raises the holes per reamer and lowers the reamers needed.
- Get it right
- Base it on your own records for this material; the reamer maker can give a starting figure.
What this means: Smallest radial stock you accept
- What it is
- The least stock per side you accept for the reamer, below which it tends to rub and burnish instead of cutting.
- Units and format
- Enter a number in mm: millimetres. The form accepts 0 mm to 5 mm. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 0.08 mm as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- Only moves the lower edge of the stock window; it does not change the times.
- Get it right
- Use your own practice or the reamer maker’s guidance for the size and material.
What this means: Largest radial stock you accept
- What it is
- The most stock per side you accept for the reamer, above which it is overloaded and the hole size and finish suffer.
- Units and format
- Enter a number in mm: millimetres. The form accepts 0.000001 mm to 5 mm. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 0.2 mm as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- Only moves the upper edge of the stock window; it does not change the times.
- Get it right
- Use your own practice or the reamer maker’s guidance for the size and material.
What this means: Highest spindle speed available
- What it is
- The highest spindle speed the machine can run, checked against the speeds the drilling and reaming need.
- Units and format
- Enter a number in rpm: revolutions per minute. The form accepts 0.000001 rpm to 100000 rpm. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 4000 rpm as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- Only moves the speed pass line; small drills are the ones most likely to need more speed than the machine has.
- Get it right
- Use the machine’s maximum, or a lower limit set for the holder or tool.
Method and formulas
- Pilot drill = finished diameter − allowance; radial stock = allowance ÷ 2.
- Spindle speed n = 1000 v_c ÷ (π D); feed rate = n f; feed per tooth = f ÷ z.
- Drilling travel = depth + point length D ÷ (2 tan(point ÷ 2)) + clearance (as the drilling cycle planner tool); reaming travel = depth + clearance, doubled if the reamer retracts at feed.
- Time per hole = drilling time + reaming time + two positioning moves; holes per reamer = life ÷ depth.
- Example: drill 9.75 mm, leaving 0.125 mm a side; 38.952 s a hole, 32.46 min for 50 holes, 1,500 holes per reamer.
Limitations
- Speeds, feeds, allowance and reamer life are your inputs; the plan does not choose them.
- Hole size, straightness and finish depend on the drill, the reamer, the machine and the alignment; the plan only checks the stock and the times.
- Example values are illustrations. Replace them with values for your actual task.
Typical uses
- Plan a drill-and-ream operation for a batch of holes
- Check the stock left for the reamer
- Estimate cycle time and reamer use
Who it is for
- Machinists
- Process planners
- CNC programmers
What you get
- Pilot drill size and radial stock
- Drilling and reaming spindle speeds and feed rates
- Feed per reamer tooth
- Time per hole and for the batch
- Holes per reamer and reamers needed
Interpreting the result
- Too little stock makes a reamer rub and glaze the hole; too much overloads it and spoils size and finish: the stock window matters as much as the speed.
- Retracting the reamer at feed doubles its time in the hole, which often makes reaming the longer of the two operations.
References
- Machinery’s Handbook, 29th edition (Industrial Press, 2012), printed pp. 853, 1059, 1084–1092. Topic reference; no source tables or recommended settings are reproduced.
Learn the Concepts Behind This Tool
These KEVOS® Library readings explain the method this tool uses, with worked examples.
Method explained here · Library collection
Drilling, reaming and tapping: making holes that are the right size, in the right place
What it covers: A practical guide to holemaking for designers, buyers and workshop leaders: drill types and points, deep holes, reaming allowances, boring, countersinks, tap selection and tapped-hole design.
Method explained here · KEVOS® original book
Drilling, reaming and tapping calculations
What it covers: Calculate drilling speeds, feeds and hole times including point length, estimate drilling power and torque, choose tap drill sizes and time synchronised tapping cycles.
KEVOS® tools are screening and decision-support utilities. Verify important financial, engineering, safety, legal or operational decisions using appropriate professional standards and your organisation’s approved data.
Open the Reaming Plan (Drilled Size, Stock, Speeds, Cycle Time, Holes per Reamer) calculator