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Unusual spindle arrangement - Deckel S1 grinder

TNB

Stainless
Joined
Aug 18, 2002
Location
France
I'm in the process of adapting a Deckel S1 spindle to another T&C grinder and examining the parts list, I stumbled across this view of the cartridge :

IMG_1688.jpg

What catched my eye is the belleville washers at the rear end.
In my limited experience with that type of cartridge, springs are usually used to preload the spindle bearings and take care of thermal expansion.
Here, the washers obviously tend to spread the cones the opposite way, in the direction that would loosen the bearings.

Since the spindle sat on a shelf for years (may be decades) before I got it, I thought about taking it apart to regrease it, but that arrangement is totally new to me.
The nut at the rear end is as simplistic as can be, without any locking system of any sort.
Can't figure out how one can be sure it will stay put once the preload is set... How preload is set is the next question that comes to mind.:confused:

Thoughts ?
 
I know there are several designs (now 3) for the S1 spindle. The one you have in stock does not have to be like the one in the drawing. That one is a bit strange design indeed but would be needed when you are using a stone backwards.I think adjustment is just a matter of Fingerspitzengefuehl.
 
What caught my eye is the belleville washers at the rear end. The washers obviously tend to spread the cones the opposite way, in the direction that would loosen the bearings.

That's weird. I don't see how this spindle could possibly work. But probably I am just being stupid. Can someone here explain it?
 
It seems like Deckel was counting on the Belville washers being stiff enough to make the locknut lock. That bearing arrangement can handle (and needs) a bit of preload, so I imagine one would apply a tenths indicator and creep up the nut until clearance was zero, and then put on another fraction of a turn. Without manufacturers instructions we can't know for sure.

I agree that design seems to be lousy in the thermal expansion department. Maybe the clearance needs to be set when the spindle is fully warmed up, and may be loose when cold.
 
The drawing could well be in error, as for the nut I believe that the nut would be tightened by bottoming on the spindle, the bellville washer taking up the preload.
I had an SG that had a spring pack arrangement, run the nut tight, spring pack provided preload.
 
Tom

I have hard time imagining a design engineer going through the task of drawing the whole shebang without realizing something's wrong with the bearings arrangement... Then no one at the office telling him he should take some vacation ! ;)

So if we consider the drawing is good (read : on par with the spindle I have), take a second look at it and you'll realize that the thing you bottom when you tighten the nut is not some kind of shoulder on the spindle, but the ball bearings themselves !
And then, the belleville washers set would tend to spread the cones (read : induce some play instead of prealoading the assembly).

That is why it is a very unusual design to me.

Kees

Could you please tell us more about the two other designs you are aware of ?
I can't imagine a T&C grinder that would be specifically dedicated to using the wheels backward...:confused:
 
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The inner race has a sliding or press fit on the spindle, it is not threaded on. The only thread is in the nut. The purpose of the belleville washers might be to avoid any looseness if the races wear or the spindle heats up, creating bearing play. Notice that the drawing states "Reparatur nur im Werk" meaning no user repairs!
Ole
 
take a second look at it and you'll realize that the thing you bottom when you tighten the nut is not some kind of shoulder on the spindle, but the ball bearing themselves!

Yes, you are right. So the bellville washers are not there to take up "thermal expansion" movement? They are only there to provide some resistance to the nut when turned? How is thermal expansion managed?
 
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Ole

Again, the direction the Belleville washers act in that design would tend to *add* or create some play in the assembly, rather than taking it up !

Following your guess, one would think the inner race is mainly held by a press fit on the spindle.
Now let's say the race heats up and expand, becoming loose on the spindle. The washers will tend to push it away from the outer race, increasing play.

Doesn't make sense. :skep:
 
I agree that there must be a mistake in the drawings. However, I suspect that the mistake is the orientation of the bearings. I agree that having the bearings mounted the other way doesn't make too much sense, since you would now need to block the outer races fro moving outward.
But, as a friend of my father that worked for ABB used to sarcastically comment during work meeting with his Swiss and German colleagues: "Why simplifying things, when this marvel of complication works?"

Paolo
 








 
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