topic Re: Internal and external helical spline in 3D Part & Assembly Design

Internal and external helical spline

JK_9273484 — Thu, 01 Feb 2024 06:23:11 GMT

Dear all,

I have searched the PTC and this user community portal for help in creating parametric internal and external spline parts. There are many posts on these but none of them have a solution.

Has anyone solved or found an easy method to generate internal and external helical splines?

Thanks and regards,

Jay

Re: Internal and external helical spline

MartinHanak — Thu, 01 Feb 2024 07:56:22 GMT

Hi,

I am sorry I do not know what is:

internal helical spline
external helical spline

Re: Internal and external helical spline

JK_9273484 — Thu, 01 Feb 2024 08:00:26 GMT

Hi,

Attached is the image of the shaft and hub connection with a helical spline.

Thanks,

Jay

Re: Internal and external helical spline

StephenW — Thu, 01 Feb 2024 11:43:52 GMT

https://www.youtube.com/watch?v=IzMRAvO0p2M

https://www.youtube.com/watch?v=WSgJ927Xv90

Re: Internal and external helical spline

Patriot_1776 — Thu, 01 Feb 2024 15:26:51 GMT

I would do that as an assembly with a skeleton part in there with curves in the skeleton part driving the shape of the teeth (with clearance) and the helix. It LOOKS like the section is normal to the long axis, not the helical trajectory, though I may be wrong. You can sweep features with the section normal to the spine with the option: "Normal To Trajectory", or remain constant to a reference using the option: "Constant Normal Direction", in your case the flat end. You can do a straight spine for your trajectory and use trajpar in the section relations for the twist (simplest), or you can wrap a curve around a cylinder to get the helix and use that to control the twist as a second trajectory and again using the straight spine, I'd go with the first option since you don't need the variable twist rate or reversal the wrap could give you.

Here's something I did for fun, I got a true involute geartooth form without using a CS and equation, and then made a sort of "herringbone" gear.

Best of luck!

Re: Internal and external helical spline

Patriot_1776 — Thu, 01 Feb 2024 17:55:58 GMT

Here's a STEP file. Note that even in different sections parallel to the Z plane, the tooth form is EXACTLY the same no matter where in the "swoosh" you place the section. THAT, is what the "Constant Normal Direction" does vs being normal to the trajectory. In a helical gear or gear like this, the tooth form needs to stay perfect normal to the gear axis.

Re: Internal and external helical spline

Patriot_1776 — Fri, 02 Feb 2024 20:09:18 GMT

Oh, and I created the involute without using a CS and equation....so, how did I do it?

Re: Internal and external helical spline

Patriot_1776 — Sat, 10 Feb 2024 23:51:27 GMT

No guesses?