Bottom Tap callout on a drawing 1

[nld]

Does anyone truly know how to callout a bottom tap on a drawing?

 

[pylfrm]

nld,

Are you referring to an actual tap (tool used to create internal threads), or to a threaded hole?

If the latter:

(e) The drawing should define a part without specifying manufacturing methods.

pylfrm

 

[3DDave]

The callout is by specifying the desired depth of the thread and not allowing the pilot hole to go much farther or, somewhat oddly, to specify that compliant threads shall extend to within a certain distance of the bottom of some aspect of the pilot hole.

Most drawings are for inspection purposes, by which time the tool used is long gone. If you are creating a process drawing I'd recommend creating a controlling document for the tapping tools and use those in the instructions.

 

[nld]

I surmised that there is not a specific way or to put it another way, NO, you simply defining the tap depth and either a “DO NOT BREAK THRU” note or show a section which would have a dimension which controls the depth of the tap drill if there is a specific wall thickness to be maintained beyond the end of the drill point. If really critical, the use of a more costly process, a flat bottom hole, but again specified with a controlling dimension.

The only time I have ever specified a bottom tap on a drawing was for a Heli-Coil STI tap. But that was when a machine shop requested it so they could determine the tap drill depth.

Thanks Guys

 

[mkcski]

nld:

The Y14.5-2009 Standard has the below as a Fundamental Rule. I agree with the above, define the product on the drawing and let mfg and QA figure out how to make and confirm the design requirements.

1.4(e) The drawing should define a part without specifying
manufacturing methods. Thus, only the diameter
of a hole is given without indicating whether it is to be
drilled, reamed, punched, or made by any other operation.
However, in those instances where manufacturing,
processing, quality assurance, or environmental
information is essential to the definition of engineering
requirements, it shall be specified on the drawing or in a
document referenced on the drawing

Certified Sr. GD&T Professional

 

[nld]

Thanks! All set.