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  1. #1
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    Default Help with my project for university

    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.
    3.jpg2.jpg1.jpg

    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!

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    A look through this 1916 publication might suggest to you what surfaces could be done on "classic" milling machines.

    Note the frequent use of dedicated fixturing

    A treatise on milling and milling machines .. : Cincinnati Milling Machine Company : Free Download, Borrow, and Streaming : Internet Archive

    ph

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    Redesign the part without that bridge linking the two round parts. Then they can mostly be done on a lathe. The third part can be the bridge. Final ops would be to add milling features to attach them together.

    Frankly I don't know what your design intent is but they way it is is not particularly friendly to subtractive machining processes.

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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.
    3.jpg2.jpg1.jpg

    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!
    Start with what you have been taught so far, and what you think would be a good solution here for each operation.
    Also, where are your drawings ?

    Then we have something to HELP you with.

    Don't ask us to doo all your homework.

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    This can all be done on a mill, but you will find your order of operations is the most important thing. If you are starting with a casting or forging, you will need to figure out the first op, which you will use to locate the second and third

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    I cannot modify the part. It has to be like this.
    4.jpg

    I'm just need a little hint. Initially I wanted to machine some of the revolution surfaces on a lathe but I don't know if that bridge from will allow it.
    I'm looking in that book right now. Thanks a lot!

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    If I were a full time professional machinist, I’d no bid this. That tiny neck is fragile and the whole design is a PITA. You’ll need to design fixtures not just to hold part while machining but also to strengthen it. Smart design of your fixtures is my hint.

    As a non professional, yes, I could make this, but more hours would be invested in the jigs than machining one part.

    L7

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    Quote Originally Posted by steliansavca View Post
    I cannot modify the part. It has to be like this.
    4.jpg

    I'm just need a little hint. Initially I wanted to machine some of the revolution surfaces on a lathe but I don't know if that bridge from will allow it.
    I'm looking in that book right now. Thanks a lot!
    Drawing is better. Even though I can't blow it up enough.

    Now, what do you think you should do ?
    Throw something out there.

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    As long as this is a theoretical exercise, model the part in a format that you can import into Mastercam or similar program for postprocessing into machine code. Define the required tools. Specify a block of aluminum of a size that will encompass the part and allow it to be machined with a retaining dovetail for holding in a 5-axis vise.

    Hint: The assignment as you relate it ("to be done on classic machine tools") is virtually impossible, and if I were the teacher you would get an "A" for saying so. To cite just one example, the sharp internal corners where the bridge intersects the round surfaces are not practical to execute on manual machine tools unless you consider a Keller to fit that category. The only practical subtractive solution is 5-axis CNC (using some very small endmills near the end).

    To save time, drop that class and sign up for one whose instructor has some real-world experience, because this one clearly does not.

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    all the fillets and radius edge breaks makes it a pain in the pooper for a 3 axis mill, get rid of those and it would be possible just not easy

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    Guys, you're making it harder than it is. It's a casting- it doesn't get machined all the way out.

    Only the red areas highlighted in the OP get machined. Bores and holes, don't overthink it.

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    Well, I certainly hope it is a casting. And he does state that.

    What is noticeably missing here are any tolerances on the various surfaces themselves and in the dimensions between them. For all we know, the as cast surface may be OK for some or even all of those surfaces. Loose tolerances would allow easier fixturing. And tighter ones would require a lot more in those fixtures and their planning.

    A properly dimensioned drawing, with PROPER TOLERANCES is the real starting place. And that should include the angles between the various features and the tolerances for them. Then you need a starting place (feature) from which the others can be set up in some sequence. There is probably more than one way to do this.

    As others have said, making the fixtures will probably take a lot more time than doing the machining on this part. I do not know of any shortcuts there, perhaps others here have more experience with this. I would develop a step by step plan and post it here for comment and possible changes. Then, while making it, take photos and continue to post your progress here as new ideas may surface during that process.

    PS: Just why does it have to be made on "classical machines"? Is that part of your grade? Or is that all that is available in your college shop? Could you use another shop, perhaps one with CNC capability?



    Quote Originally Posted by jancollc View Post
    Guys, you're making it harder than it is. It's a casting- it doesn't get machined all the way out.

    Only the red areas highlighted in the OP get machined. Bores and holes, don't overthink it.

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    Does a “classic machine” require a “classic machinist”? :-)

    L7

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    I’m not the mill guy but guess you might start with a precision cast part, then establish two axes of the part by slab milling both side s-7 s-8 in one pass with spaced slab mill cutters, turn the part 90* to locate off s-7 and bore s-1.
    Next with using s-1 and s7 s8 for square right angle run S18 17 16 15 13 14 11 9 10 6 and perhaps s5 in one fixturing. Last locate off any feature and run s2 3 4.
    Old school a horizontal mill, a vertical mill and a drill press with a turret (or change tools).(classic machines)

    Likely school not having a horizontal mill so-7 s-8 done with an end mill cutter in the vertical mill with one fixturing.
    *Again I'm not the mill guy so expect better for that guy.

    We had to program a part with many of the same feature at Carboloy CNC school but we got to use a cnc chucker,

    That part is difficult in a CNC chucker.

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    This is how I would do the first op with a 3axis mill. For just a couple, I would use a 3 jaw on the mill holding onto the OD of S18 with a jack under S5(or float a vise clamped on the s5 side for dampening). So I can get at the S18 bore and S14 Threads. The other three ops are pretty simple.

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    Guess I did not notice s14 had threads, would be very tough on an old manual Bridgeport...CNC for that would be much better. Likely a modern school would have a CNC mill.

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    Quote Originally Posted by AARONT View Post
    This is how I would do the first op with a 3axis mill. For just a couple, I would use a 3 jaw on the mill holding onto the OD of S18 with a jack under S5(or float a vise clamped on the s5 side for dampening). So I can get at the S18 bore and S14 Threads. The other three ops are pretty simple.

    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

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    Quote Originally Posted by jancollc View Post
    Guys, you're making it harder than it is. It's a casting- it doesn't get machined all the way out.

    Only the red areas highlighted in the OP get machined. Bores and holes, don't overthink it.
    Well, I sure missed that! Never mind. Guess I just assumed a college instructor would assign something impossible. Seen it more than once, but that's another story.

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    My friend John Woolly made a single cylinder air compressor at a Michigan university, I think he even poured the block casting. machined most of the parts. I have it out in my shop and it still works. No I don't use it. It has the university initials casted in the side or the block.

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    Quote Originally Posted by Oldwrench View Post
    To cite just one example, the sharp internal corners where the bridge intersects the round surfaces are not practical to execute on manual machine tools unless you consider a Keller to fit that category.
    Bridgeport used to sell a cherrying head. I used one once, just about wore ma arm out. Crank crank crank crank crank, but it did work.


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