Fadal Thrust Bearing Part #s needed

I picked up a used 4020 about a month ago and there is excessive backlash in the z, the most likely candidate is the thrust bearings.

Does anybody have the part number for the z axis thrust bearings? and are they the same on all 3 axis'?

Fadal nc. Is the website don’t forget the seals that go with them


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I use koyo s1802 on all 3 axis. Paying 27CAD per
Ive got the chiller disconnected from the ball screws, so i dont bother replacing the seals.

You will likely need to cut out a .002-.003" shim to put between the inner faces of the inner races to take any play and slop from mount out\preload the bearings.

Make sure you install them properly, and pack the bearings with (i use a urea based) grease.

Hope this helps

macds said:

You will likely need to cut out a .002-.003" shim to put between the inner faces of the inner races to take any play and slop from mount out\preload the bearings.

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I don't understand this.
You are using non paired bearings? Is it .001, ,002, .003 shim and how do you know the right number?
Many years ago we would grind and shim bearing pairs and spacers. Tenths would matter getting the preload right.
I'd buy a DUx pair.
While not as fussy as spindles do not over pack the bearings with grease. They have a cc load, buy syringes on amazon and put in the right amount.
Bob

It just spaces the pair apart then the top part tightens down with bolts to apply preload


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D Nelson said:

It just spaces the pair apart then the top part tightens down with bolts to apply preload

Click to expand...

You do not want to know how much this thinking makes me want to cry.
Bob

CarbideBob said:

I don't understand this.
You are using non paired bearings? Is it .001, ,002, .003 shim and how do you know the right number?
Many years ago we would grind and shim bearing pairs and spacers. Tenths would matter getting the preload right.
I'd buy a DUx pair.
While not as fussy as spindles do not over pack the bearings with grease. They have a cc load, buy syringes on amazon and put in the right amount.
Bob

Click to expand...

Youre totally correct Bob.
I should have said "youll have to figure out the shim you need".
Even when buying matched preload pairs (if you can find them) an NO... fadal cncs' pairs are NOT matched.... you need to account for how much slop your aluminum bearing mounts have had hammered into them.

I use urea based grease, and have hand packed the bearings. Im NOT saying my method is 100%, by any means.
But in reality, you do the thrust bearings for an hour of labour and $40 an axis.... run it for a year\year and a half... do thrust bearings.

Not talking about a Huron here.

And NO, Im not (I dont think so...) a hammerhead...
Its about picking battles.
Pissing around for a day setting thrust bearing preload on a 10K machine thats uber easy to repair, and isnt doing rocket science work, in my mind isnt worth it.

Absolute respect for you btw Bob.

CarbideBob said:

I don't understand this.
You are using non paired bearings? Is it .001, ,002, .003 shim and how do you know the right number?
Many years ago we would grind and shim bearing pairs and spacers. Tenths would matter getting the preload right.
I'd buy a DUx pair.
While not as fussy as spindles do not over pack the bearings with grease. They have a cc load, buy syringes on amazon and put in the right amount.
Bob

Click to expand...

Hey Bob.. Years ago I looked high and low for matched sets of the bearing size Fadal uses..

I could not find them.. I might not have known where to look, or whatnot, but I couldn't find them.


As for the shim.. THAT IS IMPORTANT, and its not that hard to get a shim stack that will give
you zero backlash in the bearings, yet will still last long term.. I have't replaced a single
bearing stack I've assembled personally on any of my Fadals in over 10 years.

I've bypassed the ballscrew cooling. They are big enough screws as it is. The rapids
are slower than shit, and the accelerations are like a Smart Car running on 2 cylinders.
The seals suck, and if they leak at all, they leak straight into the thrust bearings.

Back to the shims.. I've been in a rush, and just said screw it and tossed in a .005" shim.
That was a timesaver until a month or so later when I was buying and installing
more thrust bearings... I've also had the carrier worn out so much that I had to install
a shim on the outer race so that the carrier could clamp the bearings together properly...

If anybody cares to hear my "Hi Tech", yet not completely proper, yet good enough method
of setting the shim size, just say so.. I'm too damn tired to type it out right now.

Never taken one of these apart. The 1802 number above is confusing.
Is this a tapered roller or duplex ball bearing setup used here?
Maybe I'm the walking and talking moronic dumbshit in this thread. (Would not be the first time )
Bob

The shimming is important. And the 0.001" shim they supply may not be enough. Try it with 0.001 and see how it feels. If its too loose add another. You want to feel some resistance (preload) but it shouldnt be bar tight. Use common sense. I would also reccomend removing the coolant lines.

I didn’t see it listed but it requires:
2 ac bearings 7304b 20x52x15
3 seals skf 12360
1 seal skf 11138
And a 7/8 preload shim between .001-.002

The bearings I usually see in there are nsk bearings but I’m sure any quality bearing will work. Misumi used to carry the correct ones for $15 a set but as of late I’ve struggled to find the exact ones.