Which, 8" Or 10", Dividing Head For Pm940m

Here is a picture of the dividing head. Does anyone have the hole counts for each of the plates?

upload_2015-5-13_11-55-16.png
 
I'd say the limiting factor is size: what do you plan on holding with it?

All things being equal, it is only $50 more for the extra capacity.
 
My 12Z has basically the same work envelope and I'm considering a bs-1 (5" center height) as it will hold my 6" chuck and at 80 lbs is the biggest one I want to lift on and off the mill table. I briefly looked at a bs-2 but at over 100 lbs I decided I want nothing to do with it. I'm not getting any younger. :)

But planeflyer21 has a point: what do you want to do with it?
 
Elsewhere there is a similar unit with 24 holes for direct division and three plates with the following rings of holes (the following numbers may not correspond to the picture):

15, 16, 17, 18, 19, 20, # Plate A
21, 23, 27, 29, 31, 33, # Plate B
37, 39, 41, 43, 47, 49, # Plate C

I hacked together a program to see which divisions are NOT possible: there 22 in the first 99, 64 in the 100's; 75 in the 200's; and 84 in the 300's. These are NOT possible even divisions, using the holes listed above. Corrections, if any, are welcome.
 
planeflyer21 said:
I'd say the limiting factor is size: what do you plan on holding with it?

All things being equal, it is only $50 more for the extra capacity.
Click to expand...
I was thinking about making the largest gear at any given pitch or module.
 
wrmiller19 said:
My 12Z has basically the same work envelope and I'm considering a bs-1 (5" center height) as it will hold my 6" chuck and at 80 lbs is the biggest one I want to lift on and off the mill table. I briefly looked at a bs-2 but at over 100 lbs I decided I want nothing to do with it. I'm not getting any younger. :)

But planeflyer21 has a point: what do you want to do with it?
Click to expand...
Does it seem likely to be able to take the gear cutter at center line height of 5 inches ? The cutter would be at 3:00 o'clock between the dividing head and the spindle.
 
5" from the top of the mill table? If I understand what you are asking, no problem. I have 20" of Z axis travel as I believe you do as well. Again, if I understand your question, I could put the dividing head in my 5" vise and still be able to get the head high enough.

Or am I misunderstanding the question? :)
 
wrmiller19 said:
5" from the top of the mill table? If I understand what you are asking, no problem. I have 20" of Z axis travel as I believe you do as well. Again, if I understand your question, I could put the dividing head in my 5" vise and still be able to get the head high enough.

Or am I misunderstanding the question? :)
Click to expand...
Yes. That was what I was asking. Thanks.
 
JPH said:
Elsewhere there is a similar unit with 24 holes for direct division and three plates with the following rings of holes (the following numbers may not correspond to the picture):

15, 16, 17, 18, 19, 20, # Plate A
21, 23, 27, 29, 31, 33, # Plate B
37, 39, 41, 43, 47, 49, # Plate C

I hacked together a program to see which divisions are NOT possible: there are 22 in the first 99, 64 in the 100's; 75 in the 200's; and 84 in the 300's. These are NOT possible even divisions, using the holes listed above. Corrections, if any, are welcome.
Click to expand...

I have to run the program again with worm gear ratio 40. That's what my latest research shows for B&S original dividing heads that look similar.

I re ran the program with worm ratio 40 and the results are similar.

Then there is compound indexing where I think the direct plate can be moved as well as the plate with the holes, per each iteration. More hacking to the program to accommodate this, if indeed it is an allowed way to index.

If some one already has the answer to question, how many ways can a circle be divided with this machine, I would appreciate it.

If someone has a similar unit, I would like to ask the following. Using the plate that has 17 holes in a ring (circle), can you crank the plate 15 hole in the direction that makes the work piece turn in a counter clockwise direction; then advance one hole in the direct index so that the work moves in the clockwise direction. My calculations show that the work piece circle can be divided exactly into 51 part of a circle.

What I am really asking is, for each iteration, can the crank be moved 15/17 of a turn and at the same time can the direct plate (the one with 24 holes), can it be turned hole, 1/24 of a full circle.

If they can be independently moved, then I have a bit more hacking to do on my code to find all possible uniform divisions of the circle, with the holes as given above.
 
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