how does a rotary table work free sample

A rotary table is a precision work positioning device used in metalworking. It enables the operator to drill or cut work at exact intervals around a fixed (usually horizontal or vertical) axis. Some rotary tables allow the use of index plates for indexing operations, and some can also be fitted with dividing plates that enable regular work positioning at divisions for which indexing plates are not available. A rotary fixture used in this fashion is more appropriately called a dividing head (indexing head).

The table shown is a manually operated type. Powered tables under the control of CNC machines are now available, and provide a fourth axis to CNC milling machines. Rotary tables are made with a solid base, which has provision for clamping onto another table or fixture. The actual table is a precision-machined disc to which the work piece is clamped (T slots are generally provided for this purpose). This disc can rotate freely, for indexing, or under the control of a worm (handwheel), with the worm wheel portion being made part of the actual table. High precision tables are driven by backlash compensating duplex worms.

The ratio between worm and table is generally 40:1, 72:1 or 90:1 but may be any ratio that can be easily divided exactly into 360°. This is for ease of use when indexing plates are available. A graduated dial and, often, a vernier scale enable the operator to position the table, and thus the work affixed to it with great accuracy.

Rotary tables are most commonly mounted "flat", with the table rotating around a vertical axis, in the same plane as the cutter of a vertical milling machine. An alternate setup is to mount the rotary table on its end (or mount it "flat" on a 90° angle plate), so that it rotates about a horizontal axis. In this configuration a tailstock can also be used, thus holding the workpiece "between centers."

With the table mounted on a secondary table, the workpiece is accurately centered on the rotary table"s axis, which in turn is centered on the cutting tool"s axis. All three axes are thus coaxial. From this point, the secondary table can be offset in either the X or Y direction to set the cutter the desired distance from the workpiece"s center. This allows concentric machining operations on the workpiece. Placing the workpiece eccentrically a set distance from the center permits more complex curves to be cut. As with other setups on a vertical mill, the milling operation can be either drilling a series of concentric, and possibly equidistant holes, or face or end milling either circular or semicircular shapes and contours.

To create large-diameter holes, via milling in a circular toolpath, on small milling machines that don"t have the power to drive large twist drills (>0.500"/>13 mm)

with the addition of a compound table on top of the rotary table, the user can move the center of rotation to anywhere on the part being cut. This enables an arc to be cut at any place on the part.

Additionally, if converted to stepper motor operation, with a CNC milling machine and a tailstock, a rotary table allows many parts to be made on a mill that otherwise would require a lathe.

Rotary tables have many applications, including being used in the manufacture and inspection process of important elements in aerospace, automation and scientific industries. The use of rotary tables stretches as far as the film and animation industry, being used to obtain accuracy and precision in filming and photography.

In this simple diagram of a drilling rig, #20 (in blue) is the rotary table. The drill string, while the rotary table rotates it. (Note: Force is not actually applied from the top (as to push) but rather the weight is at the bottom of the drill string like a pendulum on a string.)

A rotary table is a mechanical device on a drilling rig that provides clockwise (as viewed from above) rotational force to the drill string to facilitate the process of drilling a borehole. Rotary speed is the number of times the rotary table makes one full revolution in one minute (rpm).

The rotary table is also called a turntable. Most rotary tables are chain driven. These chains resemble very large bicycle chains. The chains require constant oiling to prevent burning and seizing. Virtually all rotary tables are equipped with a rotary lock". Engaging the lock can either prevent the rotary from turning in one particular direction, or from turning at all. This is commonly used by crews in lieu of using a second pair of tongs to makeup or break out pipes. The rotary bushings are located at the center of the rotary table. These can generally be removed in two separate pieces to facilitate large items, e.g. drill bits, to pass through the rotary table. The large gap in the center of the rotary bushings is referred to as the "bowl" due to its appearance. The bowl is where the slips are set to hold up the drill string during connections and pipe trips as well as the point the drill string passes through the floor into the wellbore. The rotary bushings connect to the kelly bushings to actually induce the spin required for drilling.

Most recently manufactured rigs no longer feature rotary drives. These newer rigs have opted for top drive technology. In top drive, the drill string is turned by mechanisms located in the top drive that is attached to the blocks. There is no need for the swivel because the top drive does all the necessary actions. The top drive does not eliminate the kelly bar and the kelly bushings.

Years ago, before I learned CNC, I owned a Phase II 8″ horizontal/vertical rotary table that I purchased from Kap Pullen’s Getmachinetools.com store. He has them at a good price, BTW, and he’s a darned nice fellow to deal with as well as being a frequent HSM contributor. Anyway, its a nice little table, but I hadn’t done a whole lot with it for quite a while after purchasing it. As is so often the case, one day, a project landed on my doorstep and I was glad to have it.

Before I could get started, however, I had to make some accessories for it. Basically, I needed some T-Nuts to fit the table, as well as a little fixture that makes it easy to hold a plate up off the table through a hole in the center so you can machine it. The latter, what I call a “plate machining fixture”, was inspired by something similar I saw the Widgitmaster of CNCZone fame using to make Dremel clamps for his mini-router:

The Plate Maching Fixture and 3 Homemade T-Nuts. T-Nuts are easy to make: square a block to the proper dimensions, mill the side reliefs, drill, and tap. These are much smaller than the mill’s Bridgeport standard T-slots, so I made them myself and I’m using 1/4-20 bolts with them. They’re made of mild steel.

I turned the round spigot using the 4-jaw on the lathe. I’m making the fixture out of MIC-6 aluminum plate, which is pre-ground very flat on the sides. This is a 5 inch by 3 inch piece. I’ve clamped it to the rotab using my T-nuts and the regular mill clamps and step blocks. It is sitting on parallels to make sure I don’t cut into the table. You can also see how I’ve clamped the rotary table to the mill table using a big cast iron V-block I have. You can never have to many blocks with precision faces hanging around!

Having a 4-jaw chuck on your rotary table is mighty handy! Because it’s a 4-jaw, you can dial in the workpiece by adjusting the jaws until it is perfectly concentric with the table’s axis of rotation. The best way is to make an adapter plate that attaches to the back of the chuck in the same way that your lathe does so you can exchange lathe tooling with the rotab. Here is an example:

For the example, the chuck is threaded onto the adaptor plate, and then the holes in the adapter plate’s flange are used to bolt down to T-nuts on the table.

In my case, I bought a 4-jaw from Shars brand new, and simply drilled some through-holes in the chuck to mount to the table directly without an adapter plate:

First, you want to make sure your part is properly centered on the table. To do that, I clamp the table down on the mill table (no special place is needed), put my Indicol indicator holder on the mill spindle, and find some round feature on the part to indicate on. For example, on the plate milling fixture above, indicate on the round boss, or on the center hole. Spin the table and bump the part in until spinning the table doesn’t move the indicator.

Second, locate the center of rotation directly under the mill spindle. You can simply use the X and Y table handwheels to do this. Use that Indicol to indicate off of a circular feature you want centered under the spindle. Turn the indicol around on the spindle and adjust the handwheels until the indicator stays put relative to the spindle position. A Blake Coaxial indicator will make this last even simpler.

When you’re rounding partially by cranking a part around on the rotary table, it’s really easy to go a little too far and screw things up. The answer is to drill the end points to make the exact stopping point on the rotab a lot less sensitive:

Centering with a Blake indicator is really fast, but what if you don’t have a Blake, or worse, what if your mill is too small to accomodate one? Here is a nice solution I found on a German site. This fellow has made an ER collect fixture for his rotary table, and has taken care that when installed on the table, the axis of the collet is aligned with the table’s axis. He can then place a dowel or other straight pin in the collet and line up until it will go into a similarly sized collet on the spindle. Nice trick! It’s similar to how Widgitmaster showed me to align a drill chuck on a QCTP to the lathe centerline with a dowel pin held in the lathe chuck.

Our product range includes single and multiple axes, tilt/rotating tables, and indexing and high-speed spindles. Additionally, we offer customized solution tables for customer requests or OEM projects.

Customer satisfaction is our highest priority. Due to a high degree of vertical integration, our customers have one point-of-contact and the guarantee that all components are manufactured and assembled to your specifications.

Even for EDM machines that have been in use for decades, we will work with you to determine the ideal rotary indexing table and/or rotating/indexing spindle solution.

Our state-of-the-art rotary indexing tables and customizable reference and clamping systems provide endless application possibilities and highly efficient solutions.

Customer satisfaction is our top priority. You specify the task and together we’ll find the optimal solution for your production challenges and products.

Our product range includes single and multiple axes, tilt/rotating tables, and indexing and high-speed spindles. Additionally, we offer customized solution tables for customer requests or OEM projects.

Customer satisfaction is our highest priority. Due to a high degree of vertical integration, our customers have one point-of-contact and the guarantee that all components are manufactured and assembled to your specifications.

Even for EDM machines that have been in use for decades, we will work with you to determine the ideal rotary indexing table and/or rotating/indexing spindle solution.

Our state-of-the-art rotary indexing tables and customizable reference and clamping systems provide endless application possibilities and highly efficient solutions.

Customer satisfaction is our top priority. You specify the task and together we’ll find the optimal solution for your production challenges and products.

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Rotating components are common in motion applications — robot arms, winders, spools, spindles, and rotary tables are just a few examples. And while creating rotary motion is easy, when air or liquids need to be transferred from a stationary supply to a rotating component for cooling, heating, lubricating, or transmitting fluid power, the task becomes more complicated. This is where rotary unions come in.

Rotary unions provide an interface that allows fluid media — air, steam, or liquid — to be transferred between a rotating component and a static component. They’re designed to accommodate a wide variety of media conditions, including very high and low temperatures, flows, and pressures, including vacuum applications. And unlike other fluid transfer mechanisms, rotary unions work for applications involving any combination of rotation angles, including continuous rotation in one direction.

There are numerous designs and configurations for rotary unions — in fact, they’re often custom-designed for the application — but all rotary unions are made up of four basic parts: the housing, one or more bearings, the shaft, and one or more seals.

The housing is typically the stationary part and is connected to the media supply. The shaft is independent of the housing and rotates with the connected rotary equipment. Media can flow through the union radially or axially via ports in the housing. The rotating part is supported by radial bearings — typically one or more fully sealed deep groove ball bearings.

The most important component of the rotary union is arguably the sealing mechanism, which prevents or reduces leakage between the rotating and stationary components, and must do so with minimal friction and wear. Seal types range from simple lip seals to more complex spring-loaded mechanical seals that automatically adjust to minimize the pressure on the seal faces, reducing friction and wear.

Of course, the fluid transfer should ideally be leak-free, but in some applications, completely leak-free transfer is not possible. For these cases, the media is prevented from being released into the environment by a collection system that recovers the leaked media, protecting surrounding equipment and personnel.

This video from Dynamic Sealing Technologies Inc. demonstrates how rotary unions transfer fluid between rotating and stationary component, with examples of their use in various industries.

The type of media is especially important, since the housing, shaft, and seal materials must be compatible with the fluid flowing through the union. Fluid media can range from water to highly corrosive liquids and steam, and manufacturers address the challenges of each by offering a wide range of materials, not only for the housing and shaft, but also for the seals.

Although single- and dual-flow designs are most common, rotary unions can include multiple independent flow paths that allow different media to be transferred concurrently without mixing. It’s also common for slip rings or fiber optic rotary joints to be integrated with rotary unions, allowing the passage of both fluids and electrical or fiber optic cables.

In motion control systems, rotary unions can be found in robot joints, especially for transferring air or fluid to end-of-arm tooling. They’re also used for passing vacuum or air pressure through rotary air bearing stages, and for supplying coolant and lubrication to machine tool spindles.