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Metalworking (rec.crafts.metalworking) Discuss various aspects of working with metal, such as machining, welding, metal joining, screwing, casting, hardening/tempering, blacksmithing/forging, spinning and hammer work, sheet metal work. |
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#1
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lost my balls, need bearings
i had bought a second CNC Excello 602 for parts. My main machine needs
a tighter spindle so I took the old head apart today. I'm glad i had an old unit to learn on, it was tuff going. I had to make up a couple super special tools and spent more time machining than wrenching. I learned the spindle cartidge can just be dropped out without removing the head, big time saver on the main machine. I'd kind of like to replace the lower bearing seal on the hi/lo gearbox but that means removing the head so I'll likely skip this part. When I finally got the spindle cartridge apart, little ball bearings fell all over the floor. A couple evaporated into thin air. I guess thay aren't good enough to re-use anyway. I need to order bearings, the manual calls for: 2 each 7206 CTC/C78G05 1 each 7010 CTC/C78G1 1 each 7208 CTC/C78G I can order locally and PAY. Anybody suggest a lower cost bearing supply outlet? Karl |
#2
Posted to rec.crafts.metalworking
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lost my balls, need bearings
"Karl Townsend" wrote in message ... i had bought a second CNC Excello 602 for parts. My main machine needs a tighter spindle so I took the old head apart today. I'm glad i had an old unit to learn on, it was tuff going. I had to make up a couple super special tools and spent more time machining than wrenching. I learned the spindle cartidge can just be dropped out without removing the head, big time saver on the main machine. I'd kind of like to replace the lower bearing seal on the hi/lo gearbox but that means removing the head so I'll likely skip this part. When I finally got the spindle cartridge apart, little ball bearings fell all over the floor. A couple evaporated into thin air. I guess thay aren't good enough to re-use anyway. I need to order bearings, the manual calls for: 2 each 7206 CTC/C78G05 1 each 7010 CTC/C78G1 1 each 7208 CTC/C78G I can order locally and PAY. Anybody suggest a lower cost bearing supply outlet? Ebay. You need a good interchange chart to double check but in all likelyhood the first 2 on your list are simply #206 in Barden and something like 2mm9206 in fafnir for example. http://www.ntnamerica.com/product-su...rchange-search The last few digits (IE the "ctc/c7xx" ) part of the bearing are generally not important for the purposes of a spindle bearing--main thing needed being physical size ( ID OD and thinckness ) and actual contact angle. SEE http://www.ebay.com/dsc/i.html?LH_Ti...arings+2mm920* AND http://www.kalamaprecision.com/beari...g%20manual.pdf |
#3
Posted to rec.crafts.metalworking
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lost my balls, need bearings
"PrecisionmachinisT" wrote in message news:F4edncYvs_DDP8fSnZ2dnUVZ_vWdnZ2d@scnresearch. com... "Karl Townsend" wrote in message ... i had bought a second CNC Excello 602 for parts. My main machine needs a tighter spindle so I took the old head apart today. I'm glad i had an old unit to learn on, it was tuff going. I had to make up a couple super special tools and spent more time machining than wrenching. I learned the spindle cartidge can just be dropped out without removing the head, big time saver on the main machine. I'd kind of like to replace the lower bearing seal on the hi/lo gearbox but that means removing the head so I'll likely skip this part. When I finally got the spindle cartridge apart, little ball bearings fell all over the floor. A couple evaporated into thin air. I guess thay aren't good enough to re-use anyway. I need to order bearings, the manual calls for: 2 each 7206 CTC/C78G05 1 each 7010 CTC/C78G1 1 each 7208 CTC/C78G I can order locally and PAY. Anybody suggest a lower cost bearing supply outlet? Ebay. You need a good interchange chart to double check but in all likelyhood the first 2 on your list are simply #206 in Barden and something like 2mm9206 in fafnir for example. http://www.ntnamerica.com/product-su...rchange-search The last few digits (IE the "ctc/c7xx" ) part of the bearing are generally not important for the purposes of a spindle bearing--main thing needed being physical size ( ID OD and thinckness ) and actual contact angle. SEE http://www.ebay.com/dsc/i.html?LH_Ti...arings+2mm920* AND http://www.kalamaprecision.com/beari...g%20manual.pdf http://www.ebay.com/itm/7206-Nachi-A...em1e5b1a cc65 A gold or silver colored box generally denotes a higher quality class 9 |
#4
Posted to rec.crafts.metalworking
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lost my balls, need bearings
You need a good interchange chart to double check but in all likelyhood the first 2 on your list are simply #206 in Barden and something like 2mm9206 in fafnir for example. http://www.ntnamerica.com/product-su...rchange-search The last few digits (IE the "ctc/c7xx" ) part of the bearing are generally not important for the purposes of a spindle bearing--main thing needed being physical size ( ID OD and thinckness ) and actual contact angle. Can you tell me how to measure the contact angle on my existing bearings by chance? here's the chart i got from the above link with the numbers off the bearing itself (SKF7206 B G) http://www.ntnamerica.com/products/b...id=RBSRA&ctc=B It gives me the code for contact angle not the actual number Reason I ask, I found this in a fafnir 3M (25 degree contact angle) http://www.ebay.com/itm/FAFNIR-3MM20...em4cfadc db80 Sounds like a really good bearing pair Thanks for your help, I'm studying this. Karl |
#5
Posted to rec.crafts.metalworking
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lost my balls, need bearings
"Karl Townsend" wrote in message ... You need a good interchange chart to double check but in all likelyhood the first 2 on your list are simply #206 in Barden and something like 2mm9206 in fafnir for example. http://www.ntnamerica.com/product-su...rchange-search The last few digits (IE the "ctc/c7xx" ) part of the bearing are generally not important for the purposes of a spindle bearing--main thing needed being physical size ( ID OD and thinckness ) and actual contact angle. Can you tell me how to measure the contact angle on my existing bearings by chance? here's the chart i got from the above link with the numbers off the bearing itself (SKF7206 B G) Sorry no way to measure after the fact http://www.ntnamerica.com/products/b...id=RBSRA&ctc=B It gives me the code for contact angle not the actual number As a practical matter, contacy angle will vary depending upon the ratio of how much load is to be placed on the end of the spindle as compared to side loading. So for machine that is used mostly for drilling you want to take that in consideration as opposed to if you are going to be millling all of the time then you want a higher rating in the direction so your bearing set will more closely approximate a standard ball bearing IE something like 15 degrees Reason I ask, I found this in a fafnir 3M (25 degree contact angle) 25 or 30 degrees is about middle of the road for a milling machine although Fadal uses a 15 deg in the lower set and 30 deg in the upper so YMMV http://www.ebay.com/itm/FAFNIR-3MM20...em4cfadc db80 Sounds like a really good bearing pair pinch them together in a vice with a shim on the outer race and jiggle the inners to measure preload (if any ) if you are unable to obtain specs from the manufacturer. But if I my memory of Fafnir's numbering systemthat is correct that is a matched set that's intended for duplex universal mounting which means they can be mounted face /face or back /back and either way you will end up with zero preload. Thanks for your help, I'm studying this. No prob, I'll be out for the weekend but I'll check back when I return. |
#6
Posted to rec.crafts.metalworking
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lost my balls, need bearings
"PrecisionmachinisT" wrote in message ... "Karl Townsend" wrote in message ... You need a good interchange chart to double check but in all likelyhood the first 2 on your list are simply #206 in Barden and something like 2mm9206 in fafnir for example. http://www.ntnamerica.com/product-su...rchange-search The last few digits (IE the "ctc/c7xx" ) part of the bearing are generally not important for the purposes of a spindle bearing--main thing needed being physical size ( ID OD and thinckness ) and actual contact angle. Can you tell me how to measure the contact angle on my existing bearings by chance? here's the chart i got from the above link with the numbers off the bearing itself (SKF7206 B G) Sorry no way to measure after the fact http://www.ntnamerica.com/products/b...id=RBSRA&ctc=B It gives me the code for contact angle not the actual number As a practical matter, contacy angle will vary depending upon the ratio of how much load is to be placed on the end of the spindle as compared to side loading. So for machine that is used mostly for drilling you want to take that in consideration as opposed to if you are going to be millling all of the time then you want a higher rating in the direction so your bearing set will more closely approximate a standard ball bearing IE something like 15 degrees Reason I ask, I found this in a fafnir 3M (25 degree contact angle) 25 or 30 degrees is about middle of the road for a milling machine although Fadal uses a 15 deg in the lower set and 30 deg in the upper so YMMV http://www.ebay.com/itm/FAFNIR-3MM20...em4cfadc db80 Sounds like a really good bearing pair pinch them together in a vice with a shim on the outer race and jiggle the inners to measure preload (if any ) if you are unable to obtain specs from the manufacturer. But if I my memory of Fafnir's numbering systemthat is correct that is a matched set that's intended for duplex universal mounting which means they can be mounted face /face or back /back and either way you will end up with zero preload. Thanks for your help, I'm studying this. No prob, I'll be out for the weekend but I'll check back when I return. Your typical modern milling spindle has a duplex set that has the inner races locked into the lower housing...basically its clamped tightly onto the spindle with a jam nut and then is fitted rigidly into the housing so that it cannot permanently migrate up nor down by even a tiny amount unless fairly HUGE pressures are applied. Its clamped onto the shaft with a jamb nut which by itself would cause a zero-preload condition...but since the assembly is then pressed up into the spindle housing against a shoulder into a cavity that is just a *tiny bit shallower* than the bearings' height......( only shallower by a 1/2 thou or so, mind you ) but this is how your preload actually comes about... The upper bearings are different, basically they are intentionally allowed to float in the axial plane, no attachment to the housing at all other than some way to keep them from falling clear off if they were do inclined to do so--reason this is done is so that the shaft lenght can grow due to heating without having it affect preload ( binding or sloppiness would occur otherwise ) and also so that undue problems don't arise with trying to incessantly chase tool length as the spindle warms up which can be a real PITA especially where you are under cnc control. Your mileage may vary but the above probably describes the vast majority of milling spindles out there today with a fairly high degree of accuracy. |
#7
Posted to rec.crafts.metalworking
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lost my balls, need bearings
On 3/9/2012 4:09 PM, Karl Townsend wrote:
i had bought a second CNC Excello 602 for parts. My main machine needs a tighter spindle so I took the old head apart today. I'm glad i had an old unit to learn on, it was tuff going. I had to make up a couple super special tools and spent more time machining than wrenching. I learned the spindle cartidge can just be dropped out without removing the head, big time saver on the main machine. I'd kind of like to replace the lower bearing seal on the hi/lo gearbox but that means removing the head so I'll likely skip this part. When I finally got the spindle cartridge apart, little ball bearings fell all over the floor. A couple evaporated into thin air. I guess thay aren't good enough to re-use anyway. I need to order bearings, the manual calls for: 2 each 7206 CTC/C78G05 1 each 7010 CTC/C78G1 1 each 7208 CTC/C78G I can order locally and PAY. Anybody suggest a lower cost bearing supply outlet? Karl It has been a while since I ordered any bearings, so I don't know the status of these companies. But look for Reid Tool Supply or W.M. Berg inc. |
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