Thanks Jan, that does help me understand a bit more. I bought these bearings because they said they were ABEC 5
It says on the bearing 0770 and "Explorer", I found this on the SKF website. SKF Explorer angular contact ball bearings are manufactured only as bearings for universal matching with P6 dimensional accuracy and P5 running accuracy. --- On Thu, 11/3/11, Jan de Kruyf <jan.de.kr...@gmail.com> wrote: From: Jan de Kruyf <jan.de.kr...@gmail.com> Subject: Re: [Emc-users] OT, Ball screw bearings, preload To: "Enhanced Machine Controller (EMC)" <emc-users@lists.sourceforge.net> Date: Thursday, November 3, 2011, 3:10 PM Oh dear, I slipped up. (Again) I clicked on the "preload" link in the speck sheet that Bruce linked to. and lo and behold SKF puts the link for preloaded bearings on a normal bearing spec sheet. So my apologies for not noticing earlier. Then in this case you will need to measure your bearings out on the table and see if the one ring is higher or lower than the other when you support just one of them and let the other rest on the balls in loaded position. then you make some sums and make up 2 spacer rings, one for the outer races and one for the inner races of the bearing set. Those rings are turned as accurately as possible and normally ground on the faces, but if you turn very well you might get away with just the lathe. the difference in hight between the outer ring and the inner ring match the bearings in such a way that the balls in each of them are comressed by about 5 um. So if the bearings were perfectly true and the inner ring and the outer ring were level when one ring is floating and resting on the balls, then the one distance ring is made 0.01mm shorter than the other so that when everything is tightened the balls get compressed with the right preload. Asides, perhaps now we see why people are prepaired to pay the premium and let SKF worry about the right gap for the preload. cheers, have fun j. On Thu, Nov 3, 2011 at 8:27 PM, Andy Ibbotson <andyi_w...@btinternet.com>wrote: > Be careful here, the bearings purchased are BE CB P. The CB denotes an > axial CLEARANCE class of bearing i.e. > > http://www.skf.com/skf/productcatalogue/jsp/viewers/tableViewer.jsp?tableName=1_3_t1&maincatalogue=1〈=en > > If you want preload then you new universally matched pairs (+ lots more $) > which are marked with GA GB or GC depending on preload i.e. > > http://www.skf.com/skf/productcatalogue/jsp/viewers/tableViewer.jsp?tableName=1_3_t3&maincatalogue=1〈=en > > GA, GB, GC bearings don't need shims as they are ground to produce the > correct preload. With type CB bearings you need a spacer between the > bearings and then some method of applying the preload, i.e. tighten by > "feel", wave washer etc. > > Hope this helps. > -------------------------------------------------- > From: "Jan de Kruyf" <jan.de.kr...@gmail.com> > Sent: Thursday, November 03, 2011 4:08 PM > To: "Enhanced Machine Controller (EMC)" <emc-users@lists.sourceforge.net> > Subject: Re: [Emc-users] OT, Ball screw bearings, preload > > > Hallo, > > look at the picture quickly: > > > > > http://www.skf.com/skf/productcatalogue/jsp/viewers/tableViewer.jsp?tableName=1_3_t3&maincatalogue=1〈=en > > > > the left side picture is normally the situation when there is a big nut > on > > the shaft to hold the bearing in place. This nut either has a counter-nut > > to lock it or it is of a special construction so it can be secured. If > > this > > is the case then make sure the nut-face that holds the brearings is > > perfectly flat and square. > > The right picture is the case when the outerrings need compressing by a > > specially made ring (again perfectly flat and square). The shaft locknut > > does not need to be quite as perfect in that case. > > > > In both cases the object of the exercise is to close the natural gap > > between the rings. This will give the bearings just the right preload. > > > > j. > > > > > > > > On Wed, Nov 2, 2011 at 6:02 PM, Bruce Klawiter <bmkl...@yahoo.com> > wrote: > > > >> I bought new bearings for the ball screws on my mill, SKF 7204 BECBP. > >> > >> > http://www.skf.com/skf/productcatalogue/Forwarder?action=PPP〈=en&imperial=false&windowName=null&perfid=123002&prodid=1230020204 > >> > >> I have read conflicting information on how to install them. > >> It appears the best way would be installing them back to back, but I > have > >> read the inner rings should be clamped tight and also read the outer > >> rings > >> should be clamped tight when there back to back. > >> > >> I am not sure I understand the proload either and can't decipher what it > >> is form the SKF website. > >> > >> This is what I think I need to do, find what the preload is (weight) and > >> measure the defection of the outer race when this weight is placed on > the > >> bearing. > >> > >> Take this measurement X 2 and shim between the the races of the two > >> bearings and clamp tight the inner rings and I will have the correct > >> preload. > >> > >> Do I have this right. > >> How do I find the preload > >> > >> Your help is greatly appreciated, > >> Bruce > >> > >> > >> > ------------------------------------------------------------------------------ > >> RSA® Conference 2012 > >> Save $700 by Nov 18 > >> Register now! > >> http://p.sf.net/sfu/rsa-sfdev2dev1 > >> _______________________________________________ > >> Emc-users mailing list > >> Emc-users@lists.sourceforge.net > >> https://lists.sourceforge.net/lists/listinfo/emc-users > >> > > > ------------------------------------------------------------------------------ > > RSA(R) Conference 2012 > > Save $700 by Nov 18 > > Register now > > http://p.sf.net/sfu/rsa-sfdev2dev1 > > _______________________________________________ > > Emc-users mailing list > > Emc-users@lists.sourceforge.net > > https://lists.sourceforge.net/lists/listinfo/emc-users > > > > ------------------------------------------------------------------------------ > RSA(R) Conference 2012 > Save $700 by Nov 18 > Register now > http://p.sf.net/sfu/rsa-sfdev2dev1 > _______________________________________________ > Emc-users mailing list > Emc-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/emc-users > ------------------------------------------------------------------------------ RSA(R) Conference 2012 Save $700 by Nov 18 Register now http://p.sf.net/sfu/rsa-sfdev2dev1 _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users ------------------------------------------------------------------------------ RSA(R) Conference 2012 Save $700 by Nov 18 Register now http://p.sf.net/sfu/rsa-sfdev2dev1 _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
