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  1. #11
    Quote Originally Posted by Karl View Post
    Ref discussion in thread above. Is this bearings on their side I see in this commercial machine?
    Yes it is - alas badly designed commercial machines are nothing to be surprised about.

    Check out the one in the background...potentially much better.
    Old router build log here. New router build log here. Lathe build log here.
    Electric motorbike project here.

  2. #12
    Hi Karl,

    For any CNC machine design you just need to ask yourself one question: If I apply the required load to the cutting tool will it deflect less than the accuracy I'm after, or vibrate less than the surface finish I'm after?

    If the machine meets those requirements by a reasonable margin then its a good optimal machine. Problem is that although the load requirements are fairly well known (5N wood up to 75N steel as a guide) unless you have access to an FEA programme, and can mesh up the CAD and carry out the analysis, you won't really know how much the tool will deflect under this load. Therefore the advice given in this thread is the arrangement which we believe gives the best performance and lowest risk for those type of bearings. Whilst it might be the case that the bearings on their side arrangement would also give sufficient performance for what you want to do (and I have a feeling it would be), for the same cost the top / bottom arrangement should be superior so it makes sense to use that one.
    Building a CNC machine to make a better one since 2010 . . .
    MK1 (1st photo), MK2, MK3, MK4

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