Trimming one solid with another... Not happening

Dear all,

 

I am trying to model an electrical junction box but just cant trim some of the unwanted portions inside the junction box.

 

I have placed two solids, one merged into the other so that there is no gap between them and the transition is uniform. now i want to remove the extra bit of piece left inside.

 

surprisingly the trim command is not working ... please let me know where i am going wrong.

 

thanks in advanceACAD-electrical fittings.dwg

Welcome to the forum.

 

The TRIM command is used on 2D entities.

The command you want to use is the SUBTRACT command.

You might do well to open your MODELING toolbar or panel to familiarize yourself with

a selection of 3D modeling command options.

Welcome to the forum.

The command you want to use is the SUBTRACT command.

 

I want to retain the external coupler part and delete the internal remainder part. if the main body of the junction box could slice the smaller coupler....... it would serve. but just cant do it.

please forgive me for not being able to explain properly but i hope the attached image will help clarify the things better.

 

thanks again

I want to retain the external coupler part and delete the internal remainder part. if the main body of the junction box could slice the smaller coupler....... it would serve. but just cant do it.

 

Sorry, I just looked at your drawing, looks different than what I expected from your description.

Subtract is still a way to do it, but not using the existing solid.

Start by using the UNION command to combine the two parts into one 3D solid item, from which you will SUBTRACT the unwanted parts.

Create a new 3D cylinder of the diameter of the inside of your junction box and use that to SUBTRACT that shape from the

piercing solid. Then create another 3D cylinder and use that to remove the passage through the fitting and side wall into the box, also using the SUBTRACT command.

Edited June 9, 2012 by Dadgad

Sorry, I just looked at your drawing, looks different than what I expected from your description.

Subtract is still a way to do it, but not using the existing solid.

Start by using the UNION command to combine the two parts into one 3D solid item, from which you will SUBTRACT the unwanted parts.

Create a new 3D cylinder of the diameter of the inside of your junction box and use that to SUBTRACT that shape from the

piercing solid. Then create another 3D cylinder and use that to remove the passage through the fitting and side wall into the box, also using the SUBTRACT command.

 

is there a simpler way of accomplishing the job. may be i am complicating the things unnecessarily. please have a look at what i am trying to achieve.

is there a simpler way of accomplishing the job. may be i am complicating the things unnecessarily......

 

The method you are trying to use is logical, but AutoCAD has some cool tools to automate things as well. Have a look at the demo below showing two of these tools: SHELL and PRESSPULL

 

This is the way I would do it using the INTERFERE, SHELL, EXTRUDE, SUBTRACT commands:

*EDIT* After watching Nestly's video, his is definitely a preferred method. Me personally, the reason I use INTERFERE is because I've been caught in the past needing to edit certain "extremities" of a solid body part (for instance, flanged openings to a water tank). Using INTERFERE gives me my desired results, but keeps the objects separate from the "main solid body". For the record, in this tutorial of mine the final SUBTRACT does union the pieces - I wouldn't do this in a real world scenario.

 

Create solids first.

 

Use the INTERFERE command to find the interference of the two solids. Make sure to uncheck "Delete interference objects created on Close". Use SUBTRACT to omit this "extra mass" by selecting the secondary solid and the newly generated interference solid.

 

Reverse angle, main body transparent to see results:

 

Use SHELL to remove top face and shell the main body:

 

Create a Circle on the face of the secondary body:

 

Use EXTRUDE to create a mass into the main body. Use SUBTRACT to subtract this extrusion from the main and secondary body:

 

Final result is a complete body with the desired results.

The method you are trying to use is logical, but AutoCAD has some cool tools to automate things as well. Have a look at the demo below showing two of these tools: SHELL and PRESSPULL

 

 

 

 

thanks a lot. mission accomplished.

 

but the basic question remains.... is there a way to trim the smaller cylinder along the inner surface of bigger cylinder? i am sure there is..... just want to know how?.

 

secondly i would like to know how to place a horizontal cylinder on the middle of the bigger cylinder wall? which osnap should be used as there is no reference point on the walls of big vertical cylinder. i know again this is not needed now.......but just to hone my skills.

 

 

thanks again for your help.

thanks for this alternative method....... i was trying to use the intersect command but didnt know how to use the resultant intersection. thanks again.

It's not that it can't be done, it's that you're trying to walk standing up in a hammock. Your steps are backwards. Don't shell the small cylinder yet. If you use Nestly's or my method in the proper order you will have exactly what you need to get accomplished.

 

Also, don't be scared to continue working in your standard Views in 2D space. This provides extreme control in placement of objects. You can use OSNAPS in 3D space easily if you learn to use the OSNAPZ variable to your advantage.

 

For instance, in my tutorial above, I placed the 3D objects in a Top View and Front View, aligning everything first. Only until that was complete did I go into a 3D view to continue my modeling.

thanks for this alternative method....... i was trying to use the intersect command but didnt know how to use the resultant intersection. thanks again.

No prob. Most people know about the INTERSECT command, but rarely know and use the INTERFERE command, which gains you invaluable control in solid editing (in my humble opinion of course).

You can use OSNAPS in 3D space easily if you learn to use the OSNAPZ variable to your advantage.

 

For instance, in my tutorial above, I placed the 3D objects in a Top View and Front View, aligning everything first. Only until that was complete did I go into a 3D view to continue my modeling.

 

 

I wish if you could elaborate it a bit further for lesser mortals like me.

 

i took a long long method of aligning the two cylinders......by drawing 3 mutually pependicular lines in the centre of the cylinder and a lot of other commands....

 

your remarks eagerly awaited.

There's really nothing to it. Just create your 3D Solids, then go back to Plan View (or Top on the NavCube). Stay in 2D Wireframe mode. Use OSNAPZ to lock the 3D models into place so when you snap to other objects, it doesn't knock them out of whack on the Z axis. Then MOVE/COPY etc just like you do in 2D to align the 3D objects to your liking. Do this in other Views as well, such as Front or Left/Right Views (using the NavCube). Also, make sure to study the UCSFOLLOW variable to help re-align the UCS when you change Views for even more control.

 

Just FYI, when venturing off into 3D space, there are a lot more variables that come into play to make life easier.

Can you trim the smaller cylinder? Yes. Extrude an arc equal to the I.D. of the larger cylinder and use the resultant "surface" to SLICE the smaller cylinder. Command is SLICE. The option to use is SURFACE.

 

Can the TRIM command be substituted? No.

thanks for the explanation. i learnt so much from you all. thank you very much indeed.

Here's another demo that may be of some use. It shows one method for locating the smaller cylinder in the middle of the larger cylinder, and also a bit about subtracting/slicing.

 

Great work Nestly. You have always been a huge asset to this forum and I have lots of respect for a man of your talents.

I hereby request that nestly be given the new moniker of "CADTutor Cinematographer".

I hereby request that nestly be given the new moniker of "CADTutor Cinematographer".

 

I second that motion! nestly really makes Camtasia sing while displaying insightful solutions and impressive depth of knowledge.

If only he had made one about the OPTIONS by Osmosis command before he forgot it.

It would have made a nice addition to your screencast library.