How to Change Bearings - COA Square Col


Results 1 to 6 of 6

Thread: How to Change Bearings - COA Square Col

  1. #1
    Member Danal's Avatar
    Join Date
    Sep 2019
    Posts
    3
    Downloads
    0
    Uploads
    0

    Default How to Change Bearings - COA Square Col

    I have a Charter Oaks Automation Square Column mill with the factory 3-phase motor and VFD controller. Which works quite nicely, by the way.

    I have a symptom where the spindle runs with very little, almost zero, runout when I dial indicate the R8 taper inside, running with no load. However, when I cut, the entire thing wobbles. I've tried numerous collets and bits... so that isn't the cause. I'm assuming the load of cutting is causing the bearings to show slop where running a bare spindle (with the head sideways 90 deg to make reaching everything easier) does not.

    So...

    Can anyone point me to a post, guide, or documentation on how to change the bearings? And perhaps what bearings to order? I have searched, but I have not found... :-)

    Thanks!

    Similar Threads:


  2. #2
    Member
    Join Date
    Oct 2005
    Location
    USA
    Posts
    99
    Downloads
    0
    Uploads
    0

    Default Re: How to Change Bearings - COA Square Col

    Are the gibs adjusted?



  3. #3
    Member Danal's Avatar
    Join Date
    Sep 2019
    Posts
    3
    Downloads
    0
    Uploads
    0

    Default Re: How to Change Bearings - COA Square Col

    Quote Originally Posted by Ron Thompson View Post
    Are the gibs adjusted?
    Yep. X and Y locked, Z as tight as I can get them and still advance.

    Also, I shouldn't have said "the entire thing" wobbles; I should have been more specific: Column, gearbox, etc, seem stable to the eye. Bit (endmill) wobbles. A lot. As mentioned, tried numerous R8 collets and different endmills. I'd believe a couple could be off, but not the six or seven, from different sources, that I've tried. Dial Indicator on the smooth part of the endmill near the collet, no load (not cutting) indicates +/- 0.001 or even 0.0005 Total Runout. Dial up in the R8 taper, no collet or endmill, indicates as near +/- zero as I can determine with my Dial and clamps. I can't measure the wobble while cutting, but my eye tells me it is above 0.1

    Only under load does it wobble.

    Mill is about 6 years old, used very little, seemed to cut very smoothly when new. Now getting to (trying to) use it a lot, ran into this problem.

    Gearbox does not leak.

    Keep the suggestions coming...



  4. #4
    Member
    Join Date
    Jun 2010
    Location
    Australia
    Posts
    4252
    Downloads
    4
    Uploads
    0

    Default Re: How to Change Bearings - COA Square Col

    I would check the TOP bearing for looseness.

    Cheers
    Roger



  5. #5
    Member Danal's Avatar
    Join Date
    Sep 2019
    Posts
    3
    Downloads
    0
    Uploads
    0

    Default Re: How to Change Bearings - COA Square Col

    Thanks for everybody's help and suggestions. Now resolved.

    1) Ron asked a great question in the very first reply to my post: "Are the gibs tight?" They gibs were tight, the literally gibs in X/Y/Z (column)... but... I did not understand how the tightener for the spindle itself worked. It was so loose on my machine that it could not be tightened. It was just spinning internally. Once I disassembled everything, and saw how it "pinches" the spindle to remove play, and how it has to be touching the spindle to tighten, there was a huge "AHA" moment. I set it back up properly as I reassembled things, and it both works and I understand how to use it...!

    2) Raised the RPM quite a bit. I was cutting WAY WAY too slowly before, perhaps I was thinking of drilling. I was probably cutting at 5 or 10 RPM. As each "wing" of the tip of the endmill circled around, that's one wobble. I raised RPM to about 600. Much better results. I'm cutting with manually applied "cutting fluid", and probably won't go any faster as long as that is the setup.

    As an aside, I have a 3rd party coolant kit, haven't installed it yet because that will involve lifting the main part of the mill, and it is a beast. These experiences encourage me to go to the trouble to install the coolant kit. The mill is cutting really well with manually applied fluid; with coolant, the cuts could only be better.

    3) Disassembled, greased, and reassembled EVERYTHING in the spindle. I believe the bearings were fine; their preload spacers are certainly locked correctly now! Again, I don't think anything was really wrong or contributing to the wobble; at the same time, it really did need grease in a lot of places. So I'm glad that I did dis/re-assemble. Also, that process led to me truly understanding the spindle "lock" (or "anti-play") mentioned in item (1) above.


    To be clear, this was all Operator Error. Me. Lack of knowledge of the machine. Cutting at way too low an RPM. THANK YOU to those who patiently replied with ideas. Part of the resolution was dis/re-assembling things and the knowledge gained; part of the resolution was thoughts triggered by your kind comments.

    .

    P.S. For anyone who has never removed the spindle:

    Remove the clamp on thing that moves the Z indicator in the faceplate. Remove the whole assembly.
    Remove the left side knob that holds the spring winder and remove the winder (careful! It Bites!) and the screw that holds the shaft end of the spring.
    Remove the entire cross-shaft of the raise/lower mechanism. It will come out the right side (be ready to restrain the spindle).
    Remove the spindle downard. It is heavy, don't drop it.



  6. #6
    Member
    Join Date
    Jun 2010
    Location
    Australia
    Posts
    4252
    Downloads
    4
    Uploads
    0

    Default Re: How to Change Bearings - COA Square Col

    I would normally run a 6 mm carbide cutter at 3000 RPM on aluminium alloy. Some go much higher. Steel, maybe a bit slower.

    I do NOT use flood coolant. I use air blast to clear the chips and pulsed mist lubrication - only enough to keep the cutter surface wet. Read up on MQL for details. eBay has the hardware.

    Cheers
    Roger



Tags for this Thread

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  


About CNCzone.com

    We are the largest and most active discussion forum for manufacturing industry. The site is 100% free to join and use, so join today!

Follow us on


Our Brands

How to Change Bearings - COA Square Col

How to Change Bearings - COA Square Col