### Parameters Tab

This tab defines the general gear parameters used for measurement. PC-DMIS Gear requires these parameters to perform accurate measurements. Most of these values can be found in the drawing for the gear. If some of parameters are not provided from the drawing or if their value does not yet correspond to the drawing, the corresponding value can be estimated in order to make the measurement possible.

Gear Definition dialog box – Parameters tab for cylinder gears

Gear Parameters Area

Number of teeth: This box specifies the number of teeth around the gear.

Normal module or Diametrical pitch: Please consult the appropriate gear standard for the definition of this parameter. The heading for this box changes between “Diametrical Pitch” (for Inch) and “Normal Module” (for MM) depending on whether you selected Inch or MM as your unit of measurement.

Normal pressure angle: Please consult the appropriate gear standard for the definition of this parameter.

Face width [b]: This box specifies the width along the face of the gear tooth. It is always a positive number. See A in the diagram below.

A - Face Width
B - Tooth Height

Addendum modification coefficient [x]: Please consult the appropriate gear standard for the definition of this parameter.

Gear Area

The options in this area allow you to specify whether the gear is External (teeth on the outside) or Internal (teeth on the inside).

Units Area

The Inch and MM options in this area define the units of measurement to use in the created part program and for any typed distance values in PC-DMIS Gear.

Flank Direction Area

The options in this area define the flank direction of the gear:

Straight: Select this if it is a spur gear.

Left: Select this if it is a left-handed helical gear.

Right: Select this if it is a right-handed helical gear.

Helix Angle Area

This area contains options that define the angle of the helix
of the gear.

Complete Gear Area

Select whether or not the gear is a complete gear. Choosing Yes, means the gear is a complete gear all the way around. Choosing No means the gear is an incomplete (or segmented) gear. For segmented gears, the Incomplete gear definition area becomes available for selection.

Incomplete gear definition Area

This area is available for selection if you have an incomplete (or segmented gear). Using the box, you can type values to define the ranges of tooth segments available for this type of gear. Alternately, you can use the ... button to define the segmented gear using the resulting Edit dialog box. To delete an existing segment list, highlight the data that needs to be removed and press Delete.

Quality Standard and Grade Area

The options in this area define the standard used to create the gear and the standard against which you will measure the gear. The standard number is shown after gear standard type, for example, AGMA 2000-a88. Choose from the AGMA, DIN, ISO or JIS gear standard and specify the Grade for the selected standard.

Note: The Number of Teeth represents all the teeth that would be present around the gear if there were no gaps in the tooth pattern. Hence, the purpose of defining segmented gears is to remove the gaps from consideration for measurement. The incomplete gear shown below would be defined as having 36 teeth rather than the 18 teeth (six teeth in three actual segments) that actually exist.

Example of a Segmented Gear

For example, to define the above segmented gear, after first defining 36 teeth, you would add six segments of six teeth each for a complete gear. You would then select and clear the missing segments and end with three segments of 18 teeth with values something like this:

The Edit (segment) dialog box shows a range of three segments of six teeth each, making a total of 18 teeth. Notice that the teeth segments ranging from 7-12, 19-24, and 31-36 were cleared from the list to reflect the three incomplete or missing segments

When you click OK, the teeth segments appear in the Tooth box.

There are two ways to generate the segment list:

- Using “Auto Range”: When checked, all segments of teeth will be calculated according to Number of Teeth (as specified from the Parameters tab) Start Tooth No., End Tooth No. and Segments Number. For example, you could do the following for a gear with 26 teeth:

1. Select Auto Range to automatically define gear segments.

2. Type 4 for the Segment Number value, which means the all teeth will be divided equally into 4 parts.

3. Type 1 for the Start Tooth No. value, and type 4 for the End Tooth No. value. This will measure tooth #1, #2, #3, #4 in every section (since we are working with 26 teeth divided by 4 segments, there should be 6 teeth in every section) and tooth #5, and #6 are not measured.

4. Click Add, to populate the segment list. You will see the result is “1-4”, “7-10”, “13-16” and “19-22”. This defines the teeth to be measured. You may need to experiment with this method to get the desired result.

5. Click OK to save the segment list or Cancel to close without saving your changes.

- Manually adding segment ranges: When Auto Range is unchecked, you can add segments manually. Segments Number is disabled in this case, and you need to specify Start Tooth No. and End Tooth No., and then click Add to add the defined segment to list. Continue this process until each segment is defined. For example, you could do the following for a gear with 26 teeth:

1. Deselect Auto Range to manually define gear segments.

2. Type 1 for the Start Tooth No. value, and type 4 for the End Tooth No. value.

3. Click Add to add the segment “1-4” to the list.

4. Repeat steps 1 and 2 for the ranges "7-10", "13-16", and "19-22". This completes that same list that was created in the Auto Range example.

5. Click OK to save the segment list or Cancel to close without saving your changes.