Coil Help

[Anonymous]

Greetings everyone,

Well I hope someone can help me out with this problem because frankly I am about to give up. I have to model a complex drawer pull for a client that has me stumped. At the center of the pull is a coiled square that loops around in a circular pattern and then ends on the opposite side. The idea is that it matches a railing on a stair way near the place they want this. I have tried and tried to get inventor to recreate this and so far I have had no luck. Either the geometry doesn't end where I like or the twist looks totally unnatural. 

I have even gone as far as to use the new free form functions in 2015 and although I got a little closer the results still were not what I was looking for. I am attaching a screen shot of the model in its current state and the railing in question. 

Any ideas?

Dan

[wrw0007]

Can you attach your current model?

[blair]

Probably much easier doing this as an Assembly IAM file and then derive to a IPT if you really want a single part file. It looks like the center section could be done with the Coil command and then either Pattern to get the remaining three pieces. Most likely would require a Sweep to start, then Coil and finish with a Sweep.

The path is probably not a true consistant coil/pitch. I guess if you can get close to the rotation angle and outside "diameter" you would be close enough for the "Smithy".

[Anonymous]

I am attaching the file and a jpg.

Thank you for the response....The problem is that since there are four bars none of them go through the center line of the coil. I tried creating a revolution of a surface and then creating a coil and projecting the patch via 3D sketch but it just came out bad looking and it didn't end where it needed to. Honestly I have worked so long on this now that I think I am starting to get tunnel vision and am repeating my previous mistakes without even realizing it. 

I have very little time spent with the coil command and its nuances so I am sure I am missing just one key detail. 

Dan

P.S. No comments please about the model tree not being cleaned up. I am just doing this fast before I have to step out.

[blair]

That's why I would treat this as a IAM file and create a single coil with the pitch required and then sweep each end. Each one of the bars by it's self looks like an individual coil.

If you wanted to do it as an IPT, you would need to create a work axis that's not centered but off center. I should be able to look it this either tonight or tomorrow morning.

[wrw0007]

I have attached my attempt at this. You can try to make it work for your application if you'd like.

I started off with a sketch to define the size of square bar and a circle started on the origin and tangent to the center of the square bar profile.

After that I created a parallel plane to define the height of the spiral. (In this case I'm using half of the heigh (height/2)

I then created a sketch on this plane to define the centerline diameter of the spiral. (If the outside diameter is your critical dimension you will need to experiment with this)

Now that everything is defined, I created a loft between the two guide circles to get the shape of the centerline.

Next I created the full profile of the square bar and the 2D path for it to follow.

I projected this 2D centerline path onto the 3D shape to create half of the "true" centerline.

From there I mirrored that centerline twice to get the inverse. (this creates a visable edge on the model that I don't know how to avoid[it looks great without edges though])

Now that the centerline and profiles are created, a simple sweep (parallel not path) will complete your bar.

Circular pattern your bar around the origin axis and its "complete"

I have named what I believe to be the critical dimensions as

half_height which defines your height.

CL_dia which defines the larger centerline diameter

sq_size which defines your square bar size

Being that i made size assumptions based on your image you will need to tweak these. I suggest doing this by going to Manage>Parameters.

These critical dimensions should be safe to change within reason. I would not touch the others unless in sketch environment.

If this solves your questions please select "accept as solution and give kudos if it was of help.

[JDMather]

...and my quick and dirty attempt.

[wrw0007]

I love seeing different methods of getting from A to B. Great work.

I never use coil. Thats noticable by the way I made my model. I didn't even consider making a coiled surface.

Can you walk me through that step in your model? I feel it will be useful for other aspects of my work.