Hey guys

I've got a question about linear dimension and how to align correctly to them to get the most "correct" way measure them.

Ive got two examples:

You got a square block, lets say 100x100x100 (L x H x W) and you want to measure the lenght 100 (direction of Y+ in machine/program).

I see two ways to measure it in CMM.

1. Either measure one side (plane) of it (Y+/Y-) and align it as primary. Then evaluate the 2D lenght between the Y+ and Y- planes.

This would simulate you measuring it with a height gauge. (since you place it on the primary plane and then place the tip of the height gauge on the other plane.

2. You measure the top plane (Z+), align it as primary, then measure a line in Y+ direction and rotate Y+ around Z+. And then evaluate 2D distance between Y+ and Y- planes.

I cant find a way this would simulate any manual measurement equipment, but a lot of people tend to use this method.

You want to measure the distance between two inner holes. They are both supposed to have the same center in example X.

1. You do as the first example. Primary on a plane in the direction you want to measure, and then evalute the distance between the holes(circles).

2. construct a line between the circles, and use this line as rotation. Then evaluate the distance between the circles.

First example simulates a height guage again. You rest the plane on primary, Zero on the lowest point on the height guage, and measure the distance to the lowest point of the other circle, then add/remove radius.

Second example simulates a caliper, since you use the direction of the circles (wether they are in center or not) and then add/remove radius.

I really dont like linear dimensions, they confuse me. Alignment, type of element (plane, point etc).

Any one got some good sources of information for this? (besides expensive courses)

I've got a question about linear dimension and how to align correctly to them to get the most "correct" way measure them.

Ive got two examples:

**Example one:**You got a square block, lets say 100x100x100 (L x H x W) and you want to measure the lenght 100 (direction of Y+ in machine/program).

I see two ways to measure it in CMM.

1. Either measure one side (plane) of it (Y+/Y-) and align it as primary. Then evaluate the 2D lenght between the Y+ and Y- planes.

This would simulate you measuring it with a height gauge. (since you place it on the primary plane and then place the tip of the height gauge on the other plane.

2. You measure the top plane (Z+), align it as primary, then measure a line in Y+ direction and rotate Y+ around Z+. And then evaluate 2D distance between Y+ and Y- planes.

I cant find a way this would simulate any manual measurement equipment, but a lot of people tend to use this method.

**Example two:**You want to measure the distance between two inner holes. They are both supposed to have the same center in example X.

1. You do as the first example. Primary on a plane in the direction you want to measure, and then evalute the distance between the holes(circles).

2. construct a line between the circles, and use this line as rotation. Then evaluate the distance between the circles.

First example simulates a height guage again. You rest the plane on primary, Zero on the lowest point on the height guage, and measure the distance to the lowest point of the other circle, then add/remove radius.

Second example simulates a caliper, since you use the direction of the circles (wether they are in center or not) and then add/remove radius.

I really dont like linear dimensions, they confuse me. Alignment, type of element (plane, point etc).

Any one got some good sources of information for this? (besides expensive courses)

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