BF, BK, FF, FK BallScrew supports


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Thread: BF, BK, FF, FK BallScrew supports

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    Question BF, BK, FF, FK BallScrew supports

    Hi guys, this is my first official post to the forum. I am a new CNC hobbyist & planning to do some DIY machines for my needs. I was wondering if anybody can point out and explain the difference between the ballscrew supports mentioned in the title. Also, does anybody knows of a way to actually DIY one of those with wood, metal or plastic.


    Thanks

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    BK are blocks for the fixed end of the screw. That means they have two angular contact bearings to stop axial and radial movement.
    BF are for the other end of the screw (floating end). They have a simple ball bearing that stops radial movement but allows axial movement (slides in housing)

    FK is the same as BK but a different shape.
    FF is the same as BF but a different shape.

    Google images for what they look like.
    The F series are designed for face mounting (mounting screw perpendicular to a plate) where as the B series are for mounting parallel to a surface but can also face mount.

    It's unlikely you can make anything cheaper and better than the Chinese ones unless you have a mill or lathe.

    Of note with the Chinese blocks: the angular contact bearings are usually not matched or preloaded properly. On all mine, when I've removed the dust shields there has been considerable play. Taken apart I can get a 0.25mm feeler gauge between the outer races of the bearings. The bearings require shims between them (0.2 to 0.3mm in my case). Whether you shim the inside or outside races depends on which orientation you choose (back to back or face to face).



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    Thanks man. very detailed information for my newbie understanding capacity but i do understand now. Which company do u recommend for getting these blocks?



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    I got my blocks and ball screws from Misumi. Certainly not the cheapest out there, but really nice quality.

    Support Units - Fixed Side?MISUMI?Product Specifications

    Took me a while to figure out their website, but well worth the time.



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    Heads up I haven’t tried using fk/ff on any of my bk/bf ballscrews however when I asked my ballscrew supplier about using them they said that ballscrews using bk/bf bearing blocks are processed differently which would require different machining between the bearing blocks. What this entails I do not know but I was going to order a set and find out. My guess it must be a diameter and possibly depth issue. Otherwise machining my own from some 8620 makes a lot of sense to get a clean custom fit besides we have 7 retrofits to donhere at the shop so it makes sense to look at a a set and take from the design for a factory looking fitment on each individual machine. Something to consider before someone spends $70 on an expensive pair of bearing blocks.


    Quote Originally Posted by pippin88 View Post
    BK are blocks for the fixed end of the screw. That means they have two angular contact bearings to stop axial and radial movement.
    BF are for the other end of the screw (floating end). They have a simple ball bearing that stops radial movement but allows axial movement (slides in housing)

    FK is the same as BK but a different shape.
    FF is the same as BF but a different shape.

    Google images for what they look like.
    The F series are designed for face mounting (mounting screw perpendicular to a plate) where as the B series are for mounting parallel to a surface but can also face mount.

    It's unlikely you can make anything cheaper and better than the Chinese ones unless you have a mill or lathe.

    Of note with the Chinese blocks: the angular contact bearings are usually not matched or preloaded properly. On all mine, when I've removed the dust shields there has been considerable play. Taken apart I can get a 0.25mm feeler gauge between the outer races of the bearings. The bearings require shims between them (0.2 to 0.3mm in my case). Whether you shim the inside or outside races depends on which orientation you choose (back to back or face to face).




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BF, BK, FF, FK BallScrew supports

BF, BK, FF, FK BallScrew supports