Okuma LS "Center Pushout Bar"
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  1. #1
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    Default Okuma LS "Center Pushout Bar"

    Hello Everyone!

    After several years of trying to find a bigger lathe that was in excellent condition, and getting so frustrated by all the time wasted going to look at machines that turned out to be worn out junk that I almost ordered a brand new Hwacheon, I recently bought a 18" Okuma LS lathe.

    I haven't got it permanently situated and wired up yet because I'm going to insulate, drywall, and air condition my garage, but I did test run it through all the speeds before I bought it... Gears and bearings sound good, good oil flow in the sight glasses. The ways, leadscrews, and nuts are in excellent condition. So, since I've got a bit of downtime with my projects, I'm focusing on tooling up. Manuals and most of the big items were included, but I need a 4-jaw chuck, as well as my focus for this post - the fascinating "center pushout bar" which was included with each lathe as a standard accessory.

    As you can read on the attached page from the manual, hammering out centers is strongly discouraged, and it obviously matters enough that they took the care to manufacture and include this special tool... But how many LS owners actually have this item? It seems like something that would get lost because most people would not recognize it as a lathe accessory and it would get left behind even if it was sitting right next to the lathe. How big a deal is it really, to gently tap out something in the spindle taper like my 5C collet adapter? Either way, I suppose this is an accessory I would like to acquire, or I will make one. Perhaps someone got a parts machine and has a spare? Or maybe post up some better pictures than the grainy images from the manual along with some key dimensions?

    Thanks for any info. I was surprised in reading all the Okuma posts here that I was unable to find any mention of this interesting tool...

    Regards,
    Jon
    Attached Thumbnails Attached Thumbnails 008.jpg   006.jpg   009.jpg   046.jpg  

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  3. #2
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    The first obvious question is does the machine have the center and accompanying sleeve? I find it hard to believe someone selling the machine would know what both the center and sleeve were for, without knowing what the pushout bar was.

    Secondly, I highly doubt a heavy rod with perhaps a brass cap screwed on the end would do any more damage than a screw type removal tool would do to a spindle.

  4. #3
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    Yes I got numerous different centers and sleeves with the lathe that fit the spindle, including the 5C adapter for the collet closer which is currently stuck in it. Unfortunately, there’s a good chance that the seller did indeed have this tool but didn’t know what it was. Apparently his business partner was the machinist and passed away, and so the shop is being closed down and liquidated. I bought the lathe but until I got home and read the manuals, I was unaware of the center pushout bar and thus did not look for it when I was there. I have reached out to the seller many times to the point of becoming an irritation but he will not reply to me despite my offering generous compensation.

    The thing about this tool that appeals to me and what makes it so much better than tapping out centers with a hammer or brass rod, is that it actually puts zero force on the spindle bearings... When you’re knocking the center out with a rod or hammer, the bearings take the impact, since they’re the only thing holding the spindle in the headstock. The pushout tool screws into the back of the spindle and forces the center out the front with the forces absorbed by the spindle itself with the bearings unaffected.

    So many original tools were included, even the Okuma embossed tool box with foam tray holding all the original wrenches, and this lathe was the guy’s ‘baby’, I bet the bearings have never felt the impact of a hammer in their life... I’m going to keep bugging the seller... he seemed a bit flaky and it wouldn’t surprise me if the money I paid him for the lathe got injected into his arm or snorted up his nose, but maybe when it’s gone and he wants more, he’ll become very interested in finding this tool for me.

    Jon

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    Quote Originally Posted by JDToumanian View Post
    When you’re knocking the center out with a rod or hammer, the bearings take the impact, since they’re the only thing holding the spindle in the headstock.
    Ya, I agree. When I first got my lathe I used a wood dowel to knock out the 5C adapter. I only did that once because it drove me crazy banging against those very expensive Gamet spindle bearings. Since then I use a bearing splitter which pulls the adapter out of the spindle without any undue stress to the bearings.

    Ted

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    My Okuma LS is missing this tool too. Looks like its easy enough to make a simple copy of though.

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    I own a copy of the LS (Dong Yang) and i bought the machine new and it came with that push out bar....tried it once and it was a pain to use actually....hard to hold the center to prevent
    it from falling out and bouncing off the ways....while turning the screw...
    Haven't seen it in some time...pretty sure its here in the shop somewhere and I,just made a quick look and its not readily at hand....

    Personally think its work for nought.....lots of high quality lathes out there and this is the only one that thought this feature was necessary....Can think of lots of other stuff i need for the shop and my machines before
    i would spend time making that.

    Cheers Ross

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    Quote Originally Posted by JDToumanian View Post
    The pushout tool screws into the back of the spindle and forces the center out the front with the forces absorbed by the spindle itself with the bearings unaffected.
    That's nice. "Elegant", even. B'lieve I'll copy the concept. Not as if one even needed a drawing, what with the machine-tool it has to fit right "in your face".

    I don't see why it would take any significant time or cost in materials to just go and make one, each of several machine-tools, either. Do you?

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  12. #8
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    I can see the benefits of the removal tool, but suspect there's still some small shock that will go through the spindle bearings just from elastic deformation and sudden release when the center gives way.

    If you want low stress, the bearing splitter or specialized variant mentioned above will do a better job and have lower stress due to the more "immediate" contact from spindle to center adapter. Less material to build up the compressive load means less "pop" when it gives.

    And, umm, who among us hasn't tapped (or hammered) on a piece of stock in a chuck to dial it in. Lathe spindle bearing must be oversized to deal with such trauma.

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