Why do new parts "disappear" from the parts list?

adam_hey229

Hi all, I'm very new to CAD and Onshape, so please forgive a newbie question, but I have several extrusions in my model where I have selected Solid & New in context dialog. While that is open, the extrude does show in the parts list in bold, but when I click the green tick, the part disappears from the parts list

This achieves the extrude I'm after

…and it appears as a new part:

…but "part 3" disappears when I click the green tick:

I want to export this to be 3D printed and I need several parts to export each as an STL file.

Here's my document:https://cad.onshape.com/documents/8cd5a60aa8522c999b060382/w/8330b095762815a5f155ef90/e/6cc5690b2b072abebb54283b

Perhaps this is better posed as a separate thread, but I want to extrude off the highlighted cylinder above to get the two cylinders to "slot" into each other. So a smaller diameter extrudes and slots into a matching cavity in the cylinder that butts up to it. So it forms a sort of lap joint. Sorry, I'm unsure of the technical term for that type of connection.

The problem I'm having is that I can't find a way to select the appropriate face to extrude to add to one cylinder and remove from its neighbour

Thanks in advance!

nick_papageorge073

1. The feature called "mirror 2" is the one consuming part 3, not feature "right branch extension".
2. Your modeling technique is all wrong for this pipe. What you are after is called "sweep". Here is the help section on sweep: https://cad.onshape.com/help/Content/sweep.htm?Highlight=sweep

rick_randall

Don't forget to do the free "self paced courses" in the "learning center" These courses are well thought out, and start with beginner material and get progressively more difficult. Do yourself a favor, and spend some time training - and go back and review this material over & over.

I do this, and still find little things that I missed (or didn't understand) the previous times through. This training will knock off many hours of struggling while learning.

Between the "help section","learning center"and the "forums", you should be able to self teach. -Good luck-