Cincinnati? Dividing Head

[Canadium]

That looks almost identical to the problem I had with my dividing head! In my case there were plenty of hammer marks on the outside of the cradle which I surmised told the whole story of how this came to be. I concluded forcing it back together would probably cause some thing to break and any way I wanted the thing to rotate in the cradle like its supposed to.. So I carefully removed metal until I got the desired result.

 

[Susquatch]

I recalled the same problem discussed on another thread. I came back to post but see that @Canadium has already owned it. Here is a link to his thread.

Thread 'Dividing head restoration' https://canadianhobbymetalworkers.com/threads/dividing-head-restoration.5198/

What I have learned from all this is that I will NEVER take mine apart!

I confess that it is REALLY odd that it comes apart but won't go back together.

 

[Canadium]

I recalled the same problem discussed on another thread. I came back to post but see that @Canadium has already owned it. Here is a link to his thread.

Thread 'Dividing head restoration' https://canadianhobbymetalworkers.com/threads/dividing-head-restoration.5198/

What I have learned from all this is that I will NEVER take mine apart!

I confess that it is REALLY odd that it comes apart but won't go back together.

I would expect that a relatively new DH treated properly would rotate, come apart, and go back together again as expected. A second hand DH on the other hand coming from heavy useage in industry probably got banged around a lot and may very likely have the spring effect problem.

 

[Susquatch]

I would expect that a relatively new DH treated properly would rotate, come apart, and go back together again as expected. A second hand DH on the other hand coming from heavy useage in industry probably got banged around a lot and may very likely have the spring effect problem.

I don't disagree. I have no trouble picturing that too.

But..... How does it come apart? It's not like there is some magnetic or compressive force that can be turned on and off.

 

[Canadium]

I don't disagree. I have no trouble picturing that too.

But..... How does it come apart? It's not like there is some magnetic or compressive force that can be turned on and off.

In my case it only came apart with a h*ll of a lot of heavy duty prying!

 

[thestelster]

I took the DH barrel off the base using the mini-crane while everything was on the milling machine table.

I'll take some more pictures tomorrow.

 

[RobinHood]

I wonder if the saddles “spring” because the base is machined / ground AFTER the rotating member is inserted and the DH is assembled at the factory? Finishing the base in a second op could release stresses in the CI after the saddle is machined.

This order of operation / assembly could be used to keep relevant axis aligned (parallel or at 90* as required) to each other so the final product is within tolerance.

Any “spring” would be distributed over a large area of the circumference of the rotating member and might thus not impede rotation / pivoting during normal operation. It only rears its ugly head once the two parts are separated and re-assembly is attempted.

Just some out-of-the-box thoughts on how come we have two separate DHs with the same “disease”.

Granted, it appears that both had lead a hard life prior to the current owners picking them up…

 

[Tom O]

Could you spread it with a screw Jack between the two sides maybe a little heat to relax it?

 

[Canadium]

I wonder if the saddles “spring” because the base is machined / ground AFTER the rotating member is inserted and the DH is assembled at the factory? Finishing the base in a second op could release stresses in the CI after the saddle is machined.

This order of operation / assembly could be used to keep relevant axis aligned (parallel or at 90* as required) to each other so the final product is within tolerance.

Any “spring” would be distributed over a large area of the circumference of the rotating member and might thus not impede rotation / pivoting during normal operation. It only rears its ugly head once the two parts are separated and re-assembly is attempted.

Just some out-of-the-box thoughts on how come we have two separate DHs with the same “disease”.

Granted, it appears that both had lead a hard life prior to the current owners picking them up…

I can't imagine that the DHs were somehow manufactured to have this spring in them since the spring in mine made it so tight it was impossible to rotate. I was wishing I had access to a properly functioning DH so that I could gauge exactly how one of these is supposed to work. Just how much resistance to rotation should there be? I would guess that it should be possible to turn it manually without the use of a 20 pound sledge hammer!

 

[Canadium]

Could you spread it with a screw Jack between the two sides maybe a little heat to relax it?

I had tried this sort of thing initially and found that while I was able to stretch it slightly there was a lot of resistance after 3 or 4 thou. It just felt like it would break after that and when the jack was removed it just relaxed back to its original position. Remember cast iron is not very malleable IIRC.

 

[Bandit]

Most likely a hair brained thought, has anyone checked the base for flatness before and after disassembly? This would maybe prove/disprove machineing after manufacturing. Don't know how firm" thestelster" has the disassembled base fastened to the table, however if "things ain't flat", base or table.
I "suppose" in a high use environment, a mill table may have a few thou. wear across it, and a head repetitly bolted down could stress its base into a "c"shape. 12 thou, I don't know. Does the 5.378 measurement match up with the body that goes into it? Or?
One thing that could be tried, anyone warmed the base up to maybe 150-200 degrees f ? Put the body into the freezer. Yes, I understand, the body still has to move after assembly, but are these things put together with some compression or not? Any one got a nice new one fresh out of the box? All for the cause! Dam, I don't even have one.

 

[thestelster]

Most likely a hair brained thought, has anyone checked the base for flatness before and after disassembly? This would maybe prove/disprove machineing after manufacturing. Don't know how firm" thestelster" has the disassembled base fastened to the table, however if "things ain't flat", base or table.
I "suppose" in a high use environment, a mill table may have a few thou. wear across it, and a head repetitly bolted down could stress its base into a "c"shape. 12 thou, I don't know. Does the 5.378 measurement match up with the body that goes into it? Or?
One thing that could be tried, anyone warmed the base up to maybe 150-200 degrees f ? Put the body into the freezer. Yes, I understand, the body still has to move after assembly, but are these things put together with some compression or not? Any one got a nice new one fresh out of the box? All for the cause! Dam, I don't even have one.

Hi @Bandit , I thought maybe clamping it down was causing some flex, so I loosened the hold downs completely, but no difference in measurements.

I measured the DH barrel, and it measures 5.375", so good at the bottom, but too tight at the top.

 

[thestelster]

The right strap has been welded up and trued up, and it does rotate around the barrel easily, but not loosely. And, the left rear bolt hole seems to have been repaired with a threaded insert.

But there doesn't appear to be any major dings on the base unit or the DH barrel.

 

[Susquatch]

Wish we lived closer. I'd love to lay an eyeball on that with you.

 

[RobinHood]

I don’t have any experience with the Cincinnati style DH - the main body is held differently in it’s base compare to my Universal DHs design.
After repairing the locking mechanism on mine, the spindle can be tilted effortlessly by hand with no detectable play in any direction. Locking it in place is now very positive and no longer requires huge torques on the locks.

Here is the link to the repair (post #176). In the pictures you can see the different design.

Daily Shop Improvement

The shaft bearing block design on my lathe was bugging me so I picked up some bronze bushings from PA today. The feed rod and the switch shaft are both 3/4" OD and the lead screw end is 20mm so I got bushings that are 3/4 ID and 7/8" OD and 1-3/8" long. The OD of the bushing measured .880" so...

canadianhobbymetalworkers.com

 

[thestelster]

Well, still determining how to proceed with the fitting of the DH barrel to it's cradle.

So in the meantime I need to make a gizmo which facilitates direct indexing. Thank goodness that Mr. Pete on Youtube had an episode on his Cincinnati DH so that I could get an idea of what it looks like.

Now I have to get a couple gear cutters to make the rack and pinion.

 

[RobinHood]

The direct indexing pin will be a helpful addition to your DH.