Bamboo Tripod

Well this project has been coming for a while. I found a bamboo supplier (new supplier) but it was remote from me ... so I hesitated (or procrastinated) for quite some time before jumping in. 

To be honest it was not the best online purchase experience that I have had as the poles were on the lower end of the specified size range despite the request for being closer to the high side. But I did get a positive response from a Director in the company. 

My recommendation would be to very clear in your requirements when ordering and this was a learning experience for me. 

Check out the supplier and hand pick the poles if you can.

The long (pun) and the short of it was the poles are fit for purpose. I am not sure how much variability there are in poles so I can only talk about what I have been supplied.

Warning: While I could convert to imperial I choose not to as to avoid unnecessary mistakes. I am a mechanical engineer, ex-rock climber and generally been doing this stuff for a bit so have a reasonable level of confidence. This means I am fairly cautious but also pragmatic and risk aware in my approach. I care a lot for peoples safety and have done so as part of my work and social life. This not a "how to" guide and I would expect you to have a similar level of confidence in your own ability.

Material

What I have ended up with were there 2900 mm long poles, each pole is about 3kg and taper from a nominal 65 to 60 mm outside diameter with about 10 mm wall thickness. The yellow finish was termed bleached by my supplier as opposed to natural/green.

Warning: One thing I didn't consider when I ordered the poles was to specify straightness.  I had a mild panic when I started to assemble the tripod as to how straight the poles were compared to each other!!!

For the lashing I have used 8 m of 6 mm hemp. The lashing was based upon the instructions in this link (if it dies let me know I have a copy). With the diameter of poles this was enough rope for about 9 wraps around the poles and 3 wraps around the lashing itself. Sorry about my non technical description but others have done a much better job then myself in using the correct terms ... I'm sure I would just get them wrong!

Method

How do you do the lashing ? Where are the pics !!! Umm there are none cos I found some instructions online.

I laid out the two outer poles one way and centre the other way. Why did I do this method ? Well I couldnt see how I was going to errect the tripod in my unit with the poles all together. My unit ceiling is about 2800 mm and didn't really feel like wrestling with the poles that much.

With one pole separate you can use that pole to lift the other two which fell into place with some giggering around and the structure erected. I think lashing the poles all aligned the same way would be easier for transporting but it doesn't take very long to lash the poles.

The tripod was amazingly stable just sitting on my carpet without any restraint at the base. But I have put up a back up rope at least on one side thus far until I give it a flogging. Two of the bases are butted against two perpendicular walls so they are moving no where.

The suspension point is a 25mm tube tape sling that has been larks head knotted over the lashing point. The sling was long enough to wrap around the lashing point twice which isn't a bad thing. Friction is your friend. The Carabiner is about 1900 mm above the floor.

Thoughts

While it is not clear in the photo above a lot of the load is indeed being held by the poles. The lashing are "merely" constraining there geometric proximity to each other to allow that load path/transfer. It is important to be sure the poles are in positive contact with each other as the load path will then be 100% though the lashing.

My major concern at the moment is that I feel too much tension is going though the lashing. I think its unlikely to fail spectacularly given there are at least 9 wraps  and that it will be disassembled and inspected before retying. I think the load is being held more by the lashing itself rather then being distributed to the poles. I might look at upgrading the lashing rope to a climbing grade rope to give myself a warm fuzzy.

I probably should do something about keeping the base tied together but I really don't see them moving in my application. I will start playing with it and see what happens.

This will probably sounds strange but it has been amazing what a positive feeling I have gotten from this project and living with my own tripod literally a centre point in my life (well living room at least).