CREATING A SPECIFIC FINISH NOTE for a -1 & -2 1

[RichardStarrbuck]

We have a part that is used in two (2) different ways. It is basically a mounting bracket made of aluminum sheet metal, bent @90 degrees.
Mechanically/Functionally the only difference between the two (2) parts is that one utilizes threaded inserts and one does not.

We have a -2 version (front/top/side/rear views shown in drawing)
- this is just the bent sheet metal with a few holes drilled into it.
- we give the overall/envelope/hole/bend dimensions.
- we call out masking of surface areas for grounding.

We have a -1 version (isometric exploded assembly view shown in drawing)
- this is the assembly consisting of the -2 bent sheet metal part and couple threaded inserts.
- we call out masking of the insert threads.


In the drawing notes we call out finish instructions separately.
First the -2 finish note; dictating the masking of surfaces for grounding.
After that comes the -1 assembly note; dictating the assembly of the -2 part and the inserts; which together creates the -1 version.
Then we give the -1 finish note; dictating masking of surfaces for grounding and insert threads.

THE ISSUE:
The -2 finish notes only apply if the -2 is used as the final product in the parent assembly.
The -2 finish notes do not apply if the -1 version is used in the parent assembly.

Does anyone here have any experience with use of such drawings?
I was thinking of the -2 finish note containing something along the lines of: "-2 FINISH: THE FOLLOWING FINISHING STEPS ARE ONLY TO BE APPLIED IF DESIGN ACTIVITY CALLS FOR -2 AS THE FINAL ASSEMBLY"
But I'm not sure if that is sufficient, or maybe it should be worded differently?
Maybe prior to the -2 finish note should be a note to explain the subsequent notes to follow?

 

[JNieman]

I've commonly used, and worked from, drawings made with such a tabulated note differentiated separate material or finish requirements, however:

The fact that actual physical features/geometry is different makes me think it should be separated. The use of -1, -2, etc, is of use when the part is identical up until a point (pre-finishing). However, your part is never identical, since one has drilled holes and the other has threaded holes and a helicoil/thrd-insert.

It seems to me that combining them with "except" notes would cause more confusion than not. I would probably create a separate set of drawing views for the -2 with a note saying "Identical to -1 except as shown"

 

[rb1957]

you can have multiple parts on a drawing, with separate views and separate notes.

another day in paradise, or is paradise one day closer ?

 

[KENAT]

Take a look at thread1103-422119 and extrapolate.

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[RichardStarrbuck]

Thank you for the replies.

Attached is the drawing for more clarification.

The only difference between the -1 and -2 are the finish steps and that is due to the fact that threaded inserts were added to create the -1.
The -2 is the base part of the -1 assembly. There are no physical changes to the part other than adding the inserts.

Typically in our shop this drawing shows two (2) versions of a single part and would not be two (2) separate part numbers. You cannot have the -1 without building the -2 first.
The masking dictated in the -2 finish is also, by default, applied to the -1 version with the addition of masking the threads of the added inserts.
-1 is used for applications that would required threaded inserts
-2 is used for applications not requiring threaded inserts


All I'm trying to do is dictate that for use of -2 as the end product you do not proceed to the -1 assembly and finish notes. I just don't know how to properly write it in technical terms.
Is tabulation in fact the proper way to convey this information? Or can I use the existing notes by adding a little more information?

EDIT: I now realize that I may need to attach a bigger file, apologies if it cannot be read clearly.

 

[KENAT]

The way I've seen it is that you have a parts list with a qty column for "-1" and a qty column for "-2" in your case in the "-1" column you'd have qty 2 while the other column would have '0'.

Posting guidelines faq731-376

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

 

[pylfrm]

RichardStarrbuck,

It sounds like the sheet metal part is not yet coated when the inserts are installed for the -1 assembly, but the -2 part (sheet metal without inserts) is coated. If so, then the -2 part is not really a subcomponent of the -1 assembly, is it?. Perhaps you need a -3 part which is just uncoated sheet metal.

Or perhaps I've misunderstood this all. A readable drawing might help.


pylfrm

 

[tbuelna]

Personally, I always prefer to use separate drawings and unique numbering for detail parts and assemblies. With the current CAD/PDM systems available, it is no big extra effort to do things this way. Configuration management and effectivity can get complicated when you combine detail parts and assemblies on one drawing, that could potentially be used at the same next assembly. Each part or assembly should have its own unique identification number and documentation that is used to purchase/accept/inventory the product.

 

[JohnRBaker]

Personally I would make two part files (Drawings). As far as the rest of the world is concerned, the fact that you have two 'dash numbers' means that you have two different parts already so why not create two Drawings and be done with all the hassle and anxiety over how to make one Drawing do the work of two. Question, is this drawing being done using a CAD system? If so, you're not really saving anything by trying to get one Drawing to do the work of two. Just finish one Drawing, save it, then reopen it, do a 'Save As' and give it a new name, make the changes required for the second part and save it. Job Done.

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EX-Product 'Evangelist'
Irvine, CA
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[tbuelna]

In the aerospace industry, the typical practice for dash numbering is odd dash numbers (-1, -3, etc.) are as shown, and even dash numbers (-2, -4, etc.) are mirror image (opposite) configurations. The reason for this is because many parts/assemblies used on aircraft have left/right hand symmetry.