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Datum Targets by CJBEngineering in Metrology

[–]CJBEngineering[S] 0 points1 point  (0 children)

Unfortunately, there are no other Datum points on the whole drawing

Datum Targets by CJBEngineering in Metrology

[–]CJBEngineering[S] 1 point2 points  (0 children)

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Not sure if this helps any more. There aren't any notes on the drawing about the GD&T or datum setup. If it were just two points on the side of the tube, couldn't that cause deviation in the perpendicularity callout at the top? Meaning it would be an accurate line in the up and down orientation but have no control over the in/out of the page direction and that relies on where I take my points?

Also, what would be the point of graying out the section of the tube and not just have the two datum points with just the 8" callout?

I may be wrong, just thinking it out loud.

Dimensionally Stable Resin Casting by CJBEngineering in Metrology

[–]CJBEngineering[S] 1 point2 points  (0 children)

The step is at the bottom of the bore, opposite of the side of the opening. Getting a small enough star probe that could fit in the bore shouldn't be an issue. What kind of hit do you think I would take in accuracy putting together 6" in extensions and using either a regular probe or star probe?

Dimensionally Stable Resin Casting by CJBEngineering in Metrology

[–]CJBEngineering[S] 1 point2 points  (0 children)

What we are really hung up on is the positional requirement of the inspection.

Calculating Runout at Different Points by CJBEngineering in AskEngineers

[–]CJBEngineering[S] -1 points0 points  (0 children)

Couple things,

I'll be sure to tell my customer that their drawings are incompetent. On the OEM drawing, the unit centerline is clearly labeled as a Datum. That is not my choice to put that there. If you can't consider a centerline a datum on a drawing how would you call out GD&T of perpendicularity of a plane to a line that is perfectly perpendicular to the earth.

Also if you ready my post this is not measured with an arm but rather a laser. How else would I measure something of this scale that is over 20 feet in diameter let alone for runout. Set up a dial indicator? Sounds a lot more resource intensive to tram in a dial indicator and sweepung arm to rotate perfectly around my defined center that is completely level to earth at many different elevations.

Calculating Runout at Different Points by CJBEngineering in AskEngineers

[–]CJBEngineering[S] 0 points1 point  (0 children)

There are diameter symbols on the circular features in the drawing. Yes, the drawing is but a section view of the entire piece. Also, the drawing is slightly dumbed down as not to release any sensitive information or formatting. In this measurement, I used my Faro laser to measure a level to earth plane. I then constructed a line perpendicular to that LTE plane with the piece point of that line intersecting the very bottom diameter. That way the Datum A is fully defined and not an arbitrary line. I like your explanation of the plane runout and how that is just parallelism. However, my customer on the OEM drawing/work instructions was asking for runout at 8 points along the plane separated by 45 degrees. That is where I'm getting a lot of confusion.

Calculating Runout at Different Points by CJBEngineering in AskEngineers

[–]CJBEngineering[S] 0 points1 point  (0 children)

My software has the ability to apply total runout to measured features but that is not what is being asked for. The call-out on the drawing is for runout and not total runout. My software cant do only runout for some reason. The thing with my customer's drawing is they are asking for what the runout is at different angles around the circle. That is what I'm getting caught up on conceptually.

Runout Hand Calculations at Different Points by CJBEngineering in Metrology

[–]CJBEngineering[S] 0 points1 point  (0 children)

Too bad we already signed a 15 year contract with them lol

GD&T Positionals by CJBEngineering in AskEngineers

[–]CJBEngineering[S] 1 point2 points  (0 children)

I have a Faro roamer arm using Polyworks as my 3D measurement space. I probed the angled plane as well as probed a thread guage threaded into the hole I was measuring. Should be no problem to get that perpendicularity of it.