Cutting midpoint groove in non-planer geometry

[Anonymous]

Hello All, 

First post, so be gentle please. I've been doing some searching to figure out how I might be able to do this but have not come across anything that seems to work as yet. I've been working with some existing geometry and am trying to make some modifications to suit what I'd like to do with it. Currently using Fusion 360 version 2.0.9006

What I'm trying to do: I'd like to cut a groove in to the inside of the enclosed cut out in the model - so its an equal depth of around 2mm all the way around, a thickness of around 2mm and so it follows the midpoint of the geometry (ie distance from the groove to the front edge, and the distance to the back edge remains equal around the whole section).

What I've tried already: I've tried various versions using offset planar extrusions but that doesn't produce the desired result. I've also tried using projected geometry of the hole section geometry, offsetting that sketch and again attempting to cut that shape out of the geometry. I think the way of doing it is going to be along the lines of projecting the desired sketch to the geometry then using an offset cut or something similar but I can't seem to get to that stage.

Unfortunately I'm new to Fusion 360 and am relatively new to more complex CAD tasks in general so more complex geometries like this are rather challenging to work with! I've attached the model so hopefully you can have a look and see if you have any ideas of how to do this - If you'd like a more detailed explanation of what I'm trying to do let me know and I'll happily try to explain a little better.

Any help would be greatly appreciated. Thanks in advance for any replies!

Ben

[davebYYPCU]

Inside what?  Something to do with that largest sketch?

There are at least 4 insides.

I take it that you want a rebate,

but the outline of the opening labelled 2 has a big step, circled yellow,

The wall face at 4 is less than 2 mm.

Capturing history will make things easier to debug.

It's not clear so far please add more details.

[Anonymous]

Hi David, 

Thanks for the response. Hopefully this sheds light on the issue.

The red line in the pic below shows where I'd like to be able to cut the groove - so it follows that internal surface of the cut out created by the sketch where your '1' and '2' is. But also so that it remains at the midpoint between the front and back surfaces and the same depth from the surface that I've drawn the red line on. Ideally this would go around the entirety of that surface - so on each of the a,b,c and d surfaces.

The dimensions aren't a huge concern for me (if it cuts through etc that isn't an issue) and I can address that afterwards - its really the method of getting the groove cut where it needs to be that I'm struggling to find. This is an existing part that I've been attempting to modify so I'll need to change various things so it will suit the application.

I would like to be able to insert a sheet in to the groove created but this cutout - so the cross section of the groove if you looked where the 'a' is, for example, looked like this...

Realistically it doesn't need to be perfect as it is hidden, but having an even sized groove would be beneficial. If you need some more detail let me know!

Thanks

[Anonymous]

Hi, 

Thanks for the response. Hopefully this sheds light on the issue.

The red line in the pic below shows where I'd like to be able to cut the groove - so it follows that internal surface of the cut out created by the sketch where your '1' and '2' is. But also so that it remains at the midpoint between the front and back surfaces and the same depth from the surface that I've drawn the red line on. Ideally this would go around the entirety of that surface - so on each of the a,b,c and d surfaces.

The dimensions aren't a huge concern for me (if it cuts through etc that isn't an issue) and I can address that afterwards - its really the method of getting the groove cut where it needs to be that I'm struggling to find. This is an existing part that I've been attempting to modify so I'll need to change various things so it will suit the application.

I would like to be able to insert a sheet in to the groove created but this cutout - so the cross section of the groove if you looked where the 'a' is, for example, looked like this...

Realistically it doesn't need to be perfect as it is hidden, but having an even sized groove would be beneficial. If you need some more detail let me know!

Thanks

[davebYYPCU]

Took an easy way out, parallel stepped inside from that main inside face.

You can adjust the surface position and size as desired.

[Anonymous]

That's pretty much what I'm looking for - I can adjust the geometry to fit.

I don't really understand how you did it though. Is it essentially an extrude of the edges of that inside face? Or have you had to use some other features to do that?

[davebYYPCU]

Timeline icons can be edited to find the settings.  (Move excepted)

Surface Patch to fill the inside hole, moved it inboard (by an amount?) and aligned to the hole opening.

Thicken to a solid body, and then the outside ring face was Offset outwards, to give the depth of cut.

The Combine Command is used to cut the groove with the now oversized plate, and it's deleted in the process.

Might help....

[TheCADWhisperer · Accepted solution]

I used a similar, but slightly different technique.

I suspect you want it split in the center of the faces, but that would take more effort...

[Anonymous]

@davebYYPCU Thanks for the details, I'll see if I can replicate it using the patch and offset and can modify the geometry to suit!

[Anonymous]

@TheCADWhisperer  Thanks for the reply, could you give some steps for how you put the groove in if it differs from the previous post? Any details or screencasts you have would be great to see. It looks like a similar patch>offset>thicken type approach based on the bodies in the part.

When you say making it symmetrical between the two faces would be more effort what sort of effort do you think it would be and how would you suggest going about it? If I know what sort of route to use to get there I'm happy to spend the time learning how to do it.

Thanks for any extra feedback.

[TheCADWhisperer]

@Anonymous 

The file that you attached did not have a feature history Timeline.

I generally do not work without feature history.

[Anonymous]

@TheCADWhisperer  - Had a look back at the model, I didn't realise you'd put the feature history in there! 

I had to turn it off after importing and converting from STL to a solid body which is why the original didn't have any of the modifications in the timeline - I'll be sure to keep that in place when working with solid bodies in the future.

As there aren't a huge number of steps in the timeline you had, would it add a significant number to get it to the point where it stays in the center of the two faces? Or would it need a completely different approach?

[TheCADWhisperer]

---

@Anonymous wrote:

I had to turn it off after importing and converting from STL...

---

This doesn’t look like stl to me?

Attach the original file here.

[g-andresen]

Hi,

I recommend that you study the principles of parametric and direct modeling. Then you will have a better chance to make informed decisions about your approach.

günther

[Anonymous]

@TheCADWhisperer , my mistake, you're suspicions are correct - this isn't the stl version. This file started life as a solid body.

I'll take the methods suggested away and will have a look at repeating them while trying to figure out how to keep it in the midpoint of the faces, thanks all for the help. I'll hopefully be able to delve in to the methodology behind it all as my familiarity grows!

[TheCADWhisperer]

Having a complete feature history Timeline would make the entire endeavor much easier.