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_t3maincatalogue=1lang=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=PPPlang=enimperial=falsewindowName=nullperfid=123002prodid=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
Re: [Emc-users] OT, Ball screw bearings, preload
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_t1maincatalogue=1lang=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_t3maincatalogue=1lang=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_t3maincatalogue=1lang=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=PPPlang=enimperial=falsewindowName=nullperfid=123002prodid=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
Re: [Emc-users] OT, Ball screw bearings, preload
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.comwrote: 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_t1maincatalogue=1lang=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_t3maincatalogue=1lang=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_t3maincatalogue=1lang=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=PPPlang=enimperial=falsewindowName=nullperfid=123002prodid=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
Re: [Emc-users] OT, Ball screw bearings, preload
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.comwrote: 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_t1maincatalogue=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_t3maincatalogue=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_t3maincatalogue=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〈=enimperial=falsewindowName=nullperfid=123002prodid=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
Re: [Emc-users] OT, Ball screw bearings, preload
If there are single row bearings just look at the thickness of the races the workout which direction takes thrust load one side of a race is thin the other thick. Then decide face - face or back - back mount depending on application and required moment stiffness. -- From: Jan de Kruyf jan.de.kr...@gmail.com Sent: Thursday, November 03, 2011 7:10 PM To: Enhanced Machine Controller (EMC) emc-users@lists.sourceforge.net Subject: Re: [Emc-users] OT, Ball screw bearings, preload 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.comwrote: 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_t1maincatalogue=1lang=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_t3maincatalogue=1lang=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_t3maincatalogue=1lang=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=PPPlang=enimperial=falsewindowName=nullperfid=123002prodid=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
Re: [Emc-users] OT, Ball screw bearings, preload
On 2 November 2011 16:02, Bruce Klawiter bmkl...@yahoo.com wrote: I have read conflicting information on how to install them. Let me add more then 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. In the case of a matched-pair of bearings then you would want to clamp both, and then the preload would be correct. Assuming that the bearings are fitted to a seat on the ballscrew with a screwed clamp ring, I would clamp the outers together big-side to big-side with a spacer ring between them, then tighten the clamp ring until the preload is right. Which, in my case would be based entirely on guesswork and intuition. If you want a better basis for right and you know what the required preload is ( the motor torque and the leadscrew pitch might not be the worst basis) then you can calculate the required clamp-ring torque on the basis of the thread diameter and a friction guess. You can use the equations here (http://euler9.tripod.com/fasteners/preload.html ) with the simplification that you have no collar friction as the inner race you are tightening against is free to rotate. -- atp The idea that there is no such thing as objective truth is, quite simply, wrong. -- RSA#174; Conference 2012 Save $700 by Nov 18 Register now#33; http://p.sf.net/sfu/rsa-sfdev2dev1 ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] OT, Ball screw bearings, preload
Bruce, On a bearing set: I believe the preload will be correct without shims. I have rarely seen preload changed/set with shims. The outer rings are usually together between the rollers/balls. On a shaft with bearings on each end: assemble the components and measure the free play calculate shim requirements for removing/correcting end play HTH Stuart On Wed, Nov 2, 2011 at 11:02 AM, 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=PPPlang=enimperial=falsewindowName=nullperfid=123002prodid=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 -- dos centavos -- RSA#174; Conference 2012 Save $700 by Nov 18 Register now#33; http://p.sf.net/sfu/rsa-sfdev2dev1 ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
