GD&T tube profile tolerances are always double the VTube-LASER tangent point envelope tolerances. So, a GD&T profile tolerance of 3 mm is VTube-LASER's 1.5 mm envelope tolerance. All tolerances shown below are half the GD&T profile tolerances.

(You can read more about VTube-LASER Tangent Point Tolerance Envelopes in "VTube-LASER Tangent Point Tolerances")

See this end profile image to visualize why GD&T profiles are double the VTube-LASER tangent point tolerance envelopes.

This image shows a tube with a 0.060" diameter and a 0.030" envelope to visualize the envelope's scale in VTube.

This is an example from a print shared with us by a customer. Most customers prefer this method for specifying tube shape tolerances using GD&T.

The call-out in the green circle shows GD&T symbols that indicate a datum and tolerances using a feature control frame (the boxes with information). The GD&T tolerance of 6 mm becomes a VTube-LASER envelope tolerance of 3 mm in space for the center legs of the tube.

The GD&T tolerances at the end in the red circle show a profile tolerance of 3 mm and a perpendicularity tolerance of 2 mm for the end component.

The end call-outs refer to the end component's shape and position relative to the tube - not the tube shape. See the comments below about the end component.

Read the GD&T feature control frame for the tube shape like this:

• Each straight is considered a "Datum A" because the call-out says "9 X the OD of 9.53.
• The circular symbol that looks like a target indicates "true position." "True position" means that the tolerance is interpreted as a 3D position and not to be locked to an X, Y, or Z axis.
• The tolerance is 6 mm larger than the 9.53 mm OD - because the circle with an M indicates that this is the MAXIMUM MATERIAL CONDITION. This means that the tube wall cannot exceed the tolerance in space.
• The equivalent VTube-LASER tolerance for this tube in the middle straights is 3 mm - because VTube-LASER deviations are considered spherical radius true positions.

Read the GD&T feature control frame at the end component of the tube is understood like this:

• The half-circle indicates a profile tolerance. The inside of the end component must conform to the profile of the end of the tube's diameter (9.53) because the datum is "A" - which is the tube diameter.
• The tolerance for the end profile is 3 mm.
• This is a maximum material condition, which means that the ID of the end component cannot exceed 3 mm outside of the 9.53 diameter. In VTube-LASER terms, the ID of the fitting is constrained to 1.5 mm of tolerance.
• It would be best to measure the ID with calipers and confirm that it is not more than 1.5 mm away from the diameter in any direction.
• The next feature control frame shows an upside-down. It indicates a perpendicularity tolerance of the face of the end component.
• This tolerance cannot exceed 2 mm from perpendicularity from datum B.
• So, the component face may not wobble more than 2 mm from the axis formed between points 1 to 2 - because the circle with an M indicates that this is a MAXIMUM MATERIAL CONDITION. This means that the fitting face cannot twist, relative to the tube, more than that tolerance in space.
• To find the exact equivalent in VTube-LASER, we suggest using a machined adapter with a 90-degree bend attached to the end component. Set the tangent tolerance for that adapter's centerline to 1 mm because VTube-LASER deviations are considered spherical radius "true positions."