How do I match two threads, if the bolt consists of two parts?

[Anonymous]

Hi, I am an engineering student at Texas A&M, and I am a little bit confused.

I am assigned to make a pully to meet certain specifications, where I need to make a key which holds the pully and shaft together and create a way to secure the key.

The meathod I have used is to insert the key such that part of it fits into a square keyhole, while the part which extends from the key hole completes the cylinder made by the shaft. I have theaded the shaft and the key, but the threads do not line up. Is there a way for this to be done, such that a nut could be screwed onto it?

I have included 3 screenshots in this post and the 4th screenshot in the post below.

[Anonymous]

This post provides the 4th screenshot.

[JDMather]

Do as multi-body split from solid, but because the thread is a cosmetic bitmap - not sure that will work without adjustments.

Do you realize that it is just a picture - not actual threads?

Where did you get the idea to thread the key?  This would be very highly unusual.  The shoulder of the nut will hold it within the pulley.

How will this slot be cut square up to the shoulder of the next cylindrical feature?

What version of Inventor are you using?  2010? 2016?

[Paul-Mason]

Dose the bolt/key have to turn with the pulley? is the blot driving something else?

How about posting the FULL briefing/specs that might help us come up with better help or an alternative for you.

[Anonymous]

I, too, think it is quite unusual. This is not my design. The only part I designed was the key (the half square, half cylindrical thing). Yes, I understand they are not actual threads, but I am not quite certain as to how they exactly represent threads. I am still being trained on inventor. I am using inventor 2016.

The reason I threaded the shaft is because I needed a way for the entire unit to hold together. The shoulder of the nut could be enough, but I need a key, as specified in the instructions. As formed by the shaft and the pulley, a square hole would be formed. So I filled the square hole with the key. In the real world, I would never have made the key, and, instead, I would have simply made a rectangular piece protrude out from the shaft (as opposed to making a trough) to grab the square trough in the pulley.

I have included a picture of our instructions and a better image of the assembled product.

[Anonymous]

I've got to be honest with you, I have no idea. We simply desinged a shaft and pully in class and were told to do an assingment with those things. The assingment is shown in my repsonse above this one.

[JDMather]

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@Anonymous wrote:

 In the real world, I would never have made the key, and, instead, I would have simply made a rectangular piece protrude out from the shaft (as opposed to making a trough) to grab the square trough in the pulley....

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No - you cannot do that.  Have you had a machining class?
The shaft would be turned on a lathe and the keyway slot milled (with round end at the shoulder) and a key added between the shaft and pully - just as you have done.  But the key would be a bit less length than the pully and a washer and nut to hold it together.  Because the key protrudes half way into the pully - it cannot come out the shaft slot when the washer and nut are secured.

Shorten the length of your key.
The key is not threaded.
The key slot would have a rounded end (an artifact of the tool) at the shoulder.

The cosmetic thread are converted to Simplified Thread Representation in the 2D drawing.

Because thread nomenclature is standard - there is no need to introduce the complexity of real helical thread unless the part will be 3D Printed.

These topics should have been covered in your instruction.

I recommend that you attach your assembly here for further instruction.

[Anonymous]

Okay, I think I know what you are saying. So, the key can remain a rectangular prism and the shaft can continue to have a long trough? Then, the shaft could be threaded and the key inserted, but the key would only need to be as long as the pulley hole is deep or a little less? Then, I could have a washer which would press against the face of the pulley and a nut to secure it?

I could be totally off.

I have not had a machining class. I this is my first engineering graphics course, and I am brand new to inventor. We've spent most of our time in AutoCAD.

I have made an edit to the key. Now, it is the same length as the hole of the pulley (I do not know if we need to get too in depth yet), and I could apply a washer and nut to the bolt to secure the pulley? An image is included below. I do not, yet, know how to make an assembly diagram. Also, I beleive I have to do a special download to get the fasteners, so, I am not able, yet, to include the washer and nut.

I am quite literal, so, I apologize if I take anything too literally. Thank you for your time and patience.

[hosford]

you may want to try something like this.

internal threads are much cheaper to make then external.