HELP, Indicating a vice, on a X/Y Table which is built into a Rotary Table
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    Default HELP, Indicating a vice, on a X/Y Table which is built into a Rotary Table

    I'm relatively new to machining. I purchased a Bridgeport Stage I mill that has a YUASA 12" with a 10"x 10" X/Y Table built into it. (Apparently no one I've talked to has ever seen one) There is no hole in the center of the X/Y table. I need to center a piece of round stock in a vice attached to the X/Y table (sitting on the Rotary Table). Open to any and all suggestions on how to indicate a bolt hole on the stock??? Thanks!

    rotarytable2.jpg

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    Presuming you have a lathe, a reasonably close way to indicate a threaded hole is to first turn the head of a screw of the same thread round, then thread the screw into your part. The round head is now what you indicate against.

    This method isn't perfect, as you can have thread OD to screw pitch axis errors, but it's generally good to ~.005". If you need better than that there are purpose made threaded gauges that are meant for this use, but they're relatively expensive.

    As to indicating in the part, your Rotab has the capacity built-in. Place your part in the vise, then rotate the assembly and watch for deviation of the thread center from Rotab center. Use the X-Y travel to lower the error and repeat. When your thread is at center, you then just use rotation and your indicator to true the vise to X, or whichever way you want to orient it.

    Keep in mind that your combination of Rotab and vise is very close in weight to the listed capacity of the machine, so I would suggest not using it for larger work where you'll move the mill table too far from its center. To much overhanging weight will damage both the machine and cutting accuracy.

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    Not sure what you're trying to do here... The table is what is called a cross slide rotary table, nothing new or unusual there, but not everyone has seen them I suppose. Do you just need to drill a hole in the shaft or do you need to do some sort of radius work? If just drilling a hole, set the part with a dial indicator by either bumping the vise or spinning the rotary part of the table. Then center up to the shaft and locate center/edge with an edge finder and drill your hole. If you need to do something more complicated, we'll need to know what before it's possible to offer any good advice.

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    so lets say you want to put a centered feature in the centre of round stock.

    1. put it in the vice and center it on the table by eye.
    2. put an indicator on the quill (or table or anywhere else) and measure parallel to one axis of x-y table. turn rotab 180°, split difference.
    3. do same for other axis of x-y table. now stock is centered on rotab.
    4. center rotab/stock under spindle by eye. put indicator on spindle. measure parallel to one axis of mill. rotate spindle 180°, split difference.
    5. do the same for other axis of mill.
    6. run spindle at low rpm and rotate rotab simultaniously. here is you accuracy.

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    You're thinking too hard. It's a round part, so ignore the rotary table. Hell, ignore the x-y slides on top of it as well.

    Find one edge of the part in X using the mill table. Find another edge using the mill in Y. Locate your hole from those edges.

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    Saying that you need to center a piece of round stock suggests you're working on the end of round stock sticking up.

    So, if you just clamp your stock in the vise where it's convenient, get the X-Y slides approximately centered, then use the mill table axes to get the stock roughly centered under the spindle. Now, as you spin the rotary you'll see how far off your stock is from center and use the X-Y to get centered.

    There are some strategies to minimize the number of movements in centering if you really want to dig to the heart of the process.

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    As mentioned by myself and fc, there's really no need to center the table in the rotary axis if he just wants to poke a hole... we need to know exactly what he wants to do before sending the guy on some sort of quixotic odyssey. In fact, if there's no rotary work going to be done, my first suggestion would be to remove the rotary and put the vise directly on the milling machine table.

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    Any of you guys notice the ship in the background?

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    Quote Originally Posted by Gordon Heaton View Post
    Any of you guys notice the ship in the background?
    Not until you pointed it out, but I sure would like to see a better picture of it now. OP did you scratch build that?

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    Quote Originally Posted by eKretz View Post
    As mentioned by myself and fc, there's really no need to center the table in the rotary axis if he just wants to poke a hole... we need to know exactly what he wants to do before sending the guy on some sort of quixotic odyssey. In fact, if there's no rotary work going to be done, my first suggestion would be to remove the rotary and put the vise directly on the milling machine table.
    This ^^

    Entirely depending on what you want to do, but IME, those rotary tables aren't used too much, plus you can raise the knee and not have a mile sticking off the table.

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    I used these cross-slide rotary tables for many years in a couple of shops that had dozens of them, one on each Bridgeport mill. They can be very versatile if you know how to use them.

    Think of the cross-slide as the means of centering the work piece (such as your round stock) or locating the center of any radius you need to cut over the center of the rotary table. The Bridgeport mill’s X and Y then becomes the offset to cut the desired radius.

    It helps to first get the spindle directly over the center of the rotary and set the zero on the DRO and/or BP dials. There is a number of tricks to do this. The one I like is to disengage the rotary table so it can freely spin by hand and mount an indicator on the cross slide then spin and indicate the machine spindle. Move the BP’s X and Y until the you get zero on the indicator. Always be mindful of the backlash when doing this. It takes some patience at first. Hope this makes sense.

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    The combo Rotabs had a lot of utility back before CNC was big. Now, just occasional use in real shops, maybe still handy for home-types. But at that size, I wasn't kidding - they're pretty heavy.

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    Quote Originally Posted by Milland View Post
    The combo Rotabs had a lot of utility back before CNC was big. Now, just occasional use in real shops, maybe still handy for home-types. But at that size, I wasn't kidding - they're pretty heavy.
    Thanks to all who replied!
    The part I referenced is the Carriage Block for a .22lR Gatling gun with 10 twelve inch barrels. I need to do a 10 hole bolt circle. Then there multiple flats to mill. Finishing off with some lathe work.

    There is no hole in the vice, X/Y Table, or Rotary Table to center from.

    Here is a picture of the work piece I'm referencing.
    carrageblocsm.jpg

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    Ambitious part for just starting out

    I'd start with doing the hex in the part first
    That will give you many options to hold for the the rest of the operations

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    Thanks! Hex is a hole with an insert. (newbe's way out! lol)
    But, as you can see there are advantages to using the Rotary Table.

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    I'd mount the whole affair in a 4 jaw chuck and put it in the lathe. No easier way to find center.

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    I have an Advance cross slide rotary, and it does have its uses,(and yeah it's heavy...300ish pounds). There are way easier and faster methods to do this job. A chuck in a dividing head or an indexing head would be the way I'd go. The drawing appears to show that this is an assembly and there are multiple pieces, is that right?

    If you don't have an indexer or dividing head you can use this table but there's no reason the table and vise need to be fully centered for a hole pattern. Use the cross slides to set the part zero (while rotating the table) with an indicator mounted on any solid part of the machine, then sweep the part with the spindle rotation (indicator mounted in spindle) to zero the spindle on center.

    Calculate the hole offset to the first hole and move the milling machine table (not the rotary slide) to that location. Drill your first hole, then rotate the rotary table the correct number of degrees to the next hole, etc.

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    Quote Originally Posted by fciron View Post
    You're thinking too hard. It's a round part, so ignore the rotary table. Hell, ignore the x-y slides on top of it as well.

    Find one edge of the part in X using the mill table. Find another edge using the mill in Y. Locate your hole from those edges.
    Years ago I posted a similar question as the OP.
    The answer was more or less- "take all that crap off the mill table".

    I look at all that stack of mess and think the same here- take the rotary and the xy table off the mill and put it on a shelf somewhere.
    Put it back on for the few jobs you need it for.
    Then bolt the vise to the table like god intended and get on with it.
    An edge finder is your friend.

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    If you are new to machine work you don't need that lash up, put it on the shelf. Clamp your part to the mill table, calculate the bolt circle holes x y positions, Drill the holes, job done. Easy peasy.

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    Do you even have enough room left for a drill chuck?
    Get rid of all that unnecessary complexity.
    Put the part in a vice directly on the mill table.
    Center the spindle on the part with DTI.
    Use and XY bolt hole calculation table to find your locations.
    Sell that thing and get yourself a DRO and a regular rotary table

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