Gear Ref. Frame

Gear Ref. Frame



Before CMM-Manager can perform various gear-related measurements and reporting, the Gear Reference Frame must be established. This affects target point location and nominals, thus it is critical to be defined at the expected position with respect to the gear for the accurate result. The command should be inserted after Define Gear but before gear check functions like Lead Check and Profile Check.



There are 2 methods of establishing the Gear Reference Frame: Manually Set Up and Use Current Ref. Frame.

Manually Set Up



CMM-Manager offers the ability to manually probe features to define a specific Gear Reference Frame. This can be helpful in the instances where a part's reference frame is separate from the gear center, or if probing the teeth in DCC mode for alignment proves problematic. This can often be the case for fine gear teeth or when limited repeatable fixturing is available. It requires measurement based on the given instructions so there is inherently less flexibility in measurement.

External Gear

The gear should be placed in the CMM such that...
  1. Gear's rotational axis is normal to the machine table.
  2. The gap between 1st and last teeth is facing toward the front of the CMM.
  3. If there is a boss on the gear, please position it facing up or down based on how the Boss Depth direction is specified in Define Gear.
When performing the alignment in Run Mode...
  1. Manually measure the main bore as a cylinder. This will be the primary datum for the gear reference frame.
  2. Manually measure the top surface as a plane, which will become the secondary datum.
  3. Position the tip approximately at the center between the first and last teeth and click the OK button. CMM-Manager automatically measures two points: one on the left flank of the first tooth and the other on the right flank of the last tooth. The mid-point is used as the tertiary datum.
The resultant reference frame is shown in the picture below. Z-axis is leveled to the datum cylinder (+Z up). The intersection of the cylinder & datum plane is used to set the origin. +X will be clocked to align with the center of the 1st tooth.




Internal Gear

The gear should be placed in the CMM such that...
  1. Gear's rotational axis is normal to the machine table.
  2. The gap between 1st and last teeth is facing toward the front of the CMM.
  3. If there is a boss on the gear, please place it facing up or down based on how Boss Depth is specified in Define Gear.
When performing the alignment in Run Mode...
  1. Manually measure gear's main bore as a cylinder. This will be the primary datum for the gear reference frame.
  2. Manually measure the top surface as a plane, which will become the secondary datum.
  3. Position the tip approximately at the center between the first and last teeth and click the OK button. CMM-Manager automatically measures two points: one on the left flank of the first tooth and the other on the right flank of the last tooth. Mid-point of these points is used as the tertiary datum.
The resultant reference frame is shown in the picture below. Z-axis is leveled to the datum cylinder (+Z up). The intersection of the cylinder & datum plane is used to set the origin. +X will be pointing between 1st and last teeth.




Straight Bevel Gear

The gear should be placed in the CMM such that...
  1. Gear's rotational axis is normal to the machine table.
  2. The gap between 1st and last teeth is facing toward the front of the CMM.
When performing the alignment in Run Mode...
  1. Manually measure the main gear axis as a cylinder. This will be the primary datum for the gear reference frame.
  2. Manually measure the bottom surface of the gear, which will become the secondary datum.
  3. Position the tip approximately at the center between the first and last teeth and click the OK button. CMM-Manager automatically measures two points: one on the left flank of the first tooth and the other on the right flank of the last tooth. Mid-point of these points is used as the tertiary datum.
The resultant reference frame is shown in the picture below. Z-axis is leveled to the datum cylinder (+Z up). The origin will be located at the apex of the pitch cone. +X will be pointing between 1st and last teeth.




Use Current Ref. Frame

As an alternative to the manual setup shown above, this option enabled the user to define the necessary reference frame ahead of the time. There are few benefits to this approach:
  1. Datum features can be measured in DCC, allowing the gear inspection to be automated.
  2. If the reference frame is already set up on the gear to inspect other dimensions beforehand, selecting this option will simply reuse it instead of performing a redundant alignment.
  3. Customizable alignment scheme. For example, the datum scheme on your part is such that a plane is the primary datum instead of the rotational axis. In this scenario, the desired ref. frame should be created then select this option as the pre-built manual method assumes that the center axis is the primary.
The desired alignment should be taught before inserting the Gear Ref. Frame command with the Use Current Ref. Frame option. Also, the defined reference frame must match the one created by the manual method for the gear measurement and reporting to function properly. See below for expectations and requirements for each gear type below.

Show Prompt for Safe Move - This can be selected to suggest the operator to manually jog the probe before performing the tip change and subsequent DCC measurements.

External Gear

The gear should be placed in the CMM such that...
  1. Gear's rotational axis is normal to the machine table.
  2. The gap between 1st and last teeth is facing toward the front of the CMM.
  3. If there is a boss on the gear, please place it facing up or down based on how Boss Depth is specified in Define Gear.
The origin of the current reference frame before the Gear Ref. Frame function is expected to be at the point where the rotational axis and the top surface intersect. +Z should be pointing upward, and +X is between 1st and last teeth as well as facing toward the front of the CMM.


When executing the program, CMM-Manager will automatically measure two points: one on the left flank of the first tooth and the other on the right flank of the last tooth. Positive X-axis will be rotated in the direction of the 1st tooth afterward.

Internal Gear

The gear should be placed in the CMM such that...
  1. Gear's rotational axis is normal to the machine table.
  2. The gap between 1st and last teeth is facing toward the front of the CMM.
  3. If there is a boss on the gear, please place it facing up or down based on how Boss Depth is specified in Define Gear.
The origin of the current reference frame is expected to be at the point where the rotational axis and the top surface intersect. +Z should be pointing upward, and +X is between 1st and last teeth as well as facing toward the front of the CMM.


When executing the program, CMM-Manager will automatically measure two points: one on the left flank of the first tooth and the other on the right flank of the last tooth. Positive X-axis will be rotated in the direction of the 1st tooth afterward.

Straight Bevel Gear

The gear should be placed in the CMM such that...
  1. Gear's rotational axis is normal to the machine table.
  2. The gap between 1st and last teeth is facing toward the front of the CMM.
The origin of the current reference frame is expected to be at the apex of the pitch cone with +Z pointing toward the ceiling, and +X is between 1st and last teeth.

 


When executing the program, CMM-Manager will automatically measure two points: one on the left flank of the first tooth and the other on the right flank of the last tooth. Positive X-axis will be rotated in the direction of the 1st tooth afterward.