Need Help!- Spindle bearing preload

[chevyguylt1]

Guys,

The shop bought a fadal 6030 and i am trying to replace the spindle bearings....... how do you set the PRELOAD on the bearings? I have read a few people talking about setting them to 1500 PSI., but how would i acomplish that?

Any info & help would be greatly appreciated!!!

Chris

[carbidecraters]

1) Place a Pressure Gage (SVT-0066) on the table and align it with the Spindle
nose.
2) Set an indicator on the Head and touch the indicator tip on the nose of the
Spindle.
3) Jog the head (Z axis) down until the pressure gage reads 1000 pounds.
4) Zero the Indicator.
5) Jog the head (Z axis) up until it is no longer in contact with the pressure
gage.
6) Depress the “Tool In Out” Button on the keyboard.
7) Release Button.
8) Read the value on the indicator.
If adjustment is necessary on a adjustable spindle then turn the spindle
preload adjustment nut clockwise to tighten and counter clockwise to loosen.
Listed below are the "Fadal factory recommended specifications" for the
various spindles.
RPM Rating Preload setting: (Deflection at 1,000 psi. Lube Method
15,000 / 10,000. 0014-.0017 (Can Not be adjusted) Air/Oil
7,500 0013-.0015 (Adjustable preload) Grease Pac
10,000 0013-.0015 (Adjustable preload) Grease Pac
15,000 0017-.0019 (Adjustable preload) Grease Pac

[HuFlungDung]

In general, the actual preload on the balls is always very light. Where a huge number might come from is the tightening torque on a nut which is clamping inner race + spacer + inner race into a stack. This brings the races into position where they apply a light pressure to the balls. No matter how much more you tighten such a locknut, the preload on the balls will not change because the spacers are what create the preload, which is basically ground into the bearing at the factory.

In a back to back or face to face paired bearing assembly, no spacers are used, of course, and the factory preload occurs when the races meet. But if the bearings must be seperated by the spindle design, then typically, both spacers would be exactly the same length, between the inner and outer races. It is possible to monkey around with the preload under these circumstances, by altering the length of one spacer relative to the other one.

So, you may not know exactly what you have. When I rebuilt my Haas spindle, I made up the bearing and spacer stack and applied pressure to the stack with a plate on top, via use of a hydraulic press, and moderate pressure. From this, I could get a feel for the length of the outermost spacer relative to the inner one (which is not accessible in the stack). Now I went totally on a hunch and a bit of experience , but I lapped only one end of the outer spacer length carefully (with a lot of careful checking of the length to make sure I was keeping the ends parallel) until it took firm finger pressure to slide the outer spacer back and forth in the stack. That, I concluded, was the preload I wanted. It worked out well, too.

Haas retains their bearings with shrink fit spacers, not nuts. So the actual preload on the stack is unknown. All I did was heat the spacer, drop it on the spindle and let it cool. Then, because it would be a little bit loose lengthwise after cooling off, I bumped it on tight against the stack with the press. One little pop sound occurred when I did this, indicating to me that the spacer had moved just a wee bit as it settled into final position.

[scadvice]

Originally Posted by carbidecraters 1) Place a Pressure Gage (SVT-0066) on the table and align it with the Spindle nose. ... 4) Zero the Indicator. 5) Jog the head (Z axis) up until it is no longer in contact with the pressure gage. 6) Depress the “Tool In Out” Button on the keyboard. 7) Release Button. 8) Read the value on the indicator. ....

Carbide, I love your post... but this one confuses me (I'm old... humor me) If you jog up after zeroing the indicator, your no longer at zero, so how can you measure deflection?. What am I missing?
Steve

[carbidecraters]

Copied and pasted from Fadal TSM

[Scanfab]

Set the indicator base on the side of the spindle, not the table.. This is how I envisioned it while reading the instructions, not based on facts, knowledge or experience.
Hmm:
If I had the facts, knowledge, and experience of how long it takes to become a good machinist-I never would have become a machinist. I would've chosen a job that you can master in UNDER 10 years. Thats why not having the facts is good, because now I'm a very good machinist!!(Did take 18 years though(and I'm still learning every day)

[Neal]

Scanfab--
I've been doing this kind of work for over 30 years. I even work for a machine tool builder and spent YEARS in the aerospace industry working on the machines myself. Sometimes I think I know nothing other times I realize I don't know everything I don't know!!!

Neal