topic Re: Creating spars for multiple slotted parts. in Inventor Forum

Creating spars for multiple slotted parts.

joh13399 — Wed, 06 Apr 2022 06:34:20 GMT

Hello. I have an assembly with about 13 parts that were CADed in from old drawings in the 70s. The drawings do not have dimensions, and the scans were 300 DPI :-(. As a result, the parts are marginally accurate at best. Here's a picture of the assembly:

As you can see, there are many slots in this assembly, and there is a spar in one of the slots at the bottom.

I need to create 32 of these, and I'm worried about my process. my strategy so far is to use a 3d spline between the slots, and loft a rectangle through the spline. For the purposes of these parts, a rectangle is all the profile needs to be.

Is there a way to create these spars faster? I'm not sure that manually clicking each point is what I want to do 12x32 times.

Here are the givens:

each part has the same number of slots.

each slot may not be coplanar to each other slot that holds a spar.

each slot is rectangular, and have the same dimensions (3/32" wide x 1/4" deep)

each slotted part is currently assembled and grounded.

the slots are not at regular angular intervals, or regular directional intervals, and are off by a percent or 2.

There's no way to get higher resolution scans

Thanks in advance for any wisdom, CADing parts from bad scans with no dimensions is... difficult.

Re: Creating spars for multiple slotted parts.

joh13399 — Wed, 06 Apr 2022 06:41:41 GMT

Also, here are the files, I plan to release them as open source later, so feel free to use them, but keep in mind they're not finished.

Re: Creating spars for multiple slotted parts.

mpatchus — Wed, 06 Apr 2022 12:49:14 GMT

I've done a number of model planes, and there are two workflows that I have used.

Option 1, you can either sweep the 3/32" x 1/4" spars using guiderails along each corresponding slot.

Option 2, loft each spar using the slots.

Lofting tends to create more of a "stepped" spar, where the sweep will generate a smoother spar, but sometimes creates a twist to the spar.

I have a P51 Mustang that I modeled around here somewhere, I'll see if I can find it.

Re: Creating spars for multiple slotted parts.

joh13399 — Wed, 06 Apr 2022 16:59:19 GMT

That's what I was afraid of. Unfortunately, that means a LOT of time to make these in the near future. Well, if anyone else has some clever ideas, please let me know.