How to accurately constrain a splined shaft to a splined gear?

Answers

• eric_pesty Member Posts: 2,172 PRO

  May 17

  Always a good idea to create an explicit mate connector in both the spline and gear with "matching" orientation. Otherwise you can use the "realign" option in the mate connectors to line them up the same way.
  Or possibly model both the gear and spline in the same part studio (may not make sense depending on what you are doing though…).

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• dan_beavers Member Posts: 9 EDU

  May 17

  I can mate them approximately. The problem is the rotation. The splines don't line up such that there is interference. I am using gears and shafts that others have generated. Also, the peaks on the shaft are flattened and the corresponding valleys on the gear are rounded.

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• martin_kopplow Member Posts: 790 PRO

  May 18 edited May 18

  @dan_beavers

  In these cases, I usually create an explicit mate connector in both the shaft and the gear and realign the connectors to a reference point on the spline and make the gear and shaft the owner entitiy of said connectors, all within their part studio(s). This makes matching them in the assembly very easy, on an intuitive if not quasi-automatic level. Also, this is much safer downstreams, compared to aligning mates in the assembly. Let me know if you need an example.

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• dan_beavers Member Posts: 9 EDU

  May 18 edited May 18

  @martin_kopplow Yes, an example would probably help me understand. I understand about doing it in the part studio. If you could use these parts, it would help.https://cad.onshape.com/documents/65734b40e6c4759e97ed2caf/w/4e2dc6501d0a3883945c903a/e/91814ed87fe3dbcff39708c2?renderMode=0&uiState=682a371cda76cf549de1df3e

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• martin_kopplow Member Posts: 790 PRO

  May 19 edited May 19

  Hi @dan_beavers , you'll probably need to make the (private) dokument readable for me, else I cannot use your parts.

  https://cad.onshape.com/documents/a73a39e35afbb0e4d944bde6/w/459912529e5b95b328fed1f5/e/018dffda0eedc5e3984985ab?renderMode=0&uiState=682b1c745889b855c164704b

  Here's one simplified example- I used a gear and a shaft to be matched by means of a key. The same goes for splines.

  1. First, I created the parts in a part studio and then DELIBERATELY misaligned them, just to show that it doesn't matter.
  2. Then, I added a mate connector to the gear and another one to the shaft.
  3. In the mate connector edit box, I made sure the SECONDARY axis of each connector is aligned with a face or a line that is part of the keyway I later want to align and both the secondary axis' (In my examle that's the red X-axis) point towards the keyway: Depending on you use a line or the end face you might be 90° off and need to hit the mate connector rotate button one to three times to make that happen.
  4. I made sure the mate connector origin were the shaft rep. the gear, so the mate connector gets carried through to the assembly together with their owner parts later. That is the bottom box within the edti box.
  5. I inserted all parts into the assembly.
  6. I created a Reference Mate Connector E.G. at the origin (If you already have a machine or anything else in the assembly you could use that instead).
  7. I created a rotate mate between the shaft and the 'machine', just so the shaft can do what shafts do.
  8. I found the gears's (already aligned in part studio) mate connector and the shaft's (already aligned) mate connector and created a fixed mate between them. They just jump into place.
  9. I applied a fastened mate beween th ekey and the shaft keyway.

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• dan_beavers Member Posts: 9 EDU

  May 19

  @martin_kopplow Sorry, I thought it was public by default. It is now public. I will try to see how your method works with splines later. Thank you for your response and the effort you have expended!

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• dan_beavers Member Posts: 9 EDU

  May 19 edited May 19

  @martin_kopplow I think I did what you suggested but it did not work for me. What did I do wrong? Also, the gear should be adjacent to the motor, not on the end of the shaft. (I saved a few versions.)

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• martin_kopplow Member Posts: 790 PRO

  May 20 Answer ✓

  @dan_beavers

  I looked into your document and slightly modified the definitions of your two part studio mate connectors and reversed the fastened mate in the assembly.

  1. You cannot place the connector on the spline edge itself, for there might be an offset between the gear and shaft splines, so that this would make the fit excentric.
  2. You need to put both mate connectors right on the geometrical axis of the gear resp. the spline in the part studio. Ideally, you'd use their common face (where the both are to touch in the assembly).
  3. You need to find (or define) a refenence to use. Lacking any immediately clickable references, I created a sketch on both the parts for this purpose. The sketches center on the spline base circle segments.
  4. Align the secondary axis with the reference.

  Find the result here:

  https://cad.onshape.com/documents/f51c5a902c3aa8033be2a7d7/w/ad498b791b6f6da82bc43798/e/2827adb17a30a8fa23a07e83?renderMode=0&uiState=682c5020c903661b1545cf44

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• dan_beavers Member Posts: 9 EDU

  May 20

  @martin_kopplow THANKS! I now understand how to accomplish this!

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