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Van Norman dividing head

excello

Aluminum
Joined
Nov 20, 2010
Location
Iowa, USA
I got this little dividing head from a junk and antique collector, probably 30 years ago . It was laying on a dirt floor in a farm type shed. I got it working, cleaned it up and painted it. It's actually a nice working little unit, even though the gears are open.

Is this a common Van Norman dividing head ? If anyone has more info / literature on these I would appreciate seeing it.

I would like to find a replacement for the broken index plate , which has 18,24,28,30,34,37 holes. That's probably going to be tough to find, so may have to make something.

I would also like to know if there is a spacer or something else that fits between the draw bar and the back end of the spindle ( see yellow marks in picture ).

Thanks,

excello
 

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Go to the following site and download the brochures on attachments, arbors etc there you will find the data on this dividing head.
Van Norman Machine Tool Co. - Publication Reprints | VintageMachinery.org
As well if you go to the following site a fellow has his own description on this dividing head.
Van Norman 7 1/2" Index Center
This is called a 7 1/2" dividing head by Van Norman and was built to work on the #1/2, #10, #6 and even the #12 Van Norman millers however on the #6 and the #12 the larger dividing head the #10 was more common.
As to what is missing normally in that hole would go the drawbar for the collets I'm not sure what you have in there now but it looks like somebody adapted something.

Harold

PS if you are thinking about selling it let me know
 
Harold Mulder - Thanks for the very helpful info and links. I see in another post that you are also looking for index plates. Hope you find some.

The drawbar is holding the center in place. The drawbar may be homemade or from something else, but the center itself appears to be the correct factory unit .
There is a very shallow step in the bore of the spindle that the front end of the draw bar is bearing against. It works OK, but I'm thinking it would be better to make a spacer to fit in there where those yellow marks are.

excello
 
For what it's worth, the later VN dividing heads have a very different, and unusual, design. Like many dividing heads, they allow the work axis to be rotated (distinct from rotating the work being divided) but the plane of axis rotation is horizontal on the VN heads while practically every other brand has the plane vertical.

You can see the beginnings of that in the swivel base on your old head.
 
Hello again.

From reading the info supplied by Harold M., it would appear these dividing heads typically had Timken bearing spindles. However mine has a plain bearing spindle. It is a long taper spindle closely fitted to the tapered bore so that the thrust shoulder just comes up to the front face of the housing. Nicely done. Picture attached.

I'm guessing this may be an older unit ?

excello
 

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Your dividing head was probably made in the 20 years between 1937 and 1956. Looking at a 1954 accessory catalog, I don't see a reference to Timken bearings for the 7.5" dividing head. The larger 10" heads (which have quite different designs) probably had roller or ball bearings rather than plain bearings.

There's certainly nothing wrong with plain bearings, given proper lubrication.
 
For what it's worth, the later VN dividing heads have a very different, and unusual, design. Like many dividing heads, they allow the work axis to be rotated (distinct from rotating the work being divided) but the plane of axis rotation is horizontal on the VN heads while practically every other brand has the plane vertical.
Having just reviewed a VN catalog from the 1950's, I see they offered 10" dividing heads in both the standard (vertical tilt) and unusual (horizontal yaw) designs.
 
Mr_Bill, I suspect you are going to have to replace your existing worm wheel and missing worm with a new matching set of worm and worm wheel. In the US, Boston Gear is one of the very few suppliers of standard catalog worms and worm wheels. (Browning does worm reducers, but not open gearing.) Their catalog makes it clear they only stock right-handed worms and worm wheels. The worm in your photo is left-handed.

Getting a new gear set will require some machining on both worm and worm wheel to fit your dividing head. It should be pretty basic lathe work. Despite the inconvenience and delay, I assure you that buying a new worm/wheel set is going to be less expensive than getting a custom worm made, or the delay in trying to locate a spare (that might not even exist!) for an accessory that was made 50 years ago in very limited numbers.

You know, or should know, that your worm wheel has 40 teeth. That's where the 40:1 ratio between index sector turns and spindle turns comes from. The next thing is to determine the centerline distance between the index axis and the worm wheel axis. You need a worm/wheel pair that matches that centerline distance accurately. Any such pair with a 40 tooth wheel will work. But the centerline distance has to be very, very close (unless you like chewing up expensive gear sets). Better hope that Van Norman used standard catalog gear choices, rather than a custom gear set. One of the complications here that a worm/wheel pair with a given ratio and centerline distance does not have a given worm or wheel diameter. The gear designer can use a fat worm or a skinny worm, with compensating changes to the wheel diameter. If the designer sticks with a standard pitch, that starts narrowing things down quickly, but even with a given pitch, the designer can still make choices about tooth addendum and dedendum that will affect diameters.

Have a look at the Boston gear catalog, starting at page 85. On page 98, you will see a table of available centerline distances. Limit your attention to the entries with a 40 ratio. See if any of the matches correspond to the centerline distance on your dividing head. If you don't find a match, resign yourself to a very expensive repair, or a probably futile search.

If you do find a match, you might get incredibly lucky and find that you only need the worm (LH, of course, which would be a special order) instead of the worm/wheel pair. It's not just the pitch diameter that must match the missing worm on your dividing head. It's also worm thread pitch (which is grossly obvious) and the pressure angle (which is not nearly as obvious from a visual inspection) and maybe a few other subtle features. I don't know if that's plausible (due to ancient standardization) or astronomically unlikely. Maybe Zahnrad Kopf or someone who does gears all day long will know. If I were in your shoes, I would consider myself incredibly lucky to find a new worm/wheel set with the right centerline distance, and just buy it without pushing my luck any further.
 
Thanks for all the info and details. Today I called Boston gear and chatted with them. We have determined that the gear is as you stated Left hand. The pitch is probably a 15 pitch. They recommended that I buy the 16 pitch right hand worm gear and the associated worm. This would be a $75-$100 expenditure and I only paid $130 for what I have. I would then still have to figure out a shaft, handle and mounting system as all of that is missing. Still a lot of work but doable.

My original thought was to find a gear or make one. Then Manufacture the other items as needed. The reason I was asking for the Worm diameter is so I could possibly make something that was like the original. After studying things I have figured out the the OD of the worm to be close to 1.25" so today I made several test worms and ended up with a Delrin part that is functional. So now I can work on the shaft and mounting and other items. If the missing parts show up somewhere of course I would be interested. I don't need or want a museum piece just something that is functional and works. I already have 4 different divider plates from my rotary table that I will be able to use with my new custom mount.

I figure give it a try and if it doesn't work I can buy the gears from Boston as recommended. Again thanks for the info and help. I am somewhat new in the mill area but have a bit of experience in the lathe area.

Bill In Cincy
 

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Have you made any more progress Mr Bill? I bought 1 recently. Had to make a spring clip for the sector arms. Opted for a 3 jaw chuck rather than try to collect any of the VN 'C' type parts. I've found some of the indexing plates - but don't want to pay such high prices. I do have the (A)18,24,28,30,34,37 plate. The other plates are(B)38,39,41,42,43,46 & (C) 47,49,54,58,62,66. These plates do not interchange with the VN #10 versions. Since the hole circles on the #10 have different counts than the ones listed above, it should be easy to buy with confidence if cost is no object.
 

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For reference, here are my VN #10 vertical swing & B&S #2 for comparison.
 

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Van Norm Parts 7-1/2" Dividing Head and Index Plate Size Question

Hi all, new owner of a 7-1/2. Mine has two nuts under the pointer arm on top of a Hayward spring. The outermost has a set screw and came right off. The inner is threaded, but no set screw, spanner hole or slot, and is very soft, I dinged it with a brass hammer :angry:

  1. Anyone else run into a set up like this? I'm pondering using the mill the drill a spanner hole.

  • Along with cleaning and lubricating, I wanted the diameter of the single indexing plate. I've seen them described as (A), (B), (C). Anyone happen to know if this is what Van Norm called them?

TIA

Ron
 
A few pics of the 7 1/2.

Adjusting the worm preload.

20181021 04.jpg

All together. In order are indexing plate, sector arms, spring clip, preload nut, indexing arm assembly & retainer nut.

20181021 05.jpg

I see no reason to modify this setup.

Now for the indexing plates: The only markings they will have are the number of holes in each circle. Maybe these pics will help you. Note the outside diameter & mount hole diameter as these are unique to only the Van Norman 7 1/2.

20190309 VN IP.jpg

A few plates I found to fit mine (random ebay listings with no indication that they are for this divider.

20190201 09.jpg

Bought those in Feb & sold spares in March. I simply set up a search for dividing head plates & focused daily on the unusual outside diameter of 4 7/8. Some are proud of what they have - but occasionally a good deal can be found!

Show pics of the nuts you were describing please.
 








 
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