hardinge TM mill vertical head question

David, I've taken my spindle out and disassembled it completely without any problem. Removing and installing the bearings is straight forward. But since my bearings were ok, I cannot comment on how hard new bearings are to fit for proper clearance and accuracy. Having worked with other Hardinge spindles, the bearings are most likely ABEC-7 and are provided from the supplier as a matched set. Not inexpensive, to be sure.

Best I can tell, the lower end of the spindle has a matched pair of angular contact bearings. At the top end is a single angular contact bearing that "floats" in the housing with a spring washer providing a constant axial force.

As I recall, the spindle and bearings are removed from the bottom as an assembly after removing the pulley from the top. The only tricky part was removing the spanner nut that held on the pulley but that was solved with a little ingenuity.

Regards, Jim S.

A small point but angular contact pairs have to be just that: pairs. In most cases hardinge does indeed use a high precision angular contact pair (set up with the correct preload from the factory) close to the working end of their spindles.

The bearing at the other end of the spindle is typically a radial bearing and takes no thrust. Indeed in those machines with the three bearing setup (and here I think gunner has informed me that the HLVHs use two) the third bearing has its outer race free to float in an axial direction in the casting bore.

I have however never seen a TM vertical head, much less had one apart - so the preceeding is pure conjecture on my part.

Jim

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The bearing at the other end of the spindle is typically a radial bearing and takes no thrust ...

Hardinge isn't consistent on the third bearing.

It is angular contact on my TL and presumably others. But, it is radial on others (probably most).

Correct, as mentioned the HLVH (according to gunner) uses only two spindle bearings.

The milling machine has a single outboard bearing which I believe is radial, in the main spindle. The DSM that I have has three, and the BB47 I used to have used three also, and I am sure that one was radial because I had the spindle all apart. There was no axial constraint for the outer race at all, it fits into a purely cylindrical bore.

I think they were fiddling around for quite some time, trying to find the best configuration.

Jim

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Yup. And I think it has to do with the quality of the bearings that were available at the time, and the price. I just rebearinged a DV59 Tuesday, and will be helping an RCM lurker do a very elderly HC chucker this evening on my way home. The angular contact bearing (pair) of both machines cost about $300. I wonder what the same grade would have cost in the 50s (in ratio to today)

I believe both sets of bearings are grade 9s IRRC

Gunner

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