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  1. #21
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    I start with an "op sheet"

    Just a list of operations that match with all the features required to complete the part. Tolerances mean NOTHING on an Op sheet.

    Once I list all the operations based on the machine tool for each, I can play with sequence and formulate the tooling and set ups for each operation.

    These sequence steps and tooling considerations "flesh out" the process required to produce the part.

    Then I make up a tooling sheet that describes in bold terms (not detailed) the work holding and feature location points of importance.

    These tooling details are inserted into the op sheet at the required positions to describe the sequence of process.

    I might run three or four op sheets through my mind and on paper before finalizing on one sequence that seems to make sense.
    Dollar signs are always dangling in the consideration of what where and when.

    Once an Operation plan is accepted, I see where individual steps can be optimized. Things like multiple features on single locations, combination cutting tools, fixtures that can switch between machine tools. That sort of thing.

    Then I revise and finalize the op sheet and produce both the tooling and fixturing sheets that support the piece part.

    Actually, I can't think of any other way to go about assigning costs and feasibility to a part production.

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  3. #22
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    A better drawing that we can clearly see/magnify would be helpful, can't determine much in the way of reference surfaces or tolerances with the drawing you posted. It looks like the top cap on a shock absorber with a piggy-back reservoir for a motorcycle. If so it should be possible to make this on "classic" (manual?) machinery with one to three fixtures, depending upon tolerances and surface finish requirements.

    What do you currently know about machining and how do you think this is possible? What has your research revealed so far? Provide your thoughts/experience when asking for solutions from others.
    Last edited by AD Design; 01-08-2020 at 03:03 AM. Reason: Additional thought

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  5. #23
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    First thing I'd complain about is, the print doesn't match the rendering so maybe the "designer" needs a wack upside the head with a clue stick ... that's probably not going to get you a good grade tho

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    Quote Originally Posted by steliansavca View Post
    Hello, I hope I'm not in some wrong topic..
    I've received a part from school and I have to create the machining processes in order for it. The part is complex and I really don't know what machine to chose for some surfaces.
    Attachment 274650Attachment 274651Attachment 274652

    I need help with surfaces S16, S15, S17, S18, S11, S12, S13, S14.
    The workpiece is cast aluminium.

    Also this has to be made on classic machines.

    If anyone could help me, I would be more than grateful.
    Thanks!
    what does the cast part look like?
    are there through holes?

  7. #25
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    2 days have passed, are you following post #21 and making a operations sheet ?

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    QT: [Also this has to be made on classic machines.]

    With the part held on the cross slide it could be done on an engine lathe...
    Thread cutting ability being a key factor to support a lathe.. fixturing the part on the cross side in a compound, universal vise.
    looks like 4 sets.
    s-7 s-1
    s-8
    s-9 through 18 (with travel of the cross travel from feature center to feature center.With centers horizontal to the bed.
    s-2,3,4.

    Much with a boring bar from the head stock (off-set in the chuck)

    but thinking/wondering ,how to get spot face s17 s15 with classic tooling.
    s-5 also a little of a problem.

    Perhaps multiple feeds to the carriage stop if surface finish limits would allow

    QT [I need help with surfaces S16, S15, S17, S18, S11, S12, S13, S14.]
    *Easy on a conventional mill with a rotary table... except for threading s-14.
    You might do the whole part on the mill and then just cut the thread on the lathe(if not having a CNC mill).

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    Send drawings to China, get 1000 parts back in a week.

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    Quote Originally Posted by michiganbuck View Post
    QT: [Also this has to be made on classic machines.]

    *Easy on a conventional mill with a rotary table... except for threading s-14.
    Since this is a clearly academic wanking exercise you can "easily" thread the s-14 by coupling axis feed and rotary table together with some gears and universal joints.

  12. #29
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    Quote Originally Posted by Oldwrench View Post
    ...To save time, drop that class and sign up for one whose instructor has some real-world experience, because this one clearly does not...
    That was my first thought when I saw the pics and the models. It's fine to test someone's ability with a
    challenging part but, in my view at least, the part should have some relevance to the real world. And in
    the real world you would redesign the part--at least most of us would--to make the machining/fabrication
    processes easier. That part reminds me of something designed by an inexperienced engineer who
    should have been an artist instead.

    I remember back when I was in high school taking drafting classes--a long time ago--being tasked with
    making drawings of some really complex and convoluted models. Most of them were challenging to draw
    but, even at that age, I often wondered how the Hell you would make them...

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    Agree any whats-it should have a a title...so relating to a real part.
    I wonder if the part print has a title..

    QT: ["easily" thread the s-14 by coupling axis feed and rotary table together with some gears and universal joints.] I'm not a mill guy so with an old vertical manual Bridgeport, Excello or the like doing that is above me.

    Good idea to have students try to figure process..then be shown a process that has been proven.

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    Quote Originally Posted by michiganbuck View Post
    QT: ["easily" thread the s-14 by coupling axis feed and rotary table together with some gears and universal joints.] I'm not a mill guy so with an old vertical manual Bridgeport, Excello or the like doing that is above me.

    Good idea to have students try to figure process..then be shown a process that has been proven.
    Not really a Bridgeport job, more like universal mill with helical milling setup(universal dividing head).

    Muchos fun to set up for one-offsie:


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    I don't know why so many are concerned its not a realistic part. Its an exercise to get students thinking about on how to machine the features, sequencing, work holding etc. Most likely its an imaginary part created solely with that aim. As for 'you'd redesign it"......in the habit of doing that with a customers drawing/part?

    The wankerish part is called them classical machines. Gag. Marginally better I suppose than some illiterate wanker calling them vintage when they mean old.

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    Quote Originally Posted by atex57 View Post
    Looks like most of it could be done with a milling machine with a boring/facing head and a couple of fixtures.

    Sometimes I wonder if school assignments are to give a hint of what NOT to design.

    Ed
    You beat me to it. It could be done in 3 fixtures. Designing the fixtures is the hard part.

  18. #34
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    steliansavca, what have you got so far for surfaces 1 - 10?

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    Quote Originally Posted by MattiJ View Post
    Since this is a clearly academic wanking exercise you can "easily" thread the s-14 by coupling axis feed and rotary table together with some gears and universal joints.
    The drive for Rotary or dividing head needs to be transfered Via leadscrew to get the thread pitch, and the gear ratio calculated for the wanted thread pitch.

    Havent seen any other This kind of method used rather than with x-axis leadscrew with a conventional knee mill.

    So it would need To have vertical head tilted 90 degree left or right. Dont know how big this part is, can take quite a space to rotate Since thread location is off center

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    That part looks like a shiny something I’d find inside or around a fire truck… Those guys have NO sense of humor → but they are pretty parts. Often with NO straight or square sides to anything.

    Ohhhhh, pity the poor pattern maker first!

    Good luck,
    Matt

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    That is a realistic part,as previously mentioned many motor cycle rear shocks use something similar.It is missing the oil transfer port between the two bores and threads on the short bore.
    I would't have much trouble whittling that out of block of solid material using a BP type mill and manual lathe,just a lot of time.


    I have had to make more than a few replacement cast parts out of solids as complicated as that.The fact that the exterior features are already cast just makes it quicker.

    I'd start by doing the large bores first in one setting on the mill just offset the bores.
    As simple mandril(tube type if the small hole has internal threads) to thread the long bore in the lathe.
    You now have a reference for all the other features.
    Two mandrils the same od inserted in the bores clamped clamped to a parallel on the mill and then bore the lug hole.

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  23. #38
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    I missed the threaded surface. That means I would have to design one of the fixtures so I could mount it to a lathe faceplate for threading. Design of the fixturing will depend a lot on the theoretical quantities.


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