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Modeling Bevel Gears

Discussion in 'Using Alibre Design' started by HaroldL, Mar 8, 2021.

  1. HaroldL

    HaroldL Alibre Super User

    For my latest project I need to model some bevel gears. Recalling that there has been some gear discussion on the forum I ran a search to see if any of the past discussions would be helpful. I found some posts from 2009 that had links that are now dead. Soooo, if anyone still has some of the resources that were posted back then it would be helpful, and much appreciated, if they could be uploaded to the Resources depository.
     
  2. NateLiqGrav

    NateLiqGrav Alibre Super User

    Can you link the topic? If they are links to something on the forum I should be able to fix them.
     
  3. bigseb

    bigseb Alibre Super User

    Check out this thread, might have the info you need: CLICKY
     
  4. bigseb

    bigseb Alibre Super User

    ... and HERE...
     
    Eddy So likes this.
  5. bigseb

    bigseb Alibre Super User

    There is also this software: SPIRAL BEVEL. Maybe of interest to you...
     
  6. MikeHenry

    MikeHenry Alibre Super User

    Would Gearotic (sp?) be of any use?
     
  7. HaroldL

    HaroldL Alibre Super User

    Thanks guys. I followed the link that @bigseb posted and found a parametric model that @Oldbelt created back in 2012. It looks promising but I think it has a bit of an issue. When comparing the tooth profile sketch to its place in the pattern it appears that the sides of the tooth extrusion do not taper as they should. (see image) This makes the bottom fillet between the teeth to be noncontinuous. Also the center hole becomes segmented instead of curvature continuous.

    BevelGrear.png

    I will see if I can make this work for me since my parts are not critical to build for anything other than the model I am working on, but a bit of accuracy would be nice.

    Just so you know, the gears I am working on are from a set of drawings for the USS Monitor Steam Engine by Richard Carlstedt. I found then on the Home Machinist website where he released them for personal use. Being a complete set of drawings as possible I thought it would be a good project to model instead of the scale models that I usually find to work on.
     
  8. albie0803

    albie0803 Alibre Super User

    Most bevel gears are cut to a Gleason system which has a very flat root.
    upload_2021-3-11_7-29-52.png
    If you're not going to use the model for manufacture then just draw a tooth shape that looks "about" right. We have proper gear cutting machines so my drawings are just eye candy as far as tooth shape is concerned
     
    Hunter likes this.
  9. Hunter

    Hunter Senior Member

    I agree, if you're not going to manufacture directly off the model, just draw/model it so that it looks right.
     
  10. HaroldL

    HaroldL Alibre Super User

    How much would it take for one of the Python gurus to turn one of the bevel gears that @Oldbelt created into a usable script for both ring and pinion gears? I thought I could use it as-is but, not being a "gear guy" (I think I only had to work on a gear model once or twice in my career, and I had help with that), I am having some trouble deciphering the parameters in the files and matching them to the info I have. That may be because he designed it for a specific purpose/design.

    For reference here are the drawings i am working from.
     

    Attached Files:

  11. albie0803

    albie0803 Alibre Super User

    Are you looking for eye candy models or accurate models to machine from?
    There are 3 major bevel gear systems which will give you different model shapes.
    AlibreScript doesn't do circular pattern yet.
     
  12. HaroldL

    HaroldL Alibre Super User

    I'd like them to be reasonably accurate. Not that I'm going to build a full sized engine, but if I wanted to scale it down for 3D printing it would be nice to be workable. I don't know about the different bevel gear systems. How do they compare the the drawings that I uploaded?

    Too bad about Alibre Script not patterning. Here's to wishing that Alibre would step it up with some of the modeling tools like SolidWorks has, maybe an API, but I may just be spoiled after using SW at work for so long. SW has a real nice gear tool that I think would do the job nicely.
     
  13. bigseb

    bigseb Alibre Super User

    Was the spiral bevel site no good?
     
  14. HaroldL

    HaroldL Alibre Super User

    Oh, it had some good programs, it's just that I don't have pockets deep enough to be able to afford what they're asking for it. And I didn't see a straight bevel program, not that I could afford it.
     
  15. albie0803

    albie0803 Alibre Super User

    I actually have those programs (well work does) and there is a straight bevel version if you ask. They give an accurate tooth shape as a surface that you then have to add to a model.

    Here is the bevel set with the tooth surfaces from the program. Hope it helps.
    The tooth shape is ACCURATE. We have machined bevel sets from them that mesh beautifully!
     

    Attached Files:

  16. HaroldL

    HaroldL Alibre Super User

    Thanks Albie. It does take some time to create a pattern for the gear teeth. Unless I'm doing this wrong. you would think Alibre would have some patterning tools that worked with surfaces. What I end up doing is Create Surface from Face, Move/Rotate surface, Trim model. Rinse and Repeat- for each tooth. o_O No way could I select anything to create a feature pattern.

    How do you create the tooth patterns for your gears?

    Finally a gear.png

    If anyone is interested, I put some links in a comment for one of the images in my gallery that will point you to more info on the model that these gears are used on, the drawings and the creator of them, Richard Carlstedt.
     
  17. albie0803

    albie0803 Alibre Super User

    Harold, that was the only way I could do it too, but I had a thought last night that if I created a tooth segment using a partial revolve in the correct position relative to where the tooth surface imports I could then circular pattern the segment with the tooth cut out. I haven't tried it though.
    I supplied the single tooth blank (like I supplied) to the milling operator and he was able to pattern the cutout using Mastercam
    DSCN0405.JPG DSCN0400.JPG
    We made a new pinion and recut the crownwheel

    Normally, for bevel gears, I draw a tooth shape and add it to a reduced blank, but its only eye candy for me, as we use bevel generators. It's only the few times when we actually mill the teeth that we use the tooth surface as I mentioned above
     
    Last edited: Mar 22, 2021
  18. HaroldL

    HaroldL Alibre Super User

    Well at least we were on the same page for process. Too bad Alibre doesn't have more Surface tools, circular pattern would certainly be helpful.

    I'll try your "tooth pattern" method on a copy of the model you uploaded to see how it works out and post back the results here. If nothing else it will be for process reference.

    edit:
    Well that didn't work as expected. Seems Alibre has an issue with patterning anything with a Surface or Surface created feature.

    The last effort gave this error:
    CircularPatteernFailure.png

    Here's the text of the error"
    And here's the part file for what it's worth.
     

    Attached Files:

    Last edited: Mar 22, 2021
  19. HaroldL

    HaroldL Alibre Super User

    Thanks to David Jupp in Support for coming up with a shorter method for this.

    I had to modify the first couple of steps by deleting everything in the DE except for the imported surface. Since it was already "in position", when I Saved As to its own part file it was set up to use its Reference Geometry for locating in the gear blank at the Boolean operation.
    1. First, import the surface into Alibre and position it as it would be in the gear blank
    2. Thicken it some amount to create a part.
    3. Save the part in the working folder.
    4. Open the gear blank
    5. Begin a Boolean Subtract and select the previously saved thickened surface part.
    6. Position the thickened surface part. Locating it with its Reference Geometry shown at 0,0,0 should place it correctly.
    7. Create a Circular Pattern
    8. Finally Accept the Boolean
    9. Lastly, using the Direct Editing tools select Remove Model Pieces and select all the pieces that are left in the gear grooves and click Okay. (This is where Window Select would be nice.)

    What is left is a much shorter list in the Design Explorer than the previous method.
     
  20. HaroldL

    HaroldL Alibre Super User

    Too bad there isn't an AddOn for Alibre that does gears like this.
     
    cadtec and MKR like this.

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