Spindle bearings

[RKR]

I have take out my old spindle bearings from my vmc15xt but forgot to look in which directions the bearings were installed (angular contact bearings)
Has somebody a drawing or can somebody tell me how the bearings shouls be installed?

Thanks Kees

[Neal]

The marks on the inner race face each other.

[gotis]

how many Bearings?

[RKR]

What kind of marks shouls i look for? i see an X on the bearings. Is that the mark that you mean Neal?
The old bearings were NSK 7210C and NSK 7012C. What kind of bearings do you recommend. I prefer to use SKF bearings . Do you have a number for the SKF bearings? Or another international brand like FAG or NSK or INA.
Fafnir bearings are not available in europe.
How much should the preload be for the complete spindle package?

Thanks. Kees from Holland

[Machtool]

How much should the preload be for the complete spindle package?

The preload procedure is in one of the Fadal Manuals. You basically set a dial test indicator, and bring down the against a load cell until you have 1000 pounds (454 kilograms) force on the spindle nose, then measure the deflection, when you release it. Those specs are on page 49 of 68 here.

http://www.compumachine.com/Support/..._and_Motor.pdf

Those dimensions are in Imperial. Which spindle do you have, 7500 rpm? If so you keep tightening that nut until you have 0.0013” – 0.0015” (33um – 38um) deflection.

Those numbers you gave, NSK 7210C and NSK 7012C. There should be some more on them. That is just the size and the contact angle. The preload is missing. I’ve done a lot of these, they are normally light preload, but I have seen medium come out of the 7500 rpm ones. Its some what arbitrary, as the way the preload is set by the top nut.

If yours is the spindle I’m thinking off. Just below the pulley, there is a lock nut. That sits just above a spacer with a conical style washer onto of it. Its that nut you adjust to stiffen the spindle. The upper pair of bearings do not go against a shoulder on the spindle. The outer rings are held against a shoulder in the housing, but the inners are free to float down the 50mm journal that they are sitting on. You can over tighten that nut, as there’s nothing stopping the upper two bearings being pushed downwards – no shoulders. It’s a very fundamental design.

The “C” in those numbers you gave is a 15 degree contact angle. In SKF 15 degrees is the suffix “CD” so the equivalents in SKF would be.
7210 CD P4A DT A & 7012 CD P4A DT A. Being tandem pairs, 15 degree, light preload. The preload is the last figure in the designation A for light, B for medium, C for Heavy etc.

In your part of the world, FAG would be an option, the numbers are very similar.
FAG B7210 C .T.P4S.DUL & B7012 C.T.P4S DUL. Those are Pairs. FAG also do a universal single bearing second last Suffix “U”. You would need 4 of those. Or just the pair each of the “DU’ designation.

If you can talk to a decent FAG bearing rep. They have other options. I’ve upgraded some of the spindles with their HSS series that are sealed versions. HSS7012C & HSS 7210C. The seals really extend the life.

On all the ones I’ve seen, the arrangement is similar to “QBC -Tandem to Tandem” arrangement. Both of the 7012’s on the bottom end (tool taper) face down in tandem, They have a spacer between them.

The other pair of 7010’s on the pulley end face up. The open face, upwards.

http://www.skf.com/portal/skf/home/p...&newlink=9_4_9

If you click on third image / fig down. ” two bearing pairs in a back-to-back arrangement, series designation FBSA .. QBC (BSQU .. TDT)” You should see that arrangement, but you will have the spacer with the 60mm bore between the first & second bearings from the left, and the third & forth bearings as a pair, are separated by the distance between the shoulders in the spindle housing.

I’d use Kluber Isoflex NBU 15. The NSK catalog tells me 2.6 ml charge for a 15 percent fill for each bearing of those sizes - 7012 & 7210.

Regards Phil.

[dango]

I have photo of fadal spindle drawing so if you wants
I can email it

[RKR]

Hello Machtool, Neal and Dango for all your input.

I have ordered Fag closed bearings and hope to get them delivered next week
Dango it would help me if you can sent me the spindle drawings.
Can you mail it to; keesenmaris@gmail.com

When my vmc15xt is up and running i will let you know.

Thanks Kees

[Neal]

RKR--
Be careful as there have been several different designs of spindle used over the years. Make sure any drawing you get is for your spindle.

Neal

[dango]

dear Neal
from what I know nothing was change from the time I know 1989
till the last machine that I changed spindle it was i think from 2006
the same bearings the same way

[Neal]

There was definately different designed spindles in the time frame that you state. Around 1993 there was a major design change and there were some after that.

Neal

[dango]

I will tell you about the changes
First it was low pressure oil in the spindle
Then 91 or 93 does not remember exactly they change it to grease bearing then till 98
they had air first to the bottom then to the top at this time they change the upper and the lower plate then in 98 they had also the oily spindle with vacuum this till the time that I
know

[Neal]

Dango--
You do have part of the picture, however I have made my point. Buyer beware!!!

Neal