dividing plates

[Coomba]

Guys, what are dividing plates used for, on a rotary table?

 

[dave2176]

For dividing a circle into a specific number of segments. For instance if I want 27 holes drilled in a plate, that is 13.3333 degrees between them. Hard to find with just a degree wheel. The dividing plates can be set up to accomplish the task.

Dave

 

[Hawkeye]

The plates are commonly used with the sector arms. Here's a clipping from and old high school text that tells you how to use those.

View attachment Sector Arms.pdf

 

[frank bouten]

Most dividing heads are geared 40:1 , so if you do 6 holes in a circel thats 40:6=6 4\6 is 6 hole turns and 4\6 of a circel=2\3. Then look for circel of holes that can be divided by 3, for example 15 , so 5x3=15 and 5x2=10 so you do 6 hole turns and 10 holes . The holes are for a part off a circel.

 

[drom68]

Dividing plates are used to divide a 360deg circle into equal parts. If you wanted 27, 31, 10, etc... equally spaced holes or gear teeth the plate will allow you to do this. There is a process in using the plate, as explained above. A lot more to using a dividing plate, but pretty straight forward once you learn how to use them.

 

[caster]

Dividing heads usually have 40:1 worm gear ratio, rotary tables usually have 90:1 ratio. Make sure you have the right ratio when calculating the turns and holes. For example I need to cut a 63 tooth gear on a rotary table. 90/63 = 1 27/63 or 1 9/21. Using a 21 hole circle I would make 1 whole turn and advance 9 holes.

 

[Terrywerm]

Dividing can be a rather involved process, depending on what you need to do. As a result, it is a subject that may be a bit too involved for an in depth write up in this forum. There are two books about it that I can recommend, as I have both of them.

The first, and easiest to understand was written by Dave Gingery. The book is about various accessories that you can make for your shop, including a dividing head. In addition to plans and instructions for building your own, he includes excellent instructions on how to use it, especially for direct and indirect indexing (the most common kinds). It is available from Gingery Publishing, run by Dave's son, Vince, for (currently) $9.95 http://www.gingerybookstore.com/




The second book, which is also very good, goes into greater depth but is definitely written in a more technical manner. It is called Milling-Machine Indexing, written by Felker and Paine. It is very good also, and is available from a couple of sources. It is a great resource if you plan to get into differential indexing or something more in depth like that. It was written in 1942, but the information is still entirely current. It is available from a number of different sources. Do a search for book "milling-machine indexing" and Google or Yahoo will find several sources for you.




There is yet a third book available on the subject that I just stumbled on. I have not seen it myself, but it might be worth looking into. It is called Milling-Machine Indexing and Spiral Work by Ray E. Gifford, published in 1957. Reprints are currently available on eBay for $14.50 plus shipping.

 

[MarkStephen]

+1 on the Gingery books. Even if you never cast a part or build any machine or accessory, there is a wealth of information in those books that is explained in an easier to understand way. IMO most every home shop should have a set laying around. Book 3 is my favorite.

Mark

 

[Bill C.]

Guys, what are dividing plates used for, on a rotary table?

I have used them on Dividing Heads. Never seen them on rotary tables but most Dividing Heads are adjustable, angle, so they can be set from 90 to 0 degrees.

 

[Coomba]

I have used them on Dividing Heads. Never seen them on rotary tables but most Dividing Heads are adjustable, angle, so they can be set from 90 to 0 degrees.

I was looking at a rotary table at Shars and they offered a dividing plate with it,(for a price)when you purchased the table. that's why I asked the question the way I did. They show the plate mounted to the handle.