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Spindle problem with cincinnati tool and cutter grinder 2 spindle
PekkaNF:
Thank you. I'm trying to educate myself as well :wave:
I could not sleep, and tried to "pair" the bearings better.
Put 0,3 mm shin between outer races and just nipped the clearing out, but that way it will not show on rotationalin sensitivity. The idea was to measure radial and axial play/movement.
I used 0,002 mm/div indicator and could not get play, some movement with finger pressure, but really next to nothing.
The interesting part that when I measure very carefully radial centricity I really can't detect any real movement on the needle, I can see it moving, but on the same place. If I coax some force I can read deflection on the measuremet system (fine adjustment of the normal magnetic stand is not up to task on micrometer scale), but hardly much TIR.
Axial TIR is differen and that I'm trying to establish..Needle moves on markings, tried to "ride" them with shim, but shim rides the markings.
Pekka
PekkaNF:
Got message that the belt will be on it's last leg in Finland. Should get it at the begining of the week. pressure is mounting.
Played a little more with the bearings, a little gentle swipe on best diamond lap I had and burr on markings is now nearly non detectable.
Checked the straighness of the bearing rings. They look pretty straight even wth a dial indicatot that has resolution of 1 µm. I can see 1-2 µm high/low difference, not yet sure how does that realtes to ball races. Have to figure how to stablize measuremet the way that it produces meanigfull results - to align inner/outer rings to mimize excentricity.
Pekka
PekkaNF:
Got some time to do bit more testing with the bearings and with/no preload. Turns out that the required shim thickness depends how you stack the bearings. Although bearing inner and outer races are pretty good and coaxial with ball raceways, they are not the same axially. Simply they are not optimized to work as matched pair.
Knowing all that I know now, I may have tried matched pair angular contact bearings. What I don't know if buying C3/P6 bearing would have changed things. I'm playing here with standard (CN) SKF Explorer 6305 bearing.
I found combination that exact bearing faces are shimmed next to each others and IR/OR are turned in relation to produce almost no preload, almost no play and only 2 µm axial throw on outer ring. On most "uneconomical" orientation the error is nearly 20 µm....interestingly both configurations produce very little of radial throw. That probably means that fitting them into spindle tube will not change things.
Next decision is what bearing grease I should use.
1: I have standard new grease SKF:n LGMT 2
http://www.skf.com/group/products/lubrication-solutions/lubricants/general-purpose-industrial-and-automotive-nlgi-2-grease/index.html
NLGI 2, oil viscosity is 40 °C, 110 mm²/s
2: I have least five years old Klüber spindle grease, two diifferent varities, They are kept cool storage, packed well, plastic bag wrapped around them....But open tub and most used.
3: Order 50g tube of Kluber ISOFLEX NBU 15? That would be right stuff, bit overkill for this one.
Pekka
gerritv:
I would guess that matched sets are put together by doing what you are: measuring each one and marking perhaps the high spot. On the visible bearings on my spindle there is a vague circular spot marked on each outer race.
Gerrit
PekkaNF:
Matched bearing sets I have seen have markings IR/OR to show orientation.
I am not sure if modern bearings are matched only by selection of components or there is some grinding involved. I got once 15 years ago bearing that had inner race sides ground, and max/min marked with permanent marker on rings and handwriten note in the package.
Did not do anything Yesterday on this one, had plenty of other activity.
Pekka
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