dividing plates, dividing head

[eskimo]

whats the difference between a dividing head
Dividing Heads - Universal | machineryhouse.com.au (http://www.machineryhouse.com.au/Universal-Dividing-Heads)

versus a indexing head
Indexing Heads | machineryhouse.com.au (http://www.machineryhouse.com.au/Indexing-Heads)

versus dividing plates for my rotary table
Dividing Plates - Rotary Tables | machineryhouse.com.au (http://www.machineryhouse.com.au/Rotary-Table-Dividing-Plates)

do they all do the same thing?..i guess I might need one or the other
I am thing of having a go at making a quill & a shaft and cutting spline and gear etc for that little hi speed Waldown Brobo I scored...which came without them:~

[Big Shed]

It is my understanding they are all basically the same thing, just a different way of doing it. Most dividing heads can be set to different angles, whereas most rotary tables can only be used at 2 angles.

Indexing head - Wikipedia, the free encyclopedia (http://en.wikipedia.org/wiki/Indexing_head)

[eskimo]

It is my understanding they are all basically the same thing, just a different way of doing it. Most dividing heads can be set to different angles, whereas most rotary tables can only be used at 2 angles.

Indexing head - Wikipedia, the free encyclopedia (http://en.wikipedia.org/wiki/Indexing_head)

extract from wiki link
The tool is similar to a rotary table (http://en.wikipedia.org/wiki/Rotary_table) except that it is designed to be tilted as well as rotated. 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.

thanks big shed...i'm a little more wiser..i think

[Michael G]

The other thing about indexers is that they are intended (or were originally intended) to go to set positions - in the Hare and Forbes photo there are some toothed discs that are used to make this easier. It looks like those ones are venturing into dividing as well.
As Fred said, the dividing head and rotary table with indexing plates will do the same thing. The key differences are that a rotary table will allow you to machine arcs which a dividing head probably won't (different gear ratios involved), but a dividing head will allow you to tilt and if you have a universal dividing head, allow you to index to some really odd numbers.
For cutting a 6 or 8 tooth spline, any of them would probably do the job.

Michael

[Stustoys]

Its all a little blurry between dividing heads and rotary tables. Most rotary tables have a tee slot plate, most SEMI Universal* heads had a chuck(spindle nose).
The indexing head is a rotary table that has indexing plates which are much faster than dividing plates and worn wheel, though aren't likely to be as accurate. (I think some semi universal heads can also do that). Though the one you linked to can only go up to 24 divisions with its indexing plates.


*A Universal head has an extra set of gears between the dividing plates and the worm.

D003 | BS-2 Dividing Head - Universal | machineryhouse.com.au (http://www.machineryhouse.com.au/D003)

Stuart

p.s. Slow hands Stu lol. Michael why do you say you cant machine arcs with a dividing head? the 40:1 ratio? I'd think dividing heads would be a lot less rigid though.

[Michael G]

(Bound to be shot down for this one...)
Two reasons that I'd give-
Firstly, the gearing ratio. A typical dividing head is 40:1, a rotary table is 90:1. I can certainly feel the cutter pulling on the job when using a R/T. I suspect that at 40:1 you would lose control for all but the lightest cuts.
The other is the way they index. Continuous cranking on a R/T is what they are made for. A dividing head is not going to crank around easily - the sectors will get in the way etc.

Michael

[pipeclay]

What are the sectors you refer to?

[Michael G]

The brass fingers that help get the right number of divisions. I guess you could remove them and fill the space with a spacer.
You'd probably want to change the spring loaded handle too.

Michael

[pipeclay]

You would have the same result when using the rotary table if dividing plates were used.

[rusty steel]

Hello Eskimo,
I am sure that others will have much more knowledge of these machines than me but in my case, I have what H&F call a Super Indexing Head (although it is not a Vertex) . It has a notched plate for every 15 deg. and a vernier dial which supposedly gives 10 second increments. I would say it is a compromise of the three systems. eg.
When it is in the horizontal position,it takes up more vertical space than a rotary table. Even with the chuck removed and a faceplate fitted (I have a 10Kg.weight from a body builder set to make one), it is not as compact.
I don't think the rotary tables have the notched plate, but they have the 10 second vernier dial and a chuck can be fitted.
For serious gear cutting including helical gears, I think the dividing head would be the best. I assume they can allow gears with any number of teeth to be cut, with the correct dividing plates.
Dividing plates can be fitted to the rotary table and the indexing head which may be a better option than using the vernier dials.

Just buy one of each- Problem solved.:D

[Ueee]

Hi,
The other downside with a rotary table for dividing (with the 6" vertex i have anyway) Is that the plates only allow you to do 2-100 division x1, then only even numbers above 100. So you cannot index a 127 tooth gear for a lathe gear train.

[pipeclay]

Not many manufacturers do a plate that allows 127.
You would also have the same result with the dividing head unless you use a universal.
You could allways try to get your 127 with the rotary with the use of the vernier scale.

[Retromilling]

With a 40 -1 head if the dividing plate has a 17 hole ring then advancing every 4 holes on the 17 ring will divide a circle by 127 .

[Stustoys]

With a 40 -1 head if the dividing plate has a 17 hole ring then advancing every 4 holes on the 17 ring will divide a circle by 127 .
Would you like to show you workings for that?
I cant make it work. I get 170 divs

Stuart

[pipeclay]

I am not sure about divisions but I think 4 holes on a 17 plate will move 2.11 degrees,when you want to be spacing 2.83 degrees abouts.

[eskimo]

thanks guys.....but some of these answers are above me at the moment

maybe I need one so that I can have a play.....or get some plates for the rotary table and have a play with that till I realise its limitations:? decisions decisions

[Jekyll and Hyde]

Would you like to show you workings for that?
I cant make it work. I get 170 divs

Stuart

The Engineers Black Book would agree with you there. Interestingly, the book doesn't list 127 divisions at all in its table (page 68).

[Stustoys]

I believe thats because 127 is a prime number. So for a rotary table or semi universal head you would need a 127 hole plate*. Which you could make on your rotary table (though I'm thinking it would have to be pretty big diameter), then when you divide the job any errors in the plate will be reducted by what ever the ratio your worm gear is.

Stuart

*I checked this with 90:1 and 40:1 ratio and my maths says its correct...... for what ever that is worth hehe

[Ueee]

thanks guys.....but some of these answers are above me at the moment

maybe I need one so that I can have a play.....or get some plates for the rotary table and have a play with that till I realise its limitations:? decisions decisions
What exactly do you think you will use one for-just your splines or are there other things in the pipeline? If your thinking of gear cutting then the RT and plates will do you for most of the work. Michael G and i are passing ideas back and forth on an indexing plate capable of 127t gears for members to use. It may not yet happen but it then it might.
If it is just the splines then the indexing plates and a tailstock would be a much cheaper option....then you can spend the rest of the coin on other tools:D

[eskimo]

What exactly do you think you will use one for-just your splines or are there other things in the pipeline? If your thinking of gear cutting then the RT and plates will do you for most of the work. Michael G and i are passing ideas back and forth on an indexing plate capable of 127t gears for members to use. It may not yet happen but it then it might.
If it is just the splines then the indexing plates and a tailstock would be a much cheaper option....then you can spend the rest of the coin on other tools:D

Thanks Ueee....I dont have anything else in mind other than trying my hand at the splined shaft for the little hi speed waldown

and with more money to spend?....gee dont tell her that tho....definitely earns points that recommendation.

[Michael G]

The other option is that if you just want a spline with a set number of grooves making up a clamp block that will allow you to clamp in say 8 orientations?
(Imagine an 8 sided block with a hole up the middle to fit your material)

Michael

[eskimo]

The other option is that if you just want a spline with a set number of grooves making up a clamp block that will allow you to clamp in say 8 orientations?
(Imagine an 8 sided block with a hole up the middle to fit your material)

Michael

that means measuring to make the block Micheal...no good for me....if you consider last nights stuff up....(too embarrassed to tell what it was...but lets say I didnt measure right)

for the small cost I will get some plates for the rotary table...it is at this stage only going to be a once off

[Retromilling]

I am not sure about divisions but I think 4 holes on a 17 plate will move 2.11 degrees,when you want to be spacing 2.83 degrees abouts.

2.83 deg. is right but I can't show you any math as I use a spread sheet calculator.
It has been right so far but it may well be wrong for 127 holes as I have never tried that yet .