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IndustryArena Forum > Metalworking Machines > Benchtop Machines > Help in interpreting results of Rollie's Dad method for aligning spindle on my Mill!

# Thread: Help in interpreting results of Rollie's Dad method for aligning spindle on my Mill!

1. ## Help in interpreting results of Rollie's Dad method for aligning spindle on my Mill!

Hi everyone!!

I have just changed the stock bearings of my Sieg X2 mill for angular sealed ones. (7206-B-2RS). As I have disassembled the head of the mill, I need to align the spindle cast of the head with the cast that connects to the collumn.

So I've set-up the Rollie's Dad method for aligning the spindle with the collumn. I put the needle of the indicator right under the 14mm lenght rod, 12mm diameter, to first align the Y (spindle tilted away or closer to the collumn)

My mill and my measurements are in mms.

In the near Collet part of the measurument, I zeroed in the indicator the middle value, so I have the -0.02 -> 0 -> +0.02. (So the sum of both divided by two, to get the mean, is zero).

The positive values mean that the spindle runout is going closer to the collumn (pressing the needle) and the negative value means that the spindle is tilting away from the collumn). Am I right so far?

In the far end of the 12mm rod, I all positive values. I have 0 -> 0.045 -> 0.09, so the mean value is 0.045.

So taking both mean values, I have 0.045mm of tilting closer to the collumn (downwards as my setup is mounted parallel to the bench) in more or less 14mm of rod lenght.

So far my assumptions are right?

But now, how do I improve it? The desirable result to achieve would be to get for instance, the same -0.02 -> 0 -> +0.02 in the closer part of the collet and -0.045 -> 0 -> +0.045 in the far end? So both deviations are equal up and down? Is this what this adjust is about?

So I should shim between the two casts in order to "lift" the spindle a bit?

Thanks for reading and I'd appreciate any help in understanding this .. theory...

Regards, Rodrigo

2. ## Re: Help in interpreting results of Rollie's Dad method for aligning spindle on my Mi

I am not familiar with this method of testing, so I am only interpreting your results.

It seems to me you have two problems. But first, is the rod only 14mm long, did you make a mistake, is it 14cm?

I am trying to imagine the axis of the spindle, it has a theoretical alignment to the column. But is seems that the axis has an actual wobble that is much bigger than the alignment error to the column.

I suggest before working on the alignment, look into the causes and fixes of the wobble. Make sure the bearings you just replaced are correctly installed. Make sure the collet in the spindle, that holds the rod, is accurate also. It will be very difficult to get good machining results with a spindle wobble that you described ( assuming the rod is 14mm long).

3. Originally Posted by cncuser1
I am not familiar with this method of testing, so I am only interpreting your results.

It seems to me you have two problems. But first, is the rod only 14mm long, did you make a mistake, is it 14cm?

I am trying to imagine the axis of the spindle, it has a theoretical alignment to the column. But is seems that the axis has an actual wobble that is much bigger than the alignment error to the column.

I suggest before working on the alignment, look into the causes and fixes of the wobble. Make sure the bearings you just replaced are correctly installed. Make sure the collet in the spindle, that holds the rod, is accurate also. It will be very difficult to get good machining results with a spindle wobble that you described ( assuming the rod is 14mm long).
Sorry. The rod is 14cms long, 12mm diameter. I made a mistake.

4. ## Re: Help in interpreting results of Rollie's Dad method for aligning spindle on my Mi

The desirable result to achieve would be to get for instance, the same -0.02 -> 0 -> +0.02 in the closer part of the collet and -0.045 -> 0 -> +0.045 in the far end?
Yes.
-0.045 + 0.045 = 0
Rollie's Dad Method will check alignment even if the spindle has some run-out or the test rod is less than perfectly straight. Use a rod with consistent diameter (no taper).

So both deviations are equal up and down? Is this what this adjust is about?
Yes

So I should shim between the two casts in order to "lift" the spindle a bit?
That's the easiest way and it's the way I did it. It takes some trial and error. Cheap feeler gauge sets are a handy source of shim stock.

5. Originally Posted by cyclestart
Yes.
-0.045 + 0.045 = 0
Rollie's Dad Method will check alignment even if the spindle has some run-out or the test rod is less than perfectly straight. Use a rod with consistent diameter (no taper).

Yes

That's the easiest way and it's the way I did it. It takes some trial and error. Cheap feeler gauge sets are a handy source of shim stock.
Thanks a lot! That’s what I was thinking but I wasn’t sure I was doing right!!

Best regards!

6. ## Re: Help in interpreting results of Rollie's Dad method for aligning spindle on my Mi

Yup, on the right track. After what seemed like 30 times removing and replacing the head to shim it, I stopped at -.0003" (0.00762mm) out for the Y, don't remember the X. The bad part is, even just removing the head with no other changes would change my readings... I still have to get my mill put back together after doing the KBMM-125 board upgrade and stiffening before I actually tram the column/table.