Compound indexing for 127

[Terrywerm]

After reviewing the math behind the process, it isn't actually that bad, but most indexing heads and rotary tables use a number of flat head screws to attach the plate to the head, not a stop pin like the book talks about. If you need to turn the plate and the crank together for a certain number of holes, what do you use as a reference for when to stop turning the plate? I might have to experiment with this a little bit. I don't doubt that it works, I just don't completely understand a couple of the pieces of the puzzle.

 

[Smithdoor]

Yes it use two index circles making the gear
here is part of a chart it when up to
250
Had the dividing head sold it back in the 70's
The last one I cut was 53 teeth
On the chart it use 43 holes and 49 holes
The 43holes x 40 = 1720 parts
Then add in the 49 hole x 1720 parts = 68,800

Dave

After reviewing the math behind the process, it isn't actually that bad, but most indexing heads and rotary tables use a number of flat head screws to attach the plate to the head, not a stop pin like the book talks about. If you need to turn the plate and the crank together for a certain number of holes, what do you use as a reference for when to stop turning the plate? I might have to experiment with this a little bit. I don't doubt that it works, I just don't completely understand a couple of the pieces of the puzzle.

 

[Reeltor]

After reviewing the math behind the process, it isn't actually that bad, but most indexing heads and rotary tables use a number of flat head screws to attach the plate to the head, not a stop pin like the book talks about. If you need to turn the plate and the crank together for a certain number of holes, what do you use as a reference for when to stop turning the plate? I might have to experiment with this a little bit. I don't doubt that it works, I just don't completely understand a couple of the pieces of the puzzle.

Terry,

My universal Van Norman dividing head has a lock for the location of the plate. By releasing the lock and leaving the index pin in a hole you can turn the entire mechanism. I don't know if semi-universal heads have this feature or only the universal ones. I definitely don't understand most of pieces of this puzzle and would need to see a YouTube of someone demonstrating the process.

Mike

 

[Ebel440]

This won't really help but you don't need an indexer on a Cnc to make a new plate you could just do it as a bolt circle.

 

[Terrywerm]

I did some more research on this and found that the older index heads came with the stop pin feature for compound indexing, but it has largely faded away since the advent of NC and CNC and the ability to layout a hole circle on a mill without an indexer. So, those of you that have some of the older index heads may have this ability. The newer ones do not, but I found a couple of YouTube videos showing what one fellow did to be able to do compound indexing with a modern indexing head.

[video=youtube;exruE7sHXso]https://www.youtube.com/watch?v=exruE7sHXso[/video]

[video=youtube;S1zovk1KODs]https://www.youtube.com/watch?v=S1zovk1KODs[/video]

I also did some digging and found the necessary numbers for 127 divisions in Machinery's Handbook:



Keep in mind that this chart assumes a 40:1 ratio as you would find with an indexing head, and they will not work with a rotary table, which usually uses a 90:1 ratio. Sadly, a chart does not exist for a 90:1 ratio, nor did they supply the math to figure it out, and I have not yet gotten through it myself with any real success, so I suspect I am missing something.

Hope you all find this useful!

 

[Smithdoor]

That is closer than a cnc is and lower cost
I will take time for 90 tooth worm good news have the work is done
I have some where the math on this type.
Just think of doing this without a computer or even a calculator


Dave

I did some more research on this and found that the older index heads came with the stop pin feature for compound indexing, but it has largely faded away since the advent of NC and CNC and the ability to layout a hole circle on a mill without an indexer. So, those of you that have some of the older index heads may have this ability. The newer ones do not, but I found a couple of YouTube videos showing what one fellow did to be able to do compound indexing with a modern indexing head.

[video=youtube;exruE7sHXso]https://www.youtube.com/watch?v=exruE7sHXso[/video]

[video=youtube;S1zovk1KODs]https://www.youtube.com/watch?v=S1zovk1KODs[/video]

I also did some digging and found the necessary numbers for 127 divisions in Machinery's Handbook:

View attachment 92952

Keep in mind that this chart assumes a 40:1 ratio as you would find with an indexing head, and they will not work with a rotary table, which usually uses a 90:1 ratio. Sadly, a chart does not exist for a 90:1 ratio, nor did they supply the math to figure it out, and I have not yet gotten through it myself with any real success, so I suspect I am missing something.

Hope you all find this useful!

 

[OldMachinist]

I bought a set of the high number index plates years ago just for doing gears with prime number amounts of teeth like 127. I don't know if you can still get them anywhere.

 

[Smithdoor]

This for 90 tooth worm
Dave

Divisions	Plate letter	Hole circle		Number of turns	Holes		Second Hole circle	holes		No of times a round	Degrees and minutes per cut	Max error on last tooth cut in degreeds
127	C	39		6	13		49	1		9	25 ° - 31/60 '	0.0002037

I did some more research on this and found that the older index heads came with the stop pin feature for compound indexing, but it has largely faded away since the advent of NC and CNC and the ability to layout a hole circle on a mill without an indexer. So, those of you that have some of the older index heads may have this ability. The newer ones do not, but I found a couple of YouTube videos showing what one fellow did to be able to do compound indexing with a modern indexing head.

[video=youtube;exruE7sHXso]https://www.youtube.com/watch?v=exruE7sHXso[/video]

[video=youtube;S1zovk1KODs]https://www.youtube.com/watch?v=S1zovk1KODs[/video]

I also did some digging and found the necessary numbers for 127 divisions in Machinery's Handbook:

View attachment 92952

Keep in mind that this chart assumes a 40:1 ratio as you would find with an indexing head, and they will not work with a rotary table, which usually uses a 90:1 ratio. Sadly, a chart does not exist for a 90:1 ratio, nor did they supply the math to figure it out, and I have not yet gotten through it myself with any real success, so I suspect I am missing something.

Hope you all find this useful!