Issues with bolt and nut

isaac_oneil

Hello All!

I am trying to learn CAD here and lets say its difficult, but none the less I have founds some of the support videos surprisingly helpful. The one issue I can't seem to find a solution to is a way to create a bolt with out the threads being offset by default, or the bolts threads hanging in outer space. I think i may be approaching the issue the wrong way, however i don't know any other way. I am then trying to visualize the assembly of the two pieces working together in the assemblies page and am struggling to mate them in a way where they rotate and actually screw together accurately. All help is welcome and thanks for your time.

Project link: https://cad.onshape.com/documents/8b6da23130a9dee535af0c96/w/f34a388fedf1c58e1269dcd5/e/311c57341ecd57be9a0be8be

john_mcclary

Yes, I understand you're learning CAD, but the normal way is knowing when to stop adding extra detail. I just don't want you getting lost going down a path that may not be necessary.

Too much complexity will leave your model difficult to modify, and too many features will slow everything down. That's why it is widely accepted to omit things like threads unless you absolutely need them. When you hand this off to a company to machine your part, they only reference the thread callout anyway, and just cut the thread with taps, dies, or special cutters. In fact if anyone saw me drawing threads at my work I would most likely be written up

So all a machinist needs is a note that says for example:


BUT for the sake of practice and learning by all means go for it. Just understand when that starts to become tedious and making you stress out. Just leave them features out I would hate to see  you get burned out on the details when you could be making headway on the bigger picture.

As for the thread feature script I linked, all you need is a hole or shaft the nominal diameter, and the feature script will do all the heavy lifting for you.

If you still want to do it manually, then follow @Nick_Kania 's advice.

As for derived and boolean I hope this explanation helps:

Derive just takes a part from a different studio. Then inserts it into your current studio. Keep in mind a derived part is "alive". That means when you update that original derived part in it's part studio. The part you inserted is the same object and will also update. This way you don't need to re-draw the same thing over and over. And you know it will always be up-to-date. NOTE: This only works ONE WAY. Any change you make to the derived part in the new studio will not be pushed back to the original part.

Boolean is just comparing two objects and returns the result based on which type you selected:
Let's take these two cylinders as an example:


Union just welds two or more parts together. Notice the part list went from 2 parts down to just 1


Subtract removes the "Tool" from the "Target", in this case I selected the green part as a tool, and the purple as the target
The result is a single part again, but the small part has taken a bite out of the larger one.

Intersect is the confusing one at first. It only leaves behind what areas are shared between the parts
again we are left with 1 part.

You also have the option to keep your tools which will leave part 2 in the tree for later use.

david_watkins

@isaac_oneil it looks like your just making a hex bolt? There are many ways to do this and It looks fine up till you added the extrude 3 and fillets. You can just remove extrude 3 and use 1 fillet. You can pick each edge in one fillet or the top face and it will fillet all the edges for you. I also flipped Extrude 2 so the tip of the helix did not poke thru. I'm not sure what you mean by the threads being offset or hanging out in space? As for the visualizing the assembly you have it correct, just "fix" one of the parts so you can see them move. To do that right click the part ( I would do the nut) and click fix. that will keep it from moving and when you click drag on the bolt you will see it rotate. Hope that helps you get started!


https://cad.onshape.com/documents/3a06301b9e71af7a124d42dd/w/9ccc4b0236375918d6104802/e/a68b95713cf0815537cb18e1

nick_kania

Hi @isaac_oneil
First off I would recommend creating both parts in a single Part Studio (Example 1 in the linked doc) or deriving the bolt into receiver's Part Studio (Example 2 in linked doc) and use the Boolean Subtract feature to create the threads on the receiver rather than remaking them with another sweep. This will ensure that the threads are lined up when inserted into an assembly and also prevent the threads hanging out in space. As for the assembly follow what @david_watkins has suggested


https://cad.onshape.com/documents/d47ccce1fc09e6da191e41f2/w/32b7e03cf1efdd8332465691/e/4fd67c3db2dbc9ee548f9fff

isaac_oneil

david_watkins said:

@isaac_oneil it looks like your just making a hex bolt? There are many ways to do this and It looks fine up till you added the extrude 3 and fillets. You can just remove extrude 3 and use 1 fillet. You can pick each edge in one fillet or the top face and it will fillet all the edges for you. I also flipped Extrude 2 so the tip of the helix did not poke thru. I'm not sure what you mean by the threads being offset or hanging out in space? As for the visualizing the assembly you have it correct, just "fix" one of the parts so you can see them move. To do that right click the part ( I would do the nut) and click fix. that will keep it from moving and when you click drag on the bolt you will see it rotate. Hope that helps you get started!


https://cad.onshape.com/documents/3a06301b9e71af7a124d42dd/w/9ccc4b0236375918d6104802/e/a68b95713cf0815537cb18e1

This helps a bit but not quite what I was looking for. The important thing is that this is a foot. It needs to be flat on one side while still having the hex bolt head. It makes it a bit more complicated for me to make but it works. I also noticed that on both our bolts, the threads seem to almost "extrude" (don't think I used that term properly but lets roll with it for now) from one of the faces and doesn't sit flush. Is this done because I am using a center fillet instead of a fillet of the side of the thread?

Nick_Kania said:

Hi @isaac_oneil
First off I would recommend creating both parts in a single Part Studio (Example 1 in the linked doc) or deriving the bolt into receiver's Part Studio (Example 2 in linked doc) and use the Boolean Subtract feature to create the threads on the receiver rather than remaking them with another sweep. This will ensure that the threads are lined up when inserted into an assembly and also prevent the threads hanging out in space. As for the assembly follow what @david_watkins has suggested


https://cad.onshape.com/documents/d47ccce1fc09e6da191e41f2/w/32b7e03cf1efdd8332465691/e/4fd67c3db2dbc9ee548f9fff

I don't understand the usage of the boolean or the derived. I made some progress on the overall design after taking some time off from the project, and managed to get it to work and now in the assembly area if I load it in and try to make the screw mate even after fixing one or the other it doesn't seem to fix the issue, and it fails to screw in appropriately when testing it. I had it working once on accident but ever since using the assembly area for something else I have not been able to replicate it.

john_mcclary

could make life easy and let the threads be made by a feature script

https://cad.onshape.com/documents/6b640a407d78066bd5e41c7a/v/845d049782179b9faee8b6e6/e/f8aea9e5c33e02eab0854a4f

Are you 3D printing these parts?
If not:
it's normal to not bother with threads as they add unnecessary complexity to an assembly and drawing. View load times take a dive while it tries to draw each little helix.

isaac_oneil

@john_mcclary I am not 3D printing these parts but will eventually send this to a company to make for me and I would like to learn to CAD the right way an engineer might for a product that might need to hit market. It's just a personal nit-picky thing and I want to know how to do things the correct way. I have not messed with feature script as I barely know how to work with simple designs inside of OnShape, let alone build things to scale well and adapt to change the way they need to for a feature script to work.

john_mcclary

Yes, I understand you're learning CAD, but the normal way is knowing when to stop adding extra detail. I just don't want you getting lost going down a path that may not be necessary.

Too much complexity will leave your model difficult to modify, and too many features will slow everything down. That's why it is widely accepted to omit things like threads unless you absolutely need them. When you hand this off to a company to machine your part, they only reference the thread callout anyway, and just cut the thread with taps, dies, or special cutters. In fact if anyone saw me drawing threads at my work I would most likely be written up

So all a machinist needs is a note that says for example:


BUT for the sake of practice and learning by all means go for it. Just understand when that starts to become tedious and making you stress out. Just leave them features out I would hate to see  you get burned out on the details when you could be making headway on the bigger picture.

As for the thread feature script I linked, all you need is a hole or shaft the nominal diameter, and the feature script will do all the heavy lifting for you.

If you still want to do it manually, then follow @Nick_Kania 's advice.

As for derived and boolean I hope this explanation helps:

Derive just takes a part from a different studio. Then inserts it into your current studio. Keep in mind a derived part is "alive". That means when you update that original derived part in it's part studio. The part you inserted is the same object and will also update. This way you don't need to re-draw the same thing over and over. And you know it will always be up-to-date. NOTE: This only works ONE WAY. Any change you make to the derived part in the new studio will not be pushed back to the original part.

Boolean is just comparing two objects and returns the result based on which type you selected:
Let's take these two cylinders as an example:


Union just welds two or more parts together. Notice the part list went from 2 parts down to just 1


Subtract removes the "Tool" from the "Target", in this case I selected the green part as a tool, and the purple as the target
The result is a single part again, but the small part has taken a bite out of the larger one.

Intersect is the confusing one at first. It only leaves behind what areas are shared between the parts
again we are left with 1 part.

You also have the option to keep your tools which will leave part 2 in the tree for later use.