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IndustryArena Forum > MetalWorking Machines > Benchtop Machines > how do they do it? machining in tight spaces, under an overhang.
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  1. #1
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    how do they do it? machining in tight spaces, under an overhang.

    gday.

    thinking about it for a day and i think ive already solved the problem, but hey...

    i have a job that at first glance looks impossible. cant really tell but that hole is hidden under the overhang...

    Attachment 242858

    i want to spot face/counterbore that hole for clamping down what some people might recognise as a tailstock!

    Attachment 242860

    yes, i know its ugly. ive just ground away its "make-up" (ever noticed, that unlike cheap machinery, some women look far nicer without that muck plastered all over? )

    its lovely what you find in china stuff, isnt it?

    any advice or ideas would be appreciated, but im thinking this is the way to do it...

    first, clamp the base to the mill table, as thats the only accurately machined surface.

    flycut/face the top, the part that obviously has been through a shaper with some really coarse feed...

    while im at it, face off that horrible looking unmachined lumpy part so its square too. maybe even run the radius cutter down the edge

    then flip it over, clamping it down to the (now parallel) face.

    that lets me centre on the hole in question.

    then i bore that hole out an extra few mm, just because. only 12mm at this point.

    stick a boring bar down through the hole, with an "inverted" tool poked in once its through.

    write a simple bit of code with the shapes wizard... basically just use the boring bar diameter as the tool diameter on an internal circle, and chop the resulting g code up a bit,
    so rather than rapid downs and so forth, it lifts the tool UP to the spot face, then away i go... nothing fancy, nothing accurate.

    the overhang on the tool held in the boring bar will be what cuts the spot face... about 5mm or so i reckon should do it


    assuming i bore the hole to 16, that should give me a 25mm or if i really scrape the bar on the hole, 26mm counterbore.


    make sense? sound like it will work?

    sure does to me im procrastinating, talking it up, rather than doing it.

    well, its a good way of getting the procedure down in my head, ok?


    im finally making one of those cam action lockers for this thing. hence i can bore that hole out a bit more, but i really do want a nice surface for the cam supporting block to sit on.

    pic doesnt do it any justice, but it doesnt really need any...under all that bog is some rather pimply sand casting!


    im not going back outside, its too cold. the machine is a "BV20", lil bit bigger than most bench top lathes, especially with the 2hp motor i fitted to it but still a bench top

    most useless feature of it is the lack of LH thread cutting capabilitis, ive found so far. and it came with two 98T gears rather than 1 98T and one 105T gear...

    the 105 is the most important gear of all!!!!! grrrr. one day ill cut one up and install a reverser too or turn it into CNC...


    anyway. procedure is sorted.

    ill be back with pics of the result, be they good or be they a complete stuff up!



    oh! the name of the thread....i really wonder how brembo manufactures their "monoblock" calipers... gotta be a pretty neat tooling system they have! this is simple compared to that!

    Attachment 242862


    how do they bore those cylinders from the disc slot?
    with so much stuff on hand, one spends more time locating it rather than using it.

  2. #2
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    Re: how do they do it? machining in tight spaces, under an overhang.

    SIR! the project has received the green light!

    Attachment 242864


    this one should be first, i couldnt resist using that line though... now i know why i didnt use the blue led

    Attachment 242866

    it now being 2230, im going bed.
    with so much stuff on hand, one spends more time locating it rather than using it.

  3. #3
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    Re: how do they do it? machining in tight spaces, under an overhang.

    piece of cake

    first pass

    Attachment 242988

    and done.

    Attachment 242990


    real talkative bunch here.

    199 views at last count, and not one comment, not even to call me an idiot and to take my cruddy asian lathe and stick it where it wont fit.


    wrong forum i guess?

    oh well, we cant all be professionals.
    with so much stuff on hand, one spends more time locating it rather than using it.

  4. #4
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    Re: how do they do it? machining in tight spaces, under an overhang.

    for anyone that does give a rats rear end, simply used the circular pocket wizard on mach3, with 0 Z height, 0 safe Z, DOC at 0.5mm, resulting in one pass of code.

    then cut and paste, replace the initial Z move of -0.5mm to 0.5, 1, 1.5, etc... until i hit 4mm of lift in Z.
    with so much stuff on hand, one spends more time locating it rather than using it.

  5. #5
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    Re: how do they do it? machining in tight spaces, under an overhang.

    I too have wondered how they do the main piston bores for brake calipers... Figure it must be a right-angle head? I also suspect the raw casting has much of the space voided to start with, so "all they have to do" is a light rough pass and then finishing, not hog out the whole bore. Would be interesting to see!

    Suspicion "kinda confirmed":

    "At one point, we were shown some of the equipment used to machine the piston bores of “Monobloc” calipers. Monobloc means what it says: made from one piece rather than bolted together or with piston bores machined from one side and then plugged. Just as you would think, there is a gear-driven, right-angle tool head that fits into the pad space so that it can then machine the piston bores from the inside, resulting in the lightest, stiffest caliper possible (no heavy steel bolts, no bolt stress, no weakness from multi-piece construction). As you would also expect, several passes and changes of tooling are required to finish the bores and seal-retention grooves."Some cool shots of the part as it progresses through machining at the link."

    http://tinyurl.com/mxlfxd3
    CAD, CAM, Scanning, Modelling, Machining and more. http://www.mcpii.com/3dservices.html

  6. #6
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    Re: how do they do it? machining in tight spaces, under an overhang.

    i note they wont show any pics of that cutter head! by its very nature, it wouldnt be able to take much out in each pass... not exactly rigid, one would think, as compared to even a baseline boring head and spindle...


    im thinking it would vaguely resemble this?

    Attachment 243022


    just attached to a real machine possibly costs about 1000 times as much too!
    with so much stuff on hand, one spends more time locating it rather than using it.

  7. #7
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    Re: how do they do it? machining in tight spaces, under an overhang.

    I'm not sure exactly how they do it, but I think I prefer a smarter way of doing it:
    Click image for larger version. 

Name:	m6sealed.jpg 
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ID:	243380

    Why make your life more difficult than it has to be?

  8. #8
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    Re: how do they do it? machining in tight spaces, under an overhang.

    Shrink fitting, welding, probably those piston bores were done in one shot straight through and then a cap is shrunk or stir welded in. Being a premium item the cap is machined flush so everybody scratches their head and wonders "how'd dey do dat?"
    Trust me, after a you learn all this stuff in the trade it'll all mean nothing to the next bully jerk you work for, and you'll just end up leaving the trade in frustration after 20 years.
    My advice would be to read a book, cheers!
    Wisdom results from foolishness!

  9. #9
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    Re: how do they do it? machining in tight spaces, under an overhang.

    Nah, even simpler - they're just threaded caps:
    http://www.winstanleysbikes.co.uk/images/prod_12640.jpg

  10. #10
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    Re: how do they do it? machining in tight spaces, under an overhang.

    Quote Originally Posted by Zenji View Post
    Shrink fitting, welding, probably those piston bores were done in one shot straight through and then a cap is shrunk or stir welded in. Being a premium item the cap is machined flush so everybody scratches their head and wonders "how'd dey do dat?"
    Trust me, after a you learn all this stuff in the trade it'll all mean nothing to the next bully jerk you work for, and you'll just end up leaving the trade in frustration after 20 years.
    My advice would be to read a book, cheers!
    the ones coyote pictured, are the standard simple threaded caps.

    brembo does NOT use shrink fitting. maybe you should read up about their patented, unique, monoblock calipers first?

    they machine them from SOLID. they do not rely on seals. they may now use castings, having the technique down, but the point remains...they machine the cylinders from within the confines of the disc slot.

    having had seals let go before, and brembo brakes being possibly more than my bike is worth... i stick to plain old double piston floating calipers


    anyways. what i was doing, for my lil job worked fine change negative z moves for positive ones, and be careful on the setup. strange, no matter how many books i read, they never explain how to do everything
    with so much stuff on hand, one spends more time locating it rather than using it.

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