Help me hollow (or shell) a model please!

bitingmidge

Hi, I am very new to Onshape (or any form of CAD for that matter) and have spent the day completely lost I'm afraid!

I am trying to draw a small dust collection fitting, and have what I think is a solid model, although it may well be a series of hollow surfaces at this point.

After much trial and error I was able to make a similar part (version 1) yesterday.  The biggest difference between the two is that the cylindrical portion yesterday was an extrude, and today it is a sweep. I have the feeling that the answer is very close but my brain is a bit computer fried!

So basically I have a loft and a sweep that don't want to play.  I did get them to work in a fashion by removing surfaces and then thickening, but there were too many bugs to persevere.  I have tried to shell to sweep a cylindrical object and pretty much every combination I could think of.  There are plenty of errors showing, but I have not been able to find anything to explain what they might be.

If someone could point me in the right direction I'd greatly appreciate it.

The drawing in question is HERE

The drawing that worked for me is HERE

sebastian_glanzner

@bitingmidge I can't make a copy of the document. Can you adjust the share settings? Then I could try to help you :-) Nevermind, now I could make a copy :-)

Here is my "solution". Please note that i changed some of the dimensions to make it work. I also rearranged, deleted and added some commands.
https://cad.onshape.com/documents/dcaf711ab117c5891fde8777/w/7e62b560fb75cc4376590b61/e/29e33e382b67b225c4be5fff

The main problem was/is the loft. Somehow I can't make a thicker shell than 1.4mm. Maybe you have to change the profiles sketches to get a "better" loft.

Here are some tipps for you:
- Make sure all sketches are fully constrained. If you see blue lines, then they are still "moveable".
- Instead of the split feature you can use the boolean command to substract (Make sure to "keep the tools" if needed)
- Use the shell command only for the pipe segments

Use the "Rollback bar" to scroll through the solution. This way you better understand what each feature changed. Also make use of the section view to look for gaps and errors in the geometry. 

This is a very complex model for a CAD beginner 
You should also check out the learning center, it has great tutorials.

sebastian_glanzner

@bitingmidge
Tipps for your second document:

- Make sure to create a "new" volume when you use the extrude command for the pipe sections
- Use boolean to substract the pipe from the plate
- Don't use too much Split commands

Have a close look in this document, I changed and deleted some features:
https://cad.onshape.com/documents/50ee5212ddabb940cbaeb72e/w/f73cd9c98d92da6a96579342/e/a7503c0dd0bee1b4c95b1771

sebastian_glanzner

@bitingmidge I can't make a copy of the document. Can you adjust the share settings? Then I could try to help you :-) Nevermind, now I could make a copy :-)

Here is my "solution". Please note that i changed some of the dimensions to make it work. I also rearranged, deleted and added some commands.
https://cad.onshape.com/documents/dcaf711ab117c5891fde8777/w/7e62b560fb75cc4376590b61/e/29e33e382b67b225c4be5fff

The main problem was/is the loft. Somehow I can't make a thicker shell than 1.4mm. Maybe you have to change the profiles sketches to get a "better" loft.

Here are some tipps for you:
- Make sure all sketches are fully constrained. If you see blue lines, then they are still "moveable".
- Instead of the split feature you can use the boolean command to substract (Make sure to "keep the tools" if needed)
- Use the shell command only for the pipe segments

Use the "Rollback bar" to scroll through the solution. This way you better understand what each feature changed. Also make use of the section view to look for gaps and errors in the geometry. 

This is a very complex model for a CAD beginner 
You should also check out the learning center, it has great tutorials.

002593

Try to make the shell/hollow smaller. This will shrink the inner dimensions of the walls!

bitingmidge

Thanks Sebastian, I think I have them set correctly now.

I have successfully re-drawn the part, and have managed to remove the end surfaces by extruding through them, which seems odd, and the whole object appears to be hollow.  ie, the extrusion (sweep) comprises an inner and outer skin, but nothing between.

If you have time I would really like to know where I have been going wrong,

Regards,

Peter

sebastian_glanzner

@bitingmidge
Tipps for your second document:

- Make sure to create a "new" volume when you use the extrude command for the pipe sections
- Use boolean to substract the pipe from the plate
- Don't use too much Split commands

Have a close look in this document, I changed and deleted some features:
https://cad.onshape.com/documents/50ee5212ddabb940cbaeb72e/w/f73cd9c98d92da6a96579342/e/a7503c0dd0bee1b4c95b1771

bitingmidge

Thank-you very much!

I really appreciate the time you have taken to reply.   I did not guess about subtracting the pipe from the plate, but one of the things I did to make it work was to create the plate after the pipe - so it's clear to me now!   

I am aware that it's not an easy place to begin, but I learned a lot during this process - perhaps not all my practices are good ones though!  I look forward to the time when I understand what is happening instead of having to cross my fingers each time I do something, but that is coming much faster than I expected.

I was going to delete those early models, but I think they should stay for the benefit of others who may follow this thread in the future.

Once again, many thanks,

Peter

sebastian_glanzner

@bitingmidge

Learning CAD is a long and never-ending process It's frustrating at first, but you get better every day and it gets easier. I think it is good when the forum participants describe their problems and others suggest a solution. In this way, both learn and the reader has something from it. 

I have used other CAD systems in the past and Onshape is in my opinion the easiest and best.

I wish you much success and happy designing

bitingmidge

sebastian_glanzner said:

@bitingmidge

Learning CAD is a long and never-ending process It's frustrating at first, but you get better every day and it gets easier. I think it is good when the forum participants describe their problems and others suggest a solution. In this way, both learn and the reader has something from it. 

I have used other CAD systems in the past and Onshape is in my opinion the easiest and best.

I wish you much success and happy designing

I have started many times over the last 20 years (and spent quite a lot of money in the process!)  This is the first that has "clicked" for me, so I am very grateful for the support as well.