Solo: Enhanced Squareness Packages

What’s the purpose of enhanced Squareness?

The purpose of enhanced squareness is to provide the best possible locational accuracy within the machine working envelope. For end users with greater needs for feature parallelism, flatness, squareness and locational accuracy - we offer the enhanced squareness packages to guarantee a level of precision during the building & calibration process which is verified at Penta Machine using precision tooling.

How does Penta machine enhance the squareness of its build?

The Solo milling machine consists of two main assemblies, the linear axes and the trunnion. The linear axis of each machine is built with perfection in mind. Linear axes are assembled with ground components & a goal of 7.6 micron/0.0003 inch flatness & squareness. Each trunnion is assembled with ground components to minimize taper in the trunnion assembly. By increasing the tolerance of the assembly we are able to provide increased levels of squareness between the linear axes and trunnion.

How does Penta machine determine squareness of the Solo trunnion?

We determine the squareness of each of the 5 axes of the machine by installing a 100mm 6-sided AA granite cube into the completed assembly, then proceed to measure the change in Z across Y & the change in Y across X. We perform this measurement at B90 degrees, B0 degrees and B-90 degrees for a total of 6 measurements. Rotations in C cannot be made once the process has been started. This is to maintain and determine squareness without the use of compensation.

A dial indicator measures a granite cube mounted to a small CNC mill.

Standard - Taper is less than 15 micron or 0.0006 inches measured 6 ways

A portion of a small CNC assembly sits on a Coordinate Measuring Machine in the middle of the build process.
A dial indicator measures a granite cube of a small 5 axis CNC. The granite cube is tilted at an angle.

Squareness options: this determines the maximum measurable deviation or taper for any of the 6 measurements across a 100mm cube.

Increased - Taper is less than 10 micron or 0.0004 inches measured 6 ways

Super - Taper is less than 5 micron or 0.0002 inches measured 6 ways

How squareness effects part accuracy

  • Single rotational axis error. Within 5 axis machining the effects of non-squareness of a rotational axis directly correlates to feature accuracy. This is because the direction or vector of the taper does not remain fixed as the rotary axis rotates. A decreasing taper of 15 micron/0.0006 inches across the X axis will translate to an increasing taper of 15 micron/0.0006 inches when a rotation of 180 degrees is applied.

  • Cumulative rotational axis error. Introducing taper in a second rotary axis results in a cumulative error. A decreasing taper of 15 micron across the Y axis in combination with a decreasing taper of 15 micron across the X axis could potentially result in a cumulative error of 30 micron/0.0012inches/ 0.44degrees.

  • Translated rotational axis error. The effects of cumulative error are heightened by the rotation of multiple axes. Our calculation of cumulative error only represents a single rotary axis, by tilting the rotary axis 90 degrees, features created at the starting position potentially see a translated positional error of 30 micron/0.0012 inches in X, Y & Z meaning features may be tilted as well as locationally off by the calculated error.

  • New features on translated & rotated surfaces. New features at rotated positions are still affected by the original X & Y tapers and are potentially cumulative to the original error. These features can have a cumulative positional error of 61 micron /0.0024 inches/ 0.87 degrees in relation to features created at the starting position.

  • Total cumulative error. Each rotary axis is affected by 2 axes of error, because the trunnion of the Solo 5 axis mill is equipped with 2 rotary axes, it has 4 potential axes of error.

What applications should consider enhanced squareness

A machine build with enhanced squareness is available for users who require a feature locational accuracy which is greater than what can be provided by the standard squareness package. The standard squareness package measures a taper less than 15 micron /0.0006 inches measured 6 ways across the trunnion. While this squareness is common in industry and relatively small, it can accumulate to a rather large deviation in feature to feature positioning. Maximum positioning error applies to any machine with taper in its rotary axes relative to the linear axes over a 100mm/4 inches cubic envelope and is not unique to the Penta Solo Milling machine.

The following stats apply to the machine at the completion of our build:

  • Standard - 15 micron/0.0006 inches taper

  • Increased - 10 micron/0.0004 inches taper

  • Super - 5 micron/0.0002 inches taper