Repeated balloon callout (again)

[vwdevotee]

I know balloons have been discussed frequently, but I can't seem to find an answer to my specific question. When a part is ballooned in multiple places (i.e. general view and detail views) what is the proper way to show it? Is there an ASME standard that drives this? I was always taught that it's proper to use a circled BOM number for each instance, but I was "corrected" by a contractor that the first instance should be circled but subsequent instances SHALL NOT have circles.

Is this just a company style question or is it formally spelled out somewhere?

 

[3DDave]

I doubt there is a standard or 30 years of picky checkers I've worked with would have found it.

Most typical is to enter REF in the place a quantity would be used.

 

[CheckerHater]

I agree with 3DDave. Handling balloons is more of a tribal knowledge.

According to ASME Y14.100 and ASME Y14.34 balloons (actually known as "find numbers") are:

1. Optional. They just save drawing space.
2. Used for cross-referencing only.

So, by their nature they already are "reference", so there is no need to create "reference reference" balloon, unless item quantities may become confusing, as 3DDave already mentioned.

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

 

[drawoh]

vwdevotee,

If there is no quantity attached to the balloon, I see no reason to not show it where ever it would be useful. If I am looking at your assembly drawing, I need to relate the elements of your picture to your BOM. If you use 3D[ ]CAD to do your assemblies and to generate your BOMs, the item numbers always will be correct. If you are using 2D[ ]CAD, or a drafting board, or your BOM is generated and controlled outside of your 3D[ ]CAD, you will have to make a significant effort to keep your item numbers correct. This could limit your use of item balloons, possibly completely.

Quantities are tricky, especially if you use the same fastener in multiple places on your assembly. This is good design practice. I have coped with SolidWorks' item quantity numbering by systematically manually entering the quantities for fasteners. I know that box is mounted by four M4X16 cap screws, and that a PCB is retained by six more of them. This makes the assembler's life easier, and I found it reasonably easy to maintain. This did not go over well with my co-workers, and they insisted on not showing quantities.

--
JHG