topic Re: Shell Problem in Inventor Forum

Shell Problem

glasairallen — Mon, 05 Oct 2015 01:57:10 GMT

Quite often I draw parts and then have them "3D Printed" and if I use an outside vendor to do the printing they usually charge by that amount of material used ... so a solid block part will cost many times more than a hollow part ... so of course I always use the "Shell" command the remove the bottom of the part and all the insides except a wall of about .050". I never have a problem with the shell command, but today that changed.

Check out the attached file of a bridge tower structure,, I want to have it made on a Stereolithography machine and then I'll make a rubber mold of that and cast them in resin.

I want to shell out the inside leaving a wall thickness of .050" and remove the bottom of the part. See attached screen shot that I have modified to show what I'm trying to do.

For some reason Inventor will not allow me to do this. I've done this on many models that I've created myself in the past but this one has me stumped. I've been using Inventor ever since the first version was released, but I'm far from an everyday user, I just stumble though it and eventually come up with the result I'm looking for ... except in this case.

Any help would be appreciated, just keep your terminology dumbed down to my model maker level.. .I am not a CAD professional, I'm a model maker.

Thanks

Betreff: Shell Problem

WHolzwarth — Mon, 05 Oct 2015 06:38:12 GMT

You could do it this way (2014 file)

Walter

Re: Shell Problem

Frank-Oosterwaal — Mon, 05 Oct 2015 06:46:30 GMT

Hi,

Your problem lies in mirror 4,5 & 9.

I suppressed them and the shell works.

You can do the mirrors after the shell but it gives a different effect because the wall thickness will be different.

But I think your model is drawn wrong.

What i would do is only make half of the part and mirror it as the last feature.

That way you mirror the solid body instead of the features.

Take a look at the model in the attachment.

DON'T do it that way it is only to show you that you only need to model half and than mirror the solid body.

Drag the end of part in the design tree down to see what i did.

Re: Shell Problem

wilkhui — Mon, 05 Oct 2015 09:16:24 GMT

Hi glasairallen,

As @Frank-Oosterwaal correctly points out, there's a problem during Mirrors 4, 5 and 9. The features being patterned (cuts into the body) aren't being made correctly on the other side of the mirror plane. I don't think you're doing anything wrong so I'll take a deeper look at this.

The suggestion to shell early in the process by @WHolzwarth is good considering your intent - shelling later on in your workflow will make the inside of your 3D print unnecessarily complicated, although I understand that your cost is by volume.

Also, Frank's suggestion to create half of the tower and then mirror the whole solid can save you time in the future.

Further, the steps at either end of the tower aren't flush with the 'ground' of your tower, you may encounter unexpected results in downstream modelling or face problems during 3D printing:

Hope this helps!

Indy

Re: Shell Problem

wilkhui — Mon, 05 Oct 2015 09:36:40 GMT

Hi again - I noticed that Sketch1 doesn't have dimensions and is overcomplicated. I've attached @JDMather's SkillsUSA document, it's a great summary of how to use Inventor and I think you'll find it useful. JD's website isn't available right now but I'm sure he'd be happy to provide you with some more material.

Please feel free to follow up with any questions.

Cheers,

Indy

Re: Shell Problem

glasairallen — Mon, 05 Oct 2015 18:26:48 GMT

Thank you all for all your great help and great suggestions.

Right after I posted this, I sat down and redrew the model from scratch and avoided a lot of the mistakes I made the first time and the shelling process worked perfectly on the second model that I drew.

I'm taking all the lessons you guys have passed on to me and learning from them.

This is a great group with some very helpful poeple. Thanks a lot.

Allen

www.gcmini.com

Re: Shell Problem

wilkhui — Tue, 06 Oct 2015 07:10:35 GMT

Hi Allen - Starting over is something we all do (I certainly still do it), I'm glad you were able to get the model you needed.

Best wishes and don't be a stranger to the forum 😄

Indy