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Cincinnati Dividing Head

Rick_B

Stainless
Joined
Sep 16, 2011
Location
Winston Salem, NC
This is my third attempt to get this posted - the first two never showed up? I either screwing something up or am violating a rule?

In any event I purchased a Cincinnati universal dividing head and am looking for some guidance on disassembly. I'm at the point of trying to get the rotating head out of the trunnion. There is a bolt that projects through the rotating head out through the trunnion. It seems the only way that bolt will come out is from the inside which seems to require that the spindle come out first.

I'm wondering if anyone has experience with disassembling one of these dividing heads? If ths post sticks I'll post some pictures

Thanks
Rick
 
Thanks Bill - now that I think the post is sticking - the only markings on the dividing head was a patent number - 432621. This was issued to Frederick Holtz and Cincinnati milling machines. I did find the patent drawings but so far they have not been too helpful. Here's some pictures - the first 4 are as received and the 5th shows the bolt that I am struggling with at this point.











I think to get the rotating head out of the trunnion that bolt needs to come out (from the inside) which means, I think, that the spindle needs to come out?

Thanks
Rick
 
I can't help with the disassembly but I wouldn't be surprised to hear someone say your DH is from the last part of the 19th century. Is it a standard 40:1 DH?
 
I'm not sure about the ration yet - I have some older Cincinnati documentation that indicates a 40-1 but I'm not sure if it is the same vintage as the head I have.

Rick
 
Just a WAG here, but I'd start by removing the index plate and see if there isn't a way to pull the hollow lock bolt out towards the operator's position.
You may have to remove the helical milling drive shaft and then remove all the indexing drive train. You should be able to remove the center body from the trunnions with the spindle still in place.
:confused:
 
Go to you tube and look for Keith Rucker, he did a Brown & Sharp. The procedure might be similar enough to give some insight on yours.
 
Yes the spindle must come out.. The bolt will come out other side..

Plain bearings only, nothing going to fly out at you..

Looks like a fairly early DH...
 
The patent (432621) drawings show how this is assembled. Yours is probably pretty much like the drawings internally. It looks like the "worm-shaft", J, in the drawings, must be removed before the spindle can be removed. That's probably what the big hole in the side of the housing is for - rotate the spindle assembly around until the "worm-shaft" assembly is visible through the hole. The patent description tells the function of all the parts, and you should be able to disassemble it by using the patent. Lots of parts in there!

Irby
 
For folks who don't want to look up the patent, here are the drawings of the dividing head.


432621-1.jpg


432621-2.jpg


432621-3.jpg



And since this dividing head is designed to be used with a gear train connected to the mill table feed screw (as shown in the first drawing), the indexing plate is rotated by the gear train. If you want to use it as a simple dividing head, the indexing plate has to be fixed to the dividing head itself so it can't rotate. The arrows in the picture below point to a slot in the edge of the plate that can be engaged with a sliding block on the side to fix the plate from rotating.

plate%20locking.jpg



Irby
 

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irby - thanks so much for posting those patent pictures. I had to leave town for business early this morning so I didn't have a chance to do that. I've got everything off the index plate side and have the clamping bolts removed. Unfortunately I will not be able to get back to this for a few days - but keep the ideas coming.
Thanks
Rick
 
irby - thanks so much for posting those patent pictures. I had to leave town for business early this morning so I didn't have a chance to do that. I've got everything off the index plate side and have the clamping bolts removed. Unfortunately I will not be able to get back to this for a few days - but keep the ideas coming.
Thanks
Rick

Hey Rick, I read over the entire the patent on your dividing head. I'm interested in the workings of old dividing heads because I have one myself (a Garvin universal) that I will clean up and restore some day. Turns out that removing the worm-shaft "J" is very easy. Here is what the patent says about it (you have to refer to the patent drawings for all the part nomenclature):

"For rapid indexing or such work as milling reamers, taps, nuts, etc., and cutting spur wheels with less than forty teeth the worm-shaft is disengaged from the worm-wheel and a hand index-wheel U, Fig. 4, is employed. To remove the worm-shaft, it is only necessary to swing the spindle with its work-holding end down to the vertical position shown by the solid lines, Fig. 9, when the worm-shaft will register exactly with an opening c’ in the plate c. By now rotating the spindle to the left the worm-shaft will be ejected through the opening c', and can be laid aside until again wanted. It is inserted in a similar manner by rotating the spindle to the right. As the spindle is never used for work when set vertically in this position - that is, with its working end down - there is no danger of the accidental displacement of the worm-shaft, as it is always at other times held locked in place by the plate c."

The description above says Fig 9, but it's really Fig 10. And the opening "c’" is the big hole in the side plate.

The worm-shaft, collar "o", and the split nut "p" screwed onto the collar, all come out as a unit, shown in the picture below. Once out, the spindle can be removed by unscrewing the hollow plug "n" from the body "G", then pushing the spindle out. It appears in Fig 4 that the teeth of the worm wheel "I" are cut so that they curve around the teeth of the worm-shaft "J", preventing the spindle from being removed unless the worm-shaft is out.

The worm-shaft "J" to collar "o" fit is adjusted with the split nut "r" so that the worm-shaft turns in the collar but has no end play. Then the nut "r" is locked in position by screw "s". If this works like other split nut locking schemes I've worked on, tightening the locking screw changes the settings a little, so you have to iterate on the adjustments some.

The worm-shaft itself rotates on one end in a plug "t’" which is captured by the side plate "b" of the base. The other end rotates in the collar "o" which fits into a counterbore in the body "G" and is captured by the side plate "c". The fit of the worm-shaft "J" to the spindle worm-wheel "I" is set by adjusting the split nut "p" so that the spindle can rotate but there is a minimum of slop between the worm-shaft and the worm-wheel. The lateral position of the worm-shaft, and therefore the clearance between the worm-shaft and the worm-wheel, is set by the position of the split nut "p" on the collar "o" - how far the nut is screwed or unscrewed onto the collar. That adjustment is made when the collar "o" and it's locking screw "q" are visible in the side plate hole "c’". To keep the collar "o" in it's correct position in the body during this adjustment, you probably have to rotate the body "G" slightly so the collar is captured by the side plate and you still have access to adjust and lock the split nut.

One end of the worm-shaft fits into a gear "t" that meshes with a gear "u" on the indexing system, and serves to rotate the worm-shaft. The gear "t" is captured in the body "G" by the plug "t’" which is also the end bearing for the worm-shaft. Apparently the plug "t’" is only accessible when the body "G" is out of the side plates. It looks like there is a key or something between the far end of the worm-shaft and the gear. When putting the worm-shaft assembly back into the body, I guess you would have to rotate the gear by turning the indexing system so that the key lines up and engages.

Worm-shaft and collar when removed:
worm-shaft.jpg


Hopefully I'm close to what this dividing head is really like in what I infer from the patent drawings and description. Sounds like fun working on it! :)
Irby
 
Brief update - following the above excellent comments I think I understand what is supposed to happen - unfortunately somewhere along the line the spindle locked up - it was working fine until I messed with it. I had a lot of parts removed - so I decided to put it all back together and start over - hoping that would free up the spindle. I'm about 90 percent through that but I am getting ready to leave town again for two weeks so this will have to wait.

Rick
 
Hey Rick,

If by "locked up" you mean you cannot turn the spindle itself by hand, and if by "it was working fine until I messed with it", you mean you could turn the spindle before by using the indexing mechanism, then what you are seeing is perfectly normal. As long as the "worm-shaft" cannot move - is constrained by the side of the base from moving out of the dividing head, then it is nearly impossible to turn the spindle by hand. That's why they use a worm system - the spindle has a very high resistance to back-driving the "worm-shaft" and therefore the indexing mechanism. If you swing the spindle body around so the "worm-shaft" lines up with the hole in the side, then you should be able to turn the spindle in one direction - the direction that tries to push the "worm-shaft" out of the hole.

But that will probably have to wait for 2 weeks, right?

Irby
 
In case there's a need for advice on a working DH, I have the identical DH in my basement, for which I've been making the missing change gears (but in a smaller size due to various limitations). I can try out moves that you may be reluctant to attempt due to the partial disassembly. I can also cut gears up to about six inched diameter.

Look here: http://www.georgesbasement.com/ToolProjectsByGL/CincinnatiMMIndexingHead.htm
 
Thanks guys - I've been away from this project for awhile. I am in the middle of relocating so the entire shop has been disassembled and packed up. I will hopefully get back to this in the near future and will certainly update the thread.
Rick
 








 
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