info needed for 11” logan 912 lathe spindle

[eweissman]

I have a logan 912 lathe which appears to be missing a few parts on the spindle assembly. namely, two belleville washers that i believe were used for bearing preload on the rear spindle bearings? the rear bearings have some play in them. logan
has the belleville washers, but they are about $54 a piece. the parts diagram for my lathe seems to show only two washers, but the actual orientation of them is kinda unnclear from the drawing. can anyone on here give me some insight into how to install them properly? does anyone know the dimensions of the belleville washers? seems like i could source cheaper ones from mcmaster but am unsure of the actual dimensions. the part number on the diagram of the part in question is LA-1016. drawing makes it look like they go on the front side of rear spindle bearing? but if anyone has photos of how these and spacers are arranged on their spindle on an 11” 912 lathe, would be much appreciated.

[Ringo]

I have the 9" Logan with the similar crappy picture. I fought the washers orientation for quite awhile. After going through Logan I finally got it sorted out, and made a sketch for myself.
If Logan uses the same thinking in the 11" as the 9", then look at the bellevilles as a 'bowl'
the bottoms of the bowls touch, and the open sides of bowls face away
And the bellevilles fit into the same cavity as the rear bearing, so the OD is just a bit smaller then the bearing

[eweissman]

is there any chance you could share the drawing? i found a set of belleville washers on mcmaster carr that seem to fit the original dimensions very closely and they were $15 for 4 of them. logan wanted $230 for four belleville washers. i appreciate that he has to run a business, and want to pay for their knowledge, but that is quite steep. they do have some other parts i need, which were actually quite reasonable. not sure why the belleville washers were so pricey. thanks.

[J Tiers]

Those belleville washers may be a particular "force" that is not a stock type. The thickness of the material the washer is made of will set the spring force. McMaster has preload washers, but they are all pretty low force. Usually the preload amount is more than the 30 lb or so that the various McMaster parts seem to have.

Generally, the preload is a percentage of the maximum force the bearings will take. Preloading a bearing is generally to reduce deflection from axial and radial forces applied. You have to apply a reasonable percentage of the design load before the bearings "seat" to a degree that reduces the deflection to the point that it becomes linear with applied force. At low preloads, the deflection is often considerably higher for a given applied force.

I preloaded my 10" by 100 lb. It may not have been enough, the bearings can take 8000lb load, which obviously will never be seen by the little 10".

[old mart]

Bellville washers are normally stacked concave to concave, or convex to convex. Sitting them together like spoons would increase the spring rate.

[Erich]

Two bellevilles spooned together, twice the force at same deflection as one belleville.
Two bellevilles, small to small or big to big, Same force at twice the deflection as one belleville. This series and paralleling can be extended to as many washers as you care.

[J Tiers]

Two bellevilles spooned together, twice the force at same deflection as one belleville.
Two bellevilles, small to small or big to big, Same force at twice the deflection as one belleville. This series and paralleling can be extended to as many washers as you care.

Of course.

However, the stacking takes up space. The design may allow for only a certain space, in which case the type of belleville does matter, so that the required preloading can be accomplished in the available space.