Wormgear 4th axis


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Thread: Wormgear 4th axis

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    Default Wormgear 4th axis

    Wormgear 4th axis-130mm-wormgear-4th-axis-jpg

    Purchased this unit from Singles-day sales in AliExpress. Unit is with 130mm chuck and Nema 34 Stepper.
    Everything is pretty much as expected, including backlash issue.

    I stripped all to parts and backlash is due fact that worm- and main-gear are not close enough to each others.
    Gear and worm seems to fit pretty nicely together

    Wormgear 4th axis-worm-gear-jpg

    I´m thinking how to create shift main axis. It´s bit thin to machine stuff away and make eccentric bushings.

    Also I´m puzzled to weld it.. Most likely its casted aluminum. So just weld bit material on side and machine eccentric location for bearing and sealing.

    Wormgear 4th axis-welding-plan-jpg

    Outside is easy, just make eccentric cover.

    Wormgear 4th axis-cover-jpg

    So any suggestions?

    Cheers-Jukka

    Similar Threads:
    Attached Thumbnails Attached Thumbnails Wormgear 4th axis-welding-plan-jpg   Wormgear 4th axis-worm-gear-jpg   Wormgear 4th axis-130mm-wormgear-4th-axis-jpg   Wormgear 4th axis-cover-jpg  



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    Default Re: Wormgear 4th axis

    Any gear and worm is going to have backlash. It's necessary for there to be some clearance in there, or the gears will freeze up. When you write "create shift main axis" It sounds like you're going to try to move the shaft closer to the worm, using welding to build up the case and re-machining to restore the mating surfaces . This is a lot more likely to result in a rotary table that won't work at all than one improved in its function. You'd be better off building a rotary table from scratch than in trying to improve this one in that way. If you can't tolerate any backlash, start with a harmonic or cycloid drive. But as long as the thing isn't actually flopping around, it will probably work okay as-is, if you avoid changes in direction, which is where the backlash will show itself.

    Andrew Werby
    Website


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    Default Re: Wormgear 4th axis

    Yes I know, I´m not looking for 0-backlash its not going to happen in this price range.. I´m just going get max out of my spend $300 + postage.
    Just for reference at edge of chuck backlash was like 1/16" or 1.5mm which is too much. Teeth were just about 0.4-0.5mm too far from each others.

    But you are right, if I overdo my repair It will be jammed, so there are pretty accurate measurements involved here.

    Worst case losses are about 100$, which will mean I need new Chinese NMRV-40 gearbox. So we are not talking here about big $.

    Last edited by hokkaju76; 11-28-2018 at 05:50 PM.


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    Default

    Quote Originally Posted by hokkaju76 View Post
    Wormgear 4th axis-130mm-wormgear-4th-axis-jpg

    Purchased this unit from Singles-day sales in AliExpress. Unit is with 130mm chuck and Nema 34 Stepper.
    Everything is pretty much as expected, including backlash issue.

    I stripped all to parts and backlash is due fact that worm- and main-gear are not close enough to each others.
    Gear and worm seems to fit pretty nicely together

    Wormgear 4th axis-worm-gear-jpg

    I´m thinking how to create shift main axis. It´s bit thin to machine stuff away and make eccentric bushings.

    Also I´m puzzled to weld it.. Most likely its casted aluminum. So just weld bit material on side and machine eccentric location for bearing and sealing.

    Wormgear 4th axis-welding-plan-jpg

    Outside is easy, just make eccentric cover.

    Wormgear 4th axis-cover-jpg

    So any suggestions?

    Cheers-Jukka
    Hi what was the model number for that. Looks great trying to see if I could buy it



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    Default Re: Wormgear 4th axis

    Quote Originally Posted by addman16 View Post
    Hi what was the model number for that. Looks great trying to see if I could buy it


    https://www.aliexpress.com/item/CNC-...70784c4dLz8vqk

    Or search AliExpress with 130mm 4th axis.

    Actually I got pretty nice idea , it will involve 6906 and 6907 bearings. I´ll do adjustable gear mesh clearance to my drive with smaller ones and bigger ones are for new supported chuck axis.
    Lets see what happens, sad that those bearings are not too cheap locally, so I need to wait China Post.



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    Default

    Quote Originally Posted by hokkaju76 View Post


    https://www.aliexpress.com/item/CNC-...70784c4dLz8vqk

    Or search AliExpress with 130mm 4th axis.

    Actually I got pretty nice idea , it will involve 6906 and 6907 bearings. I´ll do adjustable gear mesh clearance to my drive with smaller ones and bigger ones are for new supported chuck axis.
    Lets see what happens, sad that those bearings are not too cheap locally, so I need to wait China Post.
    Interesting....
    I'm seeing some rotary tables with a harmonic drive they are supposed to help with backlash 100:1 reduction same price



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    Default Re: Wormgear 4th axis

    I'm seeing some rotary tables with a harmonic drive they are supposed to help with backlash 100:1 reduction same price
    with only 100 mm chuck, no 130 mm chuck



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    Default Re: Wormgear 4th axis

    Yes I have seen those also. But there is no data of backlash in numbers and regarding price I was bit suspicious that there is actually planetary gear instead of harmonic gear.
    This is just my guess, I have not seen any evidence to either direction. I just know that true nice harmonic gear alone is few hundred $, even second hand.
    If you are interested to buy one of those, I´d be very pleased and I believe many others if you could share your experiences.



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    Default Re: Wormgear 4th axis

    For now, I am using the worm gear like yours. But in the future I plan to use harmonic drive. I saw on ali, its not too expensive. I am still confused which part to use.

    Wormgear 4th axis-bcsf-40-bcsg-40-crb40-126-cross



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    Default Re: Wormgear 4th axis

    Wormgear 4th axis-eccentric-bearing-bushes-jpg

    Bearings arrived, now gear is assembled with eccentric bushings over smaller bearings. It was bit tinkering to find good tuning.
    But it seems to be possible to make it backslash "free"... Well at least it not wildly shaking back and worth.
    Eccentricity of like 0.3 mm would have been enough, I just took 1 mm by guess and adjustment needed was actually very small in angular vise. Bit fiddling to get it nice and snug still avoiding it to stuck.

    Attached Thumbnails Attached Thumbnails Wormgear 4th axis-eccentric-bearing-bushes-jpg  


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