Well a lathe generates solids of revolution. Anything where the work turns – cylinders and their derivatives.

 

A mill generates straight lines – the cutter rotates and the job moves in straight lines – so slots grooves etc.(and it can be a drill – plunge cutting.) They can also generate flat or nearly flat surfaces as well

 

Having said that, if you have the right attachment you can convert your lathe into a mill – won’t be as rigid nor as flexible but in smaller sizes of task it will get the job done.

 

A rotary table goes on a milling table, and allows the work to be rotated under control, normally of a worm and wheel. Cutting radial slots and parts of a circle. Depending on the table, there are also adaptors which allow gears to be cut, or specific numbers of holes to be drilled, usually but not always equally spaced. Rotary tables will normally be graduated in degrees (and division thereof) of arc.

 

A close relative of the dividing head, which is for cutting gears and multiple spaces/holes, but can also double as a very useful workholding tool..

 

 

 

A few random thoughts:

 

I would concur with Steve about the use of a vertical mill, with a DRO, as a drilling machine. I hardly ever use my drilling machine; using the vertical mill is just so much more convenient and accurate. And it makes drilling bolt patterns a breeze with the DRO. No more spotting through to one component from another; just drill the two patterns separately and they should fit together.

 

Generally the horizontal mill is seen as a production machine tool, and is less flexible than a vertical mill. However, for a given size a horizontal mill will most likely be heavier, more rigid and more powerful than a vertical mill. So, if you need to move a lot of metal a horizontal mill will do the job much faster.

 

By the way, a universal mill is not one that has both vertical and horizontal capability. It specifically refers to a horizontal mill that has a swivelling table so that, with the aid of a suitable dividing head, it can be used to machine spiral features, such as flutes on a custom cutter, or a helical gear.

 

Regards,

 

Andrew

Must admit having bought a rotary table I have only used it a couple of times to mill slots in a collet (120 degrees apart) and flats on a bolt head (60 degrees apart)

 

Mine was the 150mm table from RDG and I have a couple of questions

 

1. Should the graduations on the hand wheel align with the marks on the rotating table, by which I mean when the hand wheel has a mark in line with the reference mark on the body the line for the degree on the rotary table is not aligned with the reference mark on the body. If “yes” is there any way of adjusting this?

 

2. On the body of the rotary table there are markings from 0 to 60 which I presume is for minutes but how do I use these?

 

regards

 

John

 

Posted by Andrew Johnston on 01/03/2011 21:52:32:

 

I was going to say a bit more than the cursory sentence at the end of what I wrote – but I got dragged away! Hence the rather equivocal and badly-formed comment…

 

But yes, it’s the table that is the universal bit, hence them being correctly referred to as universal table milling machines, rather than just ‘universal’.

Wasn’t there a well made little machine that used to be advertised Sharp was it. That had  horizontal and vertical spindles.It called itself a universal, but didn’t have the pivoting table.

 

Pivoting table type mills would reallly need to be on the big side, simply because the dividing heads with the spiralling attachment driven off the feedscrew tends to be a bit large. You can get away without turning the table a long as the lead on the spiral is not too great, and more so if the thread is rounded. The result would be an approximation, but for most purposes it would be good enough. bit academic though – not a facility most would use. For most of us, it would only be used for setting up say ftapered fluted columns, and there are other ways of doing that.

 

Scheming a way of doing it -I have a 13″ 6DP gear to cut for the 4″ Little Samson. Someone does some 80mm thick cast iron slab, so a chunk of that will become a raising block for the dividing head which isn’t designed for that size of work, but its the principle.

 

For Colin a dividing head is another sort of rotary table. RT tend to be optimised for continuous movement- curved slots and surfaces. Dividing heads are optimised to provide definite stops for things like gear teeth or cutting hexagons or any other gons for that matter. (Of course with adaptors each can be either, but I think thats a fair description.)

 

waht is for sure, you need some means of dividing fairly ealry on in your career. You don’t need a full blown dividing head with all its worm gears etc, but some form of simple adaptor for basic indexing which gives the common divisions – 2,4,6,8,12 holes becomes very useful very quickly.

 

Hi mgj,

 

I’m in the same boat as you. For my traction engine I need to cut 6DP gears with ODs of 10.833″ and 11.833″, and 5DP final drive gears that are 14.8″ OD. I’ve got 16″ maximum from table to spindle centreline on my horizontal mill. So the 6DP gears will go under, with the use of 1″ riser blocks for the dividing head and tailstock.

 

However, whichever way you look at it, the final drive gears will not go under the spindle with a cutter in place. If I had the plain version of the mill rather than the universal, I would have 19″ from table to spindle, and no problem.

 

I’m contemplating three options. One, use the rotary table with the gear in the same plane as the table. Fortunately the gears have 72 teeth, so 5 degrees per tooth for simplicity. Two, similar to one, but use the dividing head with the spindle vertical. Three, make an undercutting attachment as per the picture:

 

Posted by Nicholas Farr on 02/03/2011 11:27:26:

 

If I’d had a chance I was going to mention those, but I really am aware of the ‘universal’ concept as well!

 

We haven’t developed the concept fully anyway. For Colin’s benefit we could also mention that there are different types of vertical mill, certainly in terms of turret, knee, round column vs Dovetail, CNC and all sorts of other details, I’m sure. Once you have your head around the basic principles of why milling machines are a good idea, then the scope of the subject is definitely the next thing to consider, isn’t it?

 

As for the ‘good idea to have both’ thing – well, how could I not agree? I’m very slowly restoring a Tom Senior M1 to its former state of glory (or something along those lines), and it has the knuckle head as well, so I’ll have just that.

John deserves an answer.

 

Will a scale in degrees around the edge of the table automatically line up with the scale on the handwheel. No – unless you hav some kind of resettable collar on the handwheel. In fact the scale round the edge, I don’t think I have ever used.

 

The handwheel – all depends on the ratio between the worm and wheel. so you have degees, and minutes which are 60ths of a degree, and probalby a vernier reading typically to 2 or 4 seconds of arc which are 60ths of a minute. Normally off the calculator you will get an answer in decimals of a degree which you will have to convert.

 

So if you get an answer of say 7.46 deg. .46×60 = 27.6 minutes. The remainder you convert as well. so .6×60 = 36 seconds exactly. So 7.46 deg = 4 deg 27min 36 sec. I wish they would calibrate the scales decimally!

 

Most tables have 60 or 90 to 1 ratios I think. 360/90 =4 deg per turn of the handwheel.

360/60 = 6deg per turn. Its most likely to be one of those two.

 

I’m no expert on these things – just a user, so due apologies ot Grannies if you knew all that.

Hi John, sorry I’d forgot you asked about the graduations on the handwheel. I have a Vertex HV6 and I have looked on thier website (below) and it says that the coller is graduated in steps of 1 minute and the vernier scale makes settings down to 10 secounds possible. The ratio of the table is 90:1 and the coller also has 0, 1, 2 and 3 quarted making the 4 degrees that mgj metioned, there is also a 30 midway between each of the above mentioned digits. (see pic below) The vernier has devisions of 60-0-60 in 7 graduations. I have not used this facility myself. but the coller is moveable by loosening the grub screw that can be seen, tuning to the desiered position and then tightening the screw. Once you have a reference mark alined and then turning the table noting how many dregrees, mins and secs you require, it can be done by counting the degrees by the four numbers X the number of rotations of the handwheel, plus the number of minutes on the graduations and then lining up one of the graduation marks to the number of seconds required on the vernier scale. I hope I’ve got that correct and it makes sense, yours may be slightly different, but the proceedure should be much the same.

http://www.vertex-tw.com.tw/products/products_list.php?language=_eng&cid=10

 

Regards Nick.

My Vertex rotary table (8 inch size) has an adjustable fiducial for the scale on the table part, so you can set the Vernier part on an exact mark and then adjust the fiducial to also be on a mark as well, avoiding ambiguity.

 

regards

John