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Thread: BT30 Spindle

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  1. #81
    Join Date
    Mar 2014
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    1131

    Re: BT30 Spindle

    What is the OD of the main housing on most BT30 spindles? I'm asking because my main bearings are pushing me for a big housing. The bearings are 75mm OD so when I cut the housing 90mm then I'll have 7.5mm wall. And I'll drill 6x 4mm threads for the outer part of the labyrinth seal. So that the 6 holes will be weak points. In short I have 2 choices: 90mm or 95mm housing. Please see the attached render. What do you think?

    Another question: is stainless steel acceptable for the housing?


  2. #82
    Join Date
    Jan 2005
    Posts
    15362

    Re: BT30 Spindle

    Quote Originally Posted by Azalin View Post
    What is the OD of the main housing on most BT30 spindles? I'm asking because my main bearings are pushing me for a big housing. The bearings are 75mm OD so when I cut the housing 90mm then I'll have 7.5mm wall. And I'll drill 6x 4mm threads for the outer part of the labyrinth seal. So that the 6 holes will be weak points. In short I have 2 choices: 90mm or 95mm housing. Please see the attached render. What do you think?

    Another question: is stainless steel acceptable for the housing?
    303 stainless or 416 stainless are both free machining and ideal for most things like this, you want at least a 6mm cap screws in the front cover, this is not only part of your labyrinth seal, you need good strength for your bearing preload also, so 4mm cap screw is not enough for a bearing of this size, bigger the better in that area, you can step out the diameter of front section for a length of 20 to 25mm, just so you can use a good size cap screw, around a 12mm or more wall thickness in the front where you need the cap screws

    When you machine the housing for you Bearing fit, make sure the housing is cold before you do the final measurement, and then cut for your Bearing fit
    Mactec54

  3. #83
    Join Date
    Mar 2014
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    1131

    Re: BT30 Spindle

    Quote Originally Posted by mactec54 View Post
    you can step out the diameter of front section for a length of 20 to 25mm
    Where do you mean exactly?

    Sent from my GT-I9300 using Tapatalk

  4. #84
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    Jan 2005
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    15362

    Re: BT30 Spindle

    Something like this
    Attached Thumbnails Attached Thumbnails Spindle Housing.gif  
    Mactec54

  5. #85
    Join Date
    Mar 2014
    Posts
    1131

    Re: BT30 Spindle

    OK I get it now. Thanks.

    I made the button (the part on the top that the cylinder pushes it down) however I've made a mistake on the dimensions so I'll make a new one tomorrow.


  6. #86
    Join Date
    Nov 2012
    Posts
    29

    Re: BT30 Spindle

    Quote Originally Posted by Azalin View Post
    What is the OD of the main housing on most BT30 spindles?
    Most of them have 90mm OD.

  7. #87
    Join Date
    Jan 2007
    Posts
    317

    Re: BT30 Spindle

    What about threading the upper o.d. of the lower labyrinth seal and the lower end of the spindle housing, then just screw them together? That's how I got mine designed now. I'm using cast iron for my housing as it was the cheaper alternative. But like you. my lathe isn't long enough to bore through the 12" long piece. So I'm farming that out as well. My plan is to go ahead and make the lower labyrinth seal with the threads and let whoever gets the job of making the housing use it as a gauge.

    If I recall correctly, that hunk of cast iron is 4" in diameter. My finished part will be 3.78" or 96mm in the area of the lower bearings and step down to 2.95" or 75mm. I've bought matched pair bearings, so I don't have the spacer between them like yours. The larger portion for the bearings on mine is 2.24" long. That dimension is a moving target right now and the only one that isn't firmed up. My lower labyrinth seal is intended to sit flush with the bottom of the housing, but not cover it at all. That way if there's a bit of mismatch after tightening into the bearings it's no big deal. a small set screw coming in from the side of the housing is what I intend to use to lock the labyrinth seal in place. I 'm going to bore two holes in the lower labyrinth so I can use a pin wrench to tighten it in place. They will be blind holes though.

    Your project is looking good so far, keep up the good work.

    Bob

  8. #88
    Join Date
    Oct 2012
    Posts
    342

    Re: BT30 Spindle

    My Chinese BT30 spindle is 90mm OD on the nose and the main part of the body.

    -Dan

    Quote Originally Posted by Azalin View Post
    What is the OD of the main housing on most BT30 spindles? I'm asking because my main bearings are pushing me for a big housing. The bearings are 75mm OD so when I cut the housing 90mm then I'll have 7.5mm wall. And I'll drill 6x 4mm threads for the outer part of the labyrinth seal. So that the 6 holes will be weak points. In short I have 2 choices: 90mm or 95mm housing. Please see the attached render. What do you think?

    Another question: is stainless steel acceptable for the housing?


  9. #89
    Join Date
    Mar 2014
    Posts
    1131

    Re: BT30 Spindle

    I need some suggestions about taper cone. It is a perfect fit with the taper now but it isn't grounded. I can try to grind but I fear that I'll mess it up because the grinder must be perfectly centered on the Y axis. Otherwise the taper will play inside. It is a risk for me. So what should I do? Grind and success or trash it or leave it as it is? There is no one who can do the grinding for me in my area.


    Thanks Dan. What is the size of the thinnest area in the nose? And front bearing OD?

  10. #90
    Join Date
    Oct 2012
    Posts
    342

    Re: BT30 Spindle

    What CAD software are you using? I might be able to save off a copy of my spindle, I have modeled most of the parts in Solidworks.

    Bearing is 68mm and the OD of the housing is 90mm, so 11mm wall thickness.

    -Dan

    Quote Originally Posted by Azalin View Post
    I need some suggestions about taper cone. It is a perfect fit with the taper now but it isn't grounded. I can try to grind but I fear that I'll mess it up because the grinder must be perfectly centered on the Y axis. Otherwise the taper will play inside. It is a risk for me. So what should I do? Grind and success or trash it or leave it as it is? There is no one who can do the grinding for me in my area.


    Thanks Dan. What is the size of the thinnest area in the nose? And front bearing OD?

  11. #91
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    Mar 2014
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    1131

    Re: BT30 Spindle

    Nice! I have SW too. I'll PM you my email.

  12. #92
    Join Date
    Oct 2012
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    342

    Re: BT30 Spindle

    The model is now on GrabCAD located here.

    https://grabcad.com/library/chinese-bt30-spindle-1

    -Dan

  13. #93
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    Mar 2014
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    1131

    Re: BT30 Spindle

    Thanks Dan.

  14. #94
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    Mar 2014
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    1131

    Re: BT30 Spindle

    It took my 2 days to setup the lathe for grinding the taper cone to the right angle. I used an aluminium piece as donor. I'll do the real grinding tomorrow.






  15. #95
    Join Date
    Mar 2014
    Posts
    1131

    Re: BT30 Spindle

    @Mactec54

    What about this one?

    I kept the 90mm OD but added a flange as you suggested. Length is 30mm and holes are for M8 bolts.


  16. #96
    Join Date
    Aug 2004
    Posts
    780

    Re: BT30 Spindle

    Was the wheel static and you ran the spindle ?

  17. #97
    Join Date
    Mar 2014
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    1131

    Re: BT30 Spindle

    OK the taper is grounded now. I believe it has almost zero run-out and about 4.2mm drawbar travel from close to open which is what I wanted. Now I can move on to the next part. The main part of the labyrinth.


  18. #98
    Join Date
    Nov 2012
    Posts
    29

    Re: BT30 Spindle

    The best way to grind taper is to grind it on its own bearings. May be it will be necessary to regrind taper after assembling.

  19. #99
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    Mar 2014
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    1131

    Re: BT30 Spindle

    How do they do it? On the lathe or mounted on the mill?

  20. #100
    Join Date
    Mar 2015
    Posts
    6

    Re: BT30 Spindle

    Quote Originally Posted by Azalin View Post
    How do they do it? On the lathe or mounted on the mill?
    You need to put the spindle in place to the mill where it is going to be used and grind it there.
    Here is Stan was doing that https://www.youtube.com/watch?v=CFAkb93_V3M

    BTW. So cool thread. Looking forward to see it finished

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