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Bob Quale
03-04-2005, 11:20 PM
I have a dividing table with a 90:1 gear ratio, I seem to have miss placed my indexing chart.

Might anyone have access to a chart? or link or the like?

Thanks Bob

CharlesM
03-04-2005, 11:51 PM
Bob,
Try this link:
http://www.atmsite.org/contrib/JSAPP/divide/divhead.html

Just substitute 90 for 40 and everything works the same.

------------------
Charles McGough
Sterlington, LA

mklotz
03-05-2005, 11:59 AM
Bob,

The free program, DIVHEAD, on my page can be easily customized for any
dividing head, regardless of gear ratio or available hole plates.

As an example, when run, it produces an output that looks like:

--------------------
DIVIDING HEAD CALCULATIONS

Number of workpiece divisions [14] ? (you enter desired divisions here)

DH Worm Gear Ratio = 90:1
No rapid indexing plate available
Divisions of Workpiece = 14
Ratio/Divisions = 90/14 = 6.428571429
Turns required = 45/7 = 6 & 3/7

6 full turns of crank
and 9 holes on 21 hole plate
or 21 holes on 49 hole plate
--------------------

Regards, Marv

Home Shop Freeware - Tools for People Who Build Things
http://www.geocities.com/mklotz.geo

John Stevenson
03-05-2005, 12:16 PM
Bob, Here's a text I posted back in 1998 on the same subject.
The spreadsheet is here:-

http://www.metalworking.com/dropbox/_1998_retired_files/division.xls

**********************************************
Just lately there has been a number of enquiries on the Ng about division
tables for Rotary tables / dividing heads with other than the standard
40 : 1 ratio.

The standard series of 3 dividing plates are as follows:-

Plate 1 15,16,16,18,19,20.
Plate 2 21,23,27,29,31,33.
Plate 3 37,39,41,43,47,49.

These three plate are suitable for any ratio as all the division breaks down
into prime numbers or numbers that are divisible by the holes on the plate.

NOTE 1:-
For the readers who are going to make their own plates I would miss out the
first hole [ 15 ] and move the 21 to the first plate to make room on the
second for a 28 hole circle. This is because any numbers need to be divisible
by 15 can be handled by 20,21 or 27 and a 28 is handy for 28 and 56 divisions
which is not obtainable with some of the non standard rotary tables [ see chart ].

I am posting this information in the metalworking drop box at
http://www.metalworking.com

This file will be under division.txt and an Excel spreadsheet called division.xls
will be with it. The table covers 40, 60, 80 and 90:1 ratios.

The first number is complete turns and the fraction is the number of holes on
that circle. So 3 21/33 is 3 complete turns and then 21 holes on a 33 hole circle.

These are now posted in the Public domain and are free to anyone to use as required.
There are NO restrictions on reuse or copying

Feel free to use and enjoy.

John Stevenson

mklotz
03-05-2005, 01:24 PM
John,

The standard hole plates you list are, I believe, the ones normally supplied
with 40:1 dividing heads. They will not provide all the divisions up to fifty
(the nominal standard) with a 90:1 DH, e.g.,

90/28 = 3 & 3/14 = 3 & 6/28

and the 40:1 set you listed doesn't provide a 14 or 28 hole plate.

If the OP is going to make his own plates, the 'minimum hole drilling' set for
all divisions up to fifty and a 90:1 ratio is:

3,5,13,14,16,17,
19,22,23,29,31,37,
41,43,47,49,

For a 40:1 ratio, the 'minimum hole drilling' set is:

4,5,6,17,19,21,
23,27,29,31,33,37,
39,41,43,47,49,

While the set of typical 40:1 plates you list may be the easiest to obtain in
the marketplace, my point is that the right set to self-make is a function of
the DH gear ratio.

Regards, Marv

Home Shop Freeware - Tools for People Who Build Things
http://www.geocities.com/mklotz.geo

John Stevenson
03-05-2005, 07:12 PM
Marv.
Bob didn't say he was going to make any plates, only that he had lost his chart.
Whist i accept what you say about choice of numbers I posted that list for the standard Brown and Sharp set because it is the standard.

John S.

Bob Quale
03-05-2005, 09:23 PM
Thanks guys!

I'm going away for a few days, when I get back I can settle in and do some work. I also want to try the software program!

Thanks again Bob

mklotz
03-06-2005, 02:52 PM
I wrote a short program to generate a 'turns and holes' table for:

any gear ratio
any collection of hole plates
any maximum number of divisions

It's called DIVHEADT and it's now part of the DIVHEAD.ZIP archive on my page.

Running it for a 90:1 gear ratio, the standard (i.e., 40:1) hole plates and a
(arbitrarily selected) maximum of fifty divisions produces:

-------------------------

Turns & holes/plate for dividing head with worm gear ratio = 90:1

Available hole plates =
15, 16, 17, 18, 19, 20, 21, 23, 27, 29, 31, 33, 37, 39, 41, 43, 47, 49,

2 => 45 & 0
3 => 30 & 0
4 => 22 & 8/16 or 9/18 or 10/20
5 => 18 & 0
6 => 15 & 0
7 => 12 & 18/21 or 42/49
8 => 11 & 4/16 or 5/20
9 => 10 & 0
10 => 9 & 0
11 => 8 & 6/33
12 => 7 & 8/16 or 9/18 or 10/20
13 => 6 & 36/39
14 => 6 & 9/21 or 21/49
15 => 6 & 0
16 => 5 & 10/16
17 => 5 & 5/17
18 => 5 & 0
19 => 4 & 14/19
20 => 4 & 8/16 or 9/18 or 10/20
21 => 4 & 6/21 or 14/49
22 => 4 & 3/33
23 => 3 & 21/23
24 => 3 & 12/16 or 15/20
25 => 3 & 9/15 or 12/20
26 => 3 & 18/39
27 => 3 & 5/15 or 6/18 or 7/21 or 9/27 or 11/33 or 13/39
28 => a plate with an integer multiple of 14 holes is required
29 => 3 & 3/29
30 => 3 & 0
31 => 2 & 28/31
32 => 2 & 13/16
33 => 2 & 24/33
34 => 2 & 11/17
35 => 2 & 12/21 or 28/49
36 => 2 & 8/16 or 9/18 or 10/20
37 => 2 & 16/37
38 => 2 & 7/19
39 => 2 & 12/39
40 => 2 & 4/16 or 5/20
41 => 2 & 8/41
42 => 2 & 3/21 or 7/49
43 => 2 & 4/43
44 => a plate with an integer multiple of 22 holes is required
45 => 2 & 0
46 => 1 & 22/23
47 => 1 & 43/47
48 => 1 & 14/16
49 => 1 & 41/49
50 => 1 & 12/15 or 16/20

-------------------------

If you have different hole plates, you can either download the program and use
it to generate the appropriate table or supply me with the hole plate data and
I'll run the case for you.

Regards, Marv

Home Shop Freeware - Tools for People Who Build Things
http://www.geocities.com/mklotz.geo