### Helix/Lead Tab

This tab lets you specify the required data for the measurement of the Helix
/Lead as well as the analysis parameters for each measurement. Helix/Lead measurement is optional; if you don’t want to measure the Helix/Lead, deselect the Measure it option. All the values in the Measurement Parameters area are required for measurement.

Gear Definition dialog box – Helix/Lead tab for cylinder gears

Measure: When this check box is selected, the Helix/Lead will be measured during the measurement process based on the parameters defined on the Helix/Lead tab.

Measurement Area

Number of Teeth to Measure: This value is the number of teeth of the gear on which you want to measure the Helix/Lead. The teeth measured will be as close to equally spaced around the gear as possible starting with tooth #1. The default value is 4.

Teeth to be measured: Click Edit to open the Edit Tooth list to be measured dialog box.

Edit tooth list to be measured dialog box

Create the tooth list by typing each tooth number that will be included separated by a comma. The number of teeth listed should be the same as the Number of Teeth to Measure value. For example, if you want to measure the profile for Tooth #1, #8, #14, and #20 just input 1,8,14,20 in this edit box. This value will not affect segmented gears; however, be sure not to define a non-existing tooth number. Click OK to save the tooth list or Cancel to close without saving.

Helices on left or right flank: This list lets you specify the flank to measure. Available options are: Left, Right, and Both.

- For an external gear imagine you are standing on the center of the gear and looking forward at the gear's tooth. The left flank is on the left side of the tooth and the right flank is on the right side of the tooth.

- For an internal gear, imagine you are standing in the center of the hole and are looking at a space between two teeth. The left flank is on the left side of that space and the right flank is on the right side.

Start Z Coordinate (near lower face): This value is Z coordinate location where the Helix/Lead scan begins. The Helix/Lead scans always start at the bottom and move upward.

End Z Coordinate (near upper face): This value is Z coordinate location where the Helix/Lead scan ends. The Helix/Lead scans always start at the bottom and move upward.

Diameter of Measurement: This value is the Diameter at which the Helix/Lead scans are measured.

Evaluation Area

Start of Evaluation Range (lower face): This Z coordinate value represents where on the Helix/Lead scan you want to begin the evaluation. You should use a value slightly larger than the Helix/Lead Start Z Coordinate value.

End of Evaluation Range (upper face): This Z coordinate value represents where on the Helix/Lead scan you want to end the evaluation. You should use a value slightly smaller than the Helix/Lead End Z Coordinate value.

Magnification of Deviations: This value is a percentage that all errors will be magnified by for display in the analysis.

Magnification of Range (Def. autom): This value is percentage that all errors will be magnified by for display in the analysis. If you type a zero, PC-DMIS Gear calculates the value internally.

Tolerance of Helix/Lead Angle Dev. (fHβ
): Provides the allowable distance between two design helices which intersect the mean helix at the extremities of the evaluation range. Please see the appropriate gear standard for a definition of this value.

Tolerance of Total Helix/Lead Dev. (Fβ
): Provides the allowable distance between two design helices which enclose the actual helix over the evaluation range. Please see the appropriate gear standard for a definition of this value.

Tolerance of Profile Form Dev. (ffβ
): Provides the allowable distance between the two design helices parallel to the mean helix which enclose the actual helix over the evaluation range. Please see the appropriate gear standard for a definition of this value.

Tolerance of Lead Error (Vψ): Please see the appropriate standard for a definition of this value. This value is for the AGMA gear standard
only.

Evaluate Crowning: This value determines if crowning should be evaluated. If it is check then crowning will be evaluated and if it is not checked then crowning will not be evaluated.

Minimum Crowning: Please see the appropriate standard for a definition of this value.

Maximum Crowning: Please see the appropriate standard for a definition of this value.

This button causes PC-DMIS Gear to use the values input on this tab as well as the Parameters tab to calculate the tolerances of the Pitch
and Runout
based on the standard specified.

Report Setting

Draw K-Chart: This check box determines whether or not the Tolerance K-Chart appears in the report. For a definition of the K-Chart, consult the gear standard.

Draw Grid Line: This check box determines whether or not grid lines are displayed in the report. Grid lines act as a ruler of sorts, indicating in the report how large the deviation is.

Define K-Chart: This button lets you define the parameters of the K-Chart for profile and helix/lead. See the "Define K-Chart" topic.