Making Stringer Notches

kunal_bachim

I'm making a model RC plane and need help with making the fuselage. I want to make a structure similar to this with stringers notched into the formers/bulkheads:

This is how my structure currently looks like:

I'm using the following steps currently:

1. Start a sketch on the first former and sketch the projection of the stringers in the desired locations along the perimeter.

2. Define dimensions of the width and depth of cut for each stringer notch in the former.

3. Extrude this sketch to cut out notches in the first former.

4. Sketch on the next former using the first sketch as a reference then extrude and cut out the notches in the second former.

5. Repeat steps 1-3 for each former

Constraints for making the notches are:

1. A straight stick of wood is used for each stringer so notches must accommodate that.

2. Notch depth on each former must be constant. 

This method seems to be repetitive and time-consuming. Can someone suggest a better method to go about it?

MichaelPascoe

Try using the Boolean tool. 

Create your stringers, then subtract the stringers from the other parts.

romeograham

You can create the "depth" of each stringer in the same "stringer projections sketch"...then select only the area of the stringer you need for each cut. Then cut the stringers (selecting just the stringer body you need to cut, and the correct area of your sketch) in a series of Extrudes. This way, you can drive it all from 1 sketch.

If you can provide a public link to your document (so that other folks can review / copy / make suggestions) it will be easier to show you what I mean.

Here's an example I put together that shows the process I describe above.
https://cad.onshape.com/documents/a9c6ff3adb3b697195131225/w/49ed434d89237c141a748621/e/edacc31bfae6411886307008

EvanReese

Here's my approach. I think it will work well for what you need and be pretty robust to change without lots of fiddling.

1. make the entire fuselage as a singe solid loft
2. split the notches into the face and use move face to get a single notch depth
3. split the loft into separate parts
4. extrude the faces of the new split parts (i assume you'll laser cut these or something, so you want them straight)
5. delete the extra stuff.

p.s. some of my practices are "bad" here for speed, so just reference it and do your own thing.

EvanReese

btw @romeograham I saw your workaround to prevent the mirror feature from merging everything. Try my multi-mirror feature next time. You can mirror multiple things across multiple planes at once and only merge each one to itself.

romeograham

Good point @Evan_Reese ! I admit I was distracted from your multi-mirror feature by the shiny new @MichaelPascoe Boolean Groups feature (and right then I actually didn't remember that MM does boolean each body without merging everything).

I like your approach of lofting the hull as one part (my approach had no way to create the actual correct hull shape), the serpentine split surface, and the "extrude multiple faces in one extrude feature".
However, I think the split face + move strategy for creating the notches produces some unwanted twisting in the notch faces:

(If the stringers don't need to be planar, this is no problem, of course).

I wonder if some extra steps to replace your step 2 might help:

1. extruding the stringer bodies from your sketches
2. Replace face (with an offset from the loft surface) to define the "bottom" of the notch face of the stringer bodies
3. Boolean subtract the stringers from the loft

...then move on to: split the body, extrude each rib etc etc

[edit to add this]
Here's my cleaned-up version using your approach, with planar stringers. Much cleaner than my first go.

EvanReese

@romeograham
Improvements for sure. I like that you get the stringers with this one too. I can't help but think of some Featurescripts I'd want to write if I had to do this often.

MichaelPascoe

@Evan_Reese

What?! Multi-Mirror? How did I miss this??




We need a better way to keep up with people and features. Is there a subscribe button I'm missing?

kunal_bachim

@romeograham @Evan_Reese Thanks a lot for your help!  Really appreciate it!