KEVOS® MAKEOS · Fasteners
Dowel Pin Joint Check (Pin Shear, Bearing, Fit Interference, Engagement)
Will the dowel pins locating two parts carry the sideways load without shearing or crushing the holes, what fit do the chosen pin and hole limits give, and is each pin engaged deeply enough?
Check of dowel pins locating two parts under a lateral load: the shear stress in the pins (as the bolt and pin shear and bearing tool, with equal sharing), the bearing stress on the shorter engagement in the softer part, both against your allowables, the largest and smallest interference from the pin and hole limits you enter, the type of fit that results, and the engagement in each part as a multiple of the pin diameter against your requirement.
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How this tool works
Inputs, units and where to find them
| Input | Unit | Typical source |
|---|---|---|
| Pin diameter | mm | Nominal diameter of the dowel pins. |
| Number of pins sharing the load | Number of pins that share the lateral load (equal sharing assumed). | |
| Shear planes per pin | choice | Single shear where the pin joins two parts; double shear where it passes through a middle part into parts on both sides. |
| Lateral load on the joint | N | Sideways load the joint must resist, including any shock allowance. |
| Engagement and allowables | ||
| Engagement in the first part | mm | Length of pin in the first part. |
| Engagement in the second part | mm | Length of pin in the second part. |
| Allowable shear stress in the pin | MPa | Allowable shear stress for the pin material and duty, from your design standard (hardened dowels are much stronger than mild steel pins). |
| Allowable bearing stress in the softer part | MPa | Allowable bearing stress for the softer of the two parts, from your design standard. |
| Least engagement as a multiple of the pin diameter | Least engagement in each part that your practice requires, as a multiple of the diameter. | |
| Limits of size | ||
| Pin upper deviation | µm | Upper deviation of the pin diameter from nominal, from the pin standard or drawing. |
| Pin lower deviation | µm | Lower deviation of the pin diameter. |
| Hole upper deviation | µm | Upper deviation of the hole from nominal, from the fit you specify. |
| Hole lower deviation | µm | Lower deviation of the hole. |
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: Pin diameter
- What it is
- The nominal diameter of the dowel pins that locate the two parts and resist the sideways load.
- Units and format
- Enter a number in mm: millimetres. The form accepts 0.000001 mm to 200 mm. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 8 mm as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- Shear stress falls with the square of the diameter and bearing stress in proportion to it.
- Get it right
- Use the pin size on the drawing; dowels are usually a little oversize on their nominal, which the limits below describe.
What this means: Number of pins sharing the load
- What it is
- The number of dowel pins that share the sideways load, each taken to carry an equal share.
- Units and format
- Enter a plain number with no unit. The form accepts 1 to 50. Use a whole number. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 2 as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- Shear and bearing stresses fall in proportion to the number of pins.
- Get it right
- Count only pins that can bear at the same time; with position errors one pin may take most of the load until the others bear.
What this means: Shear planes per pin
- What it is
- The number of places along each pin where it is loaded in shear: one where it joins two parts, two where it passes through a middle part into parts on both sides.
- Units and format
- Choose one of 2 options from the list: Single shear (two parts); Double shear (three parts).
- Example
- The form opens with “Single shear (two parts)” selected as a worked example. Choose the option that matches your case.
- Effect on the result
- Double shear halves the shear stress for the same load; bearing is unchanged.
- Get it right
- A dowel between a base and a plate is in single shear.
What this means: Lateral load on the joint
- What it is
- The total sideways load that tries to slide one part over the other and that the dowels must resist, including any shock allowance.
- Units and format
- Enter a number in N: newtons. The form accepts 0.000001 N to 100000000 N. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 6000 N as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- Shear and bearing stresses rise in proportion.
- Get it right
- If the bolts clamp the joint, friction carries part of the load; enter the share the dowels must take, or the whole load for a cautious answer.
Engagement and allowables
What this means: Engagement in the first part
- What it is
- The length of each pin engaged in the first part, which with the diameter sets the area that bears on that part and how firmly the pin is held.
- Units and format
- Enter a number in mm: millimetres. The form accepts 0.000001 mm to 1000 mm. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 12 mm as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- The shorter of the two engagements sets the bearing stress and the engagement check.
- Get it right
- Measure the depth of the hole in that part that the pin actually fills.
What this means: Engagement in the second part
- What it is
- The length of each pin engaged in the second part, which with the diameter sets the area that bears on that part and how firmly the pin is held.
- Units and format
- Enter a number in mm: millimetres. The form accepts 0.000001 mm to 1000 mm. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 16 mm as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- The shorter of the two engagements sets the bearing stress and the engagement check.
- Get it right
- Measure the depth of the hole in that part that the pin actually fills.
What this means: Allowable shear stress in the pin
- What it is
- The highest shear stress you allow in the pin material for this duty, from your design standard or the pin maker’s data with your factor applied.
- Units and format
- Enter a number in MPa: megapascals (1 MPa = 1 N/mm²). The form accepts 0.000001 MPa to 3000 MPa. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 150 MPa 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 shear pass line.
- Get it right
- Hardened and ground dowels are much stronger than mild steel pins; use the allowable for the pins actually fitted.
What this means: Allowable bearing stress in the softer part
- What it is
- The highest bearing (crushing) stress you allow on the hole wall in the softer of the two parts.
- Units and format
- Enter a number in MPa: megapascals (1 MPa = 1 N/mm²). The form accepts 0.000001 MPa to 3000 MPa. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 120 MPa 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 bearing pass line.
- Get it right
- Use the allowable for the softer part’s material, such as an aluminium plate or a cast iron base.
What this means: Least engagement as a multiple of the pin diame…
- What it is
- The least depth each pin must be engaged in each part, as a multiple of the pin diameter, for it to locate reliably and not tilt.
- Units and format
- Enter a plain number with no unit. The form accepts 0 to 10. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 1.5 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 engagement pass line.
- Get it right
- Use your own design practice; deeper engagement holds the pin more firmly but makes blind holes harder to clean.
Limits of size
What this means: Pin upper deviation
- What it is
- How far above nominal the pin diameter may be, the upper deviation of the pin tolerance, in micrometres.
- Units and format
- Enter a number in µm: micrometres (µm, microns). The form accepts -1000 µm to 1000 µm. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 15 µm as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- Raises the largest interference of the fit.
- Get it right
- Take it from the pin standard or drawing; positive means larger than nominal.
What this means: Pin lower deviation
- What it is
- How far above or below nominal the smallest permitted pin may be, the lower deviation of the pin tolerance, in micrometres.
- Units and format
- Enter a number in µm: micrometres (µm, microns). The form accepts -1000 µm to 1000 µm. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 6 µm as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- Raises or lowers the smallest interference of the fit.
- Get it right
- Take it from the pin standard or drawing; it must not exceed the upper deviation.
What this means: Hole upper deviation
- What it is
- How far above nominal the hole may be, the upper deviation of the hole tolerance, in micrometres.
- Units and format
- Enter a number in µm: micrometres (µm, microns). The form accepts -1000 µm to 1000 µm. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 15 µm as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- A larger upper deviation reduces the smallest interference.
- Get it right
- Take it from the fit specified on the drawing; for a basic-hole system the lower deviation is zero.
What this means: Hole lower deviation
- What it is
- How far above or below nominal the smallest permitted hole may be, the lower deviation of the hole tolerance, in micrometres.
- Units and format
- Enter a number in µm: micrometres (µm, microns). The form accepts -1000 µm to 1000 µm. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 0 µm as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- A smaller lower deviation increases the largest interference.
- Get it right
- Zero for a basic-hole fit; it must not exceed the upper deviation.
Method and formulas
- Shear stress τ = F ÷ (n × planes × π d² ÷ 4) (as the bolt and pin shear and bearing tool).
- Bearing stress σ = F ÷ (n × d × the shorter engagement).
- Largest interference = pin upper − hole lower; smallest = pin lower − hole upper; both positive is an interference fit, both negative a clearance fit, otherwise a transition fit.
- Engagement ratio = engagement ÷ d in each part, against the requirement.
- Example: 2 pins of 8 mm carry 6000 N at 59.683 MPa shear and 31.25 MPa bearing; the fit runs from -9 to 15 µm interference.
Limitations
- Equal load sharing between the pins; in practice hole position errors make one pin take more until the others bear.
- No moment on the pin pattern; a load offset from the pattern centre needs the eccentric bolt group tool. Edge distance and the strength of the parts around the holes are not checked.
- Example values are illustrations. Replace them with values for your actual task.
Typical uses
- Check dowels that locate a fixture plate or a machine part under side load
- Confirm the fit given by a pin and hole tolerance pair
- Check that each dowel is engaged deeply enough
Who it is for
- Machine designers
- Tool and fixture designers
- Mechanical engineers
What you get
- Shear stress and utilisation
- Bearing stress on the shorter engagement
- Largest and smallest interference and the fit type
- Engagement ratio in each part
Interpreting the result
- Dowels locate; bolts clamp. If the joint relies on dowel shear for its main load, check the bolts can keep the faces together as well.
- A transition fit can assemble either way, so specify the pin and hole limits that give the fit the assembly needs.
References
- Machinery’s Handbook, 29th edition (Industrial Press, 2012), printed pp. 631–668, 1720–1735, 1747–1748. 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 · KEVOS® original book
Draw the load path before sizing the clamp
What it covers: Use a free-body model to calculate fixture reactions, detect contact loss and distinguish a useful static check from a complete workholding qualification.
Useful alongside · 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.
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 Dowel Pin Joint Check (Pin Shear, Bearing, Fit Interference, Engagement) calculator