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Thread: drafting question - dash numbered drawing

  1. #1
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    drafting question - dash numbered drawing

    How are dash numbered drawings shown in the title block and data list? For example, say, a part number like 1234567-1 is a detail drawing of a bracket and 1234567-2 is the mirror image or opposite. -1 Shown and -2 Opposite would be shown on the drawing under the view of the -1 part. How would the drawing number be depicted in the title block, eg., 1234567-1, -2 ? And how would it be depicted on the Data List ? Or is the 1234567-1 drawing number shown implying that there are other dash numbered parts described on the face of the drawing. Thanks for the help.

    John

  2. #2
    Administrator Kelly Bramble's Avatar
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    I assume you are talking about engineering drawings created to MIL-DTL-31000. To diverge a little, most commercial non-DOD organizations do whatever works for them in regards to engineering drawing numbering.

    Yes, for milspec engineering drawings the dash numbering system starts -1 then increments in odd numbers, i.e. -3, -5, -7, 9, etc. A left side or opposite component is numbered sequential and as an even dash. So, for an opposite side part (Starboard as opposed to Port) of a -3 would be a -4.

    For those of you whom have never heard of this, it make sense in the aircraft world where we have parts/components that are true mirror images, particularly in the wing or airfoils.

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    Thanks for the prompt reply. So in the title block would the drawing number include all the dash numbers, eg., 1234567-1 , -2 Or just the first dash number, eg., 1234567-1 And then assume there would be a -2 at least or maybe a -3 and -4, etc. It might get kind of cluttered trying to list all the dash numbers in the title block. I just don't remember what we used to do there. I think in the parts list of the assembly drawing the parts are listed individually for each dash number. And I don't remember how they would be handled in the Data List either. You know, when your boss comes in and asks how many drawings you will be doing for this project it would be nice to have a list to look at and it helps for planning the project. If the drawing number has a dash something then you'd have to go to that drawing and see how many dash numbered parts there are and figure them in at that time. Thanks again... John

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    Administrator Kelly Bramble's Avatar
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    The drawing number is indicated once at the bottom right of the border or format title block within the "DWG NO." area. Then, just above the title block and within the parts list section we would have the pespecitive dash numbers and any other part numbers.

    Also, within the "NEXT ASSY" and "USED ON" sections, we wouls include the dasg number as applicable.

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    Hi Kelly,
    Thanks for the reply. I found a couple examples to help clarify my question. I found related information at these two links below. The first link takes you to a drawing of a modification to the B-57, a pod that is mounted to the underside of the aircraft. This drawing is the transition mating the round fuselage shape to the rectangular shape of the pod. It's called the forward transition and is the assembly drawing which includes the parts list on the face of the drawing. Several of the parts are right and left pairs and depict how the dash numbers are handled. The second link is to a military draftsman manual and talks about the dash numbered parts and how they are depicted in the title block. Not available is the detail drawing of the parts listed on the assembly drawing of the forward transition. That's what got me wondering how the part number for shown and opposite parts would be depicted on the detail drawings. Would it be the part number without the dash suffix or would the suffix(s) be included ? So now I think it is that the first suffix is show on the detail drawing and that implies that there may be more shown on the face of the drawing and to look there. I read that in some document while searching for info but can't remember the document now. The main goal here is to determine how many drawings will be involved. Note the dash numbered parts are listed individually on the parts list but those parts may be contained in one detail drawing which would make it much less expensive than drawing separate detail drawings for the mirror image of the same part. I'll include a couple pics of the drawing.

    B-57 Forward Transition drawing
    http://www.nasa.gov/externalflash/wb...Transition.pdf

    Drafting reference training manual
    http://www.tpub.com/content/draftsman/14040/index.htm

    Thanks again Kelly

    John
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    Administrator Kelly Bramble's Avatar
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    Well, first I would ignore the second link to tpub as this is old drafting fundamentals stuff.

    Your principal question seems to be that you are trying to figure out how many drawings you need? - The least amount as possible. In general, we create separate engineering drawings to depict specific manufacturing or assembly steps. So, the engineering drawing sequesnce should follow the general steps of fabrication to an end-item assembly.

    Looking at the parts list on the 5711345 NASA drawing, there will be two end-item assemblies a 5711345-301 and a 5711345-302. Looking at the notes the -301 is used on a 926 aircraft, etc...

    The -301 end-item assembly requires a number of parts and subassemblies, which can be deteremined by matching the indicated parts quantities in the column above the -301.

    There is a series of 5711351-X parts required to assemble a -301. Looks like there will be a part/drawing defining a -001, -002, -003 through a 5711351-015. That drawing will likely be a form drawing with a chart giving detail dimensions defining the difference between the perspective dash numbers.

    As far as referencing a drawing/part on a parts list - all parts in MIL-DTL-31000 have a dash number. So, yes a part or subassembly should include the appropriate dash number, even if it only has one part or dash number (-1 or whatever).

    BTW, most folks are going to separate parts list throughout induatry - better for procurement, kitting, costing, etc...

  7. #7
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    Thanks Kelly,
    Now I'm starting to get it. I'm kind of slow on this. Luckily I'm not working for anyone but myself :-) That's a great tip about the separate parts list. I retired from federal civil service 15 years ago so I'm kind of dated on the material now. I really appreciate the help. Thanks for reading through all this stuff I brought up.

    John

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    Hello members!

    I would like to introduce myself as CAD drafter and would like to get answers from forum members.

    Looking forward to your kind support!

    Regards
    Michael

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