dividing head rotary table free sample

I used a scrap riser to mill a custom knob with 17 flutes as an example, because most traditional manual rotary tables and dividing heads struggle with dividing prime numbers.

I needed two large holes in plates, 46mm and 40mm. I mounted the plates on the rotary table, set the indexer to continuous run and slowly lowered the cutting bit. This saved me from having to buy 2 different size hole saws that I might never use again.

Dividing heads allow you to divide a circle into equal fractions conveniently. Anything that involves regular action around a circle is a candidate for a dividing head.

A rotary table has no stops so it is not convenient to do large numbers of things at equal intervals because you would have to painstakingly determine the interval. Also, the rotary table does not divide the circle. For example, if you were making 13 equally spaced operations using a rotary table you would have to calculate some wierd angle for each operation and dial it in--a tedious process. For example, here are the 13 angles for a circle division:

Do you want to manually set each of these values? Have fun doing that. Now, imagine doing it for 53 divisions. You will be there all night. Not only that, the error will be a lot more than a dividing head.

Rotary tables are mounted horizontally, and most can also be mounted vertically. In both cases only at 90° to the mill table. A Dividing Head is always vertical, but can be tilted through 90°.

Dividing heads are always fitted with "indexing plates" (holed wheels and clock hands), allowing a wide range of angles to be turned. The indexing mechanism can do intermediate angles. Rotary tables can be fitted with indexing plates as an accessory, but usually the number of angles supported is limited compared to a dividing head. (A generalisation. And, because rotary tables do all common angles, the limitation may not matter.)

Rotary tables are more convenient for general work because most jobs are mounted at 90° or 180° relative to the milling table. Possibly more robust than a dividing head for rough work. When close accuracy isn"t needed, jobs can be spun rapidly by the rotary table without cranking the handle - a time saver. When accuracy is needed the handle and worm are engaged. Usually there"s a vernier scale sufficiently accurate for most work. The handle is also relatively fast because most simple angles can be produced with it. For example, easy to crank from 0, 60, 120, 180, 240, 300, 0 to cut a hexagon head. Unfortunately not all angles are "simple"!

Indexing plates are so awkward that driving a Rotary Table with a stepper motor and microcontroller is popular. You simply tell the controller how many divisions are needed, press "Go", and the computer does the rest. Apart from reducing brain strain and automating a tedious task, the computer eliminates most mistakes. Computers don"t get sums wrong, have excellent memories, and are hard to distract! Also, a computer and stepper motor will do a good job of angles too complicated for the Indexing plates.

Generalising again, I suggest most people, most of the time, only need a rotary table. I see Dividing Heads as specialist tools and have never felt the need for one. For the same reason I drive an ordinary small car rather than a Land Rover. The closest I get to off-road driving is a supermarket car park! You might live on a farm...

Unless there"s a specific reason for needing a Dividing Head, I wouldn"t spend money on one. My rotary table is used a lot, in contrast a Dividing Head is only "nice to have".

If your table has a ratio of 90:1 then you will have to turn the dial 90 turn to make the table go around once. That means that you divide 360 degrees by 90 turns and you get 4 degrees per turn. Simple enough.

So here is what you do. This is where the plates come in! This example is easy but the theroy is the same. You only need a plate with two holes but since there is no such thing you will use any plate that the row of holes you want to use will divide by 2 since you need half turns. Set your index arms so that the pin on your arm falls inside the dividing arms. Set them so that you can find the next hole of the same count. IE: If you used a 24 hole plate then you will have 12 holes between the arms thus giving you half turns each time you index.

The indexing plate is a machine tool accessory that holds the workpiece on the chuck or between two pinnacles and rotates, indexing and positioning it. Plate connected with rotary indexing table is in Diameter: 4"/100mm and Thickness: 0.28"/7mm, good for rotary tables in Model HV-3, HV-4, HV-5, HV-6, TS160. Perfect to use with dividing head for milling table.

The mill rotary table is one of the main accessories of milling machine. As a precision work positioning device, it is widely used for indexing drilling, milling, circumferential cutting, boring, etc. The rotary turn table for milling machine is made from casting with high quality, can work with a set of dividing plate.

Both vertical and horizontal with two functions. Circle cutting, indexing drilling, milling and more complicated work are possible when the vertical position of the table is used together with the tail part.

Three dividing plate set(Plate "A" - 15, 16, 17, 18, 19, 20 Plate "B" - 21, 23, 27, 29, 31, 33 Plate "C" - 37, 39, 41, 43, 47, 49). A set of wrench and screws are free for you with your installation.

An indexing head, also known as a dividing head or spiral head,indexed; that is, easily and precisely rotated to preset angles or circular divisions. Indexing heads are usually used on the tables of milling machines, but may be used on many other machine tools including drill presses, grinders, and boring machines. Common jobs for a dividing head include machining the flutes of a milling cutter, cutting the teeth of a gear, milling curved slots, or drilling a bolt hole circle around the circumference of a part.

The tool is similar to a rotary table except that it is designed to be tilted as well as rotated and often allows positive locking at finer gradations of rotation, including through differential indexing. Most adjustable designs allow the head to be tilted from 10° below horizontal to 90° vertical, at which point the head is parallel with the machine table.

The workpiece is held in the indexing head in the same manner as a metalworking lathe. This is most commonly a chuck but can include a collet fitted directly into the spindle on the indexing head, faceplate, or between centers. If the part is long then it may be supported with the help of an accompanying tailstock.

A dividing head mounted on the table of a small milling machine. The direct indexing plate and center are visible facing the camera. An interchangeable indexing plate is visible on the left side.

Indexing is an operation of dividing a periphery of a cylindrical workpiece into equal number of divisions by the help of index crank and index plate.

A manual indexing head includes a hand crank. Rotating the hand crank in turn rotates the spindle and therefore the workpiece. The hand crank uses a worm gear drive to provide precise control of the rotation of the work. The work may be rotated and then locked into place before the cutter is applied, or it may be rotated during cutting depending on the type of machining being done.

Most dividing heads operate at a 40:1 ratio; that is 40 turns of the hand crank generates 1 revolution of the spindle or workpiece. In other words, 1 turn of the hand crank rotates the spindle by 9 degrees. Because the operator of the machine may want to rotate the part to an arbitrary angle indexing plates are used to ensure the part is accurately positioned.

Direct indexing plate: Most dividing heads have an indexing plate permanently attached to the spindle. This plate is located at the end of the spindle, very close to where the work would be mounted. It is fixed to the spindle and rotates with it. This plate is usually equipped with a series of holes that enables rapid indexing to common angles, such as 30, 45, or 90 degrees. A pin in the base of the dividing head can be extended into the direct indexing plate to lock the head quickly into one of these angles.

Interchangeable indexing plates are used when the work must be rotated to an angle not available on the direct indexing plate. Because the hand crank is fixed to the spindle at a known ratio (commonly 40:1) the dividing plates mounted at the handwheel can be used to create finer divisions for precise orientation at irregular angles. These dividing plates are provided in sets of several plates. Each plate has rings of holes with different divisions. For example, an indexing plate might have three rows of holes with 24, 30, and 36 holes in each row. A pin on the hand crank engages these holes. Index plates with up to 400 holes are available.

Brown and Sharpe indexing heads include a set of 3 indexing plates. The plates are marked #1, #2 and #3, or "A", "B" and "C". Each plate contains 6 rows of holes. Plate #1 or "A" has 15, 16, 17, 18, 19, and 20 holes. Plate #2 or "B" has 21, 23, 27, 29, 31, and 33 holes. Plate #3 or "C" has 37, 39, 41, 43, 47, and 49 holes.

Universal Dividing heads: some manual indexing heads are equipped with a power drive provision. This allows the rotation of the dividing head to be connected to the table feed of the milling machine instead of using a hand crank. A set of change gears is provided to select the ratio between the table feed and rotation. This setup allows the machining of spiral or helical features such as spiral gears, worms, or screw type parts because the part is simultaneously rotated at the same time it is moved in the horizontal direction. This setup is called a "PTO dividing head".

CNC indexing heads are similar in design to the manual variety except that they have a servo motor coupled to the spindle instead of a hand crank and indexing plates. The servo motor is electronically controlled to index the work to the required position. The control can either be a simple keypad for the operator or it may be fully CNC controlled.

CNC indexing heads may be controlled in two different modes. The most basic method of operation uses simple control functions built into the dividing head. It does not require a CNC machine. The operator enters the desired angle into a control box attached to the indexing head and it automatically rotates to the desired position and locks into place for machining. Changing angles is as simple as typing a new angle value onto the control pad. This is simpler than setting up a manual indexing head because there is no need to interchange indexing plates or to calculate which hole positions to use. It is also faster for repetitive operations because the work can be indexed by simply pressing a button, eliminating the need to count rotations of the hand crank or specific hole positions on the indexing plate. A CNC dividing head may be used in this manner on either manual or CNC machinery.

Most CNC dividing heads are also able to function as a full CNC axis and may be wired into the control of a CNC machine. This enables the machine"s main CNC controller to control the indexing head just like it would control the other axes of the machine. This can be used to machine complex 3D shapes, helices with a non-constant pitch, and similar exotic parts. This mode of operation cannot be used on a manual machine tool because it requires a full CNC controller to operate.

I guess I should explain how the dividing works. As you may have noticed there is no degree scale. Well you don"t need one and you don"t need trig tables. You will need a calculator.

The dividing head is essentially a horizontal (though sometimes tiltable) shaft with a wormwheel on it that can be driven round by means of a worm. The shaft has various means of holding a workpiece.

This may seem very similar to a rotary table. It is different in that there is no table to mount the workpiece on. Instead it is possible to mount a center in the shaft or mount a chuck onto it. Usually dividing heads are supplied with a tailstock. This is essential when using a center with the dividing head. It can also be very useful for supporting the workpiece when using the chuck. Most professional dividing heads, regardless of size, usually have a ratio of 40:1 between turning the handle and the shaft rotating. Strangely, smaller ones often have higher ratios, often 90:1.

On all dividing heads the worm is turned by means of a handle. Each turn of the handle can be divided by means of a dividing plate that contains a number of rings each with a different number of holes in it. The handle has a pin that can be moved to fit the holes in any one of the rings of holes.

Dividing heads can be split into three types. These are closely related to their size and complexity. These are the “plain”, the semi-universal and the universal. There is also a rather rare type that swivels in the horizontal plane.

In this case, firstly the shaft can be tilted. Secondly, and what makes the universal dividing head universal is that it has an auxiliary input at the back of it. When this is turned it rotates the dividing plate.

In the case of the universal dividing head the dividing plate can either be fixed or it can be rotated by turning the auxiliary drive shaft. When used as a plain dividing head the dividing plate is locked in position. When used for helical milling the dividing plate is unlocked and can be turned by means of the auxiliary input.

On all dividing heads the worm is turned by means of a handle. The handle either contains a retractable pin or the other end of the handle contains a  pin that can be locked into a hole in a dividing plate.

This plate has several rings of holes spaced equally around the plate. The number of holes in each ring is different. The indexing pin, whether it is in the handle or separate, can be set so the pin will fit in any hole in any one ring of holes on the division plate. Using this means that movement of the spindle on the dividing head can be made by any number of spaces.

This handle might appear to be just a handle. But when using a dividing head to make, for example, a spur gear, there are a large number of movements the operator must make using this handle. The handle shown above is just about as good as possible. The features to watch out for are:

The dividing plate is the key to dividing the circle.  Often a dividing head is supplied with three dividing plates. Each plate contains a number of rings of holes. This means that one turn of the handle can be divided into the number of holes in the particular ring. Working this out is covered under“Dividing the circle”.

On some dividing plates the holes are only drilled to nearly halfway through the plate. There is another set of rings of holes on the other side of the plate so the plate can be fitted and used either way round.

When the dividing plate is fitted properly all of the “zero” holes will be in line and will be vertically above the shaft of the handle. Usually, next to each of the zero holes, is stamped the number of holes in the ring.

As a completely separate feature a dividing head often has an indexing feature that is separate from the division plate. This means that the shaft of the dividing head can be used as a simple index head.

In the example above, the holes for indexing are just to the left of the division plate. The indexing pin is the black knob on the top of the dividing head. On larger dividing heads, where the wormwheel is totally enclosed there may be a completely separate plate that can be fitted on the main shaft just for indexing.

On dividing heads that can be tilted, the shaft the handle is mounted on is fitted eccentrically in a sleeve that can be rotated. This not only enables the spacing between the worm and wormwheel to be adjusted it can also be used to disengage the handle from the shaft driving the worm. The fig. shows the arm for controlling the engagement of the worm and worm wheel.

In the above photo, the dividing plate and the lower gear are permanently connected together. The handle which is to the left of the dividing plate is connected to the shaft which is fitted with the worm. This is inside the dividing plate/bottom gear assembly. When the worm is disengaged this shaft moves downwards so that the bottom gear in the photo is disconnected from the gear above it. This top gear is is connected to the auxiliary input. In this situation the dividing plate etc. is free to rotate. When the worm is disengaged what happens here has no impact on what is happening to the main shaft.

When the worm is engaged The diving plate can be used in one of two ways. In the first it is locked. This is done by a small tab which is held in place by the cap screw at the top of the preceding photo. This tab fits in a slot on the back of the dividing plate.

Alternatively, when the auxiliary input is in use this tab is withdrawn. The auxiliary input drives the top gear. The worm is engaged with the wormwheel. So the top gear drives the bottom gear. This rotates the dividing plate. The pin on the handle is in one of the holes on the dividing plate. As this handle rotates so does the worm and hence the wormwheel and workpiece.

The spindle always has a hole all the way through it. At the front end, the spindle, on larger dividing heads, often has a taper and/or a thread or some other means of holding a chuck.

On larger dividing heads the spindle has, at the back end, a thread so that an extension shaft can be screwed into it. This enables the dividing head spindle to be driven directly, but this will only work if the worm has been disengaged from the main shaft.Though this is a rather unusual feature it is, surprisingly, one that could be easy to implement on any homemade dividing head.

Rather like the rotary table the dividing head always has some means of locking the spindle in the same way as the table can be locked on the rotary table. And it is used in a similar way. If the workpiece is being machined between two points the lock has to be off. If the workpiece is to be machined at one point, as when cutting a tooth on a spur gear, the spindle should be locked.

It might seem odd but dividing heads can be either left or right handed. That is, with the dividing plate facing the user, the nose of the spindle can be either to the left of the dividing head or to its right.

This is significant is when a universal dividing head is driven by the leadscrew on the milling table. If the auxiliary input is on the left then access to the leadscrew will have to be on the left. If the table has power feed at one end then, often, the dividing head will have to have its auxiliary input at the other end of the table.

A key feature of a dividing head is the center height. This is the height between the axis of rotation when the shaft is in the horizontal position and the milling table. In general, the higher the center height the better. But this of little use if the largest diameter of workpiece will not fit between the milling table and the bottom of the cutter being used.

Even more important is that it is too big if it cannot be safely and easily moved on or off the milling table. The weight goes up far faster than the center height. A center height of 100mm could easily be the most that many model engineers could safely manage.

If the dividing head is in the horizontal position, the maximum diameter workpiece it can hold is bit less than twice its center height. This can be increase by mounting the dividing head (and the tailstock if used) on raising blocks. But whether this is useful depends on whether there is still enough space between the cutter and the milling table.

In the figure another use is shown. In this case the dividing head is raised so its axis is near the height of the spindle when it is nearly horizontal.

Universal dividing heads have an auxiliary input at the back of the head. This is used for helical milling. This is where, as the milling table moves along, the leadscrew is used, via a gear train, to rotate the workpiece being held by the dividing head.

Notice that the exposed part of the auxiliary input is only the near end of the shaft. The large diameter bit is a boss. This is used for fitting the quadrant arm onto the dividing head.

Often when the auxiliary input is being used this will involve a gear train. The gears are mounted on an arm that fits a boss round the shaft of the auxiliary input. An arm like this is often used for a similar purpose on a lathe. On the lathe it often is designed to rotate through 90° and so is known as a quadrant arm. On a dividing head it is usually just a straight arm. It rotates simply by the angle it is fitted onto the boss on the auxiliary input of the dividing head.

A gear train often starts with a gear on one shaft such as the end of the leadscrew. At the other end it is often on the auxiliary input to the dividing head.

Compact precision CNC rotary table, suitable for single part or small batch production in precision engineering. A horizontal or vertical assembly is possible. You can not buy a better quality!

It is suitable as 4th axis on engraving and milling machines for engraving, lasering, drilling, grooving, milling or for use on a tool or surface grinding machine. Square, hexagonal, gear milling of any pitch or 3D machining is possible.

Compact precision CNC rotary table, suitable for single part or small batch production in precision engineering. A horizontal or vertical assembly is possible. You can not buy a better quality!

It is suitable as 4th axis on engraving and milling machines for engraving, lasering, drilling, grooving, milling or for use on a tool or surface grinding machine. Square, hexagonal, gear milling of any pitch or 3D machining is possible.

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Dividing head, dividing head, tool holder for grinding, drill grinding machine, milling cutter grinding machine, drill grinding holder, milling cutter holder

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The Grizzly Customer Service and Technical Support Teams are U.S. based. Parts for the rotary table may be available online and shipped from the Grizzly parts warehouse in Springfield, MO.