Post & Arm with rotating over head track system.

[Joel Yzerman]

Hi Everyone,

I'm designing and making this post and arm for a manufacturing client.

They need the track overhead to hang the air tools from balancers, but they also need to rotate the arm to gain clearance to drop over the cover of the unit for shipping then rotate the arm back inline and staple it shut. This process is repeated at least 10-15 times a day.

The weight I'snt very much unless a worker pulls down with his own weight on the arm, which I have to account for.

My questions is:

Will the tubing I'm using (4x4x1/8 wall steel square tube) hold up with the torsional forces and tension forces ?

I really wanted to use a 6x6x1/4 wall aluminum tube but I fear overtime it will suffer from microscopic stress due to cyclic use compared to the great endurance steel has with repeated use. Or would 3x3x1/4 wall steel be better than the 4x4 1/8th steel

Anything else you notice might be an issue or if you can recommend thing that would be great.

My drawings are attached.

??

Thanks !

Joel

 

[driftLimiter]

Will the tubing I'm using (4x4x1/8 wall steel square tube) hold up with the torsional forces and tension forces ?

What are the stresses due to torsion and tension calculated in your analysis?
Also curious what kind of deflection the tube experiences as it is a long cantilever for a 4" tube. What does your analysis suggest?

 

[BAretired]

Why is the drawing so faint? I am having trouble reading it.

 

[Joel Yzerman]

Hi,

I'm still in design stage, have yet to submit to my engineer.

I made a mock up in my shop to see where it deflects and how much. Bit of tension/compression in the arm tube 12" off the post vertically and it does experience torsion when the tracks are rotated perpendicular.

The original request was for a post and jib swing arm.

I attached a PDF as well you can zoom in on that and see details, the picture ones aren't as nice as they're converted from pdf online.

My question this time is :

I figured extending the arm out a bit from the post and then the tracks hanging off that point would help spread or Share the stress, as compared to a jib swing arm which puts all the force directly on the post. I'm trying for a lighter easier structure as opposed to a big giant heavy thing that spans 10ft directly off the post. Maybe I'm completely backwards in my thinking?

Thanks ,

Joel

 

[Joel Yzerman]

Which steel square tube would perform better in this case?

3x3x1/4 wall or
4x4x1/8 wall

Is a larger thinner perimeter stronger than a smaller heavier one ? Or same ?

I'm thinking the 1/4 wall because really I need more material in my tension flanges of the tubing, I could maybe weld a flat bar to the top of the arm tube to keep it from deflecting.

Thanks

Joel

 

[dvd]

You are definitely re-inventing the wheel on this project. Why not purchase?

Jib crane search

 

[Joel Yzerman]

They have a unique need to have the track overhead and be able to get it out of the way.

I figured this design was ok , the only thing I found online was a small jib crane type thing that's way over rated for this.

I'm not reinventing the wheel just re configuring for their unique needs.

I'm more so looking for Ann answers to my tubing size comparison question.

 

[BAretired]

I couldn't find the PDF you say is attached.

BA[/color]]
Which steel square tube would perform better in this case?

3x3x1/4 wall or
4x4x1/8 wall
Is a larger thinner perimeter stronger than a smaller heavier one ? Or same ? You're a structural engineer and you're asking that? Give us a break!

Why ask us? We don't know the loads. Why limit the choice to those sizes? What is wrong with:
4x4x3/16, 4x4x1/4, 5x4x3/16, 6x4x3/16 or even 6x6x3/16 wall if needed? You were prepared to go to 6x6x1/4 aluminum HSS.

 

[Joel Yzerman]

Theres a link at the bottom of my first post you click on , prompts a download.

I'm no engineer, I've designed alot so I have a small understanding, with feedback I can improve the design.

I thought engineers reply to these ??

My apologies if I'm in the wrong place.

 

[3DDave]

PDF:

https://files.engineering.com/getfi...-4a03-af98-174c3cff4a23&file=Steel_tree_1.pdf

 

[Joel Yzerman]

Thanks 3d Dave ! , I couldn't get it to work. Haha

 

[dvd]

Research and copy existing designs - use someone else's learning curve.

LKGoodwin

 

[Joel Yzerman]

Much appreciated, I did see that one before, it was definitely a good option.

Swinging that big jib around all day takes too much energy, if that dude had my design he'd have an easier time and could access more area without even moving the crane at all. The tracks would be parallel overhead his table.

my engineer will help me determine specifics I just figured if anyone else out there had some design experience with something like this I could chat with them.

Thanks everyone for your time.

 

[dvd]

Good luck and have fun with your project.

 

[3DDave]

Good engineers design. Great engineers steal.

Well, OK, not steal so much as avoid re-inventing the easily available solutions.

No matter what, the load is being carried by the post. Adding a joint in it doesn't make the load disappear, it makes the load path more complicated.

Some of the answers are an hour or so of work and you said you have your own engineer.

 

[Joel Yzerman]

3d Dave , much appreciated.

Ya I mean 99% of my current knowledge is from someone else's trials , engineering analysis etc, me just being an employee at the time lol

I've designed and fabricated everything from 60 ton lowbed trailers to tiny architectural brackets, railings, floating stairs etc. I find joy in designing and being creative with it, an to your point not getting off path too far from what's been designed already, all the engineering that went into someone's project I can just use for free with a little research it's great.

People come to me for modified versions of existing products, that's why I always have a tough time but I wouldn't do anything else haha and in the end it always gets ironed out thanks to forums like this and info people offer.

I'm meeting with the client tomorrow I'll see if maybe I can center the track under the arm instead of such a big offset on one side. That will help reduce the torsional forces on that arm. Like you say no matter what still tension/compression on the post but just a tiny bit since it's not actually a crane.

 

[BAretired]

In hindsight, Joel Y, I feel I overreacted yesterday and I apologize. Your idea seems to have merit.

 

[Joel Yzerman]

BAretried - Much appreciated.

My ideas are always way outside the box haha I'm used to it.

Good news the client today actually doesn't need the offset arm or the fixed arm extension off the post either.

Were going with a 6" Diameter x 1/4 wall round post with two smaller jib style arms that rotate right off the same post independently (8Ft max span off the post.) Slider tracks will hang below the arms.

Once I'm finished I'll post the final design.

Thanks !

Joel