Is Acetal a suitable material for a hub axle?

General cycling advice ( NOT technical ! )
Brucey
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Re: Is Acetal a suitable material for a hub axle?

Postby Brucey » 4 Mar 2018, 11:32am

The utility cyclist wrote: .....how long the part would last is a massive guess because all those saying don't do it have ZERO data to back up what will happen. Whether it will work at all, whether it will literally fail just after getting around the block, after 5 miles, 50 miles, 500 miles. Nobody knows how good/bad/indifferent it will be....


in essence, you said that before.

You were wrong that time, too.

cheers
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reohn2
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Re: Is Acetal a suitable material for a hub axle?

Postby reohn2 » 4 Mar 2018, 1:51pm

Sorry I missed this post earlier
The utility cyclist wrote:Sometimes people like you post atuff without thinking, that doesn't amaze me, it's pretty commonplace here.

I was thinking alright that's why I didn't contribute to something I knew nothing about.
As I posted,until I'd Googled and did a bit of reading I didn't know what Acetal was,and what was clear after that reading and some contributions from forum members who I trust to know what they're talking about due to their track recor on here,it became obvious that you didn't have anymore knowledge about Acetal than I did.

Whilst what was being described is probably not the best solution,

It's obviuos that after acertaining some knowledge about Acetal,it isnt any solution.

a solution if they indeed can get the part made and fitted.how long the part would last is a massive guess because all those saying don't do it have ZERO data to back up what will happen. Whether it will work at all, whether it will literally fail just after getting around the block, after 5 miles, 50 miles, 500 miles. Nobody knows how good/bad/indifferent it will be.

But people have posted the properties of Acetal(before you posted on the thread) to show that it's totally the wrong material for bicycle wheel replacement axles,what you're saying is trial and error is a better test than established scientific knowledge.
Frankly I find than a silly conclusion to draw in the face of scientific knowledge,and why I posted what I did about you post.

Part of the learning process is about having failures, sometimes satisfying oneself means you don't always make the best decision for best end result. However this is part and parcel of how invention and progress comes about and on an individual level.

There is no need for invention or trial and error when there is scientific data to refer to that proves beyond doubt oherwise.
It's funny how people can say on the back of a bit of information on a search engine tgey are experts even when there is no known use specific to what is wanted to be made and used.

Where has anyone claimed to be experts on the "back of a bit of information on a search engine" I certainly haven't only that it supports what the knowledgable people on the forum who can be trusted by their track record.

I also object to posters calling others stupid for even attenpting it.

There some people on the forum who are engineers,scientific engineers,etc who've proved their knowledge on technical matters time and time again,and most of whom are quite patient people,and personally I am thankful for their input.
Only one person used the word "idiocy" to describe the use of Acetal as a material for a hub axle and whlist its a strong description it's not wrong given Acetal's scientifically known proprties

Then you wheel in complaining about the overwhelming scientific evidence layed before you in previous posts by those knowledgable indviduals,and attack those who have taken the trouble to give good sound scientific based advise.

As I posed previously,your posts sometimes totally amaze me.
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pete75
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Re: Is Acetal a suitable material for a hub axle?

Postby pete75 » 4 Mar 2018, 4:02pm

The utility cyclist wrote:Yes, anyone trying to do something differenrt or what is outside what is generally accepted is an idiot :roll:
Why not try uninformed or misguided instead of throwing insults about someone trying something outside the norm!
I suppose however you've all used this matetial so have first hand knowledge and some facts to back up claims with respect to how it would perform specifically for the use mentioned?
Lets see the data then, what you don't have any, what a surprise!

Whilst there might be some predictability about outcome in this instance isn't trial and error and trying different things how we learn and progress not just individually but as a species?
Maybe if those of days gone by had heeded people like those on this thread we'd be still stuck in the dark ages.
Suggest your friend gets it made, see what happens, report findings and learns either the hard way that it was a waste of time and money or that it works for them.


Be interested on your views about making teapots from chocolate? Most consider it a silly idea but you????


The utility cyclist wrote:I also object to posters calling others stupid for even attenpting it.


Read the OP. He himself asks if the idea is foolish. Foolish and stupid mean pretty much the same thing.

Pneumant
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Re: Is Acetal a suitable material for a hub axle?

Postby Pneumant » 4 Mar 2018, 4:30pm

As the OP I can confirm that my friend has abandoned any thoughts of birthing an axle using Acetal. However this thread is generating some good debate leading to me pondering what is Acetal actually good for?
This site https://www.amcopolymers.com/resin-families/acetal mentions typical applications being gears, bearings, bushings, plumbing components, seat belt, door handles, door lock components, automotive fuel caps and fuel system components, pump impellers.
I can see that these are mostly low stress type components with the possible exception of bearings and bushings (I am happy to have this assumption corrected)?
I am confused as to how Acetal bearings and bushings could give good service given the thread responses so far, I have also read that Acetal can ignite/burn when subject to high friction!

Brucey
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Re: Is Acetal a suitable material for a hub axle?

Postby Brucey » 4 Mar 2018, 5:09pm

bearings and bushings don't have to be high stress. Acetal can also have a self-lubricating characteristic, hence the use of Delrin in derailleur pulleys.

If the load and speed are low then there is basically no chance of making enough heat through friction to cause ignition.

cheers
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iandriver
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Location: Cambridge.

Re: Is Acetal a suitable material for a hub axle?

Postby iandriver » 5 Mar 2018, 9:01am

Pneumant wrote:As the OP I can confirm that my friend has abandoned any thoughts of birthing an axle using Acetal. However this thread is generating some good debate leading to me pondering what is Acetal actually good for?
This site https://www.amcopolymers.com/resin-families/acetal mentions typical applications being gears, bearings, bushings, plumbing components, seat belt, door handles, door lock components, automotive fuel caps and fuel system components, pump impellers.
I can see that these are mostly low stress type components with the possible exception of bearings and bushings (I am happy to have this assumption corrected)?
I am confused as to how Acetal bearings and bushings could give good service given the thread responses so far, I have also read that Acetal can ignite/burn when subject to high friction!


Can I design something from the ground up in a different material is probably one question.
Can I take a steel or alloy part and replace it to identical dimensions with a different material is a totally different question.

I.E, alloy replaced steel for a lot of frames, but the tubes in alloy are thicker, they needed a rethink due the the materials properties. Same with carbon fibre.
Perhaps you could build a hub with plastics, but with much thicker axles for stiffness etc. and perhaps some wear faces having inserts of other materials. That's a whole different ball game.
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NATURAL ANKLING
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Re: Is Acetal a suitable material for a hub axle?

Postby NATURAL ANKLING » 5 Mar 2018, 9:55am

Hi,
You could engineer a hub out of plastic but without metal inserts / possible metal sprayed? the bearing faces would have to be large and big to use a plastic for a bearing face and then speed would as said be a problem with heat.
Plastic on metal is used very well but low speed low force normally, plastic simply does not have the characteristics you need for practical parts and cost.

Kiddy tow along carts have plastic wheels as do wheelbarrow's, but the bearings are metal / metal on plastic low speed wheel barrow, also these wheels have a low lateral force ratio compared to load carried, and are speed limited on the specs kiddy carts.

The problem comes with the axel which is a small radius so high pressure due to load over bearing area........................
Plastic is a thermal insulator and heat dispersion is important with any heat generated by moving parts............

Its all possible but care in careful design and consideration of forces needed..................

Edited-
You only need to watch "Red Bull Soapbox" to see bad design and non existent consideration of lateral forces on spoked wheels......
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Vorpal
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Re: Is Acetal a suitable material for a hub axle?

Postby Vorpal » 5 Mar 2018, 11:56am

The utility cyclist wrote:People are not just saying it won't work/don't bother but calling the person stupid for trying.
I suggest those saying it's futile present their data and lay off the insults.

Next time, please just use the 'report' button.

Thanks.
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