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  1. #21
    Deep groove ball bearings are intended to work only with radial forces and not with axial forces.

    Metal shielded bearings are more efficient over rubber sealed as rubber sealed has more friction.

  2. #22
    Hi Irving,Ross

    These tapered roller bearings are for the Lathe spindle as I'm aware the Deepgroove are not satisfactory for the lathe spindle.
    This is common to the Mini lathes and the deepgroove come standard with the mini lathes.

  3. #23
    Got to admit here that I have built this very 4th axis. I use it on a router and have cut oak, beech and Iroko, it works perfectly well with a 6:1 reduction and a 3Nm stepper. Although the materials I have cut are a little harder than cheese, and I intend to try PVC an HDPE soon, you'd be mad to think of using it to cut metals.

    It cost more to build than buying a rotary table and converting it; even given I am in the happy position of getting the main shaft, backplate and ally plates etc for free. I used my router to machine the plates and the lathe at work to bore the backplate for the chuck and it STILL cost more than a bought solution but I'm happy as it was a good excersise.

    Jeff.
    Nothing is foolproof......to a sufficiently talented fool!

  4. #24
    Tom's Avatar
    Location unknown. Last Activity: 30-11-2016 Has been a member for 7-8 years. Has a total post count of 172. Referred 1 members to the community.
    Quote Originally Posted by GeorgeD View Post
    Axial forces or Friction?
    I fancy a "Friday night pub quiz"....

    George, the question is in two parts:

    1) What is the difference between these two identically sized bearings? The answer I'm looking for is not 12.03
    http://simplybearings.co.uk/shop/p17...duct_info.html
    http://simplybearings.co.uk/shop/p51...duct_info.html

    2) Assuming it was suitable for the task, which one would you install into your (hypothetical):
    a) Moon lander
    b) Nuclear submarine
    c) Power station
    d) Gantry crane
    e) Precision 4th axis
    f) Miscellaneous 23.5hr/day, production critical machinery
    g) Front car hub
    h) Rear car hub
    i) Shonky 4th axis built as a learning exercise

    Winner gets a pint. *In true pub quiz style, I reserve the right to fall asleep before the end of the discussion and not notice it's all finished until I see that all but one table is looking depressed.

    By the way, it's not a loaded question. I haven't built my first shonky 4th axis yet, but when I do, it WILL be shonky.

  5. #25
    We'll see how we get on with my shonky 4th axis.

    PS its a tapered roller bearing and it wasn't from Simply bearings/these bearings are specifically for the Mini lathe spindles ie they're the replacement for the deep groove bearings.

  6. #26
    Quote Originally Posted by Tom View Post
    I fancy a "Friday night pub quiz"....

    George, the question is in two parts:

    1) What is the difference between these two identically sized bearings? The answer I'm looking for is not 12.03
    http://simplybearings.co.uk/shop/p17...duct_info.html
    http://simplybearings.co.uk/shop/p51...duct_info.html

    2) Assuming it was suitable for the task, which one would you install into your (hypothetical):
    a) Moon lander
    b) Nuclear submarine
    c) Power station
    d) Gantry crane
    e) Precision 4th axis
    f) Miscellaneous 23.5hr/day, production critical machinery
    g) Front car hub
    h) Rear car hub
    i) Shonky 4th axis built as a learning exercise

    Winner gets a pint. *In true pub quiz style, I reserve the right to fall asleep before the end of the discussion and not notice it's all finished until I see that all but one table is looking depressed.

    By the way, it's not a loaded question. I haven't built my first shonky 4th axis yet, but when I do, it WILL be shonky.
    Me ME MEEE!!!!

    One is photographed from the left and the other from the right! I CLAIM MY PINT!

    BTW, anything wrong with using angular contacts like the guy in the video did?

    Jeff.
    Nothing is foolproof......to a sufficiently talented fool!

  7. #27
    Trick question!! Bearings are things you Yomp along to get to the next check point/Pub and you use Mils!! (much better than silly degrees 'cos there's lots of them, In fact 6400 if what's left of my grey cell filing system is still operational!!)
    Last edited by Wobblybootie; 30-07-2010 at 06:55 PM. Reason: Punctuation
    Tim G-C

    I disapprove of what you say, but I will defend to the death your right to say it.

    (attrib. Voltaire but written by Evelyn Beatrice Hall "The Friends of Voltaire" 1906)

  8. #28
    Tom's Avatar
    Location unknown. Last Activity: 30-11-2016 Has been a member for 7-8 years. Has a total post count of 172. Referred 1 members to the community.
    Quote Originally Posted by Smiler View Post
    I CLAIM MY PINT!
    Jeff, the pint's yours! You may have to remind me, but don't be shy!

    Ref the angular contact bearings, I'm not really sure. I think the way the big boys do it is to pair a set of single row angular contact bearings opposite each other, and preload them, either next to each other at the chuck end (as a matched pair, with a simple roller at the other end of the shaft), or preloaded along the whole length of the shaft (a non-matched pair, one at each end). I reserve the right to be proven wrong.

    As george says, the mini-lathes ship with deep-groove bearings, and the upgrade is to replace them with taper roller bearings. This mod works quite nicely (I've done it), but I don't think you'll see taper rollers in this application on much bigger equipment. I think the mini-lathes get away with it because the loads are low. Which is lucky because the larger angular contact bearings, especially in matched pairs are not cheap.

  9. #29
    Hi George,

    I think that without meaning to you are upsetting alot of people on this forum :exclaim:

    You certainly are looking at alot of new things - making a cnc machine, learning how to cast ali at home, making a 4th axis, learning how to weld. If it was me I'd tackle these skills one at a time, and take some of the advice offered along the way on this forum, but I think that you are one of those people who only learns when he has tried it out with his own hands. I hope it all turns out how you want it to.

    I think you can put some axial load on a deep groove bearing, and using a ramp cut rather than plunge when milling/routing where possible should help a bit, so for Ross's application it's worth a look. If you've found a source which says no axial load I'd be interested in a link.

    Another factor with bearing quality is inclusions (impurities) in the race way. Less inclusions should give a longer life. Got this info at a Timken presentation, so bit of a sales pitch but sounds plausible.

    With regards to your machine, can I ask what it is that you intend to make on this new cnc machine with the 4th axis? That might generate some helpful comments.


    Ross,
    When you've got some more info it would make a good post to see your spindle design (post#20). I cheated and bought ready made, but would be interested to see where you're at. To make it accurate, well balanced, smooth, quiet, durable, and run at very high speed has it's challenges!
    Last edited by routercnc; 30-07-2010 at 07:38 PM. Reason: extra question to Ross
    Building a CNC machine to make a better one since 2010 . . .
    MK1 (1st photo), MK2, MK3, MK4

  10. #30
    If you've found a source which says no axial load I'd be interested in a link.
    Me too. Ive been looking at the info from the bearing manufactures SFK,NSK etc and they all say the same thing, I wasnt going to get in to here but what the Hell. deep groove are the fastest but provide low axial resistance (when compared to tapered or AC), if they couldnt take any axial load then the shaft and housing would move independantly No.....

    Ross,
    When you've got some more info it would make a good post to see your spindle design (post#20). I cheated and bought ready made, but would be interested to see where you're at. To make it accurate, well balanced, smooth, quiet, durable, and run at very high speed has it's challenges!
    I plan to, just got a bit more research to do. Making it accurate and smooth seems to mean throwing at it ( mulitple angular contact with different contact angles, correct Diameter and spacing for ridigity with oil/air mist lubrication, easy) :whistling: so thats why I was looking at a modified deep groove set up to reduce cost as after all it would be a low use DIY spindle

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