Can't shell an object in solidworks

I am using solidworks 2010. I have a scan of a gas tank that I paid a lot of money for. However, the scan is completely solid, and I need to shell it. I've searched for like 12+ hours now, and tried a bunch of different methods including offset surface, thicken, and so on. I really could use some help here. I am afraid to upload any file as I did pay a lot of money for this, and I don't want to give it away. I can post a picture of what it looks like for starters. I am a beginner with solid works, so go easy on me.

Are you sure it is even a proper solid? All those lines on the model's surface are odd. In what file format did you get the model? If it's a mesh, then no wonder you cannot shell it, as you need a solid for that.

At top left where it's written "tank (Default< < Defa...", if you click on the plus sign, do you see a list of features? Having a look at the feature tree would help us figuring out what the shape is.

If it's a solid, with such a convoluted shape, it is quite possible that shelling would fail.

I've only taken training courses on SW, I've never worked with it. But I recall there was some kind of geometry inspector that could tell you if the shape is a valid solid.

Forgot to add, shelling will only work if all the surfaces can be offset by the value you set. After a second look at your picture, I'm pretty sure the side ribs and the threaded bottleneck will prevent shelling from working. These are usually details you add after shelling a solid.

I'm afraid getting what you need may require quite some proficiency in surface modeling.

They gave it to me in 2 formats, .IGS, and .X_B

I am assuming it is a solid as I can export to .stl put it in Cura and print it setting the infill to 0 and just picking my shell thickness. I've printed up to 40% models of this.

The ultimate goal here is to print a full scale version in shapeways for actual use as a fuel cell. There is a company out west that is using the same process to make fuel cells for military drones. They do seal the tank with something though. (gold seal?)

I had thought about removing the filler neck and mounting tabs then shelling and putting those features back on. Although I am not sure how to do that yet. I did remove the filler neck once in meshlab and used it as a "negative" to make a filler cap.

The feature recognition isn't working, the shape is too complex most likely.

It may be a solid, but how was it constructed?

At work I have a file of a thermoformed plastic part that was modeled in Rhino then imported back to Solid Edge. It is a stitched set of surfaces, and it's impossible to thicken into a solid sheet because many of the surfaces are intersecting. I've taken upon myself to rebuild it on the side because it bugged me.

Your model seems to have a lot more stitched surfaces than mine. So as I said, depending on how it was modeled in the first place, it may very well be impossible to shell because it has self-intersecting geometry.

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Antslake
I am assuming it is a solid as I can export to .stl put it in Cura and print it setting the infill to 0 and just picking my shell thickness.

You should not assume it's a valid solid just because exporting it to STL and printing it worked.

Have you looked for the geometry inspector like I suggested?

Also, if you paid a lot of money for this model, shouldn't it be the responsibility of the contractor to give you an actual workable model?

Cheers

Norm

The model was a laser scan done with a $90k laser scanner by Konica Minolta. I paid for the scans, not for working models I guess. They are no longer doing it either so I really can't go back to them. It was $1200 to have the tank and 2 shrouds scanned. The shrouds are fine because they are solid.

I don't know what program they used to scan these. Even if they shelled it for me, I would have to make design changes to accommodate printing as opposed to molding. The original tank has aluminum mounting tabs, and brass nuts molded in 8 different spots to mount the shrouds and fuel valve. Those will have to be plastic now, and I will have to thicken those areas.

When I load the model and try to do a feature scan, it won't let me, says I have to do it manually. I just did a Geometry Analysis, but I don't know what I am looking at

Thank you for trying to help me BTW

As far as I know, all a scan can do is get a point cloud. A CAD tech then needs to create a 3D model out of this point cloud. But I have never used the technology so I might be mistaken.

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Antslake
I just did a Geometry Analysis, but I don't know what I am looking at

Are you seeing any written text on reported errors? Do you think you can post a screen capture? Not that it will really help, to be honest. Might just confirm (or not) what I was thinking.

Best of luck with this project.

From my VERY LIMITED nowledge of Solidworks... I think NormandC has the right approach.
I would try reducing it to the main body and shell that, then put all the mounting tabs and other bits back on.

You can probably validate the approach by sketching up something conceptually similar that "shouldn't" be shellable.

The person who did the original scan came through and shelled it for me no charge. He didn't have to do that either. Only thing is I do not know how he did it, so if I should need to change the thickness of the shell, I would be lost. I don't think he had to remove the tabs to shell it. He also combined the location of the holes in the tank that I needed. So hopefully now I can make a complete ready to use model.

The cool thing is I am that much closer to having the worlds first ATV (ATC) with a 3D printed repo gas tank. It's still $1400 from shapeways, need to get over that hurdle.

BTW, I've printed these scaled down on my printer. Shelling was possible in Cura, but useless to me to make a full scale model with reinforcements in the proper spots and threaded holes to hold the shrouds and petcock.

[apshobbies.com]

I'm glad it worked out.

$1400 sounds like a hell of a lot of money. How big is that tank is? What's the 3D process by Shapeways? I wonder if you could get cheaper quotes from local prototyping shops.

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Antslake
The person who did the original scan came through and shelled it for me no charge. He didn't have to do that either. Only thing is I do not know how he did it, so if I should need to change the thickness of the shell, I would be lost. I don't think he had to remove the tabs to shell it. He also combined the location of the holes in the tank that I needed. So hopefully now I can make a complete ready to use model.

The cool thing is I am that much closer to having the worlds first ATV (ATC) with a 3D printed repo gas tank. It's still $1400 from shapeways, need to get over that hurdle.

BTW, I've printed these scaled down on my printer. Shelling was possible in Cura, but useless to me to make a full scale model with reinforcements in the proper spots and threaded holes to hold the shrouds and petcock.

[apshobbies.com]

Well, chances are he just knew the object - or was lucky and chose the right face to shell it from - or KNOWS solidworks - some combination....
Personally I find it quite disturbing that (given the current maturity of the state of this art) you are using a 3D printer to make a fuel cell.
My own prints are fair to reasonable, but the thought of a delaminated wall in any part of a fuel cell scares the heck out of me.
For this application you NEED PERFECTION and I think we're "not there yet"

Do KNOW that a spoonful or so of almost any "flammable" liquid can produce devastating results.

Edited 1 time(s). Last edit at 11/03/2014 05:49PM by RegB.

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RegB
Personally I find it quite disturbing that (given the current maturity of the state of this art) you are using a 3D printer to make a fuel cell.
My own prints are fair to reasonable, but the thought of a delaminated wall in any part of a fuel cell scares the heck out of me.
For this application you NEED PERFECTION and I think we're "not there yet"

Do KNOW that a spoonful or so of almost any "flammable" liquid can produce devastating results.

You better go tell the military, because they use them in their drones. Just a little FYI, do a google search on 3D printed fuel cells and prepare to get blown away. We ARE there.

This is the company doing it: [www.nwrapidmfg.com]
Matter of fact, I need to give them a call again and see if their pricing structure has changed at all.

Heck, NASA 3D printed a rocket nozzle! What makes you think we can't print a fuel cell?

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Antslake

Quote
RegB
Personally I find it quite disturbing that (given the current maturity of the state of this art) you are using a 3D printer to make a fuel cell.
My own prints are fair to reasonable, but the thought of a delaminated wall in any part of a fuel cell scares the heck out of me.
For this application you NEED PERFECTION and I think we're "not there yet"

Do KNOW that a spoonful or so of almost any "flammable" liquid can produce devastating results.

You better go tell the military, because they use them in their drones. Just a little FYI, do a google search on 3D printed fuel cells and prepare to get blown away. We ARE there.

This is the company doing it: [www.nwrapidmfg.com]
Matter of fact, I need to give them a call again and see if their pricing structure has changed at all.

Heck, NASA 3D printed a rocket nozzle! What makes you think we can't print a fuel cell?

I didn't say "it can't be done"
Perhaps I was too inclusive in my modesty ?
I'll re-phrase it;
The MAJORITY of "us" can't do that reliably enough to be SAFE.
Depends who the "us" and the "we" are...
(Is that better ?)

I appreciate the concerns of safety, don't get me wrong, but isn't the spirit of reprap about pushing boundaries? Of course if I were to do it myself I would approach this with the utmost caution. I have been researching this for about 2 years now. That's why I need to build my own machine to do it because a reprap won't. If not, then the technology to do it will become cost effective soon enough. I'll be ready.

I think when you build your machine (of whatever design) you will appreciate how very, very hard it is to perfect the printing process.
Tuning, calibration, call it what you will, it takes a LOT of time and experimentation to get anywhere near perfection with these machines and to contain flammable materials you CANNOT have leaks due to delamination, weakness between layers, potential splitting due to cooling stress, etc.
This won't be a vibration free environment, the shaking and rattling around will uncover weaknesses that your eye won't - and that will be when things are nominally up and running with LIVE FUEL.

If I were faced with this I would probably settle for the print you have as a mere container shell.
Within that I would put a flexible fuel "bag" of known strength and suitability.

Second choice, perhaps line what you print with some "coating" that can relied on, though I don't know what.

Best,

\R

.

More excellent advice, thank you. I have thought about all those things. I plan on making the machine very robust out of 6061 aluminum plate and high temp glass for windows. I will be using ball screws with high temp silicone grease, and placing the drive mechinisms outside the build chamber (stratsys patent *cough).

I can't use a fuel bag because there needs to be a drain on the bottom. NWmanufacturing uses a sealing process called "gold seal". I've rsearched a little but have idea what it is. Sealing nylon will be difficult as nothing sticks to it. I did bookmark a potential product but haven't contacted them yet to ask. I am sure there is something out there.

I have some other ideas to ensure perfect lamination. If they work out I will post them in these forums and link back here.

SolidWorks user here, late to the party. If you have .igs and .x_b files, you have a proper BREP solid model. Whoever did your scanning had an expensive piece of software make the solids from the scan data. It is very unlikely that you'll get it to shell in one feature. There will be small faces that SW doesn't know to delete, and small radii that need to disappear, that sort of thing.

Use the move/copy body tool to make a copy of the body. Split the copy into many pieces so you can work on one small area at a time. Start figuring out which faces can be offset and which can't. Use linked values to tie all the offsets to the same parameter. Get what you can to offset, then start filling in the holes using surface tools (loft, sweep, fills, whatever you can get to work). Once you have everything offset, knit the offsets together and make another solid (either in the knit feature or using a thicken feature). Subtract the knitted solid from the original scanned solid to get the model you need. Delete the pieces of the copy of the original solid (delete the bodies, not the features).

I hope that helps. Sorry there's no magic way to get it to shell. You are in for a steep learning curve.

Edited 1 time(s). Last edit at 11/09/2014 01:20AM by Dale Dunn.

So many options....

I would try cavity command in SW to do what you want. I think it may work better. 2010 may have had it, think mold cavity, something to play with.

Guys, Antslake solved his problem and moved on more than a month ago.

I got someone to do it, but didn't learn myself. Dale Dunn seems to be exactly right. I am having trouble learning how to do all that. Trying to learn from youtube is frustrating most times. People make tutorials with no sound or instruction and move so fast you have no idea what they are doing. They assume you are at their level. If I was at their level, I wouldn't need to watch the tutorial. I really wish I had the time and money to take a solidworks course.

I learned most of my surfacing (which really isn;t nearly expert level) from presentations by Ed Eaton at the DiMonte Group (engineering consultants). Ed has always made his presentation materials for SolidWorks World (user convention) available. You can get them all here. He even has a presentation specifically about shelling, which I haven't seen yet. Anyhow, the materials are complete enough that you can understand what he's talking about even though there isn't a recording of the presentation. I recommend you take them chronologically to get some of the basic principles before attempting a complex task.

Be aware that surfacing work in SW is not easy. Even the experts resort to trial and error getting what they need. For me, a complex shape usually takes about 3-5 times the work evident in the file when I'm done. If you have access to the SW World presentations (SW subscription required, I think), there a lot of good ones with audio and video showing how to get things done.

I stumbled across a lynda tutorial on shelling, until then I thought that you ALWAYS
had to specify a surface from which to "hollow it out".
The tutorial is quite specific on this; If you don't specify a face from which to shell the whole object becomes hollow.

I haven't tried it, so this is FWIW, etc.

Edited 1 time(s). Last edit at 12/19/2014 06:44AM by RegB.

Thanks for that Dale, I will check it out!
BTW, I recieved the first successful print of one of the shrouds that go along side the gas tank. Came out so nice going to get the other one, and someone else ordered a pair!
3D printed short track shroud for the ATC250R: [youtu.be]
Here's what it looks like on the trike:
World premiere test fit 3D printed shroud: [youtu.be]
I have high hopes for the tank, but prices need to drop just a little more. Shapeways gave a 20% off coupon for the holidays!

Thanks from me too Dale,
I now have that site duly book marked.