How to Measure a Cope Angle in a Tube

This article discusses how to measure coping and the tube shape in VTube-LASER. The method measures the coping as if it were an additional straight on the end of the tube. In this method, an adapter pipe that joins the main pipe at the coping can be treated like an extra end-straight on the pipe in VTube-LASER.

STEP 1: Design a Coping Adapter in a Solid Modelling Program

In this example, we designed an adapter in SOLIDWORKS that simulates the joining pipe to the main pipe.

This adapter acts like an additional leg on the end of the tube (see the red section).

Remember that because VTube calculates diameters on the fly, it never matters if the adapter diameter is the same as the main pipe. VTube-LASER will be able to find the centerline of this geometry, which is exactly what you need to check for the coping.

The length of the adapter is not important, but the longer it is, the more accurate the VTube math engine can be in projecting to the centerline.

Now, export this model to a STEP file for import into VTube-LASER.

STEP 2: Import the Model with the Adapter into VTube-STEP

Every VTube-LASER includes VTube-STEP as a mode. Switch to STEP mode, clear the project, and import the STEP model created in the solid modelling program.

STEP 3: Collect the Surfaces with the Adapter in VTube-STEP

Use the Collect feature to build a collection of cylinder surfaces. Include the adapter as the end straight.

STEP 4: Rebuild the Model in VTube-STEP

Right click and rebuild the model.

STEP 5: Confirm the Parametric Model in VTube-STEP

You can now confirm the new parametric model (the model that is controlled by new XYZ coordinates) by pressing F9 to turn on and view the point labels.

STEP 6: Switch to VTube-LASER Mode and Measure the Part

Switch to VTube-LASER, attach the adapter (temporarily) to the coping on the part, then measure and qualify the entire part with the adapter.

It is not a problem that there is no radius at the first intersection between the first and second straights. The measurement and qualification will still produce useful information about how to adjust the tube and the coping.

STEP 7: Setup and Align the Measured Part

In this alignment, we used 321 Plane Line Point alignment to lock the tube to itself, and allow all the error to float to the coping end of the tube.

The pink tube is the measured aligned tube. It allows you to visualize how far out of the envelope the coping is when the adapter is attached.

STEP 8: Get the Rotational Adjustment

You can also print out a Bender Corrections Only report to see the exact rotational adjusting to make to the part when cutting the coping.