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[machinist] The Newbould Indexer - description of how it works
- From: Lawrence London <lfljvenaura@gmail.com>
- To: machinist@lists.ibiblio.org
- Subject: [machinist] The Newbould Indexer - description of how it works
- Date: Mon, 25 May 2020 01:53:17 -0400
A serrated-tooth indexer with multiple numbers of teeth combinations (such as made by AA Gage in Michigan) had all the accuracy and mechanical
characteristics I wanted, but were not direct-reading.
By this time, a week had gone by and I had decided a differential serrated-tooth mechanism was the only way to go.
Now… How to make it easy to use? That was the question. The following week was spent hour after hour, sometimes till the wee hours in the
morning, punching different combinations of teeth into my Frieden rotary calculator, looking for a combination that would be easy to use.
Finally, after all that time I was sitting at my desk about 10AM, with a nice warm sun on my back, looking all those notes scattered on the desk,
and decided there was no combination to be had. All combinations required a mathematical calculation to determine the final angle, and none would
provide a movement of exactly one second of arc.
Damn… I said to myself. I don’t want to have wasted all that time. I’ll find another way. What if I make the second set of teeth 61 minutes to
give me a one-minute differential from a 60-minute set, what happens?
That gives me 354.09836 teeth leaving a small tooth at the end of the circle, now what? OK, I’ll just clear a spot on the other disk for that odd
tooth. But I can’t move it, it won’t fully engage… Well, if I take out another tooth it will. Now I have two positions with exactly one minute
differential.. That’s handy, but what good are two positions? Not much, so I’ll take out another tooth. Now I have 3 positions. Damn… If I keep
this up, I won’t have any teeth left on the opposing set. But wait.. If I clear 60 degrees worth of teeth, I can go back to my original start and
will have moved exactly one degree. Eureka… That’s it. I can make the differential whatever is easy to read as long as I subdivide the previous
set’s division in equal parts.
That thought process took about 10 minutes. I was able to find a mechanical solution to a mathematically impossible problem, by not limiting the
number of teeth to an integer.
A serrated form of engaging members is about 2,000 years old. The first patent for a differential set was made in Netherlands before I was born.
All those which were designed to be engaged in a variety of positions, used a whole number of teeth (integers) in the circle.
There are only 3 elements, or characteristics if you will, to the Newbould Indexer. Serrated teeth, the differential principle, and the use of an
non-integer number of teeth with a corresponding open space on the engaging member. Remove any one of these three elements, and it no longer
works as a direct-reading indexer. That makes it basic, and that’s why it was put in the Smithsonian.
How it came to be in the Smithsonian is another story if y’all are interested.
[]
How I think it works is like this, it has three sets of face gears. I guess they are just V shape and it is akin to a dog clutch type sort of
thing. On one set the pitch between the teeth is 1 degree. That is move one gear one notch moves it one degree.
Now the next gear set the tooth pitch is one degree and one minute. But this has a dilemma that the last tooth is a tiny tooth which is OK when
it fits in the mating gear as it is cut the same, but it will not fit anywhere else. So the solution was to remove the next tooth on one side,
then the next, removing 60 teeth from one gear.
Then you cut the next gear set. It is one degree, one minute and one second between teeth. And the same again, you end up with a dodgy tooth at
the end, so cut out another 60 teeth.
So you want to index one degree one second. So you move the first gear set clockwise two notches or two degrees. Then you move the third gear set
backwards one tooth or one degree one second. So you have moved forward one degree one second.
The reason to cut out sixty teeth out of the two gear sets is once you move either of the two sets 60 teeth, you have moved either a full degree
or a full minute but it leaves plenty of teeth to engage for locking together.
[]
It indexes every 8 degrees.
The top pitch is 24 degrees, making 15 teeth
The bottom pitch is 16 degrees making 22.5 teeth. Odd tooth is marked in red.
Difference = 8 degrees.
Starts closed at zero degrees.
Opens, indexes middle "adapter" disk one pitch of 16 degrees.
Closes, top plate forced to rotate 8 degrees to engage.
Repeats until end of clearance area, totaling 24 degrees rotation of top plate.
Middle plate returnes to start position, top plate stays at 24 degrees.
Repeating would index another 24 degrees to total 48 degrees
This means the adapter plate goes back and forth in the open area and effectively ratchets the top plate in 8 degree increments.
Make the adapter plate free rotating, and you can set any 8 degree angle at random.
Change pitches to suit for desired increments.
[]
Video on You Tube
https://www.youtube.com/watch?v=3EGGuR5YziE
listed as the 28th basic mechanism invented
Published on Jan 3, 2017
A model of the Newbould Indexing mechanism as invented in 1971 by Richard Newbould. Used for quick and accurate direct reading angular indexing.
Is listed as the 28th basic mechanism invented. A description written by R J Newbould of the model shown is as follows;
It indexes every 8 degrees.
The top pitch is 24 degrees, making 15 teeth
The bottom pitch is 16 degrees making 22.5 teeth. Odd tooth is marked in red.
Difference = 8 degrees.
Starts closed at zero degrees.
Opens, indexes middle "adapter" disk one pitch of 16 degrees.
Closes, top plate forced to rotate 8 degrees to engage.
Repeats until end of clearance area, totaling 24 degrees rotation of top plate.
Middle plate returnes to start position, top plate stays at 24 degrees.
Repeating would index another 24 degrees to total 48 degrees
This means the adapter plate goes back and forth in the open area and effectively ratchets the top plate in 8 degree increments.
Make the adapter plate free rotating, and you can set any 8 degree angle at random.
Change pitches to suit for desired increments.
[]
See OxToolCo's youtube Monday Night Meatloaf #115 near end for the Newbold Indexer model 202 that is the production model- single arc seconds of
division.
--
https://www.instagram.com/avantgeared/?hl=en
characteristics I wanted, but were not direct-reading.
By this time, a week had gone by and I had decided a differential serrated-tooth mechanism was the only way to go.
Now… How to make it easy to use? That was the question. The following week was spent hour after hour, sometimes till the wee hours in the
morning, punching different combinations of teeth into my Frieden rotary calculator, looking for a combination that would be easy to use.
Finally, after all that time I was sitting at my desk about 10AM, with a nice warm sun on my back, looking all those notes scattered on the desk,
and decided there was no combination to be had. All combinations required a mathematical calculation to determine the final angle, and none would
provide a movement of exactly one second of arc.
Damn… I said to myself. I don’t want to have wasted all that time. I’ll find another way. What if I make the second set of teeth 61 minutes to
give me a one-minute differential from a 60-minute set, what happens?
That gives me 354.09836 teeth leaving a small tooth at the end of the circle, now what? OK, I’ll just clear a spot on the other disk for that odd
tooth. But I can’t move it, it won’t fully engage… Well, if I take out another tooth it will. Now I have two positions with exactly one minute
differential.. That’s handy, but what good are two positions? Not much, so I’ll take out another tooth. Now I have 3 positions. Damn… If I keep
this up, I won’t have any teeth left on the opposing set. But wait.. If I clear 60 degrees worth of teeth, I can go back to my original start and
will have moved exactly one degree. Eureka… That’s it. I can make the differential whatever is easy to read as long as I subdivide the previous
set’s division in equal parts.
That thought process took about 10 minutes. I was able to find a mechanical solution to a mathematically impossible problem, by not limiting the
number of teeth to an integer.
A serrated form of engaging members is about 2,000 years old. The first patent for a differential set was made in Netherlands before I was born.
All those which were designed to be engaged in a variety of positions, used a whole number of teeth (integers) in the circle.
There are only 3 elements, or characteristics if you will, to the Newbould Indexer. Serrated teeth, the differential principle, and the use of an
non-integer number of teeth with a corresponding open space on the engaging member. Remove any one of these three elements, and it no longer
works as a direct-reading indexer. That makes it basic, and that’s why it was put in the Smithsonian.
How it came to be in the Smithsonian is another story if y’all are interested.
[]
How I think it works is like this, it has three sets of face gears. I guess they are just V shape and it is akin to a dog clutch type sort of
thing. On one set the pitch between the teeth is 1 degree. That is move one gear one notch moves it one degree.
Now the next gear set the tooth pitch is one degree and one minute. But this has a dilemma that the last tooth is a tiny tooth which is OK when
it fits in the mating gear as it is cut the same, but it will not fit anywhere else. So the solution was to remove the next tooth on one side,
then the next, removing 60 teeth from one gear.
Then you cut the next gear set. It is one degree, one minute and one second between teeth. And the same again, you end up with a dodgy tooth at
the end, so cut out another 60 teeth.
So you want to index one degree one second. So you move the first gear set clockwise two notches or two degrees. Then you move the third gear set
backwards one tooth or one degree one second. So you have moved forward one degree one second.
The reason to cut out sixty teeth out of the two gear sets is once you move either of the two sets 60 teeth, you have moved either a full degree
or a full minute but it leaves plenty of teeth to engage for locking together.
[]
It indexes every 8 degrees.
The top pitch is 24 degrees, making 15 teeth
The bottom pitch is 16 degrees making 22.5 teeth. Odd tooth is marked in red.
Difference = 8 degrees.
Starts closed at zero degrees.
Opens, indexes middle "adapter" disk one pitch of 16 degrees.
Closes, top plate forced to rotate 8 degrees to engage.
Repeats until end of clearance area, totaling 24 degrees rotation of top plate.
Middle plate returnes to start position, top plate stays at 24 degrees.
Repeating would index another 24 degrees to total 48 degrees
This means the adapter plate goes back and forth in the open area and effectively ratchets the top plate in 8 degree increments.
Make the adapter plate free rotating, and you can set any 8 degree angle at random.
Change pitches to suit for desired increments.
[]
Video on You Tube
https://www.youtube.com/watch?v=3EGGuR5YziE
listed as the 28th basic mechanism invented
Published on Jan 3, 2017
A model of the Newbould Indexing mechanism as invented in 1971 by Richard Newbould. Used for quick and accurate direct reading angular indexing.
Is listed as the 28th basic mechanism invented. A description written by R J Newbould of the model shown is as follows;
It indexes every 8 degrees.
The top pitch is 24 degrees, making 15 teeth
The bottom pitch is 16 degrees making 22.5 teeth. Odd tooth is marked in red.
Difference = 8 degrees.
Starts closed at zero degrees.
Opens, indexes middle "adapter" disk one pitch of 16 degrees.
Closes, top plate forced to rotate 8 degrees to engage.
Repeats until end of clearance area, totaling 24 degrees rotation of top plate.
Middle plate returnes to start position, top plate stays at 24 degrees.
Repeating would index another 24 degrees to total 48 degrees
This means the adapter plate goes back and forth in the open area and effectively ratchets the top plate in 8 degree increments.
Make the adapter plate free rotating, and you can set any 8 degree angle at random.
Change pitches to suit for desired increments.
[]
See OxToolCo's youtube Monday Night Meatloaf #115 near end for the Newbold Indexer model 202 that is the production model- single arc seconds of
division.
--
Avant Geared
walnut and oak serving and kitchen cutting boards
https://sites.google.com/site/avantgearedhttps://www.instagram.com/avantgeared/?hl=en
- [machinist] The Newbould Indexer - description of how it works, Lawrence London, 05/25/2020
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