how to use a rotary table manufacturer

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.

The rotary table is simply a round flat surface that can be rotated. What makes it interesting is that the table is driven round using a worm and wormwheel arrangement. This means that if a workpiece is mounted on the table it can be machined as it rotates.

On a rotary table the ratio between the worm and wheel is often about 40:1 on a small table but increases with the size of the table. For example a 360mm (12-inch) table might have a ratio of 120:1.

Rotary tables are calibrated round the edge in degrees and have a handle which turns the worm and which, in turn, will rotate the table by 360º divided by the ratio of the worm and wheel. For example, a 360mm (12-inch) table with a 120:1 worm and wheel will rotate by 3º per turn. The handle mechanism has a rotating dial and a Vernier so the angle, on a larger rotary table, can be measured to a few minutes.

Naturally any worm and wheel arrangement on a rotary table is likely to have some backlash. Sometimes this can be compensated for by adjusting the distance between the worm and wheel. Usually any backlash can be ignored if the movement, when machining, is always one way.

The same mechanism can sometimes be used to disengage the worm from the wormwheel. This is useful on large rotary tables because it enables the user to turn the wheel quickly to get from one position to another. (It is not possible to machine the workpiece whilst doing this.)

All rotary tables have a hole in the middle of the table. This is usually a parallel-sided hole but some, especially on smaller rotary tables it is tapered.

This hole can be used to take spigots that can be used to align the rotary table or align the workpiece on the table. Sometimes it is possible to fit a bolt through this hole using various spacers, washers, etc to hold the workpiece on the rotary table.

It is possible the get a device that has a taper on one end that is designed to fit the taper as found on some small rotary tables. The other end has a thread that is designed to fit the backplate as used on the chucks used on some lathes.

All rotary tables can be mounted in the horizontal position on the milling table. Some are designed so they can also be mounted vertically without any other hardware.

Most have slots in the base so they can be bolted to the milling table. Some do not but have a flange so that they can be clamped to the milling table.

It is possible to buy rotary tables that have the facility to tilt the table built in to them. Some even can be tilted at any angle in either or both of two planes at right angles. But all of this adds significantly to the height and weight of the rotary table.

The usefulness of being able to tilt in two planes is very limited and would probably not justify the space it would take up. But a rotary table that tilts in one plane can be useful. This setup can easily be emulated by fitting a rotary table to a tilting table.

Most rotary tables have some means of locking the table at any particular position. Very often an operation is done whilst the table is being rotated in which case the force of the cutter cancels any backlash. However when an operation such as drilling is being done at a particular point then the table should be locked.

Very often a cut needs to be made between two points at the ends of a particular arc. Usually it is not possible to make the cut in one go but several passes are needed. In this case it is useful to have two stops so each cut will start and stop at exactly the same points. This is very useful for preventing mistakes.

The fig. shows a stop. The movable part clamps to the top of the rotary table’s table. Two of these are needed. The fixed part has been fitted to the hole normally used for the locking mechanism as shown in the previous fig.

It will be noticed that the same hole on the rotary table is used for both locking and for a stop. But, of course, in practice, it  will, at any one time, only be needed for one function or the other.

For milling any particular workpiece on a rotary table one has to allow for the space around the workpiece for the clamps used to hold it. For example a 200mm rotary table might hold a workpiece that had to have 120mm hole cut into it. It will be shown later how to effectively extend the diameter of a rotary table. It is often desirable to get the largest rotary table that will fit the milling machine table. However larger rotary tables can be very heavy.

With a large milling machine the practical limit is probably the largest you can lift safely. It is possible to have some sort of lifting gear but this all takes time. It is worth looking carefully before buying because for a given diameter, different makes or different methods of construction can cause a rotary table to vary dramatically in weight.

There will usually be enough space between to milling table and the cutting tool to fit a rotary table to do any required job. But there is always the height of the workpiece to consider. If other devices are to be mounted on the rotary table then the space rapidly disappears.

Most rotary table are set up as shown above to be rotated by a certain number of degrees. This is done using the calibrations on the table marked in degrees.

If it is necessary, when using a rotary table to divide a circle into a number of equal sectors then it is necessary to divide 360º by the number of sectors required. On a small rotary table, the table might only be calibrated to 5°. On larger ones they might be calibrated to individual degrees round the edge but will have a vernier arrangement on the handle so they can be set to a certain number of minutes. This gives us the angle between the sectors. Each time we move from one sector to the next we have to add the angle per sector onto the last angle. For any but the simplest numbers, the chances of getting this right are not great.

It is possible to have dividing plates fitted to a rotating table, as shown above, but this is unusual. But since dividing plates are always fitted to dividing heads these will be covered under dividing heads.

It is quite common to need to be able to divide a circle into so many parts. With dividing plates this is easy and is covered elsewhere. for a rotary table using just degrees and minutes a circle can be divided by one of the following methods.

A     calculate the angle in your head or using a calculator for the origin for each sector and write them down. Most simple calculators will give decimal angles whereas the rotary table is marked in degrees and minutes.

B     use a spreadsheet to produce a list of angles. These will probably be decimal angles. But is then quite easy to turn decimal degrees into degrees and minutes.

C     Use tables showing the angles for each position for a circle divided up to 200 sectors can be found in Appendix C. These are in degrees and minutes.

D     use the table for the first 200 sectors that can be found in “Tables for [the] Cooke Optical Dividing Head” published by Cooke, Troughton and Simms.

rotary filing—that is, running a circular cutter withfile-like teeth in the headstock of alathe.Rotary filling and later,true milling were developed to reduce time and effort

A CNC rotary table is the precision positioning accessory that can provide a reliable 4th axis or even 5th axis for modern machining centers. Utilizing a computer-controlled rotary table can turn the original 3-axis machine tools into 5-axis CNC machines, expanding the accuracy as well as decreasing the costs while performing complex machining operations at one time.

A CNC rotary table is the precision positioning accessory that can provide reliable 4 or even 5 axis cutting operation capabilities for modern machining centers. Utilizing it can turn the original 3-axis machine tools into 5-axis CNC machines, expanding the accuracy as well as decreasing the costs while performing complex machining operations.

Rotary tables typically have rigid frames and coatings, and also excellent torque capacity, which makes the small device flexible and effective for a wide variety of turning, milling, drilling, and more metalworking operations. The easy setup and seamless interface allow the operators to easily add the rotary table to fit their 4-axis or 5-axis applications. .

The working principle is similar to the basic rotary tables, which is to support the workpiece by accurately rotating the workpieces on the axis in order to locate the parts for high precision tooling. Under rapid rotation, which is driven by CNC instructions, the cutting tools of larger machine tools or machining centers can remove the material and add the feature to the products at exact intervals. On rotary tables, there are vertical and horizontal axes for various tools to perform these high-performance metalworks. To enhance the accuracy and flexibility, there are models that employ additional dividing plates and come with additonal material handling mechanisms and features.

Since 4-axis and 5-axis machining is increasingly popular today, adding the CNC rotary table as the 4th axis is an ideal solution to easily open up more complex machining options at a lower cost. Due to the arrangement, they are widely also called the 4th or 5th axis or tilt rotary. The 4th axis, which is the rotational operational direction, is added to the original three linear axes which are known as X-axis, Y-axis, Z-axis. In some cases, there are two rotational axes add to the original 3-axis machining center, achieving utmost accuracy as well as effective multiple face cutting to reach the difficult area on the surface. Rotary tables are usually mounted parallel to the ground or the bed, with the platter rotating around the vertical axis, for example with the most common vertical milling machine combination. Sometimes the machining application requires an alternative setup with the table mountet on its end so that it rotates around the horizontlal axis. Often, a tailstock is used in this configuration. Virtually all models today come with a clamping kit to mount it onto the bed of your machine tool.

The function of the high precision rotary table is also to rotate the workpiece so the cutting tool can create the contour we desired out of the workpiece. However, a rotary table with higher precision has the ability to achieve great accuracy just as its name implies. There is also a major misconception between the resolution and the accuracy.

A common example is that if a digital readout displays to four decimal places, then the high precision rotary table must also be capable of achieving the accuracy to that same value. Even though for higher accuracy to be achieved, the resolution has to also be high, but there is no guarantee that the accuracy is going to be high. The accuracy is the concept which is the difference between the actual position and the position measured by a reference measurement device. The feedback mechanism such as the rotary encoder, and the drive mechanism can influence the accuracy of the advanced rotary table.

A CNC rotary table can provide great rigidity for stable machining operations. It consists of the worktable where the metal parts are held, the rigid bearing that withstands the forces and loads during the rotation, the solid base which is used for attaching the rotary table to the machining center or other equipment, the motor, and the CNC system.

The worktable is the tooling surface where the workpieces are machined after accurate positioning. The worm gearing is the core mechanism of the table, which mesh with the steel worm which is submerged in the lubricants. Both the rigid bearings and the worm gears have large diameters. Excellent concentricity is the key to smooth operation, durability, and most importantly, accuracy. Driven by a computer and electric motor, the worktable can position the materials at exact intervals. For more flexible or critical operations, dividing plates can be added to this component.

A CNC system regulates the simultaneous 4-axis motion of the rotary table. The instructions are programmed and transmitted via CAD software, reducing the time for adjustment and monitoring by human workers.

The type and size of the electric motors utilized in can define the router accuracy as well as the efficiency of the device. Servo motor and stepper motor are two typical types that can be divided into more subtypes. The servo motor uses a closed looping variable circuit, the circuit will constantly run to keep the function. The brushes must be replaced every 2000 hours of operation in the servo motor. Compared to stepper motors, servo motors are more efficient in power consumption. On the other hand, the stepper motor has a simpler setup which are the wires that are attached to the driver. The bearing of the stepper motor is the only wearing component. However, the stepper motor consumes a great amount of energy.

There are currently several different types and models available in the industries. Each of them possess its own traits and abilities. Let us take a look at the most common ones other than standard three axis tables

The 4 axis CNC rotary table will process the workpieces by holding them in the same position while the cutting tool performs along the XYZ plane to trim away the unwanted material. In general, a 4 axis model is very versatile equipment that can be used for several different industrial processes such as engraving curved surfaces, continuous cutting, and intermittent cutting. Besides, people can also add other devices such as cam machining, blade machining, and helical grooves to the 4 axes rotary table. Such a feature is simply impossible to achieve with the machining center which has only 3 axes.

Besides the 4 axis ones, there are also 5 axis models. They have the ability to allow the workpiece to be processed automatically from five sides at one time. people usually utilized the 5 axes rotary table in the industries such as the automobile, the aerospace, and the boating industries. The reason that the 5 axes rotary table is commonly used in heavy industries is that the 5 axis machining is an important technique to be used when the components need better intricacy and quick precision. All of these have more than three axes are called the multi-axis rotary table.

The installation method of the precision rotary table can be horizontal, vertical or inverted. When installed horizontally, the workbench surface is in a flat, vertical and horizontal position. When installed vertically, a rotary table is installed so that the surface of it can run up and down. In the reverse layout, itcan be rotated upside down in a horizontal position. The location of the drive of the rotary table can depend on the mount. The drive can be placed on the back, below, on the top or on the side.

When mounted horizontally, the spinning table top drive is positioned above the table floor. When the rotary table is horizontally placed, the side-mounted drive is located on the edge of the table board. The driving mechanism of the rotary table may be manual, electrical, pneumatic, hydraulic or non-driven. For manual revolving workbenches, release the workbenches and manually spin the workbenches with the crank.

Workpieces are gathered and machined through PC and fully programmed instructions. The 5-axis simultaneous operations will be measurably more reliable than products machined via different technologies. Also, the setup is simple and provides an indistinguishable process in every production cycle, the consistency of the quality of the metal products can be ensured under critical control and precision cutting.

Since the metalwork is driven by software, the preferred frameworks can be programmed and adapted by the rotary table. Saving both the cost and the room makes themis the ideal solution for potential users who don’t want to install larger equipment and new machines which may take up a great room for a wide variety of machining applications.

Another benefit is the utmost movements can be completed precisiely and faster. There are more favorable positions, operation angles as well as accessible machining that can be achieved through the technology. The complex operations are suitable for blade, helical grooves production, and other applications required to add complex features or require critical inspection in machining processes like the manufacturing of aerospace, automotive parts, and scientific equipment.

Addding a rotational table saves time because the extra finishing jobs or other sub-operations can also be performed at one time in the machining center.

A rotary table can be used in many applications including manufacturing, inspection, and assembly. Indicators are used, for example, for assembly, manufacturing, and bottling equipment. They typically use a single item in workspaces or move relatively small layouts of items around stations for sequential work or assembly.

In automated assembly machines, the rotary tables implementation is widespread, and choosing the right mechanism is important for both improving efficiency and reducing the cost of this vital component. This guide discusses two common devices for rotating indexing and offers guidance on the right range. There are several ways to get mass mobilization when it comes to the development of rotary indexing tables. Regardless of whether the load or load in centuries of thousands of kgm2 is incredibly light. When choosing a robust rotary index solution that will match or meet your standards, there are several factors to take into account when spinning, elevating, or pushing.

When determining the influencing factors on the postitioning accuracy, the first thing to look at is the mechanical properties of the table itself. A rotary table contains six degrees of freedom. Each of these movements increases the total risk of positioning errors. Usually, a rotary table is driven by a worm gear, which is connected to the motor through a rotary encoder on the back. The position of the table can be determined by the number of pulses transmitted from the encoder to the control device.

The four main sources of error due to the semi-closed position loop are geometric errors, thermal deformation, elasticity, and wear. The sum of these errors is called angular positioning error. To greatly reduce the angular positioning error, the ideal position for installing the angle encoder is on the rotating shaft under test. The angle encoder is installed under the rotary table, and the rotary encoder is installed under the rear motor, the position loop is now considered a closed-loop system.

Precision is a relative term. About a quarter of an inch is great and will meet the accuracy of its application. Others, for example, require micron-level accuracy in measuring and indexing devices. Then, some applications fall within these extreme ranges.

The misunderstanding is that you may have used an inaccurate indexing device and made it accurate by introducing a pin or wedge locking device. These devices increase the complexity and cycle time of use, and when they are used together with a high-precision positioning device, they may cause damage and reduce accuracy.

In the actual test, by selecting specific components, motion index drive, servo rotary indexer, the measurement accuracy is as high as 5-6 microns. These are not the results approved by Motion Index Drives, but the results of customer certification. When starting and stopping large amounts of data, it is important to know how fast it takes to stop the application with large amounts of data.

In a less rigid environment or the presence of higher recoil, a faster start and stop will bring many control problems. When moving masses (whether rotating mass or linear mass), starting and stopping in a system with a backlash of several arc minutes will cause a lot of back and forth movement in the gear system. The result is a force that is difficult or even impossible to calculate. In addition, when the gear head is used in rotating applications, the farther the mass is from the center of rotation, the greater the backlash. In applications with very slow deceleration times, recoil may not be a problem.

Backlash in the positioning process is a big issue – when it comes to the beginning and stopping volumes, it"s crucial to know how quickly you need to avoid the mass of your rotary indexing table applications. In a less rigid system or where there is an increased backlash, quicker start-ups and stops can cause a lot of control issues. When shifting a mass, whether rotary or linear, starting and stopping in a system with several minutes of backlash arc will create a lot of back-and-forth motion within the gearing system. The effect is a power that can be difficult and probably hard to quantify. In comparison, as the gear head is used for rotational applications, the more the mass is from the axis of rotation, the further the backlash is magnified.

The backlash may not be a concern in systems where deceleration times are incredibly long. In the case of cam indexers, there is " Zero Backlash." The cam indexer and rotary table dynamics give an incredibly rigid, highly regulated framework. A modern cam indexer system is capable of withstanding short cycle times with stop times in milliseconds.

So you want to get the smart manufacturing going but are not sure of what to look for in rotary tables. The information provided in this section may be able to help. The primary factor is to determine the mass snapshot of inactivity. This is often overlooked when measuring a rotary table for the machine.

Another significant factor is the size of the workpiece being rotated, including how big it is and how substantial it is. You want your rotary tables to be large enough to handle enormous pieces. This is where tilling rotary tables may become handy so that the pieces can be handled without causing interior harm. They allow the quickening and decelerating of machining at appropriate rates.

The last factor is accuracy, the applications for which, for instance, pivoting a gigantic part to allow welding highlights on it where the individual stop positions can be genuinely free. On an additional note, when choosing direct drive rotary tables, factors that you should consider when selecting a rotary table for your CNC machinery include accuracy, backlash, mass moment of inertia, acceleration and deceleration, speed, and environment.

Indexing system use is commonly possible in automatic assembly machines and the right process is important for both performance maximization and cost reduction.

Cam indexers are an omnipresent tool used for several decades for rotary indexing tables. They are suitable for applications that often index the same angle and need a high degree of accuracy at a relatively low cost. To place the load, a cam indexer uses a mechanical cam. A math curve is pushed onto the cam and provides incredibly smooth and repeatable movement.

Another popular alternative is a fully programmable rotary index table. A rotary table is advantageous in two different situations. Firstly, a versatile movement pattern is important. An example is if two components are running on one computer, each of which requires different index patterns. For incredibly fast placement accompanied by a long period, another condition that matches the servo pointer is. The need to accelerate the camshaft while the cam indexing mechanism was operating before starting the output movement reduced the on-demand cam indexer. Acceleration of the camshaft is possible, but there is a delay before the movement begins. There are realistic restrictions.

With an indexing table, the output rotates as soon as the servo starts moving. This is not difficult for a continuous cam indexer or a zero-backlash servo indexer, but it can also be difficult for an on-demand cam indexer. For applications with high-speed servo indexing, smooth movements are crucial. A zero-backlash preloaded reducer can achieve this. The ideal alternative for correct positioning with high dynamic response would be the zero-backlash reel drive system.

Application parameters, like a moment of inertia, indexing angle, indexing period, and residence time, are required for each indexer style. The rotary indexing table for the application should also be sized correctly by a reputable manufacturer.

The crosslide table all depends on where the slides are...above the point of rotation or below. Below is pretty much the cheap line and really is redundant putting on a mill as you already have 2 axis there. Now, slides above the pivot point allows you to position your part any where on table, center it above the pivot using the slides (U & V axis?) all with out tapping it about like a rotary table w/o slides. Also, you can then offset a part to center a desired radius elsewhere...example: you need to mill a 4" square hole with r.535 in corners. On a plain rotary table you would need to relocate the part for each corner...with topslides you use the U & V axis to position the center of R.535 over the pivot and turn the corner. This works for all kinds of stuff...milling angles off the X&Y that come tang to a rad, or even milling multiple circles or countours on a single pc w/o remounting and locating the pc. Think of 3 O-ring grooves on a hydraulic cover, or the snowman shape in a gearpump hsg. These can get confusing as now you have a manual machine with C,U,V,W,X,Y,&Z axis....wow.

The best has to be Advance 15X15. I know this unit cost $4500 15 years ago.Troyke made them also but I don"t know of others. Palmgren I thought made the bottom slide type. Alas, the 2axis CNC retros can outrun it and these are rapidly becoming dinosaurs.

Indexing tables are used in a multitude of industries and in numerous applications. Their design is optimal for many manufacturing jobs, and they are a critical component in most automated manufacturing systems. Indexing tables are best defined as a machine tool positioning device. They carry components in a manufacturing environment with a repeating process of indexing (rotating) around an axis, stopping, dwelling while an operation is performed, then indexing again to repeat the process. They are usually made of circular steel plates, with one or more spindles, a drive system, encoders, sensors, controllers and slots or mounting holes to hold components.

Virtually any manufacturing operation can be performed on a part held by an indexing table including welding, grinding, drilling, assembly, painting, inspection, testing and more. In order to maximize operational efficiency, the machine doing the operation must also be built for the same intended application as the indexing table for them to work in synch. Similarly the machine that loads the indexing table with parts must also be synchronized. They must have the same capacity and be able to manage to the same dwell time for the system to work.

If the timing of these machines are coordinated, the time to operate on or assemble a product can be a fraction of that of workers assembling a product.

Industries that use indexing tables include automotive manufacturers, bottling companies, microchip manufacturers, pharmaceutical makers, consumer products companies and many more. They are invaluable to manufacturers pushing for automation and increased efficiency in their factories, turning work that used to take days into work that takes only hours. If a simple assembly task is required on small parts in a factory, there is no better way to complete the task than by coupling an assembly tool and an indexing table.

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.

Manufacturer of standard and custom 360 degree linear rotary tables for scanning, assembly, testing and production applications. Features vary depending upon model, including worm and gear drive design with central rotating ball bearings, manual and motorized operation, hollow spindles, four mounting holes, accessible adjustment clamps and graduated knobs. Accessories such as rotating table adapter plates, brackets, platform shelves, thumbscrew locks, alternative knobs, limit switches provided. Manually operated rotary motion turntables also available. Suitable for mounting and rotation of test specimens, cameras, transducers, sensors, mirrors and other components. Stock items and repair services are offered. One year warranty. Made in the USA.

CNC rotary tables play a vital role in the performance of multi-axis machining centres. As table accuracy and reliability are of paramount concern throughout the product"s lifetime, Matsumoto Machine Corporation (MMK) has taken a pragmatic two-pronged approach to reducing indexing errors and improving performance. By enhancing both product calibration and encoder technologies the company has set new standards for rotary table accuracy.

Founded in Japan in 1948, Matsumoto Machine Corporation is a technology-leading provider of innovative, high quality jaw chucks and numerically controlled rotary tables used by industrial machine tool makers throughout the world. A key feature of MMK"s CNC rotary tables is a patented worm and wheel gear assembly developed by OTT GmbH, Germany. Unlike double lead worm gears, the OTT worm and wheel gear is able to minimise backlash, ensuring outstanding accuracy and long life, efficiency and durability.

Shaped in order to maximise gear surface contact area, thereby reducing adverse surface pressure effects, the OTT worm gear teeth are split into separate right and left parts (shank worm and hollow worm) connected by a span ring. This unique structure enables backlash adjustment simply by reducing the distance between the two parts. This design also ensures that only one side of a worm gear tooth is in contact with the wheel gear, leaving a clearance on the other side. As a result, the 2-piece split gear design will not seize up, even with zero backlash.

A further advantageous characteristic of the MMK CNC rotary table is a large diameter through-hole in the table spindle. This greatly increases machine versatility and rigidity, supporting a wider variety of chucks and jigs and the machining of longer workpieces.

By enabling most metal-machining operations to be undertaken on a single machine, the benefits of MMK CNC rotary table are far-reaching. These include the time and cost saving of single machine set-up and single fixturing setup, reduced parts handling and the elimination of tolerance errors as workpieces pass from machine to machine.

Of critical importance in this one-hit machining centre scenario is ensuring the high accuracy of CNC rotary table indexing and control throughout its working lifetime.

As with any form of precision equipment that is integrated into a machining centre by a third party machine tool maker, and which in turn is used by an end user in any number of industrial sectors, assuring consistent accuracy and performance over time presents a challenge.

As with a machine tool"s linear XYZ axes, the rotary axis is just as susceptible to uncontrollable events that may introduce angular positioning or axis alignment errors. Risking the production of defects in finished parts, these errors can be due to a number of reasons including, mistakes made in the initial machine installation, impact damage caused by collision or general wear-and-tear in use.

With its global reputation for product quality and design innovation, MMK therefore sought to equip its CNC rotary tables with a highly accurate and reliable means of tracking and controlling the indexing of its product throughout its lifetime, irrespective of the type of machine tool, workpiece complexity and duty cycle.

At the same time, in an increasingly competitive global market for CNC rotary tables, MMK also wanted to further enhance its product quality inspection processes. Specifically, the company set itself the task of augmenting index angle measurement as a key component of pre-shipment quality assurance procedures.

To provide machine tool makers and users with the ability to accurately track and control CNC rotary table indexing, MMK elected to integrate Renishaw"s super-compact TONiC™ non-contact optical incremental encoder system. Simple to install and with a compact readhead measuring just 35 mm x 13.5 mm x 10 mm, the TONiC encoder presented MMK with a minimal footprint solution capable of supporting machine speeds up to 10 m/s and resolutions down to 1 nm.

The rotary table readhead was designed to be used in conjunction with Renishaw"s RESM, a one-piece stainless steel ring marked on its periphery with 20 µm pitch graduations and featuring the IN-TRAC™ optical reference mark. With its low profile, large internal diameter and wide choice of diameters from 52 mm to 550 mm, the high stability RESM ring provided MMK with a versatile and easy to integrate scale that is well-suited to the company"s wide range of CNC rotary tables.

For improved reliability and higher immunity to any scale degradation over time, the TONiC readhead incorporates third generation filtering optics, tuned for low noise (jitter) and further enhanced by dynamic signal processing. The outcome is an ultra-low sub-divisional error of typically ±30 nm. The TONiC encoder is compatible with industry standard controllers and features a detachable analogue or digital interface inside a robust D-type connector, which can be located up to 10 m from the readhead.

MMK selected Renishaw"s compact and lightweight XR20-W rotary axis calibrator to verify the accuracy of its rotary tables during manufacturing and immediately prior to shipment. The XR20-W was used in conjunction with Renishaw"s XL-80 laser interferometer to provide a non-contact reference measurement, independent of the axis under test, with an accuracy of ±1 arc second.

Motorised by a servo-controlled drive and with data capture synchronised to axis movement, the XR20-W requires no operator intervention during measurement. Being lithium battery powered and Bluetooth enabled, it ensures quick and easy setup, and the avoidance of trailing cable hazards. The calibrator"s modular design and flexible mounting systems allow far easier setup than alternative solutions and can be readily configured for a wide variety of rotary tables, chucks and spindles.

By integrating Renishaw"s TONiC non-contact optical encoder system into its CNC rotary tables, MMK has further assured the accuracy and reliability of its products in the field, along with an overall superior motion control performance. For a wide range of different machine tools and end uses, the rotary tables" combination of compact readhead and one-piece stainless steel ring scale has delivered a higher level of tolerance to dust, scratches, grease and oil, and a reduction in indexing errors. The encoder system"s ability to output highly stable position signals of unrivalled purity and ultra-low sub-divisional error have provided smoother velocity control, improved scanning performance and increased positional stability.

MMK"s introduction of Renishaw"s XR20-W rotary axis calibrator and XL-80 laser interferometer has reduced product measurement times by a half compared to conventional autocollimator techniques. Measurement procedures have been simplified and automated. Capable of taking accurate measurements at any indexing angle pitch, the calibrator enables evaluation of the accuracy of the worm and wheel gear-driven table for ultra-fine pitch measurement movements as small as 0.001°. This has allowed any loss of motion control or worm and wheel gear efficiency to be evaluated in detail and addressed. Product performance is now backed by a thorough analysis meeting ISO quality standards.

CNC rotary tables play a vital role in the performance of multi-axis machining centres. As table accuracy and reliability are of paramount concern throughout the product’s lifetime, Matsumoto Machine Company has taken a pragmatic

two-pronged approach to reducing indexing errors and improving performance. By enhancing both product calibration and encoder technologies the company has set new standards for rotary table accuracy.

Rotary tables are used for perfection metalworking. They"re generally made with a solid base that can be clamped on to another institution. The table is a slice that rotates freely or by use of a worm( hand coil).

A rotary table is a slice- shaped metalworking device used to gain precise workpiece positioning. It enables a metalworker to cut or drill a workpiece at precise intervals around a vertically or horizontally fixed axis. A rotary table can be both manually or computer numerical controlled. Certain types of rotary tables are designed to be used with indexing plates or dividing plates for technical operations. A rotary table used together with one of these positioning plates is generally appertained to as a dividing or indexing head.

The rotary table device generally has a solid base that can be attached to a separate institution or table using clamps. This device is principally a rotating slice which holds the workpiece in place during slice or drilling operations. The slice portion of a rotary table can be freely rotated for indexing procedures or turned by an attached control arm known as a worm wheel. Tables used in high perfection operations are generally turned by a duplex- type worm wheel to compensate for counterreaction. Rotary tables used in automated essence working processes are turned by computer numerical controlled ministry.

Rotary tables are most frequently used in a flat position with the table’s axis having a perpendicular exposure. They"re occasionally mounted with the axis acquainted in a vertical fashion so that a tailstock can be used to support the free end of the workpiece. When this device is attached to a secondary table, the workpiece can be centered on the rotary table’s axis which is also centered on the slice tool’s axis. In this configuration, the axes of the rotary table, secondary table, and cutting tool are coextensive to grease concentric slice operations. This configuration also permits the secondary table to be neutralize for drilling equidistant holes in a workpiece.

Rotary tables are positioning devices that are oftentimes used in precision manufacturing applications. More specifically, they are tools that hold parts on rotating axes, which increases productivity, accuracy, and repeatability. It seems simple enough, but there are various types of rotary tables. So how do you choose which one is best for you? Let’s go through three common kinds of rotary tables – air-bearing, oil hydrostatic, and mechanical-bearing – to assist you in answering that question.

In many cases, air-bearing rotary tables will be the answer. This is due to the fact that they have the capacity to run longer than other kinds. These are exactly what they sound like; with air-bearing rotary tables, parts float on air above the table. With this, there are no contacting parts to wear the machine down, resulting in decades of maintenance-free motion. That is a significant benefit to any piece of air-bearing equipment, but these rotary tables are specifically beneficial for certain applications.

Maximizing metrology productivity can be challenging, but utilizing air-bearings can assist in boosting turnover. Additional industries such as optics, assembly lines, and light machining and grinding, can use them to increase accuracy and productivity as well.

Similar to air-bearings, oil hydrostatic rotary tables do not have any contacting mechanical parts, as they float parts on oil. These rotary tables are most commonly used for grinding and machining when smooth and repeatable motion is a necessity. They provide high load capacity and can be useful when extreme stiffness is necessary.

Mechanical-bearing rotary tables are a bit different from the other two. Just as the name suggests, this type of rotary table does have moving, touching mechanical parts. And while this does sometimes result in a shorter life than the air-bearing or oil hydrostatic tables, many organizations will still pick these out of the others. Why? They still offer high performance.

These rotary tables can be used in most applications and provide superior performance in radial, axial, and angular error motions. In all, mechanical-bearing rotary tables do the job; however, it is possible that they will not last as long as other types.

The answer to the question, “Which one is best?” is the ever-hated, “It depends!” In general, air-bearing rotary tables will provide the highest accuracy for the longest amount of time. The lack of touching mechanical parts allows this type of rotary table to last decades. However, if you need a stiffer hold, oil hydrostatic could be the better choice. And in other cases, mechanical-bearing rotary tables could be best. All in all: It depends.

But if you want to know more about rotary tables and which would be the right choice for your application, contact the experts at ABTech. We will ensure you get exactly what you need.

At Rusach International,rotary table design, engineering and manufacturing & pallet system design, engineering and manufacturing is our specialty. We can supply rotary tables from 100mm up to 8 Meters in diameter.  See our rotary table pages.  We specialize in high accuracy, up to +/- 1 arc second, heavy load capacity, large work pieces, production style, heavy duty rotary tables and pallet shuttle/storage/transfer systems.  We also have a line of standard small production tables that are very cost effective, yet can be customized per application.

Rusach International systems are not proprietary and therefore can be integrated into any machine, control system or application. We do not believe in “locking” a customer down with proprietary parts!  We work with all the major industry control, motor and encoder manufacturers.

I usually get a good many arguments started about rotary table setups. I worked in a large forge die shop, and I still do the setups the way we were shown in that shop. Probably 95% of the time you used a rotary table on a rotary head milling machine, so getting stuff on center was step #1.

The first thing to be pointed out is that the center hole and OD of the table aren"t necessarily on the axis of rotation. Easy to check, take the worm out of engagement and pull the table around by hand with an indicator zeroed on the center hole. Just like indicating a part in a four jaw.

If it is on center, that"s great. If not, you can eyeball your part on center and lightly clamp while you indicate it in by pulling the table around by hand and tapping it. If you don"t have a concentric hole or OD to use an indicator on, a center punch mark and a pump center can be used.

Once the part is on the center of the rotary tables axis, it"s a simple matter to center it under the machine spindle by locking the table and rotating the machine spindle and indicating like you would normally.

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To me, this table is just the right size and weight, not so small as to be a mere toy, but not too large, heavy, and expensive for my simple needs. I have had it for three weeks now and decided to review it after completing my first project.

When I first examined it I noticed that is seemed very well made and operated very smoothly. It definitely exceeded my expectations. I noticed it had a backlash of 20 minutes of arc, which I considered this totally acceptable. Accurate work is always done by turning knobs in one direction only. This table has a convenient knob to hold the position when it is reached. You can set the angle to about 1 minute of arc, and hold it there.

For my first project I made a couple of simple fixtures. One was a centering hold down, the other was an aluminum sub base. This is especially useful for mounting the table vertically in my drill press cross vise.

The project itself was a 2" diameter hub to mount an 8" sanding disc to a 1/2" shaft. The hub has 6 holes that I wanted to lay out precisely. Three holes run through the rim for set screws to hold the shaft. Three holes through the face attach the disc to the hub. Pictures of the hub and fixtures are attached.

Fig. 4—On this tilting rotary table, one servo controls rotation, another controls tilt. Both servocontrols are slaves to the CNC with RS-232 communication, providing five-axis capability from a standard three-axis CNC.

Fig. 1—Modern rotary tables such as this one from SMW Systems have large, widely spaced spindle bearings, large diameter wormwheels and built-in spindle brakes.

If you want to make parts similar to the complex valve body (upper left), an indexer using M-code, RS-232, or “full fourth axis” control is appropriate. Only positioning and rotary cutting moves are required. The center workpiece is a cam that requires simultaneous rotary and linear moves. You’ll need full four-axis control for such workpieces. If you want to do parts similar to the impeller on the right, the contour cutting will require simultaneous five-axis machining.

Many plant managers and shop owners dream of having the latest horizontal machining center (HMC) with all its features, benefits and sophisticated capability. While typical HMC features such as an automatic pallet changer and a 100+ cutting tool magazine are valuable, perhaps the most valuable characteristic is the HMC’s ability to machine on more than one side of the workpiece due to a built-in indexer or full fourth axis.

On complex workpieces that require machining on surfaces not 90 or 180 degrees from each other, indexing or fourth-axis rotation is almost essential to produce the piece. Even when rectangular workpieces with all surfaces 90 or 180 degrees from each other are put on a tombstone, the HMC’s built-in fourth axis of rotation creates a productivity advantage. This is true even if machining on more than one side of the part is not essential.

Any time you can increase the “run cycle,” do more cutting in one operation and avoid handling the workpiece, productivity goes up. Workpiece accuracy also improves. Unclamping and refixturing a workpiece to present a different surface to the cutting tool is always going to introduce some error.

The high cost of horizontal machining centers compared to the incredible values available today in vertical machining centers puts horizontals out of reach for many shops. Fortunately, today there are several suppliers of quality accessories that allow the VMC shop to equip its verticals with indexers, fourth axes and tombstones. These add-ons really work and give many of the benefits of an HMC at a fraction of the price.

Earlier rotary tables and indexers didn’t have the accuracy, rigidity or control flexibility of today’s models. Many shops that tried using indexers in the past had been disappointed in the performance of the older models and abandoned their use in favor of multiple operations, multiple holding fixtures and multiple handlings of the workpiece. They decided that the manual, multiple-operation process was better than trying to use ineffective early model indexers and rotary tables. Today, the situation is different. Manufacturers now offer units that are very accurate, very rigid and have a variety of control and interface options.

The best indexer and control system for you depend on the work you need to do. As with most things, different designs compromise certain capabilities to gain others. Unless you understand these trade-offs, you are at risk of selecting something other than the best system for your requirements. Let’s see what’s available, review the differing capabilities and discuss the advantages and disadvantages of each design. Once you understand the options, you can evaluate them against your requirements and then consider prices and suppliers.

Of course, such a system does not exist. Add the “lowest price from the supplier that gives the best service and support” component and it probably never will exist.

Terminology in the area of indexers is not standard. Terms such as fourth axis, indexer, rotary table and so on are used interchangeably by different machine tool and accessory companies. So, when selecting and buying, you must ask a few questions before assuming you know what you’re going to get. Also, beware of terms such as “precision,” “high precision,” “accurate,” and “rigid.” Is the “brake torque” specification some absolute break away spec or the torque at which some “unacceptable” amount of rotary deflection occurs? Is the “ten arc seconds” accuracy specification certified every one degree, or is it inspected only every 15 degrees? There are no industry standards for specifications and testing. So ask questions and deal with a supplier in which you have confidence, or buy with a guarantee of performance to make your parts.

We’ll start with the mechanical hardware and discuss the electronic control options later. There are at least three common mechanical indexer/rotary table types.

These tables provide infinite positioning as well as the possibility of rotary cutting. A servomotor controlled directly either by the CNC or by a secondary servocontrol rotates a wormscrew, which drives a wormwheel on the rotary table spindle.

The absolute position accuracy of these systems is a function of the quality (precision and accuracy) of the wormgear set (wormscrew and wormwheel), the accuracy and resolution of the servosystem, and the means of servoposition feedback. Most of these servosystems utilize an encoder to monitor the position of the motor rather than the rotary spindle directly. To eliminate any inaccuracies in the wormgears and servo system, some high-end systems use a glass scale or other encoder directly on the rotary spindle to monitor actual rotary spindle position. Figure 1 (at right) shows a typical wormgear rotary table cross section.

If controlled directly by the machine tool’s CNC, they are most commonly referred to as a “full fourth axis.” A full fourth axis has the advantages of having only one CNC program, no programming required by the operator on the shop floor, minimum chance of a crash due to operator error, and the ability to make simultaneous rotary and X, Y or Z moves to do true helical milling operations as required by some more exotic workpieces.

Claims of position accuracy are often misleading since there are no industry standards. Although some manufacturers test and certify absolute position accuracy every one degree, most do not state exactly what their specification means.For all except those few expensive systems with glass scales directly on the rotary spindle, any accuracy specification is for a new table before it has been subjected to any “crashes,” which are not uncommon. Even seemingly small crashes can damage wormgear sets.

Typical infinite positioning wormgear systems utilize a friction brake to hold position against cutting forces. When cutting forces are applied directly on the rotary spindle centerline, friction brakes are generally adequate for most work. However, when cutting forces are applied to workpieces far off centerline, such as on the edge of a part on a tombstone fixture, the resulting torque on the rotary spindle can cause it to deflect. This result is especially likely when heavy cuts produce high thrust forces.

These indexers offer discrete positioning only. Depending on the number of teeth on the face gear, the minimum increment of index might be 15 degrees, 5 degrees or 1 degree. Whatever the minimum increment, only workpieces with angles representing some multiple of the minimum can possibly be machined.

Face gear mechanisms used in indexers are similar to those most commonly found in the turrets of CNC lathes, which by function must index very accurately and very rigidly to withstand the high cutting forces the lathe turret encounters. Face gear mechanisms generally fall into two categories, the two-piece and the three-piece design. Two-piece designs require the face plate of the indexer to “lift” to disengage the face gears. Three-piece designs maintain the same accuracy and rigidity of a two-piece without the need to “lift” the faceplate. In Figure 2 (at right), note the massive face gear that locks the indexer spindle in position.

Assuming it’s a quality face gear set, absolute position accuracy is superb and is maintained for the life of the indexer almost in spite of any “crashes” that might occur. Units with true absolute angular position accuracy of 5 arc seconds or less are available. These units are ideal for the highest precision work such as line boring half way from one side, then indexing 180 degrees and line boring half way from the other side.

Some face gear systems use a servodrive to achieve approximate position and then rely on the face gear for final accurate positioning. These systems are bi-directional and fast. Any random move can be programmed with one simple command. Some other systems use a pneumatic piston to rotate to the approximate position. Typically, these systems rotate only in one direction. All moves must be equal and may require a pause to utilize more then one M-code signal to achieve position. These work but can be tedious to program, set up and operate. They are more prone to crash due to operator error then servodriven units.

These indexers are becoming a thing of the past. They have all the disadvantages of the pneumatic piston driven incremental face gear indexers. Plus, compared to face gear units, they are neither particularly accurate nor rigid. Index po