Stepped holes callout 2

[bxbzq]

Hi,
In attached print, how do you like the stepped and chamfered holes callout? I'm trying to come up with a callout simple and clear. Do you think the the callouts shown in first sheet is clear, or I have to do it like the second sheet shows?

 

[greenimi]

What standard are you using?
If Y14.5 then c'sink holes should be dimensioned per sheet 1 (included angle)
If no c'sink holes (there are chamfered holes) probably you want them with length x angle or length x length.
Sheet 2: too busy IMHO

 

[tbuelna]

When it comes to application of drawing GD&T I personally prefer adding lots of views and dimensions so that things are explicit, clear and easy to understand. With modern CAD systems it takes little additional effort to create extra dimensioned views. So why not make things as easy as possible for the person using the drawing? For this reason I like the basic approach you took with your drawing views.

Regarding dimensioning/tolerancing of the holes either approach would be acceptable, but I personally prefer the approach used on sht 1. However there are a few specific issues with what you show on both sheets. First, I agree with greenimi's comment regarding c'sinks vs chamfers. If all you require is a corner break at the hole edge then call it out as a chamfer. Also, the way your positional tolerance block is located in the hole callout the tolerance applies equally to both the hole and the c'sinks. If you only intend for the positional tolerance to apply to the hole, then the hole dimension should be listed first with the tolerance block immediately below it. If you require a looser positional tolerance for the c'sink features you can add a separate tolerance block just below each of those callouts. You also should add a prefix (such as 4X) describing the number of locations the callout applies if there is more than one. Lastly, since the hole location dimensions on sht 2 are shown as basic you need to add a positional tolerance block somewhere on the drawing for the associated features.

 

[Tunalover]

I think both section views are too busy. The first one looks better but the second one is extremely cluttered. I would do a detail view of each hole taken off the section view. The boundary of each detail view would have to be elliptical or whatever works with your CAD system to encompass each hole section. Also, SEP REQT is not required on all three FCFs. It's only required on two of the three cylindrical positional tolerances. Also, where you have two identical countersinks you don't have to repeat the callout, although there's nothing illegal about it, I would use a 2X multiplier there IMHO.



Tunalover

 

[tbuelna]

Good points. Obviously, SEP REQT is not really required with the single hole location. But given the way the other holes use the basic dimensions I would assume there is some relationship implied between the holes of each pattern. If this is the case, then there is probably no need to use SEP REQT for these hole callouts either. SEP REQT is usually only needed where there is no relationship required between the features described in the callout.

 

[CheckerHater]

If there is any possibility of misinterpretation, don't use "time-saving" symbology. Dimension every feature that is functionally important.

I assume your drawing may be "intentionally incomplete", but if it really is busy, create separate section for your elaborate hole and dimension it there. It will make it easier to interpret, and (which is often ignored) easier to make future revisions.




"For every expert there is an equal and opposite expert"
Arthur C. Clarke Profiles of the future

 

[rsm7400]

Whether right or wrong, most of our customer's prints look more like the second print

________________________________
Ryan M
Quality Engineer
3d Printer Hobbyist

 

[JNieman]

I'd use callouts like the second sheet, but call the holes out in a plan view (your top view) instead of the section. I think it's your top view. First Angle Projection still throws me off temporarily, and it's still early on a Monday for me. The section can be for graphical clarity. Double check to ensure you have the correct "order of operations", so to speak, for your features (c'sink/chamfer/thru/spotface/counterbore/etc) per whatever spec you adhere to.

_________________________________________
NX8.0, Solidworks 2014, AutoCAD, Enovia V5

 

[ewh]

Of the two I prefer the first example, but the order should be reversed with the through hole first. Holes take precedence over countersinks, with the smallest size first (at least per the examples in Y14.5). This would reflect the order that the feature would generally be machined. I would also treat the 90° countersink as a chamfer to simplify the hole callout, using a note format (1.1 X 45°).

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

 

[Tunalover]

There is no better way to show a complicated hole than in a section view JNieman. Why call out the holes in a plan view and the countersinks in a section view when you can it all in one section view (although there's nothing unlawful with that)?




Tunalover

 

[JNieman]

For reference, ASME Y14.5-2009 Section 1.8.9 - 1.8.16.2 seem to be good reference, if ASME means anything to you ( I didn't notice if ASME/ISO was specified )

Specifically, I'd check out Fig 1-38, page 17, for a start. Notice that there is a reason for the order of callout which is a general "order of operations". While the actual order the part is manufactured may differ, and the callout in no way binds anyones hands on which order to install those features, it makes for a good "rule of thumb" so it's easily read. You start with the smallest diameter and work your way to the largest, so to speak.

Sometimes, such in the case of some spotfaces, it is actually cut /opposite/ but there should be some consistency, at least, and not a completely chaotic manner of writing simply because exceptions exist, but I digress.

_________________________________________
NX8.0, Solidworks 2014, AutoCAD, Enovia V5

 

[Tunalover]

JNieman-
The figures show alternate ways to show the holes. The left options show how to do it with one section view. The right options show how to do it with two views (plan and section). My preference is to do it with one section view.

I agree that the order of the features optimally are in the order that they are performed, but any order is technically OK since the drawing is generally an end-item document without processes and the orders they are applied.


Tunalover

 

[JNieman]

Agreed - either is equally acceptable. I was just noting my (I guess dissenting) preference.

_________________________________________
NX8.0, Solidworks 2014, AutoCAD, Enovia V5

 

[bxbzq]

ok. We work to ASME Y14.5-2009. The print is first angle projection based.
I revised the print based on the first sheet:
1. a separated detailed view showing the most complicated hole.
2. call out those angled features as chamfers. BTW, what exactly is the difference between a chamfer and c'sink? I only have a feeling that c'sink is only for components like flat head screws.
3. in the stepped hole callout, through hole goes first, then larger hole.
4. about the SEP REQT, a rule of thumb here is when the features mate with different parts, SEP REQT is attached.
5. I guess the callout for number of places of same feature is never agreed by companies. I heard different stories. Here I show the number applied to the view, not to the whole part.

Any further comments?

 

[pmarc]

Geometrically SEP REQT for the single hole in the center makes perfect sense and is interpretable, therefore I do not agree with those saying SEP REQT note should be removed from the drawing (refer to fig. 4-39 in Y14.5-2009 or 4-26 in Y14.5M-1994 and imagine that the outer contour is not compound but cylindrical with diameter controlled by basic dimension).

However, what is not needed on this print is datum feature references B(M) and C(M) in profile callout applied to two planar surfaces lying at basic distance 20 from datum plane A, and in consequence SEP REQT beneath that feature control frame.

 

[Tunalover]

pmarc-
Two hole patterns are functionally unrelated to each other and functionally unrelated to the central hole so only two of the FCFs need the SEP REQT note. It would be understood that the single hole is a SEP REQT and the note is unnecessary.

I do agree that the profile of a surface tolerance should have no reference to datum features B and C.


Tunalover

 

[pmarc]

tunalover,
Your suggestion (with 2 not 3 SEP REQT notes) will just mean that the callouts applied to both patterns have to be met as separate requirements. In my opinion it will not provide clear instructions whether the 3rd callout is to be checked as another sep reqt or as a sim reqt with one of the callouts applied to the patterns.

Addition of 3rd SEP REQT note eliminates potential confusion once and for all.

 

[bxbzq]

Good point on surface profile callout. On relatively simple part, when the datum features are already defined I usually assign the same DRF to rest of features. I need to be more careful in the future.
The SEP REQT vs. SIM REQT is annoying sometimes when you have many patterns on it. A example, if a part has pattern A and B functionally related to each other, pattern C and D related to each other, pattern E and F related to each other. But these 3 groups are not related among each other. How are you gonna play with the SEP REQT notes?

 

[pmarc]

I would say there is nothing wrong in placing SIM REQT 1 under geometric callouts for patterns A & B, SIM REQT 2 under patterns C & D, SIM REQT 3 under patterns E & F (although the situation may get slightly more complicated if patterns are controlled by composite positional tolerances).

If that does not look good to you, you can always use a text note to clarify design intent.