Thru To Bore Note
Thru To Bore Note
(OP)
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?





RE: Thru To Bore Note
Regards,
Namdac
RE: Thru To Bore Note
Chris
Systems Analyst, I.S.
SolidWorks 06 4.1/PDMWorks 06
AutoCAD 06
ctopher's home (updated 06-21-05)
RE: Thru To Bore Note
RE: Thru To Bore Note
RE: Thru To Bore Note
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
RE: Thru To Bore Note
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.
RE: Thru To Bore Note
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)
RE: Thru To Bore Note
http://i3.tinypic.com/11bixhv.jpg
RE: Thru To Bore Note
RE: Thru To Bore Note
RE: Thru To Bore Note
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)
RE: Thru To Bore Note
(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.
RE: Thru To Bore Note
RE: Thru To Bore Note
RE: Thru To Bore Note
RE: Thru To Bore Note
Chris
Systems Analyst, I.S.
SolidWorks 06 4.1/PDMWorks 06
AutoCAD 06
ctopher's home (updated 06-21-05)
RE: Thru To Bore Note
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.
RE: Thru To Bore Note
http://i2.tinypic.com/11bjl0z.jpg
RE: Thru To Bore Note
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.
RE: Thru To Bore Note
Chris
Systems Analyst, I.S.
SolidWorks 06 4.1/PDMWorks 06
AutoCAD 06
ctopher's home (updated 06-21-05)
RE: Thru To Bore Note
I just did look and your drawing and was wondering what and how you are tolerancing the patterns.
RE: Thru To Bore Note
RE: Thru To Bore Note
Chris
Systems Analyst, I.S.
SolidWorks 06 4.1/PDMWorks 06
AutoCAD 06
ctopher's home (updated 06-21-05)
RE: Thru To Bore Note
I agree that giving a depth as anything other than reference makes no sense as you can't inspect it. A ref dimension to the centre of the hole you're going to might be a good idea tho'.
I was always taught that hidden detail is non preffered and sections are better but I know in some situations hidden are still useful.
Still in any situation where defining the hole using standard methods/callouts is awkward I tend to put a section.
Would wording like 'Thru to ØX.XX hole' be a way of clarifying it? Especially if accompanied by a section and reference dimension.
RE: Thru To Bore Note
RE: Thru To Bore Note
"Section 1.8.9 Round Holes: ... Where it is not clear that a hole goes through, the abbreviation THRU follows a dimension." In other words, where the geometry is clear, further detailing is not required. In this case, the section clearly shows a tapped hole from the outside wall to the inside bore, so specifying the pre-drill and tap size is all that's required. Machinists should know how to read an engineering print, so they would see the intersection, note the position and size of the cross-bore and do the math to ensure that the holes fully intersect. Adding notes such as "Thru to Bore", "To Bore", "One Side Only" are redundant at best if the drawing shows the geometry correctly in section or in phantom lines, and may confuse inexperienced machinists at worst.
The only inspection to be done on the depth of a hole thru to the bore is visually verifying that it completely intercepts the cross-bore and does not enter the opposite face of the bore. It wouldn't be an issue in this sample because there is another bore on the other side.
SoapBox time: I would be concerned saying that this drawing somehow conforms to Y14.5M-1982. There are no datums, no positional tolerances, no general size tolerances to cover the non-toleranced dimensions... Without a positional tolerance on the tapped hole, the feature could be significantly out of position which would theoretically allow the tapped hole to nick the tangent of the cross bore and exit the other side of the outside diameter. Sounds "impossible", but "legally" that part would pass inspection.
Stating that a drawing conforms to Y14.5M (any edition) sets a legal precedence that can bite you if the engineering isn't correct. End SoapBox.
Jim Sykes, P.Eng, GDTP-S
Profile Services
CAD-Documentation-GD&T-Product Development
RE: Thru To Bore Note
The drawing orignialy had a general tolerence block and such but it was removed along with notes and title block at the request of my company prior to posting. It was simply an illustration (albeit a bad one) of a note in context that I had a concern about.
That being said, I agree with you. If the hole is shown in section a note specifying depth would be redundant, but in cases where a clear section veiw is not an option the reference depth dimention that was mentioned earlier would be the best option.
RE: Thru To Bore Note
Jim
Jim Sykes, P.Eng, GDTP-S
Profile Services
CAD-Documentation-GD&T-Product Development
RE: Thru To Bore Note
I agree with your post with the exception of "specifying the pre-drill and tap size is all that's required". The only tapped hole information required is the actual thread designation and depth of thread (as req'd), except for special situations such as where the pilot depth is critical. The drawing should not tell the fabricator to tap, or what size pilot drill to use, as these are per existing specifications and would be redundant on the drawing. Every machinist should have access to the Machineries Handbook.
RE: Thru To Bore Note
tks
Jim
Jim Sykes, P.Eng, GDTP-S
Profile Services
CAD-Documentation-GD&T-Product Development
RE: Thru To Bore Note
RE: Thru To Bore Note
I'm with ewh on only calling out the thread, not how to create it/tap drill size but have also been guilty of giving more details on 'specials'.
One case I can think of though (which comes up quite often here in pneumatics) is where the thread only goes down part of the length and then the ‘tap drill’ dia continues on down to intersect with another bore or something.
We have a problem here because by default our CAD system only has the nominal and minor dia data for screw threads in it. So the tap hole ends up being the diameter of the screw thread minor diameter, not the true tap drill size. To do it properly you end up creating 2 separate holes which then leads to other problems, but there you go.
Can I just say that after looking at various engineering news boards & talking to CAD users etc it’s refreshing to come across a group of engineers that actually know & care about standards etc. I knew they existed but sometimes they seem few and far between.
Ken