How to build a pull-up bar between concrete pillars?

[nicocollu]

Hey!

I wish to build a 3.36m pull-up bar in my high ceiling apartment but am un-sure of how to approach this. I do calisthenics and wish to try to get a bar as close to Kenguru standards as possible: https://kengurupro.eu/equipment/d-02/ <- they have 34mm diameter bars, most likely solid and a certain coating. I have contacted them to get more details on the coating.

Still, this is quite a long pull-up bar and needs to take quite a lot of weight, preferably 200kg+ if possible. I have seen quite simple constructions at this length although I am not sure how to pull it off, especially with this custom length.

I am not from NZ so I do not have access to many tools etc.. I have enough to get holes into the concrete to fasten whatever system it'll be but that's about it.

Any advice would be highly appreciated.
 

[MitchellMc]

Welcome to the Bunnings Workshop community @nicocollu. It's wonderful to have you join us, and many thanks for your question about installing a pull-up bar.

It sounds like the first challenge will be sourcing pipe/bar that can span that gap without flexing significantly. Next, you'll need to find fittings, which will allow that pipe to mount onto the vertical surface.

We carry ARC 2.4m 32NB Galvanised Steel Pipe in-store, but that tops out at 2.4m long. Does it need to be one continuous bar, or could you have a join midway and a drop down from the ceiling to support the two sections? We could inquire if the 32NB pipe comes in longer lengths from our supplier, but I would expect it to flex over 3.36m. You'd likely need a 32mm pipe with a much thicker sidewall or a solid bar. After looking through our supplier's ranges, the closest I could find is 24mm thick solid bar. This would be far too thin to span that gap without flexing.

I believe the main issue faced here is the very long length you wish to span. Do you need it to be this long, or is the idea of having the bar between the two pillars what appeals to you? The project would be much more achievable if you were to use the pillar on the right and that closest wall.

Please let me know if you have any questions.

Mitchell

[nicocollu]

Hey Mitchell,

Thanks a lot for the response.

Yeah, it'd most likely be too flexible at that length. Here is a version of what I'd like that works really well: https://youtu.be/mvJHw64fxgQ?t=60 Screenshot here:

This pull-up bar seems to be close to the length I am looking for. It seems very custom made of course. Considering some of the dynamics moves in calisthenics, stability is a concern. It's okay if it flexes a bit but you might be seeing moves like this on it which greatly increases the stress load: https://youtu.be/KQUXkXLzBS8?t=108

Please see both videos with the URL as it has timestamps.

Per your red bar in the photo, that wall is terrible. Not concrete and I imagine would break very easily. I am not against some form of attachment to the concrete, something like this: 

We are now getting into the territory of custom welds and all that. Honestly not against paying for a custom build. I am just not from NZ so I wouldn't even know who to ask. I'd honestly easily pay 4-500$ for a solution.

Any other suggestions are very welcome.

[MitchellMc · Accepted solution]

@nicocollu,

I'd suspect the bars used in those videos are not common mild steel and possible hardened steel, which have been manufactured for that purpose. Mild steel in those thicknesses, which you commonly see in hardware stores, will bend and set in place instead of returning to its original form.

On the other wall, you'd be connecting to the timber framing inside the wall, which should be solid. However, you'd be able to tell whether that is an option better than I can.

If you look up steel fabricators or welding shop locations around you, you might find someone that can create the bar for you.

Let me mention the knowledgeable @TedBear to see if he has any thoughts.

Mitchell

[nicocollu]

Thanks a bunch Mitchell,

I'll try to search for that. Looking forward to the response as well.

[r23on]

The solution to this is not to use solid bar but to use tube with a 5mm or greater wall thickness. Reason for tube is that the solid bar does not have the horizontal strength and will bend. tube is more stable in this situation

here is a link that explains why and for the mathematical minded the maths to go with it

https://physics.stackexchange.com/questions/12913/hollow-tube-stronger-than-solid-bar-of-same-outsid... 

[MitchellMc]

Interesting, @r23on.

I'm just musing, but there seems to be a fair bit of conjecture, not about the math, but about the wording and interpretation. "A hollow tube can be stronger than a solid one of the same diameter." is quite different from the true statement of "A hollow tube can be stronger than a solid one of the same mass". The key is "of the same mass". A hollow tube of the same mass as a rod has a larger diameter.

In this circumstance, there's a max and min size requirement. I guess the question is then, if we're concerned about a solid bar of 34mm spanning the gap without flexing, how much larger would a hollow tube need to be to exceed the mass of the 34mm solid bar and therefore be stiffer. Typically, pullup bars range from 30-45mm in thickness. Would a hollow tube of the same mass be larger than 45mm? My math is not that good, unfortunately.

Thanks for bringing this up and adding to the discussion. I was aware of this fact, but hadn't thought about it for some time.

Mitchell

[r23on]

Hi Mitchell

I have a friend back in Melb who can do the calculation Its a matter of getting touch with him  A wall thickness of around 5mm of the tube should be close to what is need. The issue is the length of 3.6m

[r23on]

HI Mitchell

The required information can be obtained here Given the length and the weight of the person who will use it. They have all the technical info need.

Australian Tube Mills A.B.N. 21 123 666 679. PO Box 246 Sunnybank, Queensland 4109 Australia Telephone +61 7 3909 6600 Facsimile

[nicocollu]

@r23on @MitchellMc Amazing information from both of you, thank you very much.

Here is a piece of info I got from Kenguru Pro themselves:

"We use steel pipes for our 490, 1200 and 1758mm bars, for freestyle bars longer than 1800mm we use full steel rods.

Wall thickness for crossbars is not less than 3,2mm, for long ones it's 4mm."

So, it seems like for the length in question, they use full steel rods. Still, the stackexchange shared says the opposite, haha. From an amateur perspective, it makes sense to me that a tube with a min 5mm wall is a smarter choice probably because each wall does it own in accounting for the others weakness. This is the way I'd understand it.

Though I agree with Mitchells' observations of the wording in the post confused me some as well. The part concerning whether the actual bar is the same diameter, whether hollow or whole.

Thanks for the contact details r23on - I'll keep this handy. I realize I might need to contact a custom welder for this solution to be honest.