# Rotary table -Divider plates



## Brian Rupnow (Jun 16, 2010)

Today I washed all the cosmoline gunk off my Divider plates which came with my rotary table (which I purchased 3 years ago). I followed the Chinglish instructions, and after slotting the holes in the divider plates so they would actually fit the bolt pattern in the rotary table (Thats a whole 'nuther story) I was able to assemble things okay. I am beginning to figure out how the divider plates are supposed to work---fortunately I am using the rotary table to cut an eithteen tooth gear, which means 5 full rotations of my handle to accomplish the 20 degrees between cutting positions, so I can use any of the divider plates. (Mine is a 90:1 gear reduction).----Now the question---Those brass arms (I think they are called "sectors") have a screw, which when tightened will lock the angle between the sector arms---However, the two arms (now locked at some angle) seem to rotate fairly freely on the center hub.---They shouldn't do that, should they?? If I am doing some exotic pattern that calls for X number of full rotations and then count how ever many additional holes in the divider plates to let my spring loaded handle pin drop into (Which I THINK is supposed to be located by one of the sector arms)---and the arms rotate out of position---then I'll end up dropping my spring loaded pin into the wrong hole. What am I not understanding here???---Brian


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## Maryak (Jun 16, 2010)

Brian,

In the dividing plate set there is a largish spring clip which locates in a groove in the shaft and prevents the sector arms from rotating freely. They will still rotate as they must but with some resistance.

Looking at your picture you seem to have it fitted but maybe it needs bending to tighten things up a little.






The pin should be inside the sector arms and the sector arms should be set to the number of holes required + 1. e.g. X turns + 10 holes, the sector should be set to 11 holes on the appropriate holes circle.

Hope this helps

Best Regards
Bob


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## Brian Rupnow (Jun 16, 2010)

Thanks Bob---I guess mine must be okay then. they don't "flop around" but if you weren't paying attention when you were turning the handle and the pin did hit them, they would move. I guess that just means "Pay attention"!!!----Brian


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## bronson (Jun 16, 2010)

Hi brian i have a whole book just on dividing if you would like to borrow it just let me know.


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## tup48 (Jun 16, 2010)

Brian;
I will try to help if I can.

The two arms should rotate freely around the hub but not too freely.

On my RT there is a half moon spring between the arms and the hub that keeps tension between the two.
If your divider plates dont have a spring, thy are very easy to lose or it may have came without one you mite be able to put a peace of paper or even some tape between the arms and the hub to give you the friction you need. Or you may be able to dill & tap the ring on the arms for a small set screw to give some friction.

On the divider plate you mite want to put a mark on the top of the plate at the hole that you will be using with something like a Sharpie pen so you will know where you are. When going around the plate for the next tooth if you should go by where you want to stop, you will want to take a full turn in the opposite direction to get red of any back lash then come back to where you wish to be.

You dont want any distractions, it is very easy to lose count and end up ruing a gear. Cutting gears can be enjoyable (and at times almost as much fun as watching oil base pant dry) Ha, Ha. 

Good luck
Richard


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## mklotz (Jun 16, 2010)

Gee Brian, I thought you said you weren't interested in learning how to use dividing plates.

Let me see if I can explain the use of the sector arms. 

With a 90:1 RT, you have to turn the RT handle 90 full turns to make the part turn one complete revolution. Now let's suppose you want to make a 21 tooth gear. That requires turning the part 1/21 revolution for each tooth. That means you have to turn the handle

(1/21) * 90 = 90/21 = 4 & 6/21 turns 

for each tooth. That's four complete turns of the handle and 6 spaces (note I didn't say holes) on the 21 hole plate.

Put the pin in one of the holes and bring the beveled edge of one of the sector arms around to touch the left side of the pin. Now, counting the hole the pin is in as zero, count off 6 holes and place another pin. Verify that there are indeed six inter-hole spaces between the two pins. Bring the other sector arm around so its beveled face touches the right side of this last-placed pin. Tighten the locking mechanism that retains this angular separation of the two arms.

Now, when you want to index, swing the locked sector arm assembly so as to put the beveled edge of the sector arm pair against the left side of the indexing pin. Pull the pin and turn it 4 full turns, then continue to the hole that lies next to the other sector arm on the 21 hole ring. Voila, you've moved the handle 4 and 6/7 turns and you only had to count to four. Really, once you understand it, I think you'll agree that it's a very ingenious mechanism.

-----

For any other gear, with N teeth, simply compute:

90/N

and express it in a fraction with a denominator that matches the number of holes in one of your hole circles. Then proceed as above to set the sector arms.

-----

If you do a lot of dividing, it's still easier to use my program. Or, use it to check your calculations if you have concerns.


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## Brian Rupnow (Jun 16, 2010)

Marv---Thank you. I really, really didn't want to use the dividing plates. They seemed like such a black mystery to me that I was afraid to use them. However---once I read enough to realize that with 20 degree seperations I could use any of the plates, not worry about the sector arms, and "hole counting", I decided to at least see if they would fit on the rotary table. Of course, the damned things didn't, and had to be modified, but they are on there. ---Now you have to realize---I was terrified of computers too---Swore I would never use one.---Now I teach 3D solid modelling. I guess anything is possible.---Brian


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## mklotz (Jun 16, 2010)

It's far simpler than it might appear from a casual glance and it's a valuable tool to have in your arsenal. All that's required mathematically is a bit of diddling with mixed fractions. The rest is simple mechanics and will be obvious.


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## Brian Rupnow (Jun 16, 2010)

I just found this really neat video on "That other" website I hang out on. Its great---shows a man making a gear and using the dividing plates and sector plates. Make sure your sound is on when you watch it.
[ame]http://www.youtube.com/watch?v=VHTXaU7GZC0[/ame]


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## tmuir (Jun 16, 2010)

Brian Rupnow  said:
			
		

> and after slotting the holes in the divider plates so they would actually fit the bolt pattern in the rotary table (Thats a whole 'nuther story) I was able to assemble things okay.



Yes my instructions were a bit vague on assembly too and it took me nearly 2 hours to fit the plates correctly on my first use. :big:
I haven't used mine very much yet and I need to concentrate when I am using it not to mess it up, but I do love them


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## Twmaster (Jun 16, 2010)

Nice video. Thanks for the link Brian. That made it look simple.


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## allrounder (Sep 22, 2013)

Oh great explanation! I learnt it 35 yrs back and now forgot. But you opened up my old files.
Thank you


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## gus (Sep 22, 2013)

Thanks for jogging my memories to 1962 when I was taught to use divider plate to cut a 4" spur gear.
Now I can remember how the spreader arm is used. Classmate preferred to count the holes and skip using the spreader arms
and end up with a spur gear with half tooths.:hDe:He got chewed up by the same instructor who gave us theory lesson.:hDe:


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## Brian Rupnow (Sep 22, 2013)

Now that I have used my set up enough to get friendly with it, I find it works very good. I just recently cut my first set of 45 degree miter gears. There is one bit of simple black magic that I always use. It doesn't matter if I'm making a simple gear that doesn't require any partial turns of the crank, (thus requiring the sector arms) or not.--Use a black "magic marker" to draw a circle around whatever hole (or holes) you are using. that way, even if you do "bump" the sector arms and move them, its a simple thing to put them back to where they should be. The marker rubs off with a bit of paint thinner or layout dye remover.---Brian


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## Swifty (Sep 22, 2013)

Good tip Brian, I have used the same method myself as I always seem to be bumping the sector arms.

Paul.


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## goldstar31 (Sep 23, 2013)

We are back in the UK again- if only for much larger problems than 'Simple Division'. Life for many of us is not sector arms but whether real arms will ever rotate again. 
Sorry, but I have mentioned many times where readable information is. Perhaps the cheapest is- if you can afford the paper and the ink- and time to down load is A H Smith's Advanced Machine Tool Work which contains so much information that most of the questions asked here would  be even more repetitive. If you want to go the whole hog there is little to beat George Thomas's Workshop Technique's or the earlier print of his Dividing and Graduating. All been in Model Engineer in the past and our old associate Dr Bill Bennett hacked it into a book from the articles following George's illness and then death.

So if you want to know 'how it all works' rather than how to protect machine tools from scratches- that's the way. 

Me? I have the classic division plate- with a single hole it.


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## Brian Rupnow (Sep 23, 2013)

Goldstar31--Your answer smacks of "Sour Grapes" to me. We do read the technical books. We do try and help each other out with "how to" posts and explanations. That is what this forum is for.---Brian


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## goldstar31 (Sep 23, 2013)

No Sour Grapes intended but I cannot see how anyone can condense useable information into such a space. Now I have a homemade Versatile Dividing Head to GHT design with the ability to create 'any division' as well several sizes of rotary tables -both home made and bought out.
As a very young Goldstar, I had charge of a technical  library of with 5 staff and quoting the Gypsy (Queen 71) engine bit there was inches thick books merely on that engine alone and the Antarctic Gypsy's for the Auster 7's were another item altogether  and so on. 
Years later, I did a British City And Guilds in Motor Vehicle Restoration( for kicks) but it was all of 4 years and with loads of written work.

Frankly, I cannot understand how anyone can 'do' engineering involving one liners in what has to be a correspondence course. 

Sorry but I can't.

Regards

Norman


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## Cogsy (Sep 23, 2013)

Speaking for myself, virtually all the info I have learned in 'engineering' has been from this site alone. While I would not trust any of my 'work' in a production or commercial environment, I have learned to create working model engines from chunks of raw materials. This is a hobby for the majority of us and life and limb doesn't rest on the outcome of our endeavours, merely enjoyment.

As long as I can find out, or work out, how to get a particular machining process done to my satisfaction, I don't see the need for a university eductaion into the theory behind it, nor the industry 'best practice'.

If I can be frank - if you can't see the point or worthiness of a forum such as this, then why do you bother to come here?

My apologies if I have caused offence, it was not my intent.


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## Brian Rupnow (Sep 23, 2013)

Goldstar--We are not ignoramuses on this site. We design and build some fairly exotic machinery. We also have or have access to technical libraries that are pertinent to what we have to know. On the corner of my desk is "Gears and Gearcutting" by Ivan Laws. I have a couple of "Workshop Practice" series books outlining the basics of using a milling machine and a lathe. I have "The Machinery Handbook" 23rd edition. I also have "Handbook of Mechanical Engineering" by Beitz and Kutther. I have "The Handbook of Dimensional Measurement: by Farago. I have "Engineering Drawing and Design" by Jensen. I have "Canadian Professional Engineering Practice and Ethics" by Andrews and Kemper. I have "The Law and Business Administration" by Smyth, Soberman, and Eason. I have "Marks Standard Handbook for Mechanical engineers" by Avaland and  Baumeister. Pretty well every one of the builders on this forum does a goodly amount of research before setting out on a project. I have built 12 running steam engines , six internal combustion engines, and a multitude of mechanical devices to run with my engines. I have 50 years of building race car engines and professional drag racing behind me. ---Brian Rupnow


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## Philjoe5 (Sep 23, 2013)

> Frankly, I cannot understand how anyone can 'do' engineering involving one liners in what has to be a correspondence course.
> 
> Sorry but I can't.



Goldstar, kudos to you for acknowledging your limitations.  Frankly I'm with Cogsy.  I cut my first spur gears by reading posts on this forum.  First, a post here pointed me to a vendor that sold a set of 8 cutters for the price of 2 cutters from my usual vendors.  Another post pointed me to Ivan Law's book which helped in setting up and cutting operations.  Another post pointed to a youtube video showed a guy cutting the gear which answered even more questions.

Did a single "one liner" allow me to "do" engineering?  Of course not.  But a collection of them did.  I read all my books the same way.  One line at a time.

We appreciate your references to what I'm sure are excellent sources of technical information.  They are noted.

Phil


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## canadianhorsepower (Sep 23, 2013)

Goldstar, 
             the goal of this forum is not  try impressing the other 
in telling fairy tail about us.

It's about helping other Hobbyist to achieve their goal without spending
4 years at the university to do so.

Their is some stuff you don't understand

*


		HTML:
	

Frankly, I cannot understand how anyone can 'do' engineering involving one liners in what has to be a correspondence course. 

Sorry but I can't

 *

all you have to do is ask and we will explain it to you , with out being to AGRESSIVE


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## Brian Rupnow (Sep 23, 2013)

Oh come on Luc---You know darn well that I try to impress people all the time!!!---Brian


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## goldstar31 (Sep 23, 2013)

Sadly, I was  part of  a generation which left school at 14 after what was 6 years of war and I wouldn't know what an entropy was- or what to do with it. I confess that I did make the odd model using a used razor blades sharpened on a bit of glass tumbler and a 6 penny drill from Woolworths. The shapes came from broken glass- culled from blitzed houses. 

All things are relative and I did get to make a 'doodlebug' jet engine. It didn't explode like the German ones- but one can't do a lot with a 6 penny drill. I had enough problem getting a nice old fella to make me a needle valve on his battered old Myford that was too ropey to make munitions for it.

70 years or so later, I'm still using a mended old Myford! Keeps the grey matter that remains under the remaining grey stuff above it working. There's a bit of one hand working- from time to time- and I suppose that at 83 I'm solving most of my problems.


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## GailInNM (Sep 23, 2013)

This is a hobby forum with members coming from diverse backgrounds and with diverse goals.  Do not let this thread degenerate into personal attacks because someones way is not your way of doing things.  Please let the current theme of this thread drop and get back to helping each other. That is the purpose of this forum.  I do not like having to lock threads.
Gail in NM
Moderator


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## canadianhorsepower (Sep 23, 2013)

goldstar31 said:


> 70 years or so later, I'm still using a mended old Myford! 83 I'm solving most of my problems.


 
It would be nice to see some of your work.

It sound so simple to do impressive thing


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## goldstar31 (Sep 23, 2013)

Luc
Drop me your E-mail address. I'm not into these things which let all and sundry what one has. The world is not quite as honest as it was. 

I have a little home in Spain. Had it a long time from it was about the same price as a basic Mini. A few tools in the shed. A garden hack or adze, a pair of shears, a few paint brushes, a 6 penny hand drill and electric hedge trimmer. It was broken into- and most gone or smashed. Two rusty garden chairs went last week. Canada may be honest- but Europe isn't.

So you have a valid reason. E-mail please.

Regards

Norman


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## Wizard69 (Sep 25, 2013)

goldstar31 said:


> Luc Drop me your E-mail address. I'm not into these things which let all and sundry what one has. The world is not quite as honest as it was.  I have a little home in Spain. Had it a long time from it was about the same price as a basic Mini. A few tools in the shed. A garden hack or adze, a pair of shears, a few paint brushes, a 6 penny hand drill and electric hedge trimmer. It was broken into- and most gone or smashed. Two rusty garden chairs went last week. Canada may be honest- but Europe isn't.  So you have a valid reason. E-mail please.  Regards  Norman



That is what gun control does for you.   Petty crime in Europe is amazingly rampant as these bad actors have nothing to fear from the judicial system nor the home owner.


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## goldstar31 (Sep 26, 2013)

Wizard69 said:


> That is what gun control does for you. Petty crime in Europe is amazingly rampant as these bad actors have nothing to fear from the judicial system nor the home owner.


 
Initially, Sir, your comments are miles off topic. I was merely trying to advise that it not my habit or policy to compromise my  way of life by posting pictures- of what is no more than a hobby.

I do, however, take great exception to the implied inference about your macho stuff and the Brits being - cissies. However, this forum is NOT the place for such-- Division.

Thank you- from someone that has a War Pension.


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## Philjoe5 (Sep 26, 2013)

I am with Gail in NM, I don't like locking threads.  However, this thread has degenerated into a soapbox that has no contribution to model engineering.

Phil


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