How do I apply a datum to a tapered bore? 1

[mitchk]

I have a gear with a tapered bore that will be pressed onto the mating part (shaft). The centerline of the tapered bore is the primary datum. How is the proper way to dimension this on my drawing?

Thanks!

Mitch Komarmy
Quality Lab Manager
ZF Wind Power LLC

 

[fsincox]

I would reference: ASME Y14.5M-2009, fig 4-3 or 4-44 if you intend the whole feature as a single datum.
Frank

 

[mitchk]

Thanks! I currently only have the 1994 standard but I will get the new one.

Mitch

 

[fsincox]

It is just shown with the "flag" touching the face or an extension line coming from it.
Frank

 

[Mattyp88]

I am fairly new to GD&T in the industry but you could set a profile on the taper surface and set it to be a datum, similar to fig 4-3, as mentioned by fsincox

OR

Use datum targets on the diameters at both ends of the taper and let them form the axis. It is shown for cylindrical features in Fig. 4-51 of the standard.

 

[MechNorth]

You can also put the callout on the surface profile FCF used to control the conical feature. There are a number of ways to establish the datum; full surface, two sets of datum target points, areas, lines, or combinations thereof. It all depends on how the part mates up and functions.

Jim Sykes, P.Eng, GDTP-S
Profile Services

http://www.profileservices.ca

TecEase, Inc.

http://www.tec-ease.com