# indexer - rotary table



## Baithog (Dec 6, 2014)

I have been shopping, and I am confused. 

What is the difference between a universal index head and a semi-universal?

Are there index heads that are not universal, and what are they called and/or do?

It looks like a rotary table with index plates and a tail stock would do much the same job as an index head, but there must be more to it. An index head costs about twice as much as the rotary table solution.


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## Uglydog (Dec 6, 2014)

Baithog said:


> What is the difference between a universal index head and a semi-universal?



Do you have pics, a link, or manufacturer/model number?

Daryl
MN


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## Karl_T (Dec 6, 2014)

As far as i know, no firm rules on terminology here. There is a huge range in quality and features offered. For most a rotary table that can be mounted both hor. and vert. will do the job. Adding index plates will make it more accurate. You can move up to a quality index head to get things far more rigid.

Karl


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## chuckorlando (Dec 6, 2014)

I think a universal indexer as the ability to run off gears and your handle crank. So it can cut helix's. If you can only have one, buy a rotary table with plates and tail stock that does both vert and hori


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## Holescreek (Dec 6, 2014)

chuckorlando said:


> I think a universal indexer as the ability to run off gears and your handle crank. So it can cut helix's. If you can only have one, buy a rotary table with plates and tail stock that does both vert and hori



^ exactly! Universals are usually dedicated to a particular type of machine.


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## Reeltor (Dec 6, 2014)

If you are talking about Dividing Heads instead of Indexer (some use the terms interchangeably).  A semi-universal dividing head is a dividing head that is manually controlled by turning the crank.  A universal dividing head also can be controlled by turning the crank but also has a tail coming out the back to hook up to a gear train connected to the X axis of the table.   
For the most part the dividing head is used to divide a part by the number of divisions desired.  Like the hex on the end of a bolt or teeth on a gear.  I've been told that the machining takes place with the dividing head stationary. But this doesn't take into account when using the universal feature to cut helical gears; so I'm not real sure about this.
A Rotary Table has a degree scale and you need to do the math, to get the desired number of divisions; some RT's have the option for dividing plates, making it much more versatile.  The RT is designed to be turned while machining. 

Here is a shot from Shars of a "spin indexer"


Also from Shars, a semi-universal dividing head



Here is a horizontal/vertical Rotary Table




Keith Rucker with Vintage Machinery (great YouTube videos too) has a ton of information about machines on his site.  The link is for a Van Norman dividing head, if you wanted to cut a gear with 78 teeth you would check the index table for plates; find the 78 division line and see that you need hole circle 39 found on plate #2 and count 20 holes for each tooth.

http://vintagemachinery.org/pubs/detail.aspx?id=3371

Mike


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## Baithog (Dec 7, 2014)

Thanks. I don't have any plans to cut helix any time soon. I have been making dials for projects that have 50 divisions. That doesn't work out well on my inexpensive rotary table, sans dividing plates. I am also more likely to cut curved slots than gears, so the rotary table is probably better than an dividing/index head. It is also a minimum of $100 cheaper.


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## Reeltor (Dec 7, 2014)

Baithog said:


> Thanks. I don't have any plans to cut helix any time soon. I have been making dials for projects that have 50 divisions. That doesn't work out well on my inexpensive rotary table, sans dividing plates. I am also more likely to cut curved slots than gears, so the rotary table is probably better than an dividing/index head. It is also a minimum of $100 cheaper.



If you already have a rotary table, have you checked to see if a set of dividing plates are available?  Most rotary tables use a gear ratio of 1:90 so the plates may be interchangeable.  Here is a link to Grizzly's rotary table plate set; but at $141.95 plus shipping it seems pricy to me.  You may want to just make a plate with 50 divisions for future use.

http://cdn0.grizzly.com/manuals/g1760_m.pdf

I'd be interested is seeing a photo or two of  your setup marking divisions on your dials.

Mike


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## fgduncan (Dec 7, 2014)

The indexer and RT do essentially the same thing, but trade off speed for accuracy. The RT is more flexible in that, when you know how to do the math, you can do any number of divisions. BUT (note caps) you pay for the flexibility by having to do a LOT of calculations to be able to set it for each division. The dividing head on the other hand, uses plates that provide absolute accuracy and is much quicker to use. However, you have to have a plate with the correct number of holes. Since you already have a RT, you can do any indexing you could with index plates, just slower.  As indicated by others, if you can get a set of dividing plates, you can have the best of both worlds.


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## chuckorlando (Dec 7, 2014)

Very few reasons a man with tools cant make a set of plates work if they were meant to or not.

One significant difference between RT and DH is the ability to mill as the table is rotated. I mean you could mill a round on a DH but your work would be a foot off the table and no where near as easy to hold plate


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## Baithog (Dec 7, 2014)

I have a 4 inch RT from China through Ebay. I lucked out and got one of the first of the batch. You know, the first 2 or 3 go for super cheap to get the frenzy going. It came with a G-auful 2 inch 3 jaw chuck and no taper socket. The run-out is about 6 mills. I could make plates for it, but its a pretty crude chunk of iron. It would be like putting lipstick on a sow. I have a g0759 mill/drill on order that is supposed to ship the 19th of this month. I have some money in the budget for some tooling, hence my interest in an improved RT or DH.

I am looking at getting an Ellis DH with a full set of plates. The attractive thing about this DH is that the spindle is threaded 1-3/4X8, which is the same as my 10X20 lathe. I have 3 and 4 jaw chucks for that spindle thread. The bad thing about the DH is the spindle socket is B&S #9. If I can get it for less than $200, I'll ad it to my collection.


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