How do you read this?

[BANDY]

Kind of embarrassing but I can find and good info on this, we usually do parts here that don't have this requirements. The print as it shows 2 coaxial holes, but don't have tolerance for the coaxiality. It has TP .001, as you can see in the attachment. Does it mean that holes should be coaxial within .001? or it just states the fact that this holes are on the same center?

[Wingman]

Two Coaxial Holes is just a 'Description' letting you know which holes are included in the requirement.

[cmmguy]

It shows the datums each being made up by the two coaxial holes. each datum is therefore a 3D feature used together as a datum for the profile. Something tells me that they would be in conflict with each other the way they are shown,

[inspector212]

The lower portion of both callouts is a "pass-pin" requirement. (M) of the hole minus the tolerance equals the size of the pin to pass. You have to do this by hand as I don't know how to do this with the demon.

[Jan d.]

What 212 said, but if you run V4.2 (sorry...) you can evaluate this using XactMeasure GD&T.

That specific call you could not do in V4.0 (impossible) and V4.1 (had a major bug in it). I have exactly the same calls (except the coaxial hole note) and V4.2 finally allows me to analyze this as is.

Jan.

[BANDY]

Thank you ! I got it now.

[Big John]

Coaxial tolerance

Bandy,

The 1st hole has a true position tol of 0.0045" to datum A and B. The 2nd hole has a coaxial pos, or TP of 0.001" to the 1st hole.

See ASME Y14.5

John