Small spindle head

This is a discussion on Small spindle head within the General Machine Building forums.

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  1. #11
    BillTodd's Avatar
    Location unknown. Last Activity: 23-12-2013 Has been a member for 5-6 years. Has a total post count of 434. Received thanks 17 times, giving thanks to others 1 times.
    And whilst I am planning to loctite rear bearing, I don't think I will need it for the front one.
    The rear bearing should float (or at least not be too tight) to avoid stress from thermal expansion differences between spindle and casing.

    BTW interesting article on Bob Warfield's site about using standard deep groove bearing in a spindle:(scroll down a bit)
    http://www.cnccookbook.com/CCMillBeltDrive.html

    [edit]

    And this is from a bearing expert:
    [ame="http://www.practicalmachinist.com/vb/showpost.php?p=1065036&postcount=4"]Practical Machinist - Largest Manufacturing Technology Forum on the Web - View Single Post - Tapered roller vs angular contact ball bearings[/ame]

    [ame="http://www.practicalmachinist.com/vb/showpost.php?p=1065158&postcount=10"]Practical Machinist - Largest Manufacturing Technology Forum on the Web - View Single Post - Tapered roller vs angular contact ball bearings[/ame]
    Last edited by BillTodd; 02-12-2009 at 03:41 PM.

  2. #12
    bambuko's Avatar
    Location unknown. Last Activity: 30-09-2012 Has been a member for 4-5 years. Has a total post count of 21.
    Quote Originally Posted by BillTodd View Post
    The rear bearing should float ...
    That was my original plan and I have turned the housing with sliding fit for the rear bearing (as opposed to front one, which is interference fit).
    I was considering using Loctite on rear bearing after assy to keep things "solid" as I didn't expect the spindle to heat appreciably at my target max 5k rpm. But I am probably running in circles, changing my ideas every five minutes - so I will stick with original idea (rear bearing floating) and see how it works.

    Quote Originally Posted by BillTodd View Post
    ...BTW interesting article on Bob Warfield's site about using standard deep groove bearing in a spindle:(scroll down a bit)
    http://www.cnccookbook.com/CCMillBeltDrive.html...
    Yes, this is in my favourites,

    Thanks for the links!

  3. #13
    Ross77's Avatar
    Location unknown. Last Activity: 18-06-2013 Has been a member for 4-5 years. Has a total post count of 572. Received thanks 17 times, giving thanks to others 11 times.
    Ah. so you dont need such tight tolerances at low rpm then?

    That would also explain how the other spindles I have work. Couldnt work out where the tensioning nut was

  4. #14
    bambuko's Avatar
    Location unknown. Last Activity: 30-09-2012 Has been a member for 4-5 years. Has a total post count of 21.
    Quote Originally Posted by Ross77 View Post
    Ah. so you dont need such tight tolerances at low rpm then?...
    Didn't quite say this
    It's a combination of target (comparatively low) rpm and light duty, that makes me think I can get away with a simplified design.

    BTW, you have also asked:
    ...I'm interested to see what you are going to drive it with?...
    Didn't give much thought yet. Definitely nothing fancy until I am convinced that I can make it work OK.
    For the moment I have (don't laugh) sewing m/c motor and that will do for the testing.

  5. #15
    Ross77's Avatar
    Location unknown. Last Activity: 18-06-2013 Has been a member for 4-5 years. Has a total post count of 572. Received thanks 17 times, giving thanks to others 11 times.
    Sorry it was more of a question than a statement, Im still learning.

    dont think I can laugh at the sewing machine motor, I'm one of those fools converting a pillar drill to a cnc mill :heehee:

  6. #16
    bambuko's Avatar
    Location unknown. Last Activity: 30-09-2012 Has been a member for 4-5 years. Has a total post count of 21.
    Before continuing with the spindle I needed to take care of my DTI.
    Up until now it was all a bit Heath-Robinson and this was reflected in "variable" :heehee: results when it came to taper turning.
    So first thing was to make a bracket for DTI, which would allow fixing of the clock directly to QCTP:



    While at it, I have also checked my lathe (Prazimat from the old DDR)

    My usual clock (with 0.01mm resolution) detected hardly any movement, so I used my new clock from Draper (0.001mm resolution):



    Prazimat uses DIN55027 spindle head, size No3 and one can get chucks with this fitting on the back,
    but they are rather expensive , so mine are all with usual backplate arrangement.

    The reading on my Draper DTI was +/- 0.0015mm (total movement of 0.003mm) and just to check it I have tried my best DTI (with 0.0001" resolution):



    The reading was below one division, roughly about +/- 0.00005" - 0.00008", with the total movement of about 0.00015

    Now, the only thing I still need before setting the topslide with the DTI, is the straight probe for the front (instead of the usual ball-nose)
    to overcome my usual difficulty of setting the clock exactly at the centre (usually ending with the taper not exactly replicating the original :naughty:)
    Chris

  7. #17
    ptjw7uk's Avatar
    Lives in harwich, United Kingdom. Last Activity: 2 Hours Ago Has been a member for 4-5 years. Has a total post count of 348. Received thanks 12 times, giving thanks to others 2 times.
    Hi Bambuko
    Thanks for your post it appears to anser one of my long running questions as to what type fixing my lathe has, it looks very similar to the one you have although my one is chinese as the Sieg C6.
    I obtained a back plate for a C6 which fits but have had no luck in sourcing another.
    I will check the measurements for the Din 55027 fitting now that I have them.
    Peter
    Last edited by ptjw7uk; 06-12-2009 at 08:31 PM.

  8. #18
    bambuko's Avatar
    Location unknown. Last Activity: 30-09-2012 Has been a member for 4-5 years. Has a total post count of 21.
    You are welcome Peter,
    but I doubt that your Chinese lathe is using German spindle.
    It's more likely American spindle?
    Have a look at Lathe Spindle Nose & Backplate Fittings at lathes.co.uk
    Chris

    later edit:
    It would appear (from this web page) that C6 has copied some aspects of DIN short taper spindle, but missed the most important ie "taper".
    In which case it looks like it is "Sieg special" and it does not conform to any norms?
    Last edited by bambuko; 06-12-2009 at 09:19 PM.

  9. #19
    bambuko's Avatar
    Location unknown. Last Activity: 30-09-2012 Has been a member for 4-5 years. Has a total post count of 21.
    latest update:
    Finished tip for DTI to be used in clocking the tapers.
    Here being set up vertically:



    Almost ready to start turning the spindle ...

  10. #20
    bambuko's Avatar
    Location unknown. Last Activity: 30-09-2012 Has been a member for 4-5 years. Has a total post count of 21.
    Today got a chance to try clocking the taper.
    My idea was to use actual collets to set the angle - clearly an iffy idea because they are not solid, but worth a try before using something more complicated.

    When preparing the spigot I made sure it's diameter was the top of the collet range - ie when using 9mm/8mm collet, the spigot was 9mm.

    Also having clocked the largest collet, I than turned the spigot down and clocked smaller collet and checked whether the readings were the same for both:



    I have managed to clock the taper to within +/-.0008 for both collets.
    I don't know if this is good enough ... but I will try to go with it

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