Make internal threads...

I am using autocad, and I am having a hell of a time trying to make threads on the inside of an object, like a nut.

I am also having a hell of a time getting my coordinate system correct, so when I re-orient, I can still draw lines.

Does anyone know of any good tutorials out there or something?

I can draw stuff in 3D, its just these things are becoming a headache.

Thanks,

Zack

you could use openscad, it does have libraries for generating threads now. I also have a script i wrote a while ago that makes threads as well. you could see how i did it.

[www.thingiverse.com]


also some people have just sized the bolt, and then performed a difference function to removed its area from another stl.

you can use this method in openscad

difference(){//takes first object, and then removes all additional objects

import_stl("yourfile.stl", convexity = 5); //in openscad directory, or root to directory file is in

here goes thread script, or another stl file
}

Sounds like you definitely need a class or tutorial...

There are a bunch of ways to make threading... but it really depends on what you already have made.

check youtube for tutorials
[www.youtube.com] -

But really, you should look for a community college class you could take. It'll make your life 1000x easier. Or, switch to Solidworks and get the Solidworks Bible and work through it.

Managing coordinate systems in AutoCAD is a pain in the a**. This modeling method is so prehistoric! It's been years since I've had to work in AutoCAD and I'm quite happy for it.

One thing that is not clear to me, are you trying to create a 3D model of a nut, or a 2D representation of one?

If you're working in 3D you're not drawing, but modeling.

Have you tried printing a smooth hole then using a tap set to create the threads?

Andy

I did a little google search and found this web site that talks about autocad, and has some instructions for making threads


here is the forum that discusses this very issue, at least it provides you the key understanding of what to do. this one is for making a bolt.
[www.cadtutor.net]

download 3dspiral.lsp
Its an AutoLISP app for easily making spirals (2D and 3D).

Edited 2 time(s). Last edit at 09/24/2013 07:38PM by jamesdanielv.

I'm going to look into everything suggested...

I think ill try Solidworks as well... I heard from someone else that AutoCAD was based on some old stuff.

I am in fact trying to create 3D models, not 2D.

And i'm not that great at programming so I don't know how well I'll be able to do at OpenSCAD, but I will give it a shot. That video on how you were changing stuff fairly quickly seems pretty cool James.

SolidWorks is a $4000+ mid-range CAD parametric modeler targeting the small and medium businesses. It is taught in some schools and colleges and technical/engineering students can get an "educational" license for free or cheap. But for anyone else, suggesting people to use SolidWorks is just inviting them to commit software piracy. There are enough free alternatives out there not to do so.

I would be very, very interested to know how many people here on the forum who use SolidWorks actually have a legitimate copy.

imzack, the principle of creating a screw thread is the same in any CAD software. For an internal thread, you cut a hole smaller than the thread nominal size. For external thread, you model a cylinder with a diameter equal to the thread nominal size. Then, you draw a 2D profile representing the spacing between two threads. You sweep that 2D profile along a helical path. And finally, you cut this swept solid from your main solid to get your threads.

It's been a very long time since I last used AutoCAD for 3D work, but I know there is a sweep command, and there should be a helix primitive. In parametric software such as SolidWorks, you already have a helical cut feature and you only need to draw the 2D profile.

Here's a visual showing what I'm saying. This is for a screw, so for a nut the profile will need to be reversed (with the smaller side toward the outside).