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IndustryArena Forum > MetalWorking Machines > Okuma > Okuma Chucking Issue
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  1. #1
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    Feb 2021
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    Okuma Chucking Issue

    Recent purchase of MB15 trying check all functions. At this point I'm trying to MDI data ( not sure if the format is correct but no syntax error) but when I hit cycle start an alarm pops 119 Chuck open 1 and its closed. I'm not seeing fluid in the site gage but I feel the filter line moving fluid Anybody have an idea why when I input data in MDI and try to cycle start an alarm pops 119 chuck open or what to check. I have limited info or manuals on this machine so any help would be greatly appreciated.

  2. #2
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    Feb 2011
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    Re: Okuma Chucking Issue

    i have an LB15
    It uses prox switches to electronically tell the machine that the chuck is closed check these first and not just did the chuck close on your part

  3. #3
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    Re: Okuma Chucking Issue

    You may also want to check to see if you are set to ID chucking instead of OD in your parameters. If ok the adjust switches like rcs60 says.
    Experience is what you get just after you needed it.

  4. #4
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    Re: Okuma Chucking Issue

    just small details to add. Chucking Limit Switches must be adjusted to positions at cylinder stroke limits.
    jaws must be installed so, that open and close full stroke ( no workpiece yet ) activates the relevant limit switches.
    OD / ID chucking selection exactly as OkumaWiz wrote.
    and now. If you have OD chucking selected, then chuck close ( drawbar moves back ) LS should not be activated when workpiece clamped. In case of chucking fault - scatter of the workpiece - the drawbar will go to the (back) end, LS will be activated and machine stops with chucking fault alarm.
    Similar logic when ID chucking selected - the front LS activated means workpiece lost.
    Check all these conditions and then check again.

  5. #5
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    Feb 2021
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    Re: Okuma Chucking Issue

    Thank for the info.. I do see a draw bar in back with two limit switches on it might be the one .. seams its not moving much got it to move once forward and then back but not far enough to hit the switches. it seams to be hydraulic with two hoses out the bottom moves very slow maybe a hydraulic flow issue??? Machine was sitting for several years before I picked it up. Must be 3inches between switches. I don't have that on the travel on the chuck.. Any thoughts???

  6. #6
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    Re: Okuma Chucking Issue

    Moving slowly may be an indicator of low pressure setting. It should be around 300psi or so usually. Stroke will only be about 3/4" forward and back. The chuck jaw will only travel about 1/4" by comparison. If it faults, you will need to hit reset and try again. Control panel should have indicator lights on it showing clamp and unclamp condition. In order for it to work you can only have one of the proximity switches on at a time.
    Experience is what you get just after you needed it.

  7. #7
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    Re: Okuma Chucking Issue

    take out the chuck jaws to enable full stroke of the draw bar.
    Check installation of draw bar. There is a threaded connection draw bar with special "nut" of the chuck. If the nut and the chuck are wrong connected - causes reduced stroke.
    Can't tell what the full stroke would be - it depends on machine design highly. But in my opinion, 25mm ( did I understood correctly, Mr.OkumaWiz ? ) is not enough for sure. The root of the problem can be the chuck installation. "Nut" and draw bar connection.
    This connection is a bit tricky :-) And very easy to damage the thread applying too high force.
    Let me describe in details.
    Reduce the hydraulic pressure to the minimum. "Minimum" means that draw bar moves at least 85% of full stroke.
    By the way. Full stroke of the draw bar you can check when the chuck is taken away. More than 50mm ( ~2" ) is normal full stroke.
    Let's install the chuck, It's possible, that the "nut" meets the front of the draw bar and needs to be screwed on it a little in order to get the chuck seated.
    Chuck seated; balanced and fixed in the place. Draw bar and the "nut" are interconnected a little or not connected at all.
    Now we need to screw on the "nut" on the nose of the draw bar at least for 15mm ( depends on the size and design of the lathe ) . More is better until ...
    At some point the stroke is reducing with bar nose going deeper into the "nut" of the chuck. It's time to stop. If we have more than 15mm interconnection and stroke is reducing, it's enough.
    Two important notes:
    - grease;
    - turn the nut only while the draw bar is travelling. All the procedure is constant trample of the chuck pedal ( or execution "chuck close -> chuck open" part program ) and turning the nut on the travel of the draw bar. Got it? When draw bar is at the end of stroke, the hydraulic pressure creates tension on the thread connection, preventing turning.
    That's the way to get the maximum stroke. Then you can adjust your limit switches properly.
    Good luck. Don't blame me if you did something wrong. My advice is effective when you apply the technology properly.
    Okuma engineers, be ready to visit your clients. :-) as usual machinetool users make big trouble after my advices :-)

  8. #8
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    Jun 2015
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    Re: Okuma Chucking Issue

    i can confirm 25mm travel, but i don't remember if it is with the chuck on or off ?!

    Reduce the hydraulic pressure to the minimum ... All the procedure is constant trample of the chuck pedal
    travel takes longer with minimum hydra pressure; try to hit emergency stop somewhere before travel middle
    Ladyhawke - My Delirium, https://www.youtube.com/watch?v=X_bFO1SNRZg

  9. #9
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    Feb 2021
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    Re: Okuma Chucking Issue

    Thanks for the info..... Problem solved today... As I stated in my earlier message my machine was sitting for several years prior to my purchase. This caused the fluids in the head casing to thicken up causing my problem. I opened up the headstock cover and noticed a lot of hard material on the inside mainly on the gear, spline, actuator shaft. Cleaned up residue in and around everything and got the actuator to move freely as it should... problem solved. Definitely time to change all fluids and filters.

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