Using flange with scallops cut into it as datum

[jskevin]

Hello,

I have a bolt flange that has scallops cut into it so material is removed between the bolt holes. Can I use the outside diameter of the flange as a datum, now that its not a circle, but just a number of edges that are tangent to that outside diameter? I have a picture attached. Does this approach work, or maybe would it be better to make the bolt pattern datum B?

Thanks!

 

[Burunduk]

What feature(s) locates this flange in assembly? Is it the clearance holes for the bolts or maybe the center bore?

 

[TheTick]

While technically legal, you may want to put some thought into the feasibility of this. At least enough thought to get to the realization that it's not such a great idea.

 

[jskevin]

Yes its just the clearance holes for bolts which locates this part, and the OD doesn't mate with anything. So it would make a lot more sense to use the bolt pattern as datum B, right? Thanks for helping me think this through!

 

[drawoh]

jskevin,

A complex shape like your scalloped flange, can be fixtured fairly easily if you call it up at MMC. We can make tooling.

Why do you want to do this? I think the hole pattern makes a better secondary datum feature.

--
JHG

 

[CheckerHater]

How about Position of holes wrt [A] and Profile of the flange outline wrt [A]?

"For every expert there is an equal and opposite expert"
Arthur C. Clarke Profiles of the future

 

[Burunduk]

So it would make a lot more sense to use the bolt pattern as datum B, right?

Right. And profile those scallops with reference to |A|B(M)|. This will probably reflect function the best way.

 

[Tmoose]

What does the center hole do?

For that matter, what do the scallops do, and why is one missing>