Newbie- Drawing 3D curved Speaker Baffle

[ssashton]

Hi,

I am new to AutoCAD and have 2007. I have read some tutorials to get the basic skills but I am not sure the best way to use them for drawing what I want.

I want to draw a 3D-solid speaker baffle which will later be CNC cut, and it is curved in all directions!

I've drawn basically what I am after in a 2D mode, so you can see it is curved on all edges from the front view, and also the board is 'bent' along its width.

How would you guys recommend drawing this as a 3D solid that I can then round-over the edges of, subtract some shapes from etc.. ? I've tried a few things already but I'm not getting there.

You can also see a similar baffle design on the website here - R 907 Floorstanding Speaker - Description

What I want:



Uploaded with ImageShack.us

[ger21]

I think the easiest way is the LOFT command. Draw 3 cross sections, at the top, bottom, and middle, and loft them.

The alternative would be extrude, and subtract, but you need to create somewhat complex revolved solids to subtract. Keeping the bevel on the back would be the hardest part, imo.

Even with lofting, the curved top and bottom will need to be subtracted.

[ssashton]

Thanks. I realised another way too some time after posting.

I can extrude the front view, say 50mm, then also extrude the end view. Position the end extrusion over the top of the front extrusion and subtract it. That way I get the front extrusion with the curve of the extruded end view. It seems similar as the way it would actually be cut; a double thickness board with the curve parts cut away.

Can I also ask as a CNC users, how would ou guys prefer to receive designs? I thought a 3D cad file is nice becasue you can find the dimensions for all parts without needing multiple drawings, and you can also cross-section it or whatever you need.

[ssashton]

Hi Guys,

I need a bit of help again please!

I've got my basic 3D baffle shape now. See attached.

How can I put a chamfer around the edge of the face? I can apply a fillet, but I get an error when I try to chamfer. It seems like it will do straight edges but not curved ones?

How should I best go about this?

Thanks,
Simon

[ger21]

Somehow, due to how you created it, the curved face is composed of two faces. That's why it won't chamfer. You'll need to recreate it so that the face is actually one face.

Sorry, but that's all I can tell you.

[ssashton]

Whaa...

Okay I'll try another way.

[ssashton]

I'm still stuck

I tried making the baffle as a loft of 3 cross-sections as suggested. This produced a smooth face surface with no divisions. I then needed to create the curved top and bottom edge and then add a chamfer to those.

I made an eclipse type shape and tried subtracted that from the main baffle and it does make the curved edge, however I still get the same error while trying to apply a chamfer.

Please help!!

See attached.

P.S. I notice only one person is replying. Is there a more busy place to get AutoCAD help?

[ger21]

I'd subtract the chamfer.
Honestly, unless you're really, really good with AutoCAD, you'd be better off doing this in Inventor or Solidworks.

Chanfers and Fillets can be tricky in AutoCAD with certain geometry.

[ssashton]

Ahh poo I just assumed AutoCAD was the industry standard so I started learning it. I ain't learning another program now, lol!

Thanks for your help.

[ger21]

The easiest way might be to create a lofted solid to subtract. You can draw the cross sections right on the solid, to get exactly what you want.

[ger21]

Originally Posted by ssashton I just assumed AutoCAD was the industry standard so I started learning it.

Depends on the industry. It's the standard in the architectural industry, but not really in manufacturing.

Personally, I prefer it to other packages, as I can do most things much faster in AutoCAD. You just need to know how to go about it.

[BurrMan]

I cant help too much because I dont have or use the autocad, but heres what i did. I was able to chamfer it with BobCad, which has a notoriously weak fillet/chamfer mechanism, by cleaning up the geometry in this area"



Here's a file back to see if you can chamfer that area with..

As Ger mentioned, that top surface was fragmented, but most likely due to either the original curves you are working with, or the cutting objects construction method.

This area in the apex had little fragmented entities in both the top and the side, connected surfaces... I cleaned those up with a "merge command" (Not sure if/what autocad would use to merge a fragmented entity on a surface, which should be a single segment) and the chamfer would succeed.

I'm not sure about the autocad workflow for solids, but this type of stuff usually comes from the incorporation of a "Seam edge" into boolean/cutting operations where it is intersecting with other existing edges of objects, creatingt little tiny fragmented, slivery pieces that ruin further operations

Anyway, thats all I got.