Check what the
geometry means.

Guide pillar: geometry becomes mechanics

For a solid circular guide with d = 25 mm:

Area A comes from the circle’s geometry. The second moment I is the area integral of squared distance from a centroidal bending axis; it describes how effectively the section distributes material against bending. Section modulus Z converts bending moment to maximum nominal stress. Radius of gyration r connects area and bending distribution.

These geometric properties provide the link between the CAD dimensions and analytical stress/stiffness calculations.

Check the slenderness before choosing a model

The geometric slenderness ratio is approximately 32 for the full 200 mm pillar. This is not a highly slender member, so a simple Euler result should not automatically be treated as the governing compressive capacity. Material yielding, actual effective length, end restraint and contact conditions must be established before a column capacity is claimed.

The effective slenderness for a column model is KL/r, where K represents its end restraint. The calculation above uses geometric length only; it is not an allowable-load calculation.

Projected bearing area

For one bush, d = 25 mm and L = 60 mm. The projected cylindrical interface is a rectangle d wide and L long.

The pressure expression applies if a total lateral load F distributes equally among all four bushes over the full contact length. With F in newtons and area in mm², pressure is in MPa.

This projected-area calculation provides a first screening method for interface bearing pressure. A production design would additionally require bush material, clearance, lubrication, loading distribution and wear criteria.

Spacing gives a moment its reaction couple

The diagonal follows the Pythagorean theorem. The reaction relation follows moment equilibrium: two equal and opposite forces separated by s create a couple M = Fs.

A wider guide spacing reduces the reaction force required to resist the same overturning moment. The actual force distribution among four guides depends on the direction of loading, clearances and structural stiffness. Use the separation perpendicular to the force couple; the diagonal is not automatically the governing lever arm.

Equal nominal diameters do not define a sliding fit

The source geometry defines both mating diameters nominally as Ø25 mm. Nominal CAD dimensions alone do not define a manufacturable sliding fit. Production design would require an intentional tolerance class based on accuracy, lubrication, temperature, manufacturing process and service conditions.

ISO 286 fit selection would be a logical next design step.

Motion needs remaining overlap

e_initial = initial pillar/bush engagement
S = upward stroke
e_remaining = remaining engagement

This relation describes withdrawal where overlap reduces one-for-one with upward travel. While a pillar still extends fully through a bush, its full bush engagement can remain constant; use the actual endpoint geometry to identify the applicable travel interval.

The animation stroke should remain within the geometry that maintains pillar/bush engagement. The website does not claim a design stroke until it is measured from the actual CAD configuration.