Confused ....Advice needed rotary table vs dividing head

Is a rotary table the same as a dividing head - can a rotary table be converted to be used as a dividing head, and if so is just a case of getting the plates.

No, not the same. Though they both do similar jobs. Some rotary tables can be converted to dividing heads.

I have a very small rotary table and considered making up a set of division plates and indexing mechanism for it, but found it easier, quicker and cheaper just to add a stepper motor and controller Following the step-by-step (sorry) instructions on HMEM was my first introduction to Arduinos., and there is a similar project in MEW 249.

I will admit however, that I am still tempted to use the stepper driven rotary table to make a set of division plates just because I could.

Brian G

I'll have a go at the differences! Feel free to put the mistakes right.

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.)

Dividing heads are likely to be more accurately made and expensive than a rotary table. Extra accuracy costs money.

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 useful for awkward angles. Cutting a 19 toothed gear requires 19 steps of 18.9474°, which is the hard to remember sequence 37.89, 56.84, 75.78, 94.74, 113.68, 132.63° etc. The Index plate and clock hand mechanism remove the need for the operator to track the sequence but they are still a pain to use in my opinion!

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'.

Dave

Edited By SillyOldDuffer on 14/02/2021 15:56:21

Edited By Frances IoM on 14/02/2021 16:03:47

The main difference between the two is that a rotary table lets you rotate the work so radial or axial cuts can be made but a dividing head is just moved in increments. Therfore only the rotary table can be used for curved work.

Good overview here Link

I have a Rotary Table (a Vertex HV6 with a 90:1 ratio ) It is most often set with the face vertical, and at 90 degrees across the table.( Axially along the table, if you follow me ) In this position, and with the aid Division Plates, and a Tailstock it is used to cut gears .

It could equally well be used in this way to mill splines or to drill holes around the periphery of a workpiece, with what ever angular spacing required.

So in that respect it has operated as a Dividing Head.

With the face horizontal, it has been used to mill curved slots, and could be used equally well to put a radius on the end of a workpiece.

HTH

Howard

If you want to choose between one or the other, the rotary table can be set at any angle, but a dividing head cannot. The rotary table is more versatile, so make that your first choice.

My penny's worth.

Rotary tables are for moving a workpiece in an arc around a centre for machining purposes.

Dividing heads are for setting a workpiece to a specific angular orientation and fixing it there whilst a machining operation is carried out.

As such rotary tables may allow some degree of indexing and dividing heads may allow for some degree of rotation which is were the confusion comes in.

regards Martin

Thanks everyone for the complete and comprehensive replies - I will look out for a rotary table that will work with my Mill.

Sorry about the original title - I didn't realise it would make things confusing for others.

The last time I used the rotary table was to mill 7 splines. I didn't even look at the dividing plates for the rotary table, 51*26' was close enough for government work.

It has been scientifically proven that the more obscure a thread title the more views it will get -- curiosity is a wonderful thing.

It made you look ......

.

Having come late to this thread, I have to ask :

Are we now working to the original title, or the new improved one ?

... as is typical on this forum; there is no audit trail

MichaelG.

At least the new forum software will be more traceable and have far better search functions which should please you.

I expect the rest of us are working to the OP's opening post which set out his question, heading was just rather vague much like people who just put "help" as a title.

Edited By JasonB on 15/02/2021 10:03:05

Thanks for the info. Jason ... although it doesn’t answer the question that I asked.

What was the original title ?

If it was ‘Confused’ then I would agree entirely with the point made by Frances

... and the fact that I was not attracted to read on, might count against the OP’s scientific claim.

MichaelG.

As it was "I" that started this thread with the now "banned" snappy title of "Confused DOT com, whats the difference between."...... I must apologies profusely for my shameful woful excuse of a title.

I will have to think of less intriguing titles for my threads.

Science is a wonderful thing - some claims have more fact that fiction - scientific theories claimed by the uninformed are sometimes false..... IYKWIM.

For those interested - I am looking for a rotary table - it seems to be the best beginner option.

Not really the thread to ask this, going off subject, I do apologise in advance, but as Jason mentioned the new forum software, could Jason say whether it will have posts numbered for easy reference please?

Just wondering!

Chris

As far as I can see you can copy the link of a specific post which will take you back to that post rather than the top of the thread page. No numbers on RCM&E but that may not have been enabled.