Question about using the term 'THRU' on a drawing, when dealing with a pair of intersecting holes 1

[MASawtell]

Have an example of something that has me a bit confused. Have a threaded hole that will 'break through' the one side of another hole in a part, which will be shown as a 'blind hole' on a view in a part. Normally, I will put a depth that will not affect the other side of the other hole, but enough to pierce the hole completely. I have a colleague that insists that I would be putting 'THRU' for the depth, but have had the understanding that 'THRU' tells the machine shop to drill a hole completely through a part. Before anyone asks, I have a copy of ASME Y14.5-1994 (Re-affirm 2004) and ASME Y14.5-2009 in front of me, and have seen the Section 1.8.9 (1994) and Section 1.8.10 (2004) for Round Holes, which is clear on blind holes, but it would be nice if there was additional standards I could use in the upcoming debate.

 

[MASawtell]

Gentlemen, if the call out is for a threaded hole, then I believe most folks would assume there is a degree of machining involved.

 

[Tunalover]

Having not read through the thread in detail, I would just call out the diameter or thread and add the note NEARSIDE ONLY.



Tunalover

 

[CheckerHater]

Some long time ago I was designing hydraulic manifold blocks, which are (mostly) rectangular chunks of metal drilled from all 6 directions.

Holes terminating (or not terminating) into each other was matter of highest importance, and it was all in paper and pencil, no CAD at that time.

The only way to get what you want was to specify depth for every hole even if in final product the end of the hole would disappear consumed by another feature. No “TO CROSS-HOLE”, no “THRU THE WALL”.
Specifying exactly what you need was safe, straightforward and standard-compliant way to get functional part.

If it was one-time product t the shop could live with drilling couple extra unnecessary millimeters.
For production they could figure the appropriate shortcuts and make them part of the process.

Some 2 cents from the guy who designed his share of drilled holes.

 

[randy64]

CH, I can see how in a high production scenario giving a depth would be preferred. But that does not mean that THRU TO HOLE or it's variants are wrong.

 

[CheckerHater]

I never said it was wrong. I was just trying to distinguish between THRU TO HOLE being functional requirement or just "permissible".
Is there a need to emphasize relation between holes when it's not relevant?
As a matter of personal preference I said many times on this forum that now, in the time of CAD systems, the best way to clarify anything is to cut a section.

 

[ewh]

In situations involving complex geometry and intersecting holes, many at compound angles, indicating a depth is a good idea. The geometry of manifolds and precision control valves (for example) is made much clearer by including hole depths, even if a section is present and the depths are reference (depending on how the hole is called out). It is in these situations that you can save the machinist the time and headaches involved in figuring the correct depths required.
In the OPs situation and similar, THRU TO BORE is sufficient. The key is to match the method to the product.

“Know the rules well, so you can break them effectively.”
-Dalai Lama XIV

 

[KENAT]

So for me the problem with simplistically specifying a depth in this situation comes from the ASME stds.

Unless otherwise specified, all geometric tolerances apply for full depth, length, and width of the feature."

If my hole intersects another hole before it reaches the depth I state then by definition it is not meeting its size/diameter tolerance once it has intersected with that hole.

So as a minimum I have to say something 'specify otherwise'.

Posting guidelines faq731-376

http://eng-tips.com/market.cfm?

(probably not aimed specifically at you)
What is Engineering anyway: faq1088-1484​

 

[CheckerHater]

Yes, you specify that one hole being interrupted by the other hole is permissible.

 

[CheckerHater]

Did we discuss "interrupted features" sometime before?