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IndustryArena Forum > Mechanical Engineering > Linear and Rotary Motion > Just checking please - is this a tolerance fit? Small question im not a machinist.
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  1. #1
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    Just checking please - is this a tolerance fit? Small question im not a machinist.

    Attached file is of the FK20 bearing support I am purchasing. I have decided to machine a full Nema 24 to FK20 support out of a 150mm piece of 76mm x 76mm 6061. I reckon it will be nice and strong - also stuff like that always looks cool when people look ha

    Hey but the dimension Dg6 is 57mm with -0.010 and -0.029 inside the table. So does this mean I machine my block out too exactly 57mm and the FK20 comes smaller for a press or tight fit? Or do I machine in a clearance?

    Oh. The FK is on the boat I am pre making my mounts so when it all arrives I just bolt and run. I could wait I guess for it to arrive but where is the fun in that? Ha
    Attached Thumbnails Attached Thumbnails FK20.jpg  

  2. #2
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    Re: Just checking please - is this a tolerance fit? Small question im not a machinist

    Quote Originally Posted by boydage View Post
    Attached file is of the FK20 bearing support I am purchasing. I have decided to machine a full Nema 24 to FK20 support out of a 150mm piece of 76mm x 76mm 6061. I reckon it will be nice and strong - also stuff like that always looks cool when people look ha

    Hey but the dimension Dg6 is 57mm with -0.010 and -0.029 inside the table. So does this mean I machine my block out too exactly 57mm and the FK20 comes smaller for a press or tight fit? Or do I machine in a clearance?

    Oh. The FK is on the boat I am pre making my mounts so when it all arrives I just bolt and run. I could wait I guess for it to arrive but where is the fun in that? Ha
    The -.01mm is more than enough unless you have very heavy thrust loading, I usually do that type of Bearing fit between -.005mm and -.006mm
    Mactec54

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    Re: Just checking please - is this a tolerance fit? Small question im not a machinist

    Thanks. My question was more directed at the data sheet. Those numbers on the side are the recommended clearances? And the part is going to be 57mm exactly yes?

    Clearance I go for 0.005 which is a press fit on my router due to it not cutting a proper circle.

    Sent from my SM-N970F using Tapatalk

  4. #4
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    Quote Originally Posted by mactec54 View Post
    The -.01mm is more than enough unless you have very heavy thrust loading, I usually do that type of Bearing fit between -.005mm and -.006mm
    This is totally incorrect
    ... the drawing IS saying the tolerance of that feature
    57 is the basic dimension. The manufacturing size is (57-.010) to (57-0.029)... so working that out
    56.990 to 56.971 is what the drawing is saying.

    There is no mention of the mating part size....
    But a guess is, that the smallest size it can be is larger than the 56.990 size..... experience would guessimate it to be a 57H7 size .... H7 is a tolerance from manufacturing data sheets for that size range +0.000 / +0.030

    A capital letter refers to a hole ie H7
    A lowercase letter refers to a shaft ie h7

  5. #5
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    Re: Just checking please - is this a tolerance fit? Small question im not a machinist

    Quote Originally Posted by Superman View Post
    This is totally incorrect
    ... the drawing IS saying the tolerance of that feature
    57 is the basic dimension. The manufacturing size is (57-.010) to (57-0.029)... so working that out
    56.990 to 56.971 is what the drawing is saying.

    There is no mention of the mating part size....
    But a guess is, that the smallest size it can be is larger than the 56.990 size..... experience would guessimate it to be a 57H7 size .... H7 is a tolerance from manufacturing data sheets for that size range +0.000 / +0.030

    A capital letter refers to a hole ie H7
    A lowercase letter refers to a shaft ie h7
    No it is not incorrect, I did not refer to the drawing what's so ever, experience is what counts, I used to design and machine bearing assembles for SKF so no what is needed to do the job
    Mactec54

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    Re: Just checking please - is this a tolerance fit? Small question im not a machinist

    So does this mean I machine my block out too exactly 57mm and the FK20 comes smaller for a press or tight fit? Or do I machine in a clearance?
    I wouldn't consider that a critical dimension, give the bore a bit of clearance. The forces acting on that block are axial. As far as alignment, making that a press fit will cause more grief than it solves. Just my 2 cents and worth all of that.
    Anyone who says "It only goes together one way" has no imagination.

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    Re: Just checking please - is this a tolerance fit? Small question im not a machinist

    The screws are 2510s at 2600mm long. There will be both longitudinal and some small lateral from the mass right/left I would imagine?

    But thanks. I was reading about clearances and standards last night.

    Besides. One of the reasons for this project is I would like to increase the accuracy of my router to make better circles so I can actually apply these fits when I make parts. No problem with my lathe, just my diy router is not quite there yet..... very close...... just not yet. I used to love a job at work where we would heat this housing (for ages) and slip a massive 120mm bearing in. The clearances were absolutely perfect.

    Sent from my SM-N970F using Tapatalk

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