List of acceptable THRU callouts 1

[G_Apache]

Hi all,

At my place of work we're having a discussion over whether "THRU TO CENTER" is a valid/common callout.
I have seen "THRU", "THRU ALL", and "THRU TO BORE" but I am wondering if there is a generally agreed upon list of variations of THRU that would be generally understandable across companies and industries, or what you think that list would be.

 

[Burunduk]

I doubt you will find a list like that anywhere, including the ASME Y standards. ASME Y14.5 which covers the meaning of drawing requirements only mentions THRU and doesn't detail what should be specified when it's sort of THRU but not through the entire part.
However, you could help make a list for your workplace to be used in an internal standard. Try sorting which uses of THRU make sense and easily interpretable and which are not. You could conduct a survey in your workplace and in forums like this one.
I think I understand THRU, THRU ALL, THRU TO BORE, but I don't understand when THRU TO CENTER is appropriate. If the part is not hollow where the hole is drilled, then when it is drilled to the center it's a blind hole, not a through hole. If the part is hollow, then it's not really "TO CENTER", the hole only needs to break through the bore/hole/any internal feature which is at the center, doesn't it?

 

[powerhound]

In my slice of life THRU means through everything. The other option is THRU NEAR SIDE ONLY. That has covered pretty much everything I've done, I think.

John Acosta, GDTP Senior Level

 

[G_Apache]

Hi Burunduk,

This is an example of where we would use THRU TO CENTER. Basically it would be like THRU TO NEXT in Solidworks but I haven't seen prints with that callout whereas I have seen a couple with THRU TO CENTER.

I got mixed up a bit though - the middle flange thing should be on the left side so it is past the centerline.

I'll try THRU NEAR SIDE ONLY as powerhound suggested in the future though.

 

[drawoh]

G_Apache,

At the first sign of confusion, I do a section view.

Never forget that there is your version of what that means, and there is the reader's version of what that means.

--
JHG

 

[Burunduk]

Well, the left end of the dia. 2 hole doesn't reach the center...

 

[SirPhobos]

If anything, I'd denote it as "THRU TO CENTERLINE" in your example (and make sure the print shows clearly which walls that would include). But I've typically seen something more like "THRU NEAR SIDE ONLY" or "THRU ONE WALL".

-- SirPhobos

 

[CWB1]

I was taught in trade school that using "thru" and other ambiguous callouts is bad practice vs calling out the desired depth, and dont recall where but do know I saw it labelled such in either ASME or corporate standards since then with a bunch of examples. In this instance, if a machinist has the depth explicitly called out then there's no excuse not to be precise. If they cant quickly/easily find the depth then G's shaft might end up with a drill point mark on the ID opposite the hole.

 

[SwinnyGG]

There's only two scenarios where I'd ever us a 'thru' callout:

-there is a hollow part with 2 walls along the path of the hole in question, and no features between the walls which add any ambiguity: THRU NEAR SIDE ONLY

-There is a hollow part, or a solid part, or a hollow part with an unlimited number of internal features, all of which are pierced by the hole in question: THRU ALL

In my experience the two scenarios above cover something like 99% of cases involving a thru hole. For the rest, if there's any ambiguity whatsoever, I'm using a diameter with a dimensioned depth.