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Thread: BT30 Spindle

  1. #61

    Default Re: BT30 Spindle

    Nice job
    I love watching Your build
    kevin



  2. #62
    Member Azalin's Avatar
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    Default Re: BT30 Spindle

    Thanks Kevin.

    I've grounded the spindle to 45.00 for the main bearings and 40.00mm for the upper bearings however the bearings wont fit easily. It's a hard press fit. So I tried to read about tolerences and clearences but the given info is not something like I can understand. Very technical you see. Can someone help me on this?

    My 7009C bearings are 45mm ID
    and my 7008's are 40mm id

    so how much OD do I need on the splindle for a light press fit?

    Thanks in advance.



  3. #63
    Member Azalin's Avatar
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    Default Re: BT30 Spindle

    Anyway. I kept grinding until the I get the fit I want and ended up 44.98mm on the front side and 39.98mm the rear side. That's a nice light press fit. Just like I wanted.












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    Member hanermo's Avatar
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    Default Re: BT30 Spindle

    Yup.
    Just right .. sort of..

    49.98 is a loose drop fit, but if you have a less than perfect tir, it averages bigger.
    Thus, it works out perfectly.

    Normal bearings for machine tool spindles, from memory have about 0.01 mm tolerance (in 25-50 mm sizes).
    These are P4 grade.
    P4 = expensive. Industrial.

    So, with a bit of interference your result is just what you want.

    Technical.
    I have some high end bearings in class P2, for 25 and 50 mm spindles.
    They need 0.003 mm - 0.000 fits.

    I will do the fits, via lapping,
    Brass laps and diamond grits.

    First I need to do a graduated test gauge, with 1-2 micron steps.
    This is relatively easy (cnc lathe).

    From memory;
    P2-0.003 mm
    P4-0.01 mm
    P5-0.02 mm

    Your spindle accuracy is higher than the fit of the outer ring.
    Many reasons.
    Dont worry about it.
    0.02 is plenty good enough (unless you are going like me for P2, and then you will know lots about it already .. and some costs ..)



  5. #65
    Activation process G59's Avatar
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    Default Re: BT30 Spindle

    Do the bearings have dots scratched or etched or engraved on the race flanges? If they do, set them opposite of each other and it Will further reduce your total runout. I don't know about nachi but SKF and NSK, normally have them on their precision bearings.
    Just a thought. Maybe look into it.



  6. #66
    Member Azalin's Avatar
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    Default Re: BT30 Spindle

    @Hanermo
    Thanks for the info. In case I notice any play on the bearings (I hardly think) I could add .01mm thick steel sheet between the spindle and the bearings but I don't think it'll be necessary.

    @G59
    I didn't notice any scratch or mark on the flanges but I'll take a close look to the bearings tonight. What does the scratch or etch look like? Any photos?
    Thanks.


    The grinding took me a while because I didn't have a grinder so I had to build my own. Like I was saying it isn't a real grinder but it did the job well. Now that I've passed the grinding issue I could move forward. And here is the next part to make: the first part of the labyrinth seal.





  7. #67
    Member Azalin's Avatar
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    Default Re: BT30 Spindle

    Hey G59,
    I saw an "R" on the flange. No info on the net. Could this be what you are saying?





  8. #68
    Member Azalin's Avatar
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    Default Re: BT30 Spindle

    Or maybe these little "o" letters.





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    Activation process G59's Avatar
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    Default

    Quote Originally Posted by Azalin View Post
    Or maybe these little "o" letters.

    Yes the two 'O's. Those are the one's.

    Last edited by G59; 02-15-2016 at 06:17 PM.


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    Activation process G59's Avatar
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    Default Re: BT30 Spindle

    Now, in more detail, find your greatest out of round'TIR' spot on your spindle shaft, relative to the taper, and line up the 'O' on the same spot as the highest point.. Same for the outer raceway. It's not much but can help with TIR.
    Here at the shop we have a setup to simplify the procedure. We have a Nikken BT 30 endmill holder with ground shaft put into it, (it has almost zero runout,) then we use a draw bar to seat it completely into the spindle shaft, and from there mount it in a lathe chuck, then we take our measurements to find the high spots of where the bearings will sit. Oh yeah it helps to have the other end held up with live centre.
    Do the spindle body as accurately as you can with your lathe and find the high spot of where the outer raceway seats. Line up the dot on the same spot. For Nachi bearings, which I'm not familiar with, double check to see if the dots mean lowest or greatest TIR. With the bearings usually comes instructions on the whole procedure.
    I hope that answer your question, and not add more confusion to your build. Just thought the extra info would help you if you found too much out of round for your liking and now you know there are some albeit small adjustments that can be made.
    Good luck.

    Last edited by G59; 02-15-2016 at 09:03 PM.


  11. #71
    Activation process G59's Avatar
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    Default Re: BT30 Spindle

    5 Deviation of the mean outside diameter ΔDm [µm] and position of the maximum eccentricity of the outer ring
    6 Deviation of the mean bore diameter Δdm [µm] and position of the maximum eccentricity of the inner ring


    That's the meaning of the 'O's

    Your 7009C bearing specs show maximum eccentricity deviation of zero over and up to -7um under on both the inner and outer raceway. That's for P4 bearings.

    Last edited by G59; 02-15-2016 at 08:18 PM.


  12. #72
    Activation process G59's Avatar
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    Default Re: BT30 Spindle

    For bearing preload.7009C

    A= extra light preload 110 Newtons(for expected high-speed operation at or near maximum bearings specs.
    B= light 220 Newtons
    C= moderate 440 Newtons
    D= heavy preload 880 Newtons.

    The heavier the preload, the more rigid the spindle will be at the detriment of top speed due to excessive heat build up.

    Go with 250-260 newtons and you'll have good performance, good rigidity and long life provided you don't go over 8000 rpm. So in other words, torque required is, in nNewton meters= 6.32 which = 250 Newtons of preload. That's 4.666 ft-lbs of torque required during assembly for proper preload of the bearings, in SAE units of measure.

    Ok, enough of me already. Hanermo, your turn.

    Last edited by G59; 02-15-2016 at 08:56 PM.


  13. #73
    Member Azalin's Avatar
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    Default Re: BT30 Spindle

    @G59

    I'm appreciated for your help and time.
    Best,
    Suat



  14. #74
    Member Azalin's Avatar
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    Default Re: BT30 Spindle

    ah, I just find this pdf. According to it the bearings have to has a "<" mark on the outer face but I couldn't see it.





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    Activation process G59's Avatar
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    Default Re: BT30 Spindle

    Perfect. Glad you found it. Follow The pdf. I know microns are not much, but they add up quickly by the time they reach the end of a long tool.
    Doing the alignment procedure ensures longer tool life especially small tools.

    The < markings are only for matched sets. Yours we're bought as singles.

    Last edited by G59; 02-16-2016 at 09:14 AM.


  16. #76
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    Default Re: BT30 Spindle

    I have started to cut the parts of the labyrinth seal. 2080 steel is very hard however. Maybe it was a wrong choice.





  17. #77
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    Default Re: BT30 Spindle

    The first part of the labyrinth. It looks easy but took my 2 days and it's not even finished. The stock part was high carbon and too big tho. Should I get te labyrinth hardened?







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    Default Re: BT30 Spindle

    Quote Originally Posted by Azalin View Post
    The first part of the labyrinth. It looks easy but took my 2 days and it's not even finished. The stock part was high carbon and too big tho. Should I get the labyrinth hardened?
    No Hardening required, it would be good though if you could have the 2 faces Ground, where the Bearing and Spindle come in contact with it, if the 2 faces are not perfectly parallel then you Bearings won't sit square, if you can't Grind the faces, then you could lap the back face parallel to the front

    Mactec54


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    Default Re: BT30 Spindle

    hmm I doubt my lathe is that precise to grind the two faces but I have something in my mind. I'll press fit the labyrinth piece to the spindle and turn to cut the faces. So I'll have it nicely square.

    The real problem I will face soon is the housing. A 100mm round stock is too big for my lathe to drill a big hole in it. I'm going to need to ask my frind to do the rough cut then I'll do the rest.

    It's good to hear no hardening needed on the labyrinth.



  20. #80
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    Default Re: BT30 Spindle

    OK I turned the part along with the spindle. It turned out perfect.

    Sorry for the bad quality video.





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