Thru To Bore Note

[aardvarkdw]

With the change to symbol based hole notes does anyone know if the note "Thru To Bore" is still the accepted way to describe the depth of a hole that intersects another hole but does not go all the way thru?

 

[namdac]

That is still an accepted use of the terminology. I would check the ASME web site for further info.
Regards,
Namdac

 

[ctopher]

I would call out a depth. It would reduce errors of a machinist drilling through.

Chris
Systems Analyst, I.S.
SolidWorks 06 4.1/PDMWorks 06
AutoCAD 06
ctopher's home (updated 06-21-05)

 

[chancey]

I think calling out a depth would be more confusing to the Machinist. They may think you did not intend to go into the hole and made an error. How do you measure that anyway? My experience is that any of the following are clear to a Machinist. Thru to Bore, Thru to Cross-Hole, Thru One Wall just a few examples I've seen used. For further clarity you may want to put the note in spanish as well...just kiddin'

 

[aardvarkdw]

Does ASME have anything to say about this? I am in the process of convincing my company to purchase a copy of the y14 series but I haven't been able to get my hands on a copy yet.

 

[looslib]

If you say 'Thru To Bore' you are assuming that the 'bored' hole is in the part before the hole being defined as 'Thru'. What if the machinist puts in the 'Thru' hole first and the 'Bore' hole second?

The hole to a depth will work no matter how the machinist makes the part.

A drawing is to be a standalone document without sopecifying manufacturing processes.


"Wildfires are dangerous, hard to control, and economically catastrophic."

Ben Loosli
Sr IS Technologist
L-3 Communications

 

[ewh]

How can you apply any tolerances to the depth of such a hole? How can it be inspected to determine if it is WITHIN TOLERANCE? Do you make the depth a reference dimension so that tolerances would not apply? What then if the hole is not thru to bore, or kisses the other side of the bore? It would still be to the drawing, since there would be no depth tolerance involved. Do you make an exception to the standards for this type of dimension? I realize that I'm getting a little anal about this, but it is one of those gray areas that doesn't have to be.
Machinists have to be able to do simple math. It should be no problem to determine the hole length based on the bore locating dimensions. A simple work around that I have used is to call out "THRU TO BORE" and include a reference depth.

 

[ctopher]

The hole can be a max dim or a loose tol. Inspection can measure that. To have the hole say "Thru to bore", the bore has a tol and it is more difficult for the machinist to know exactly where the bore is. Drilling a hole can be measured and drilled at the same setup regardless where the bore is. It is up to the drafter, designer or engineer to figure out how depp to make the hole and have the proper callout on the dwg.
We don't know the details of the design. The hole could have ref dim's or have a tight tol, I don't know.
aardvarkdw, can you show us a pic of the detail?

Chris
Systems Analyst, I.S.
SolidWorks 06 4.1/PDMWorks 06
AutoCAD 06
ctopher's home (updated 06-21-05)

 

[aardvarkdw]

Here is an example of where my problem is.

http://i3.tinypic.com/11bixhv.jpg

 

[aardvarkdw]

A reference depth dimension sounds like a good way of doing this. That way the overall goal is clear but you are not telling the machinist how to do his job. If ASME doesn't address this, why? This seems to me to be something that engineers deal with every day.

 

[ringman]

At one time it was not proper to specify the process to achieve the required geometry of the part. Therefore, if you would indicate the diameter and the required depth in a clear manner that would eliminate part of the "Bore" problem, no?

 

[ctopher]

Thanks for the pic.
Sorry to be picky. But ...
Since you show hidden lines for the internal geometry, there isn't a need to say "thru to bore". It is also possible to just say "2X ... thru".
The same for the .620 dia hole. I would call out "thru".
For aligned section, no need to have "section A-A", only section line. I would also call out FCF's and tol for dim's or a in a note.
This is not telling the machinist how to do his job, just good drafting practice.

Chris
Systems Analyst, I.S.
SolidWorks 06 4.1/PDMWorks 06
AutoCAD 06
ctopher's home (updated 06-21-05)

 

[ewh]

My argument about tolerancing and inspection still stands.
(getting on soapbox)
You could call out the hole as .50 deep +/-.25 and it would still be uninspectable. You can't inspect something that isn't there, and the bottom of that hole would not exist. It would be impossible to confirm that the hole depth fell between .25 and .75. It may be drilled .23 deep, be fully functional, yet be uninspectable, negating ANY inspection or definition value of that tolerance callout. If the dimension has no value to the part definition, it has no place being called out as a hard dimension. As the designer, you don't care WHAT the depth is, as long as it is thru to bore. Isn't that what a drawing is supposed to do- define the part, not the way to make it?
(Getting off soapbox)
There are exceptions to this, as most things. A deeper, smaller hole intersecting with another hole of similar size would need to be tightly controlled. But that does not involve a bore, and is another situation all together.

 

[aardvarkdw]

I realized after I poted the pic that that wasn't a good example. Imagine the holes don't come out the other side...

 

[ewh]

I was busy writing my previous post, and then got to read what has been posted since. Chris is right that the hole is SHOWN as being thru to bore, and therefore should not require a depth callout. For that matter, technically it could be called out 2X thru entire part, if the alignment of the smaller holes is of importance.

 

[ewh]

Ah, behind again. Please ignore the last part of my previous post

 

[ctopher]

Normally what I would do in this case is, "2X THRU ONE WALL". I have never had any question with this When I have called out "... THRU TO BORE", sometimes I get "Which bore?".

Chris
Systems Analyst, I.S.
SolidWorks 06 4.1/PDMWorks 06
AutoCAD 06
ctopher's home (updated 06-21-05)

 

[btrueblood]

I don't like "thru to bore", and prefer using "thru wall". To me, "to bore" is too open to interpretation: is a hole with just the point of the drill penetrating "to the bore" acceptable?

In ANSI nomenclature, a hole that is "thru" must pass completely through the part, having a cylindrical form of the noted diameter (plus or minus tolerances). Thus, "thru wall" indicates that a hole of the noted diameter must pass completely thru the "wall" indicated (it should be obvious from the print which wall is intended, or else you'd better redraw the view to make it obvious).

That said, I think in 99.9% of all machine shops, either callout will be understood and correctly interpreted. In the remaining 0.1% of shops, this callout will be the least of your worries.

 

[aardvarkdw]

Sorry again for the bad examples. Neither of these are my drawings they are drawings made by our engineers who are still drawing to Y14.5-1982 and I got tasked to go through them and clean them up.

http://i2.tinypic.com/11bjl0z.jpg

 

[ewh]

Using THRU TO BORE, you could not get just the drill point breaking thru, it is the full diameter which would have to be thru to bore.
I've had managers not allow "THRU ONE WALL" (but they weren't exactly experienced in part detailing to begin with). I have used that method often.
That is a good point about the shops knowing what is required, and if not, that would indeed be the least of your worries about any parts that they are making.