Question about strengths of Aluminum/Titanium Tubing for a White Cane

[TikiTyler]

TL;DR Summary

I'm looking for some information on material strengths to determine viable options to make a custom White Cane for a recently blinded friend

I have a friend who was in a car accident causing full and permanent blindness. I've been looking to help him solve some of the issues he is running into. One of them is that he is tall, about 6'2" and the optimal length of a White Cane for moving quickly is 4 inches shorter than your height. Meaning his optimal would be about 5'10". Most options available are quite a bit shorter.
This cane needs to be as light as possible while being stiff to provide good feedback and strong enough to handle day to day usage.
We borrowed a folding aluminum cane from his rehab center to get some measurements as a baseline. Outer diameter 12.7mm thickness 1.25mm Inner Diameter around 11.45mm.


The only place those dimensions must be replicated is the tip of the cane. This used a Hook Style Cane Tip https://www.amazon.com/dp/B08H3H6MR3?tag=pfamazon01-20 (same exact head I've ordered for the project) this works by nesting inside the cane tip and using elastic band down the length of it to hold the tip in place. This also allows you to fold the cane like a tent pole. The Diameter of this shows as 10.25mm on my calipers.
Other heads could also be used such as this Slip on Style https://www.amazon.com/dp/B01LMOQ32Q?tag=pfamazon01-20
The hook style works well for folding canes which is the end goal, but want to start with a simple straight tube that could be modified to folding later.

So far local metal supplies have not had something in stock that meets those dimensions and have been too heavy as they were too thick.

One thing we have considered is a Titanium cane either straight wall, or narrower with the end flaring out or attached to a piece of aluminum the right size for the head. I don't have a solid enough understanding of the strength of the tubes to get it as light as possible while still being sturdy enough. Titanium is much heavier than aluminum but to get the same strength a much smaller tube could be used.
The idea came from seeing these available https://lssproducts.com/titanium-telescoping-cane-50/ We would go with that but its about 20 inches too short for him.
Because of the length, this gets pretty expensive to ship so I was hoping to get some advice before just buying something.

I'm no engineer, I understand most the basic concepts but don't have any experience to help me figure out good options that meet his needs. I came across this forum and was wondering if perhaps someone could help me with this.
I appreciate your time.

 

[jrmichler]

Aluminum tube with 0.50 OD and 0.444 ID (12.7 mm OD and 11.28 mm ID) is available from these suppliers. I have had good experience with the first two, and the third has been around for some time. My most recent order from McMaster-Carr had an impressive response. I got the order acknowledgement email a few seconds after entering the order, then an order shipped email time stamped 30 minutes after that.

1) https://www.aircraftspruce.com/catalog/mepages/alumtube_6061t6.php?clickkey=15313
2) https://www.mcmaster.com/products/tubing/?s=aluminum+tube
3) https://www.onlinemetals.com/en/buy...Tube-Round:OuterDiameter:0.5%22:Wall:0.028%22

I see that Online Metals will supply a 0.50" OD by 0.035" wall by 70" long titanium tube for $530.00 plus shipping.

If you want stiffness and light weight, try searching carbon fiber tube. That search resulted in a number of suppliers, none of which I have had experience with. However, I see that McMaster-Carr has carbon fiber tube.

 

[berkeman]

I see that Online Metals will supply a 0.50" OD by 0.035" wall by 70" long titanium tube for $530.00 plus shipping.

Holy smokes! I guess I didn't appreciate how expensive Ti is.

TL;DR Summary: I'm looking for some information on material strengths to determine viable options to make a custom White Cane for a recently blinded friend

The idea came from seeing these available https://lssproducts.com/titanium-telescoping-cane-50/ We would go with that but its about 20 inches too short for him.

This cane needs to be as light as possible while being stiff to provide good feedback and strong enough to handle day to day usage.
We borrowed a folding aluminum cane from his rehab center

Does the cane need to be telescoping?

 

[TikiTyler]

Aluminum tube with 0.50 OD and 0.444 ID (12.7 mm OD and 11.28 mm ID) is available from these suppliers. I have had good experience with the first two, and the third has been around for some time. My most recent order from McMaster-Carr had an impressive response. I got the order acknowledgement email a few seconds after entering the order, then an order shipped email time stamped 30 minutes after that.

1) https://www.aircraftspruce.com/catalog/mepages/alumtube_6061t6.php?clickkey=15313
2) https://www.mcmaster.com/products/tubing/?s=aluminum+tube
3) https://www.onlinemetals.com/en/buy/aluminum-round-tube?q=:price-asc:Material:Aluminum:Shape:Tube-Round:OuterDiameter:0.5%22:Wall:0.028%22

I see that Online Metals will supply a 0.50" OD by 0.035" wall by 70" long titanium tube for $530.00 plus shipping.

If you want stiffness and light weight, try searching carbon fiber tube. That search resulted in a number of suppliers, none of which I have had experience with. However, I see that McMaster-Carr has carbon fiber tube.

Hi Jim,
Thank you for the recommendations on good Aluminum suppliers those results show significantly better shipping costs than I'd found previously.

The carbon fiber seems like a good option though my friend mentioned that he preferred the metal options as the increased stiffness led to better feedback and thus more information from the cane however, I think he has only had the option of trying fiberglass instead of carbon fiber. I do have a similar problem though with the carbon fiber option just like I do with titanium, being I don't have a good idea of what dimensions would be requires to get optimal strength to weight out of it.

For the Titanium one I found https://store.tmstitanium.com/products/titanium-round-bar/3-2.5-Grade-9/24458 which I can get shipped for about $230 total. The main issue there is that matching the dimensions for Titanium will result in 66% heavier cane (from what I've read) compared to aluminum. So if I do it in Titanium, I need to find a significantly smaller tube that will still give the same strength of the Aluminum.

With both of those alternative materials, could you or anyone else help me understand what sizes I could get away with to make it lighter while being roughly as sturdy as the aluminum example?

 

[TikiTyler]

Holy smokes! I guess I didn't appreciate how expensive Ti is.


Does the cane need to be telescoping?

Yes, local Ti suppliers were able to get it for the low price of around $1100 for the same thing. I did find an online supplier for closer to $230 with shipping. https://store.tmstitanium.com/products/titanium-round-bar/3-2.5-Grade-9/24458

Telescoping is neat, I think much harder to pull off well. Especially because it could reduce feedback if not done right. Folding more like the one we borrowed would be ideal https://www.amazon.com/dp/B076P7D42Y/?tag=pfamazon01-20, but starting with a straight wall option to get started would be great.

 

[berkeman]

understand what sizes I could get away with to make it lighter while being roughly as sturdy as the aluminum example?

I don't know how hard it is to drill holes in those pieces of tubing, but perhaps you could drill a pattern of lightening holes?

 

[hutchphd]

People who understand strength of lightweight tubes and fabrication thereof are bicycle shops. I'll bet a good bike shop might be very useful for practical knowledge of these materials including carbon fiber and brazing/welding. Almost universally good folks, too. What a great gift. Good luck.

 

[TikiTyler]

I don't know how hard it is to drill holes in those pieces of tubing, but perhaps you could drill a pattern of lightening holes?

I do have a drill press, and based on some online recommendations it would be to go slow and keep it cool. That may work, but with the price of titanium I'd simply be worried I'm taking too much off.

 

[TikiTyler]

People who understand strength of lightweight tubes and fabrication thereof are bicycle shops. I'll bet a good bike shop might be very useful for practical knowledge of these materials including carbon fiber and brazing/welding. Almost universally good folks, too. What a great gift. Good luck.

Thats a great idea, there are a couple of bicycle shops in town I could go talk to.

 

[Baluncore]

You do not need to engineer another white cane product, you only need to design an extension that can be inserted into an existing folding cane. That extension, could be a part taken from another cane of the same model.

This problem should be solved by the folding cane manufacturer, making available variable length replacement segments for maintenance and adjustment of their product.

 

[TikiTyler]

You do not need to engineer another white cane product, you only need to design an extension that can be inserted into an existing folding cane. That extension, could be a part taken from another cane of the same model.

This problem should be solved by the folding cane manufacturer, making available variable length replacement segments for maintenance and adjustment of their product.

I agree that the current manufacturers should have solved this problem, but they just don't make them tall enough. I have reached out to the manufacturer of the folding white cane example to see if they would sell me an additional segment, though they have not gotten back to me yet. If they do, there is a good chance I can cut that piece to get to the right height. If not, I could order a second cane and merge them.

Part of the issue that I'm trying to solve is that as a taller person, he needs a longer cane which makes it heavier and thus more tiring to use all day. An extension would work for the folding cane, but not for any single piece cane. The folding cane will be heavier than a single piece of metal.

That single piece of metal is the information I was looking for originally, trying to see how light I can get it to reach the height he needs with similar sturdiness.

Metal suppliers around me can't get me anything for less than several hundred dollars. jrmichler Provided an excellent source that I will be using to get the right piece of aluminum.

IF someone here is able to answer the question of how small of an Titanium tube could give me similar strengths to the example tube I listed in the original post, that's all I'm really looking for. Carbon fiber sizes would be appreciated as well.

Thanks again for all of your help and suggestions so far.

 

[TikiTyler]

Part of the reason I'm trying to go through all this trouble is to make a nice option for him as he will be using these for the rest of his life. He is only 33 now and if we can find a better option than what is available, it could save a lot of head ache and effort for 60+ years.

 

[Baluncore]

I don't know how hard it is to drill holes in those pieces of tubing, but perhaps you could drill a pattern of lightening holes?

AKA the latest "drillium" technology.

Holes in aluminium tubes could be cleaner if punched from the outside, rather than being drilled.

I found a 0.10 Yen coin made in 1942, in Japan, from aluminium. I wondered why a war economy would do such a wasteful thing. Then I realised that they were coined from the punchings produced when manufacturing lightweight airframes.

Holes can catch on things, so it is probably better to have a continuous surface supported by an internal skeleton of composite fibre.

 

[TikiTyler]

Holes can catch on things, so it is probably better to have a continuous surface supported by an internal skeleton of composite fibre.

That is another reason I'd like to avoid that if possible. In addition it could make cleaning it more necessary and more of a pain. For the single rod option I'd rather close it off entirely to keep anything out.

 

[jrmichler]

It sounds to me that when the OP mentions strength, they really mean stiffness. Strength and stiffness are two completely different things. Strength refers to how hard one can lean on it before it bends or breaks. Stiffness refers to how much it flexes when one bends it.

I have never needed a white cane, so I have to guess about the properties of a good cane. It seems to me that the best white cane is both stiff and light weight. Applicable material properties include stiffness, weight per unit volume, and the ratio of stiffness to weight. Some common materials are compared below.

Steel has stiffness 30E6 PSI, density 0.283 lbs/in^3, and stiffness to weight ratio 106
Titanium has stiffness 17E6, density 0.16 lbs/in^3, and stiffness to weight ratio 106
Aluminum has stiffness 10E6, density 0.10 lbs/in^3, and stiffness to weight ratio 100
Wood has stiffness 1.5E6, density 0.018 lbs/in^3, and stiffness to weight ratio 83 (varies according to species)
Pultruded carbon fiber tube has stiffness about 20E6, density 0.056 lbs/in^3, and ratio 350

The stiffness of a tube is proportional to the material stiffness, the tube wall thickness, and the fourth power of the tube diameter. The best ratio of stiffness to weight is a thin wall tube of relatively large diameter. A pultruded carbon fiber tube has stiffness to weight ratio better than any single readily available affordable material. A search for pultruded carbon fiber tube found a number of sources. I have no experience with any of these sources. One of those sources has 0.50" OD 0.40" ID 72" long tubes for a price $42.80 plus shipping: https://dragonplate.com/dragonplate-carbon-tube-500od-x-400id-x-72.

A 0.50" diameter 0.444" ID aluminum tube will weigh almost exactly the same as a 0.50" OD 0.40" ID pultruded carbon fiber tube, while the carbon fiber tube will be several times the stiffness of the aluminum tube.

 

[Baluncore]

A 0.50" diameter 0.444" ID aluminum tube will weigh almost exactly the same as a 0.50" OD 0.40" ID pultruded carbon fiber tube, while the carbon fiber tube will be several times the stiffness of the aluminum tube.

Aluminium tube that is cold drawn, will not bend as much, as plain aluminium tube. The aluminium alloy also makes a big difference. Vacuum cleaners often have very light-weight alloy tubes. That tube is too big for a cane, but the particular alloy, and the forming process, may be worth investigating.

The term "cane" comes from some plant.
Do not discount using a dry bamboo stem.

 

[Tom.G]

The length problem could likely be solved with a folding cane.
https://lssproducts.com/revolution-advantage-folding-graphite-cane/

If it is too short, by two of them and sacrifice one to add a section to the other one (may need a longer elastic cord though); or maybe you can order one with an added section.

Cheers,
Tom

p.s. The advantage of a hook handle on a cane is that it can be hung on the back of your shirt collar (for easy retrieval) when you need both hands for something (like pouring coffee).

 

[TikiTyler]

If it is too short, by two of them and sacrifice one to add a section to the other one (may need a longer elastic cord though); or maybe you can order one with an added section.


p.s. The advantage of a hook handle on a cane is that it can be hung on the back of your shirt collar (for easy retrieval) when you need both hands for something (like pouring coffee).

Thanks Tom, that's one of the solutions I've offered to him. I contacted a manufacturer who informed that I could not buy additional lengths, I'd need to get two of them. Which for now should be a very acceptable option.

 

[TikiTyler]

It sounds to me that when the OP mentions strength, they really mean stiffness. Strength and stiffness are two completely different things. Strength refers to how hard one can lean on it before it bends or breaks. Stiffness refers to how much it flexes when one bends it.

I did address this in my original comment.
This cane needs to be as light as possible while being stiff to provide good feedback and strong enough to handle day to day usage.

The rest of your comment is exactly what I have been looking for that I was missing. Based on what you are saying it sounds like Titanium is not practical due to the size and weight restrictions of my project.

The Carbon fiber tube options sounds great. I'll likely be ordering one of those, an Aluminum tube matching my original dimensions, and a pair of folding canes to cannibalize and make one larger cane.
This way we can test all the available options early on so he can get a good idea of what options he likes. The non folding aluminum cane is because it will be a little lighter, Carbon Fiber for testing its viability, and the folding cane for convenience when out and about. That should give us a good amount of data.

Thank you all for your help.

 

[TikiTyler]

As a note, I spoke to him about the options and he said that people he has met with Carbon Fiber canes really like it. So thats a good sign though the shipping on the one found was $100 so I'll keep looking for either a premade one his height or another supplier with a better shipping price.