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Need Help In Gear Train

Discussion in 'Using Alibre Design' started by RocketNut, Jul 17, 2020.

  1. RocketNut

    RocketNut Alibre Super User

    ( ͡° ͜ʖ ͡°)

    I am trying to design a 1:10 gear train using the Gear Generator Script. As you can see the gear teeth are way too big on the driven gear.

    So I am wondering if anyone out there can help me getting the teeth correct so they mesh properly. The size of the gears can any size except the drive gear can not bigger than 150mm.

    Gear Train.jpg
     
  2. idslk

    idslk Alibre Super User

    Hello RocketNut,

    upload_2020-7-18_1-25-2.png

    The quality of the gears made with the gear generator is not on me...
    Here is an example Gear 1: Teeth 10, Pitch diameter 14, Pressure angle 20, Thickness 3, Gear 2: Teeth 100, Pitch diameter 140, Pressure angle 20, Thickness 3,
    Distance off both z-axis (14+140)/2 , geardrive constraint used, ratio 1:10
    It's only for demonstration...

    Regards
    Stefan
     

    Attached Files:

  3. JST

    JST Alibre Super User

    Doesn't it let you set the module (or diametral pitch)?

    You would pick the larger gear size and tooth count (vs a minimum of 12 teeth on pinon) letting that drive module, and then the module of the smaller gear is set, so the variable is size, which would be driven by module and number of teeth..

    If you cannot do that, or something like it, then the script may need some tweaking.....

    Btw, a two step reduction might be a lot more compact.
     
  4. idslk

    idslk Alibre Super User

    no...

    upload_2020-7-18_1-34-17.png


    Zoom on the generated Teeth

    upload_2020-7-18_1-33-53.png

    I'm not shure that the script was made for "real" production ready gears...
    Personally i would take some catalog parts.

    It' also my opinion, but i'm not the originator...;)

    Regards
    Stefan
     
  5. RocketNut

    RocketNut Alibre Super User

    Thanks, idslk but your driven gear is to small it needs to spin on a 25mm shaft.

    I plan to 3D print the prototype gears with PLA, then farm out the gears in hard nylon.

    Does anyone have a link to a good gear website?
     
    Last edited: Jul 17, 2020
  6. HaroldL

    HaroldL Alibre Super User

  7. RocketNut

    RocketNut Alibre Super User

    Thanks, Harold it looks like just what the doc ordered. I have a question tho. How do spec the O.D. of the gears?
     
    Last edited: Jul 17, 2020
  8. Lew_Merrick

    Lew_Merrick Alibre Super User

    Hey Rocketnut -- The 1st question you need to answer is, "How much power do you need to handle and what is the input (or output) RPM you need? That (along with the material of the gearset) will determine the Diametral Pitch (or Module) you need. It ought to be obvious that your output gear requires 10X as many teeth as your input gear. Does this help? [Irrational minds want to know.] -- Lew
     
  9. HaroldL

    HaroldL Alibre Super User

    I just check on Engineer's Edge web site for most of the tech stuff I need, that or my copy of Machinery's Handbook.
    Maybe albie can help out if he checks in here. As I recall he does a lot of work work with gears.
     
  10. albie0803

    albie0803 Alibre Super User

    ok a 4.5mod 10t gear has an OD of 54 and a root diameter of 34mm (34-25)/2= 4.5mm between root of tooth and bore but the 100t gear becomes 459 OD
    A comparable 6dp 10t gear has an OD of 2" and a root diameter of 1.25", therefore 0.125" between root of tooth and bore but the 100t gear becomes 17" OD

    A double compound gear train needs a 40t which is 189 OD

    You could do it with a triple compound gear train 4.5mod. 10:25,10:20,10:20 (25t = 121 OD)
    10:25 centre dist = 78.75
    10:20 centre dist = 67.5

    I can generate a tooth dxf which is what I do when I need to. It creates small lines to create the shape. I import the dxf, turn to reference and then draw a spline down the tooth face using the line ends as anchors. It creates a pretty accurate shape. I can even program in a desired backlash.
     
  11. Nick952

    Nick952 Senior Member

    When space is tight, the smaller pinion gear is often produced by cutting the teeth directly into the shaft. Obviously I don't know if this is possible or even desirable with your design though.
     
    Last edited: Jul 18, 2020
  12. idslk

    idslk Alibre Super User

    this wasn't stated in your first post...
    Basics:
    If you will have a
    you should take in mind that this is also the ratio between your two wheels -> wheel 2: max 150mm means wheel 1 = wheel 2 / 10 = 15mm.
    So no matter which size of the teeth you will choose, if you need both values (25mm shaft for wheel1 and 150mm diamax for wheel2) it won't fit!
    As stated from other members above, you may take a gear with more reduction steps...

    Regards
    Stefan
     
  13. RocketNut

    RocketNut Alibre Super User

    Yes Lew you are correct. The power that the output gear needs are very low that why I can get away with nylon gears. The input RPMs is very low because it is driven by a hand crank. Meaning the input RPMs will less than 20 RPM. You also right the drive has to 10X more theeth the the out put gear.

    albie0803: Thanks for the link, it is very helpful.

    idslk: Yes I should have mentioned the output shaft O.D. in my first post.

    I understand you all are saying. I will look into a multi-gear train to achieve the 1:10 ratio I need. What would the gear ratios you suggest for 3 or 4 gear train?

    Thanks :)
     
    Last edited: Jul 18, 2020
  14. Lew_Merrick

    Lew_Merrick Alibre Super User

    Hi Rocketnut -- As an apprentice machinist "we" (Everett Tool & Die) made gear hobs for Western Gear and Mantell Gear -- so I have a somewhat strange view of the gearing universe. -- Lew
     
  15. albie0803

    albie0803 Alibre Super User

    You could do it with a triple compound gear train 4.5mod. 10:25,10:20,10:20 (25t = 121 OD)
    10:25 centre dist = 78.75
    10:20 centre dist = 67.5
    image below not at true scale
    upload_2020-7-19_13-45-18.png
    10 drives 25
    25 and 10 connected
    10 drives 20
    20 and 10 connected
    10 drives 20
     
  16. RocketNut

    RocketNut Alibre Super User

    Thanks, albie0803:)

    I will draw it up to see how your design works.
     

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