Hello everybody,

I am re-assembling the spindle of my 1966 Weiler Matador.
This summer I bought the machine from my work. (Wow am I glad with it!)
Generally it is in fairly good condition but I noticed that the spindle head (DIN 55022) had about 20 micron radial runout, and a lot of radial play. The v-belts were in very bad condition as well (oil had come into the area of the belts) so I descided to take out the whole spindle to correct the problem. I am lucky to have the complete ariginal manual, you really need this to do a good job. I found out that the double row roller bearing had been replaced once with a new SKF bearing (I have some old measurement report in which everything is ok...). The inner ring has a tapered bore to enable fine adjustment of the radial clearance. The inner ring is pushed onto the tapered part via the gear in front of it. I could clearly see that this gear had touched the tapered part of the spindle, which should not be the case. I guess that the width of the replacement bearing was slightly different than the original one. This was the reason why the tapered bearing had never been adjusted correctly. I now added a little chamfer (manually grinded with a little grinder) and intent to reassemble the whole thing again. I have two questions which I would like to ask on this:

1) The pulley that drives the main spindle is mounted on the main spindle with two needle bearings (to allow driving the backgear) all the gears are lubricated by an oil bath. The oil can not easily enter the pulley though. Do I need to grease the needle bearings inside or are they also lubricated by the oil bath?

2) I replaced the front double row roller bearing with another second hand one in better condition. Can I adjust this bearing to zero clearance or should I allow for a few micron play on such a second hand bearing? I know about running in of these type of bearings (its on the SKF site, but only describes the procedure for new bearings).

I hope that there are a few people out there that have experience with these things and willing to react!

I would adjust it to 0,01mm measured with about 20kg of load You see the bending of the shaft with to much load
After some use that play will mostly become a bit less So you probably end up with about 0.006 to 0.008mm
New they are adjusted to 0.002mm as I remember correctly
About the needle bearings I don`t recall but some grease won`t hurt I suppose

Peter from Holland

Hi Peter,

Thank for your quick reply I did add some grease on the needle bearings just in case...

About the radial play: I have temporary borrowed a Tesa measument probe with analog readout. It can be set to 3 micron full scale on its most sensitive setting. When I try to move the spindle (just by firmly pulling on it by hand) I get about 4 micron from left to right. Should this be set to less? The radial runout is about 6 micron, but I guess this is also due to the remaining play.

From left to right is adjusted at the rear end with the trustbearing and the tapered bearing. 0,004 is oke
Up and down 0,006 is a bit tight for a used bearing But do a run in and check from time to time If it gets below 0,03 fast I would loosen it a bit

If I get a used lathe and play is 0,01mm or less I am very happy


Peter from Holland

I don't know what type of bearing the Weiler has, but I think all roller-bearing spindles require pre-load.If you have some play (even if it's less than 0,01mm, you will see it in the surfaces of your part.

As Kees says, any radial play in the bearing will not be good. The way to adjust the bearing is by warming up the lathe at a medium speed then running it with the spindle bare at high speed and check for heat round the front of the bearing. The nose should get to a warm heat, still touchable and stay there. If it becomes too hot to touch the bearing needs backing off. It is quite a long process because you have to wait till the housing cools down before adjusting again. You may be lucky and hit it first time!. Be sure that the right kind of bearing grease is used and don't pump too much in, it will churn and heat up rapidly giving you false results. There is a relief hole at the bottom of the bearing housing but the best way to get the greasing right is to watch for it weeping out just behind the spindle nose when running. when it stops weeping you can then procede to start the adjusting process.

Properly adjusted, the bearing should be perfect for many years with just a couple of pumps of grease every so often depending on how much you use the lathe. I adjusted my spindle about 10 years ago and give it a shot of grease about every 6 months.

Kees
I think it is Schaublin or AI Hembrug that recommended a radial clearance of about 0,002mm on their NN300? bearing
I can look that up on monday
If I have bought a used lathe and it has less than 0,01mm clearance I am happy
Mostly it will cutt off stock pretty good and has good surface finish
And with all the(used) lathes I checked I never had one that had no clearance
And I had some pretty decent ones



Peter from Holland

Before I started I took a deep look in the documentation at SKF of these type of bearings (NN3012 KTN SP). It shows what Kees said, that the lifetime of the bearing drops quite fast if there's to much radial clearance and highest lifetime is achieved with very small pre-load. Also I found a document which describes the procedure that Peter F. describes. According to that the bearing requires running in and after several iterations (with the lathe running at higher and higher speeds) the bearing should not get higher in temperature than 70 degr. C. after 2 hours cont. running.

But I thought this was all intended for new bearings...
If I understand Peter F. correctly I can do the same for a used bearing? (The bearing still looked good, not much marks on the rollers and a radial play of 31 micron when fully disassembled). Thanks for all your contributions by the way.

Henk
On the SKF website they go from ideal conditions
Did you also check the tolerances SKF gives with your spindel ?
Do you have the means to check them within 0,001mm?
Don`t assume they are within specs
You also did notice the gauges needed on the SKF website???
After you found out al these tolerances are oke you could go with the preload methode
IMHO a lathe spindle on a weiler matador and most other lathes is a precision bearing, not a high presicion let alone a super high presicion bearing

The method Peter F discribed works great and is mentioned in the Matadors manual but is time consuming
Start out with just under 0,01 mm clearance and work from there with the temperature related method That way you get the best result in the best time
If it gets to hot to fast with that 0,01 clearance it is time to get a new bearing

Peter from Holland

If there is clearance like Peteserve mentions the bearing should not get hot at all providing it has not had too much grease. However you will probably get chatter at the higher speeds which effectively means that the bearing should have at least a bit of preload and this is evident by the production of heat. It is impossible to measure the amount of preload with the type of bearing used as the radial clearance is taken up by forcing the tapered inner race further on to the taper of the spindle. As you know this takes considerable force, you are trying to expand the hardened inner race of the bearing and by mere microns at that. It is quite different from adjusting the preload on a normal taper roller bearing where the inner race "slides" on a parallell shaft. I would say that if the races and rollers look ok to you with no galling it would still be servicable. My Matador as far as I know still has the original bearings so they obviously have a long service life. If it is worn oval you will get chatter marks on a fine finishing cut even with preload so in my opinion that is the stage at which the bearing should be replaced . Having said all that, seeing that you already have the spindle dismantled to replace the belts and if you have a bit of money to spare it may be an idea to bite the bullet and replace it. As Peteserve has said, these bearings are high precision, not super etc etc and are relatively cheap compared with say Gammet taper rollers by a factor of at least 4/1.
When we are speaking of preload with these bearings it is only a very few microns being taken up by the expansin of the inner race so the difference between not enough and too much is really only measurable by the heat generated, too hot-too tight, poor surface finish-too loose.

Hi Peterve Peter F,

Maybe you are right Peterve in that I should just try to adjust it slightly below 0.01mm. After all its an old machine from 1966. I have seen the gauge on the SKF site and off course I don't have one at home or at work (although we do have measurement equipment which can measure well below 0.001mm) On the other hand I see it as some sort of challenge to get this machine as good as I can get, given the limited time and budget I have.

Based on your feedback I descided also to inquire for the price of a new bearing. If its not too high I may go for the advise Peter F gave me and replace it all in once. If it is beyond my budget I will do my best to adjust it as you advised.

I will let you know the outcome when I have re-assembled the whole thing.

Regardless of whether or not you get a new bearing or use the old one, you still have to adjust it. I understand that when the factory assembled these spindles they did it using the method explained in the manual. Incidently the Condor,s have the same bearing arrangement as have many of the TOS lathes, the Smart & Brown 1024 Mk 1 to name a few. Whilst mention has been made of "Super precision" bearings, in general these are non adjustable bearings which have the balls or rollers specially selected to give the degree of clearance required. The Matador bearing being adjustable does not come under this catagory but is still a high precision bearing.