Is Acetal a suitable material for a hub axle?

General cycling advice ( NOT technical ! )
Pneumant
Posts: 130
Joined: 7 Oct 2010, 8:25pm

Is Acetal a suitable material for a hub axle?

Postby Pneumant » 28 Feb 2018, 8:31pm

A friend is considering having a Mavic 501 wheel hub axle made up using a material called Acetal. I looked up Acetal and it is some sort of high strength polymer. My query is would this be up to the job? Is he being foolish to even consider this as opposed to using aluminium (the original axle material) ?

JakobW
Posts: 251
Joined: 9 Jun 2014, 1:26pm
Location: The glorious West Midlands

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

Postby JakobW » 28 Feb 2018, 9:41pm

Why are they doing this? A Google suggests Acetal's the same thing as Delrin, which has been used for derailers, but I wouldn't have thought it would be suitable for a highly-stressed component like an axle.

User avatar
andrew_s
Posts: 4791
Joined: 7 Jan 2007, 9:29pm
Location: Gloucestershire

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

Postby andrew_s » 28 Feb 2018, 10:19pm

Wiki says "Because the material lacks the rigidity of most metals, care should be taken to use light clamping forces and sufficient support for the work piece", in the machining section for Polyoxymethylene.

That doesn't sound like it would be stiff enough for an axle, giving short bearing life even if it's rideable.

Brucey
Posts: 34289
Joined: 4 Jan 2012, 6:25pm

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

Postby Brucey » 1 Mar 2018, 12:42am

Pneumant wrote:.... My query is would this be up to the job?....

Is he being foolish to even consider this as opposed to using aluminium (the original axle material) ?


No
and
Yes
respectively.

Acetal?.... :shock:

....you might as well make it from cheese.

[is this query a month early...?]

cheers
-------------------------------------------------------------------------------
~~~~~~~~~~~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~

francovendee
Posts: 841
Joined: 5 May 2009, 6:32am

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

Postby francovendee » 1 Mar 2018, 8:31am

i wouldn't want an axle made from this stuff, maybe a hub if it was fitted with a bearing. It does come in some pretty colours though :lol:

pete75
Posts: 11193
Joined: 24 Jul 2007, 2:37pm

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

Postby pete75 » 1 Mar 2018, 8:38am

Pneumant wrote:A friend is considering having a Mavic 501 wheel hub axle made up using a material called Acetal. I looked up Acetal and it is some sort of high strength polymer. My query is would this be up to the job? Is he being foolish to even consider this as opposed to using aluminium (the original axle material) ?


if someone is machining the axle the main cost will be time not materials. If a machinist is suggesting acetal as a suitable material then he's to be avoided.

MikeF
Posts: 3706
Joined: 11 Nov 2012, 9:24am
Location: On the borders of the four South East Counties

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

Postby MikeF » 1 Mar 2018, 9:22am

Is the acetal for the whole axle or for some form of bushing?
"It takes a genius to spot the obvious" - my old physics master

Des49
Posts: 602
Joined: 2 Dec 2014, 11:45am

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

Postby Des49 » 1 Mar 2018, 10:16am

The Mavic 501 hubs were lovely - except for the notched design and aluminium axle, this led to a fatigue failure sooner or later. I still have a wheel hanging up in the shed when I couldn't source another replacement axle.

If your friend has a machinist capable of making an axle up in steel that would be brilliant.

User avatar
NATURAL ANKLING
Posts: 10181
Joined: 24 Oct 2012, 10:43pm
Location: English Riviera

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

Postby NATURAL ANKLING » 1 Mar 2018, 10:50am

Hi,
Des49 wrote:The Mavic 501 hubs were lovely - except for the notched design and aluminium axle, this led to a fatigue failure sooner or later. I still have a wheel hanging up in the shed when I couldn't source another replacement axle.

If your friend has a machinist capable of making an axle up in steel that would be brilliant.

All is possible, I don't know the axel myself, but possible that you could make one up on a donor axel from another design.
Post some details and or pics if disassembled, will be a good project while we are off work told not to go in today :)
If You Don't Try You Don't Do.....Don't Do You Don't Get...I'm Still Trying....Well Very..
You'll Find Me At The Top Of A Hill...............Somewhere...After Dark..

Pneumant
Posts: 130
Joined: 7 Oct 2010, 8:25pm

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

Postby Pneumant » 1 Mar 2018, 7:34pm

Many thanks to everyone who responded & this is no joke enquiry! I also told my friend that I thought this material was not up to the job. There was no engineer's recommendation to my friend for Acetal either.
I reckon it is easy to be misled by claims that Acetal '.....bridges the gap between metals and plastics....'. and that this material might indeed be suitable as alloy axle replacement. https://lairdplastics.com/product/mater ... omopolymer
I have passed on your useful responses to my friend and advised that he avoids acetal & instead gets an axle made up in either alloy or steel. Once again thank you, this forum is tops :)
Last edited by Pneumant on 2 Mar 2018, 7:02pm, edited 1 time in total.

User avatar
The utility cyclist
Posts: 2230
Joined: 22 Aug 2016, 12:28pm

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

Postby The utility cyclist » 2 Mar 2018, 7:37am

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.

JakobW
Posts: 251
Joined: 9 Jun 2014, 1:26pm
Location: The glorious West Midlands

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

Postby JakobW » 2 Mar 2018, 9:55am

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!


a quick Google for engineering data for acetal gives a YM of between 2.9 and 9.7 GPa, and a yield strength of 66 MPa, so best-case it's ~7 times less stiff and ~5 times less strong. Given that under heavy use aluminium axles are more likely to break than steel, I can be pretty sure this is a Bad Idea.

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.


No, because a simple look at the materials data sheets suggests this is a terrible idea. No-one has enough time and energy to try out every wild idea; using simple sanity checks like the above allows you to concentrate your creativity in areas where it might actually make a difference...

Brucey
Posts: 34289
Joined: 4 Jan 2012, 6:25pm

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

Postby Brucey » 2 Mar 2018, 10:13am

only filled/fibre reinforced grades have a YM much over 3GPa, i.e. it is typically less than 1/20th as stiff vs aluminium. The material also has an unfortunate tendency to be rather brittle in cold weather.

The utility cyclist wrote:Yes, anyone trying to do something differenrt or what is outside what is generally accepted is an idiot :roll:.....


well, often, there is a reason for that.... :wink:

BTW if anyone is wondering what acetal is like, derailleur pulleys are usually made of Delrin which is a type of acetal.

cheers
-------------------------------------------------------------------------------
~~~~~~~~~~~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~

profpointy
Posts: 455
Joined: 9 Jun 2011, 10:34pm

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

Postby profpointy » 2 Mar 2018, 12:49pm

How about the paper mache axle, or maybe plastecine ?

mercalia
Posts: 10562
Joined: 22 Sep 2013, 10:03pm
Location: london South

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

Postby mercalia » 2 Mar 2018, 1:02pm

sounds like some one with more money than sense.