Trouble engaging threads

[carlhitchon]

I having trouble getting two threaded components to engage as a threaded assemble.  The model is shared here https://a360.co/2Eg62qp. I want to screw component "Nut" onto the threaded tube called "Strut Tube".  I made a revolute joint and the nut will rotate, but it does not engage with the threads on the Strut Tube.  That is the Nut does not move along the threads. It just rotates it place.

[jhackney1972]

There is no ability in Fusion 360 to physically engage matching threads.  You may be able to add multiple joints and then create a Motion Link between them to get the effect but it is a long shot.

[carlhitchon]

I think I failed to save the model before I shared it.  Here's a new share https://a360.co/2Eg62qp .  If you drag the Nut it just rotates instead of moving along the male thread. In creating the revolute joint, I moved the cursor along the edge of each thread until a joint origin appeared in the center. The Strut Tube part is grounded.

[jhackney1972 · Accepted solution]

If you move the nut revolve joint to a fixed plate and then add a slider joint to the threaded rod, you can add a motion link between the two joints.  With the proper ratio (thread pitch) you will get the simulated thread engagement.  I do not see any way in Fusion 360 to simply thread a nut on a shaft.  Of course you could just hide the fixed plate.  Assembly is attached.

Edit: I do not know what I did to the thread shaft, pardon the cut out of the body.  Turn off the Section Analysis and just drag the nut.

[chrisplyler · Accepted solution]

If you model both components from the same sketch plane, their threads will line up. Otherwise, when you joint them together, try slight offset values until the threads mesh.

You don't need multiple joints for this. A single cylindrical joint, and a single motion link. While establishing the motion link, check the box for Link to Same Joint, and it will let you relate the rotation to the travel.

[carlhitchon]

That's odd because in another design I had a threaded shaft and threaded hole with a simple revolute joint and the initial animation (shown after selecting revolute) automatically acted like a real thread. That is the component moved along the axis as it turned. However, then I discover that when driving the joint, it didn't work, the component just rotated in place.

Seems like there should be a threaded joint to make this easier.  

I'll try to follow your solution. 

Thank you,

Carl

[carlhitchon]

OK thanks I'll try that as well. Any chance you could share that model so I can see how you built it from sketches?

Very well done screencast by the way.

Thank you.

[chrisplyler]

The sketch for the rod component is just a 1/4" diameter circle, and the sketch for the nut component is just a 1/4" diameter circle and a 1/2" radius inscribed hexagon around it.

The rod is just an extrusion of its circle profile, and the nut is just an extrusion of its hexagon profile (minus the circle inside).

I had both sketches in the same place (centered on the origin), and so when threading them, the threads came out already perfectly meshed. I don't know how Fusion decides where to originate the thread twist. Ought to be user controllable, but of course it isn't. But I figured if I start both components in the same place, they'll match up. And even if you construct things differently and they don't match up, just Z-offset the cylindrical joint until they do.

[carlhitchon]

OK. Thanks for the advice.  I've been using Fusion on and off for a couple of years and there is still a lot to learn.

[Solar-emc]

 thanks for taking the time to make this video. However, you start with the components in position so I don't understand the first alignment. This means the following steps are out of context. Also, Please cascade open the browser item so we can see what's going on.  Why do people not narrate video?

[chrisplyler]

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@Solar-emc wrote:

 thanks for taking the time to make this video. However, you start with the components in position so I don't understand the first alignment. This means the following steps are out of context. Also, Please cascade open the browser item so we can see what's going on.  Why do people not narrate video?

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Read Message 8. That's where I explain that I created the two components with the proper relative positioning to start with. I didn't have to "align" anything. I also explain that, if that isn't your situation, you can move the nut onto the end of the bolt with the Joint, and use the Joint's Z-offset setting, if necessary, to adjust it's position until the threads do line up.

Cascade open the Browser items? It's just two Components: the rod and the nut. One of them is cascaded open already. Do you think there is some secret magic happening inside the other one? It's the same: one sketch, one body.

I did not narrate because I stole time from my employer to help somebody on this forum, and I do not want a coworker overhearing me giving verbal F360 instruction. I do often narrate when I'm helping from my home.

Why do people not read the entire thread? Why do people complain that the free help they've received via the kindness of another isn't good enough?

[carlhitchon · Accepted solution]

Thanks for the help guys.

Carl

[chrisplyler]

So, you just replied to your own post, and then selected your own reply as a thread solution?

Hey, if I start doing that I can really buff my forum score!

[chrisplyler]

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@HughesTooling wrote:

The fully defined indicator would be a lot more useful and visible if the icon in the timeline also changed to indicate fully constrained. It's quite easy to design and never expand the sketch folders.

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Easy, but silly. Every time you expand something in your Browser, a baby angel sings.

[carlhitchon]

I'm sorry. I didn't realize it was going to do that.

Can you or I fix it?

[chrisplyler]

I'm not aware of any way for either of us to fix it. A forum moderator can.

But it's not a big deal. I was just giving you a friendly ribbing.