# Loading quill bearings



## Mike Ginn (Jun 11, 2020)

The top roller bearing (type 30205) on my Warco Minor/Grissly G1005Z mill failed do to lack of lubrication (I was told it was sealed but it isn't).  Quite easy to replace but I could get no advice on the procedure of loading the bearing.  It needs to be tightened on the bench before final assembly.  Can anyone advise on the correct torque to apply?

A secondary question concerns the spindle adjustment on my Sieg KX1 CNC mill.  Again can anyone advise on the correct loading torque?

Many thanks in advance


----------



## retailer (Jun 11, 2020)

I replaced the bearings in my Arboga Mill a while back - the lower spindle bearing is a roller the preload is applied with a castellated nut locked with a tab washer, I tightened it enough to take up the slack and then a fraction more so I could lock the nut with the tab washer,  after the first weeks of use I noticed that I had a fraction of play in the spindle, everything had bedded in so I repeated the tightening process, this time going one extra tab space, I noticed the roller bearing getting quite warm after running for a while at top speed 4000rpm so I backed off the nut the extra tab space I had previously applied. It has been like this for over 18 months, been run at top speed and I haven't detected any temp rise in the bearing.


----------



## Wizard69 (Jun 11, 2020)

Do you mean tapered roller bearing or cylindrical roller bearing.   I'm not familiar with the specific Grizzly mill but but there are two possibilities


----------



## Cogsy (Jun 11, 2020)

retailer said:


> the lower spindle bearing is a roller the preload is applied with a castellated nut locked with a tab washer, I tightened it enough to take up the slack and then a fraction more so I could lock the nut with the tab washer,  after the first weeks of use I noticed that I had a fraction of play in the spindle, everything had bedded in so I repeated the tightening process,



In a tapered roller bearing the rollers are 'wedge' shaped and when you install them statically the roller tends sit in the bottom of the raceway. When they are spun the rollers migrate their way to their actual running position further up the raceway and this increases the clearance within the bearing. Any time you are installing tapered rollers you need to be spinning them as you set the clearance or as you discovered there will be free-play when they are run. On bench tests with front-wheel sized tapers using a dial indicator (we were training fitters to install taper rollers) resulted in something ridiculous like 40 thou of extra end float once we spun the wheel with a bearing that was tightened statically.


----------



## Tim1974 (Jun 12, 2020)

If it’s taper roller I would be going for 1 thow preload on a spindle but hmm castle nuts can be a pain to get right  ( I hate them )


----------



## Mike Ginn (Jun 12, 2020)

Thanks for the comments.  The top and bottom bearings are taper races which can only be adjusted with the quill on the bench.  Access to the load nut and castle washer is not possible when installed.  In a perfect world I would like to use a torque gauge to load the bearings BUT  "Cogsy's" advice has thrown me a bit.  I guess I could adjust, spin with a motor, adjust etc but my main question remains - how tight to nip up the bearings.  With auto wheel bearings it is usual to finger tighten then add 1/4 turn but I think a quill should be tighter.  "Retailer" comments on warn bearings and I suspect that should be the aiming point.  However it takes around 2 hours to strip the quill so I would like to get this correct first time.
Thanks guys


----------



## Misterg (Jun 12, 2020)

Hi, been lurking around here a little while.

Doesn't answer your question, but you may find this video useful:



(I didn't believe that I would sit down and watch all 90 minutes of it either, but I found the lengths that he went to fascinating.)


----------



## Mike Ginn (Jun 12, 2020)

Misterg said:


> Hi, been lurking around here a little while.
> 
> Doesn't answer your question, but you may find this video useful:
> 
> ...


----------



## Mike Ginn (Jun 12, 2020)

Wow - that's a very comprehensive video which uses the correct bearings which are loaded by virtue of their design.  Unfortunately my Chinese mill makes use of bearings designed for the steering columns of motor bikes which is never a good place to start.  My thoughts are to tighten until I feel resistance which will generate heat.  I'll then try to find a way to lubricate the bearings when assembled into the mill - without the need to dis-assemble.  However I would really like a ftlb/NM number to work with.  I expected the suppliers to have that info but Warco has no info.


----------



## SmithDoor (Jun 12, 2020)

The down side to per load is will heat up the bearings. 

My self I give no per load for longer bearing life. Tighten so it free spins

Dave


----------



## fcheslop (Jun 12, 2020)

I replaced the bearings on my RF25 several years ago. I took up all the play turning the shaft as I adjusted the nuts then just gave it about 10 degrees more .Refitted the quill assy and let it run for a good half hour checking things were not getting hot
The nuts on my mill are junk with more slop than thread and you are limited by the position of the lock washer in relation to the castle
Iv not had to redo them so guess I was lucky although all the other bearings sound like Edmondo Ross and his band and need doing
I would need to check but I think if you remove the front plate you can get restricted access to those nuts.It is a long time ago Im not sure


----------



## wazrus (Jun 12, 2020)

Mike Ginn said:


> The top roller bearing (type 30205) on my Warco Minor/Grissly G1005Z mill failed do to lack of lubrication (I was told it was sealed but it isn't).  Quite easy to replace but I could get no advice on the procedure of loading the bearing.  It needs to be tightened on the bench before final assembly.  Can anyone advise on the correct torque to apply?
> 
> A secondary question concerns the spindle adjustment on my Sieg KX1 CNC mill.  Again can anyone advise on the correct loading torque?
> 
> Many thanks in advance


----------



## wazrus (Jun 12, 2020)

I don't think there is any 'correct' pre-load to apply to taper roller bearings. How long is a piece of string? 
I reckon the best advice might be from automotive sources, where pre-loaded taper rollers have been used in front wheel hubs since the advent of the car: well, almost! The 'amount' might vary with the size of the bearing and 'or its manufacturing tolerance(s). So called 'precision' bearings are, for instance, made to tighter tolerances than  the common variety, with a price to match.


----------



## SmithDoor (Jun 12, 2020)

It is mill quill using ball bearings.
On a lathe or horizontal mills I  per-load since the spindle will heat up and expand and tapper roller bearing.

Dave




wazrus said:


> I don't think there is any 'correct' pre-load to apply to taper roller bearings. How long is a piece of string?
> I reckon the best advice might be from automotive sources, where pre-loaded taper rollers have been used in front wheel hubs since the advent of the car: well, almost! The 'amount' might vary with the size of the bearing and 'or its manufacturing tolerance(s). So called 'precision' bearings are, for instance, made to tighter tolerances than  the common variety, with a price to match.


----------



## Cogsy (Jun 12, 2020)

There is a benefit to a very small amount of pre-load on tapered rollers and angular contact bearings which extends load carrying ability and bearing life, and of course adds to the precision of the spindle. But the amount of preload is very small and the load capacity and bearing life drop off incredibly steeply after this point. When I worked in bearings we sold precision matched sets of tapered rollers and angular contacts for spindles that came with matched spacers and torque settings - but there were very expensive.

For off-the-shelf bearings fitting to a spindle I personally would adjust to zero clearance with no pre-load as it's too easy to put too much on them and have them fail prematurely.


----------



## Dusty3v0 (Jun 13, 2020)

Active Atom did a video series on spindle rebuilding.
You will need the better part of a day to watch it all.


----------



## SmithDoor (Jun 13, 2020)

Looks like good mill
But the low speed belt will slip.
Unless tighten the belt to near breaking point it will slip.

I fix this on mill which is close copy by making the center smallest pulley larger and the largest bigger too. This gives a great belt rap on small pulley so does no slip it also gave slower speed.
Note can just make new center pulley  just for low speed work too.

I am very happy with low speed and no slipping

I posted drawings and photos of modification here in the downs 

Dave


----------



## SmithDoor (Jun 13, 2020)

I see why the bearings fail.
Most quill vertical mills use ball bearings like Bridge Port.
This using a tapper roller for high speed.






						USBC HR30206 tapered roller bearing 30x62x17.25 30206J
					

30206 taper roller bearing 30x62x17.25 in stock HR30206J ship same day 30206X low price Y30206 buy now K30206 online bearing store direct




					www.onlinebearingstore.com


----------



## stevehuckss396 (Jun 13, 2020)

I think the price might have a lot to do with it also. How much can you expect from 10 dollar bearings. They are less than ideal when brand new. Of course a set of class 5 bearings would about double the price of the machine. It is what it is!


----------



## Mike Ginn (Jun 13, 2020)

Yes I agree.  For a "hobby" mill I guess the bearing is OK but it still needs to be set up in the best way possible.  I also accept that the bearing will have a limited life


----------



## toolingjim (Jun 13, 2020)

When I used to build injection molding spindles with tapered roller bearings, we set them up DRY so they could just barely be turned by spinning them using a lever with a six inch length. Then we lubricated the bearings. This was based on the idea that opposed tapered roller bearings never wear tighter, just looser. Our spindles never got over 400 rpm or so, but were under tremendous pressure.
From another source. I read long ago that one fellow converting Enco (remember them?) milldrills to CNC got tired of the crappy setup of chinese quills. Based on his methods, I would suggest the following: pull the quill and tear down the spindle completely. Wash everything clean. Check for burrs and wear and correct as needed. Reassemble with a good grease. He said the setting was a bit hit and miss: I would suggest tightening everything finger tight, giving the spindle a sharp rap with a plastic or rubber mallet on both ends to push the grease out of the way, and retightening by hand or gently with a spanner. Repeat a couple of times until the things seem to be stable and firm. He then went on to say he ran the spindle at high speed for a couple of hours to test. I would first run it at 300-400 rpm for a couple of minutes just to seat everything and push the grease out to where it belongs, then run it full speed. The quill will warm up, but his criteria for proper setup was that after two hours, the quill should never get so warm that you could not rest your hand comfortably on it. Pick a time when you can check that quill every few minutes during the runoff. If it gets hot fast, shut down and loosen. If it shows any loosness after the run, tighten a bit more and rerun. If thermal expansion affects the spindle more than the quill housing, the spindle bearings could lose preload. Not probable, but possible.
Based on my experience with my milldrill, they do get warm at high speeds, and my millldrill is well seated and old enough to vote.
Hope this helps.


----------



## BundyBearsShed (Jun 15, 2020)

The rule of thumb I use for any tapered roller bearing is if the cones face each other set at zero to two thou pre load on a new bearing. Now to gauge 0.002" you can indicate the adjusting nut and see how much of a turn will give you this 0.001 or 0.002" after you have found zero. . With some preload the machine shaft will expand slightly with heat of use and the bearings will wear slightly over time so the preload will allow for some of this.  On a bearing with the cones facing away from each other it was often zero to 0.002" end float with the same thing in mind being the expansion of the rotating part with use. Keep in mind Im a big tractor and gearbox fitter so what Im talking of is on much larger gear but I thought it might be helpful anyhow.


----------



## William May (Jun 16, 2020)

BundyBearsShed said:


> The rule of thumb I use for any tapered roller bearing is if the cones face each other set at zero to two thou pre load on a new bearing. Now to gauge 0.002" you can indicate the adjusting nut and see how much of a turn will give you this 0.001 or 0.002" after you have found zero. . With some preload the machine shaft will expand slightly with heat of use and the bearings will wear slightly over time so the preload will allow for some of this.  On a bearing with the cones facing away from each other it was often zero to 0.002" end float with the same thing in mind being the expansion of the rotating part with use. Keep in mind Im a big tractor and gearbox fitter so what Im talking of is on much larger gear but I thought it might be helpful anyhow.


Bundy, I watch a lot of your "Shed videos"! They are excellent! (If anyone is interested (which should be everyone on THIS site, look at "Bundy Bears Shed" for some very interesting and entertaining videos!)


----------



## BundyBearsShed (Jun 16, 2020)

William May said:


> Bundy, I watch a lot of your "Shed videos"! They are excellent! (If anyone is interested (which should be everyone on THIS site, look at "Bundy Bears Shed" for some very interesting and entertaining videos!)


Thanks for your support.


----------

