Prvomajska alg100 horizontal spindle movement

Hi all

I have a question, and I hope you have the answer to it [emoji16]

It's my 1962 prvomajska alg 100 mill, which I noticed have some movement in the horizontal spindle.
I've set up an dial indicator on the spindle nose, and put a chuck with a mt4 into the spindle. When I pull up/down, I get a 0.1mm reading, and if I push with full strenght I can move it 0.3mm.
This pull done 120mm from the spindle nose, on the chuck.


But, how much movement should be accepted?

And, I presume I can adjust the bearings into a more tight fit? This lead to the actual question.
Where do I adjust the slop in this bearing? I share some pictures [emoji846]

Hope you can help, best regards

Can offer an educated guess..not familiar with your machine, but it seems to employ a plain bushing style spindle.

With tapered spindles and plain bushings there are two factors in play.
First is the radial clearance...that is the side to side play at the spindle nose.

Second there is the axial clearance...that is how much movement is in the spindle front to rear along the spindle axis.


Appears to be a shim (number 46 i think) at the front of the spindle . This shim controls the position of the spindle and limits its movement to the rear....
as the spindle moves to teh rear the taper on the spindle and bushing tighten and the side to side play or clearance is reduced....

Seems her if that is your issue, to adjust, that shim or washer needs to be reduced in thickness..this is a job for a good surface grinder as this shim also controls the thrust on the spindle moving to the rear....
Knowing the taper rate of your spindle and the amount you need to correct the side play , you can calculate the thickness reduction needed to make the needed adjustment...

The second type of play that of end to end (front to rear) is controlled by adjusting nut #45. That nut controls the clearance between the front thrust bearing/spacer and the rear thrust....
Tightening that nut (45) will reduce the end play in your spindle...

It will not tighten the side to side play...

So you must first i think adjust the end play using ring nit #45 to a minimum, then test the side to side play at the spindle nose...If that is found to be too great,then material must be removed from
the spacer #46 , then the end play readjusted to suit.....

Looks as though the rear bearing is also adjustable.
Not sure i understand exactly how that setup works, but i think the ring nut on the outside pulls the inner sleeve toward the rear thereby tightening the taper and reducing the clearance.....Seems this adjustment
needs to be looked at after the main spindle adjustment has been attended to...

Again, drawing is a bit hard to read and i am making some guesses about how this all works....Make small changes and test your results carefully.
Cheers Ross

Thanks for your reply. [emoji16]

I have since I wrote it, decided to take it apart.
So I did.

It does to my surprice not spin in roller/ball bearings, but old style brass/bronz bearings.

And I also think I have found the way to correctly adjust them.

The big washer with holes, which are seen in the very first picture, I think I need to turn counter clock wise, when all are put together. This way it will push into the thrust bearing, and push the tapered brass bearing outwards. This should reduce the space between shaft and bearing.

I haven't figured out what the two small washers, closets to the spindle nose are. But maybe some sort of spacers? They have small pins, so they wont turn?
Or maybe some sort of sealing labyrinth?

Best regards

Guessing you really did not read my response above....
That nut with the holes on its OD is a retaining nut for the bronze bushing that is the main spindle bearing...
IT IS NOT AN ADJUSTMENT !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
Leave it alone.

The thrust is adjusted by tightening of loosening the ring nut to the rear of the gear.
That is why it has a pinch bolt, so you can set it as an adjustment and hold its position.
The gear and spacer act on the thrust bearing, being pushed on by that nut with the pinch bolt....the position of that assembly (nut, gear and spacer) determine the end thrust clearance.

That sets the end float on the spindle.BUT there is more! When the end float is set
to minimum (has to have some clearance) .....IF you still have excess side to side play the cure is to
reduce the thickness of the forward most washer (front of the spindle)...that is the one that sets the position of the spindle front to rear....
Removing shims from behind this washer or grinding it thinner moves the spindle and its taper further into the busing making it tighter on its OD.....

You ,AS i stated above, can determine the amount you need to remove from the washer (if any) based on the rate of taper on the spindle and the excess clearance you have side to side.....


The rear bushing is like a collet...as you tighten the rear ring nut it draws the bushing into the housing further and squeezes the bushing tighter on the shaft (spindle)....

Cheers Ross

Some additional notes:
First off looks like the front face of the bronze bushing has some distress...looks like dents r such in its face.
My opinion is that this bronze face is not the real front thrust bearing for the spindle. My belief is that the thrust is taken between the faces of the two thicker washers at teh front of the
spindle. The bronze looks to have no oil grooving of feed for lubrication, where the two steel washers seem to be grooved for oil.
Further, it appears that the bronze bushing is drilled (2 places) and so is one of the washers....My guess is that these holes line up with each other....I am guessing that the factory
intended there to be pins in those holes to prevent the rear washer from rotating against the bronze.....
Cheers Ross

Hi Rasmush, Ross,

I confirm Ross's tips regarding spindle adjustment. Here is the horizontal spindle off the ALG100 I used to own



you may see the two hardened washers closer to the nose (also seen in rasmush's pics). Front is pinned to the spindle, rear is pinned to the bronze bearing,oil groove where they face eachother. Here only the front is visible



As Ross suggested, axial play is taken by nut 45, radial play by grinding thrust washer 46 (closer to the bushing), as stated here in clear german....(have to take X off the washer to reduce the radial play by 0.1X)



Regarding the face of the bushing Ross, I think somebody tried to reinstall the spindle assembly without paying attention to the pinned rear washer, so we can see the marks from the washer pins damaging the face of the bushing. I am afraid this might not be that good, could affect spindle alignment, right?

BR,
Thanos

(happy 2018 to all!)

(maybe Bruce could confirm the translation if he sees this)

Thanks for the reply.

And of course I did read your response, but before I took it apart, I really didn't make any sense to me.
Mostly because I did struggle on language translation.

But now that I have it apart, and had some sleep after some night shifts, my thoughts are more clear. I can see my last understanding of it's construction were way off.
Sorry, minor brain fart..

But yes, the front of the bronze bearing does have allot of small marks. Those from the small pins on the washer. This I would think are a sign of several attempts from previous owner, on getting it correctly assembled.

I will try to assemble it today, and reply the outcome.

Again, thanks for the respons.
And sorry for being an idiot [emoji6]

Now I did assemble it, and all went together very well.

The spindel itself sits further in than before, so it was not assembled correct before.

The slop are reduced to an absolute minimum, and my dial indicator can't barely read any motion. So I'm satisfied.

Have a nice weekend

Best regards

Very nice, enjoy your sweet mill!

Congratulations! I always find it very satisfying to "fix" something, where the only problem is that the last person to work on it did not put it back together correctly or adjust it correctly. So no parts must be made or metal removed, just some brain/finger coordination required.

thanvg said:

(maybe Bruce could confirm the translation if he sees this)

Click to expand...

For the record:

ADJUSTMENT OF THE MAIN SPINDLE - FIGURE 12
To take up radial forces the horizontal milling spindle has a
forward bearing cone riding in a bronze bushing, while the axial
forces are taken up by an adjustable hardened thrust ring 46.
If after long usage there is perceptible change in the bearing
free-play, or if the bearing is too tight, then the locking screw
44 should be loosened and the bearing adjusted with the nut. The
bearing should be adjusted far enough that with the radial
bearing tight, with a free play not exceeding 0.01mm, the
axial play does not exceed 0.02mm. If it is not possible to
adjust the radial bearing in this way, then the thrust ring 46
must be readjusted: a 0.1mm reduction in thickness will reduce
the radial free play by 0.01mm. The required disassembly of the
horizontal spindle is possible via unscrewing nut 45 and removal
of the spindle to the rear.

(The word used for "readjustment" of the thrust ring is "nachjustieren" which might mean either screw-type adjustment or "trimming" by grinding. I'm not sure which is correct here.)

ballen said:

The required disassembly of the
horizontal spindle is possible via unscrewing nut 45 and removal
of the spindle to the rear.

Click to expand...

Something wrong here...But don't think you can remove the spindle to the rear.....
Cheers Ross

AlfaGTA said:

Something wrong here...But don't think you can remove the spindle to the rear.....
Cheers Ross

Click to expand...

You are right, it says “nach vorne” which means “towards the front”. Sorry I should have checked my translation!


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