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AP_ACTUONIX7-Bedrock
7-Bedrock
January 22, 2024
Solved

Pattern about Axis Failing - Spur Gear

  • January 22, 2024
  • 1 reply
  • 900 views

Any idea why the revolve Axis pattern keeps failing?  I have patterned the sketch with the extrude but no difference.  The sketch patterns fine, but the extrude will only do 1 additional pattern.  This is for a spur gear where I input parameters like #teeth and the model should update.  Only the pattern about axis is causing issues.  Something with my references?  I have an older spur gear file from Wildfire 2.0 that works for one feature (half the gear tooth) over 40 teeth and then the other feature (other half of gear tooth) only works up until about 30 teeth then it fails to create the additional patterns beyond that.  

File attached is of my new spur-gear where only one additional extrude pattern is being created, others are failing to generate.  Reference issue?  

Best answer by AP_ACTUONIX

I found that changing the depth reference of the tooth extrude has solved the problem.  but I do want it to be based off my chosen gear thickness distance.

1 reply

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AP_ACTUONIX7-BedrockAuthorAnswer
7-Bedrock
January 22, 2024

I found that changing the depth reference of the tooth extrude has solved the problem.  but I do want it to be based off my chosen gear thickness distance.

KenFarley
KenFarley21-Topaz II
21-Topaz II
January 22, 2024

Hmm.

If the depth change affects things, maybe you are:

(1) Working with a file that has relative accuracy set? This is terrible with geometry like this.

(2) Working in absolute accuracy but with a value that is too large? I use 0.00001 inch by default.

(3) Suffering from rounding of dimensions? This can cause havoc with rotational patterns with non-"nice" angular pitch, like 42 teeth (8.57143...degrees).

I've made a number of gear-ish parts in the past, and these are my tricks:

(a) Build a half tooth with the involute curve, mirror that, group the protrusion and mirror, then pattern that around the axis. Seems like a lot, but what I found out the hard way is if I draw the half tooth and mirror it in the protrusion sketch, the mirrored geometry doesn't update properly when I change anything that affects the geometry.

(b) Use relations to set the angular pitch of the axial pattern. i.e. angPitch = 360 / numTeeth. It calculates the exact angle and it's also kind of cool.

(c) Make sure none of the driving dimensions, like the "angPitch" are not set to be rounded. I think the config option "round_displayed_dim_values" set to "no" was something I set to avoid this problem.

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