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Making up for hardness and strength with size

  1. Oct 4, 2016 #1
    A skateboard axle is 8mm thick and typically 4140 steel. Can I make up for its hardness or other strength values with 1144 or even 1018 if I use a 20mm axle?
     
  2. jcsd
  3. Oct 4, 2016 #2

    berkeman

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    Staff: Mentor

    Welcome to the PF. :smile:

    Can you show us what you are trying to do? What kind of board are you working on? Standard, long board, Carver, etc.?

    Why do you want to change to a thicker axle?
     
  4. Oct 5, 2016 #3
    Steelhubs.com you can see pictures. Electric skateboard hub motors.

    Using Those three three metals I just made assumptions and generalizations based on the shafts and housings being larger surface area and more mass than a standard 8mm skate axle

    . I'll post the different number sheets of those materials to make it easier to see what we are comparing. I'm more than curious. If ur interested in motor.. Huge deals for forum help.
    I ran the 6000 aluminum center motors many miles and had no mechanical deterioration but really not many miles testing has gone into them and jumped to a steel center as with the thermal expansion and screw-and-glue mounting, ..

    What do you think of the 1144 center and 1018 rotor? The smaller bearing sits on a 20x7mm shaft and the housing is 32x7 i think but I'll check

    .4mm air gap.
     
    Last edited by a moderator: Oct 5, 2016
  5. Oct 5, 2016 #4

    JBA

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    Abusive impact loading on the wheel assemblies might be a problem for a lower yield 1018 material
     
  6. Oct 5, 2016 #5
    Yea. The only part wanted to be 1018 would be the bearing housings and they're minimum 32mm x 7mm. A lot of surface.
    Cant I figure the load Ability of the steel based on the size? Relate it to the 8mm skate axle?
     
  7. Oct 5, 2016 #6
    Isn't there a formula for figuring the load ability of a shaft based on its mass or surface area and material?
     
  8. Oct 5, 2016 #7

    Nidum

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    Science Advisor
    Gold Member

    There are certainly ways of working out the load carrying capacities of shafts . Draw out your assembly accurately and let us see the drawing .
     
  9. Oct 5, 2016 #8
    Cutting and pasting my drawings isn't working but please check the website steelhubs.com because it's pretty revealing. If you can tell me how to get it up I will.

    the smaller bearings in all those motors on that site are old news, I never sold them for that very high price either. They run fine. The new motor is longer and instead of the smaller bearing it's a 20x32x7 and the bigger is 40x52x7

    I have been adding high heat retaining fluid on all the slide fittings as I imagined it would better preserve things and to also kept it quieter it's appreciated). I wanted to do an interference shrink fitting but now think it's better to leave it all slide fitted and easily serviceable. But can an 1144 shaft and 1018 cold rolled housing handle it??? My no-math answer was yes assuming the increased surface area and volume will be stronger but it's all assumptions based on day to day logic.

    http://www.azom.com/article.aspx?ArticleID=6595

    Sorry this iPad erases everything when I skip to other pages looking for links but this is one of the steels and the other two and their numbers should pop up. I feel hardness or maybe other or all specifications of a material can be simply multiplied by...or divided by..a diameter or surface area or something, maybe throw some pi in mix it up and poof engineering. ?
     
  10. Oct 7, 2016 #9
    no one knows?
     
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