What is the easiest way to bend a Polypropylene stick?

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In summary, the person is thinking of using a hair dryer to soften the axe head cane and then bending it. They are also considering using a pot of boiling water to soften the cane. They think Polypropylene will be less brittle than Nylon and the cane will be less likely to shatter in the winter. They ask what to do with the former.
  • #1
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This is not homework.

I bought this cane, BUT I do NOT want the axe head, I just want to make a crook cane out of it, I do NOT want it to be a weapon, just a very sturdy cane. So my idea is to CUT the axe part off and bend the end to a curve to make my own crook cane. It is 38" long, so I have spare to make the curve crook.
https://www.coldsteel.com/axe-head-cane/

I am thinking about using a hair dryer to heat it up to soften it and bend it. I know heat is the way to soften it, I don't know whether this can work. I just want to post it here to get some idea what is the best way. What to look out and be careful so I don't over soften it and just turn to goop!!!

Thanks
 
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  • #2
I have some old Fiber filled Nylon cane, do they have low softening temp. Like Polypropylene? I want to experiment with the old cane.

Also, will a pot of boiling water hot enough to do the job where I just dip the end into the pot and take it out to bend it.

Thanks
 
  • #3
Polypropylene is a thermoplastic. A search for polypropylene properties found many good hits, and this is a quote from one such hit: A major useful attribute about thermoplastics is that they can be heated to their melting point, cooled, and reheated again without significant degradation.

So you can heat it to bend it. Further search, adding temperature to the search terms, finds that it melts at about 160 deg C, so boiling water will not melt it. One site lists the heat deflection temperature as a range from 78 to 122 deg C, so boiling water might or might not soften it enough to bend it.

If you try heating to bend, give the heat plenty of time to soak all the way to the center, at least 10 to 15 minutes in the boiling water. If it does not want to bend after heating in boiling water, you will need to heat it to a slightly higher temperature.
 
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  • #4
Thanks, I also asked about Nylon, seems like Nylon has a wider operating temperature range, from what I found, it remain ductile down to -100deg C. Polypropylene becomes brittle between 0 to -20deg C.

I might be better off staying with Nylon instead. I don't want the cane to shatter in winter in cold area.

You think Nylon will soften with boiling water?
 
  • #5
According to:
https://www.microspecorporation.com/materials/nylons/

Softening point 60C to 250C, depending on the particular grade.
The site also states that the melting point is sharp. This means the softening and melting temperatures are vey close together.

For the higher softening temperatures, you can use oil instead of water for the heat transfer fluid. (If it is flammable oil, decide how you will put out the possible fire before you start the experiment!)

(Link found with:
https://www.google.com/search?q=softening+temperature+of+nylon)

Good Luck!
Tom
 
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  • #6
yungman said:
and bend it.
I have bent various things into curves and experience tells me that it really needs a former to ensure the curve is even. Sorry if I'm telling you how to suck eggs but I think it would need a piece of timber with the wanted radius and with a groove that the cane profile will fit into nicely, all the way round the 180 degree(?) bend. If the material hasn't been heated uniformly then parts will bend easier than others. A former will help reduce this effect and you should get a nicely even shape, rather than a sharp kink where the material is softest.

From the above, it could be a bit knife-edge between soft and melting so you must experiment on a sample. If you are lucky, you may be able to bend it a bit by 100C. I'd worry about hot oil because of the nasty fractions that can come off it. Perhaps a mask would be advisable.

The cane is pretty thick but you may get it bent with careful use of a hot air gun (take loads of time). You could 'Get a feel' for how it's going with very even air heating and bend it a bit at a time, working along its length. it needs to be laid down as you work at it so it won't bend out of the wanted plane so the former should be screwed down on a thick ply sheet against a straight grooved (perhaps) batten behind the cane. You have an advantage that the plastic is a good insulator; it could be a bit like bending hot glass rod, which (they say) behaves well once you have mastered it.

This sort of job is all in the preparation but what to do, afterwards, with the lovingly crafted former? Good luck.
 
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