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Old Jan 22, 2007, 08:11 AM
Adrian Hodgson
Guest
n/a Posts
Engineering plastics: - Delrin??


OK I know my memory is going so I need help here.

Many years ago I bought some red rod! I could have bought green or
black at the time, but the seller at the jumble said it was ok for what I
wanted.

I wanted to use the stuff as a bearing surface a bit like an oilite
bearing. The job was a drop arm or swing arm pivot on a press.

Now I have finally used up all the red stuff I had and could do with some
more, but what was it really called and is the black stuff better?

If one assumes swing arms in cars etc what are they using now?

Resistant to water, chanes in temperature and good impact resistant
properties would all be nice to have together with hard wearing of course.

Answers via the news group welcome and this coming Wednesdays lottery
winning numbers by email.

Many thanks

Adrian
Old Jan 22, 2007, 10:11 AM
Tim Leech
Guest
n/a Posts
Re: Engineering plastics: - Delrin??

On Mon, 22 Jan 2007 10:42:50 +0000, Adrian Godwin
<adrian.110504@ntlworld.com> wrote:

>Adrian Hodgson <adrian@spamtraptamarisktechnicals.com> wrote:
>>
>> OK I know my memory is going so I need help here.
>>
>> Many years ago I bought some red rod! I could have bought green or
>> black at the time, but the seller at the jumble said it was ok for what I
>> wanted.
>>
>> I wanted to use the stuff as a bearing surface a bit like an oilite
>> bearing. The job was a drop arm or swing arm pivot on a press.
>>
>> Now I have finally used up all the red stuff I had and could do with some
>> more, but what was it really called and is the black stuff better?
>>

>
>Nylatron GSM, possibly ? That's got molybdenum disulphide in it.
>Not very high temperature, though, and it looks like it might creep
>under continous pressure.
>
>I've bought it from Engineering & Design Plastics of Cambridge.
>
>

ISTR it does absorb some water, though not as much as plain nylon.

Vesconite might be better if water resistance is important

http://www.vesconite.com/

They do a prompt service from South Africa if you pay by credit card.
Last time I bought some I tried their agent in the Netherlands
thinking it would be quicker or cheaper. It was neither, plus they
wanted payment by euro cheque.

Cheers
Tim

Dutton Dry-Dock
Traditional & Modern canal craft repairs
Vintage diesel engine service
Old Jan 22, 2007, 10:11 AM
Adrian Godwin
Guest
n/a Posts
Re: Engineering plastics: - Delrin??

Adrian Hodgson <adrian@spamtraptamarisktechnicals.com> wrote:
>
> OK I know my memory is going so I need help here.
>
> Many years ago I bought some red rod! I could have bought green or
> black at the time, but the seller at the jumble said it was ok for what I
> wanted.
>
> I wanted to use the stuff as a bearing surface a bit like an oilite
> bearing. The job was a drop arm or swing arm pivot on a press.
>
> Now I have finally used up all the red stuff I had and could do with some
> more, but what was it really called and is the black stuff better?
>


Nylatron GSM, possibly ? That's got molybdenum disulphide in it.
Not very high temperature, though, and it looks like it might creep
under continous pressure.

I've bought it from Engineering & Design Plastics of Cambridge.


-adrian

Old Jan 22, 2007, 10:11 AM
Peter Neill
Guest
n/a Posts
Re: Engineering plastics: - Delrin??


Adrian Hodgson wrote:
> OK I know my memory is going so I need help here.

<snip>
>> Resistant to water, chanes in temperature and good impact resistant

> properties would all be nice to have together with hard wearing of course.
>
> Answers via the news group welcome and this coming Wednesdays lottery
> winning numbers by email.
>
> Many thanks
>
> Adrian


Forget Nylon, go straight for Acetal (Delrin is Acetal, but DuPonts
trade name).

Acetal has the lowest CoF of any unmodified engineering polymer, and
pound for pound is one of the stiffest unfilled polymers you can get.
Doesn't absorb moisture, but like all polymers will change sizes
minutely with temperature, but then it is also a little bit compliant
so this really shouldn't matter much. Acetal has an inherently harder
surface than Nylon due to its high level of crystallinity.

Nylon can absorb up to 5-7% of its weight in moisture under saturated
conditions but will lose it again under dry conditions. This causes
quite an apparent physical growth and shrinkage on the parts.
On the other hand, Nylon is more impact resistant than Acetal,
especially when it has absorbed moisture which provides a step change
in toughness. Dry Nylon becomes quite brittle.

Plenty of Acetal (Delrin) on e-bay. Go for the black stuff rather than
the natural (white) as this is inherently more UV stable as the pigment
is predominantly carbon black.

The "Red Stuff"could have been anything from High Density Polythene to
Nylon to ABS to Polypropylene.

Peter

Old Jan 22, 2007, 02:11 PM
Nick Mueller
Guest
n/a Posts
Re: Engineering plastics: - Delrin??

Adrian Hodgson wrote:

> Now I have finally used up all the red stuff I had and could do with some
> more, but what was it really called and is the black stuff better?


The black is better than the red. :-)
In technical plastics, black is often a sign of added MoS2. But it needn't
be that way.

> If one assumes swing arms in cars etc what are they using now?


Something with PTFE.

Can you use ready built DU-bushings?

Nick
--
***********************************
*** Available now in NZ and AUS ***
***********************************
<http://www.yadro.de>
Old Jan 22, 2007, 02:11 PM
Adrian Hodgson
Guest
n/a Posts
Re: Engineering plastics: - Delrin??

On Mon, 22 Jan 2007 09:34:48 +0100, Nick Mueller wrote:

> Adrian Hodgson wrote:
>
>> [quoted text muted]

>
> The black is better than the red. :-) In technical plastics, black is
> often a sign of added MoS2. But it needn't be that way.
>
>> [quoted text muted]

>
> Something with PTFE.
>
> Can you use ready built DU-bushings?
>
> Nick


Thanks to all answers in the group Black stuff up to now.

Nick please explain DU to me, is it a trade name?


Adrian
Old Jan 22, 2007, 04:11 PM
Nick Mueller
Guest
n/a Posts
Re: Engineering plastics: - Delrin??

Adrian Hodgson wrote:

> Nick please explain DU to me, is it a trade name?


No, this is a type of bushing. Cheap like ????. Just google for "DU bushing"
to get overwhelmed.


Nick
--
***********************************
*** Available now in NZ and AUS ***
***********************************
<http://www.yadro.de>
Old Jan 22, 2007, 04:11 PM
John Stevenson
Guest
n/a Posts
Re: Engineering plastics: - Delrin??

On Mon, 22 Jan 2007 20:01:11 +0000, Adrian Hodgson
<adrian@spamtraptamarisktechnicals.com> wrote:

>On Mon, 22 Jan 2007 09:34:48 +0100, Nick Mueller wrote:
>
>> Adrian Hodgson wrote:
>>
>>> [quoted text muted]

>>
>> The black is better than the red. :-) In technical plastics, black is
>> often a sign of added MoS2. But it needn't be that way.
>>
>>> [quoted text muted]

>>
>> Something with PTFE.
>>
>> Can you use ready built DU-bushings?
>>
>> Nick

>
>Thanks to all answers in the group Black stuff up to now.
>
>Nick please explain DU to me, is it a trade name?
>
>
>Adrian


No it's Depleted Uranium, keep clear of it <g>

..
--
Regards,

John Stevenson
Nottingham, England.

Visit the new Model Engineering adverts page at:-
http://www.homeworkshop.org.uk/
Old Jan 22, 2007, 04:11 PM
Adrian Hodgson
Guest
n/a Posts
Re: Engineering plastics: - Delrin??

On Mon, 22 Jan 2007 21:33:44 +0100, Nick Mueller wrote:

> Adrian Hodgson wrote:
>
>> [quoted text muted]

>
> No, this is a type of bushing. Cheap like ????. Just google for "DU
> bushing" to get overwhelmed.
>
>
> Nick


They looks like outer steel lines oilites.

Thanks for the info.

Adrian
Old Jan 22, 2007, 08:11 PM
Tony Jeffree
Guest
n/a Posts
Re: Engineering plastics: - Delrin??

On Mon, 22 Jan 2007 21:02:48 GMT, John Stevenson
<john@stevenson-engineers.co.uk> wrote:

>No it's Depleted Uranium, keep clear of it <g>


I thought it was something to do with taking the piss...<G>

Regards,
Tony
Old Jan 23, 2007, 06:11 PM
Newshound
Guest
n/a Posts
Re: Engineering plastics: - Delrin??


"Nick Mueller" <muellernick@gmx.de> wrote in message
news:1503204.AQo7LyjYZf@yadro.de...
> Adrian Hodgson wrote:
>
>> Nick please explain DU to me, is it a trade name?

>
> No, this is a type of bushing. Cheap like ????. Just google for "DU
> bushing"
> to get overwhelmed.


Made by Glacier; sintered bronze on a steel backing (like a big end shell),
and the bronze bit is impregnated with PTFE. Used dry. Very impressive low
friction, low wear, long life. No connection with Glacier, I just used to
use them on friction and wear test rigs. I can't remember offhand but they
probably also have a better PV factor (pressure multiplied by speed) even
than expensive Vespel because the bronze conducts the frictional heat away.


Old Jan 23, 2007, 06:11 PM
Adrian Hodgson
Guest
n/a Posts
Re: Engineering plastics: - Delrin??

On Tue, 23 Jan 2007 22:48:43 +0000, Newshound wrote:

>
> "Nick Mueller" <muellernick@gmx.de> wrote in message
> news:1503204.AQo7LyjYZf@yadro.de...
>> [quoted text muted]

>
> Made by Glacier; sintered bronze on a steel backing (like a big end
> shell), and the bronze bit is impregnated with PTFE. Used dry. Very
> impressive low friction, low wear, long life. No connection with Glacier,
> I just used to use them on friction and wear test rigs. I can't remember
> offhand but they probably also have a better PV factor (pressure
> multiplied by speed) even than expensive Vespel because the bronze
> conducts the frictional heat away.


Thanks for the information.

I think I will go for the black engineering plastic initially as I see two
advantages for me.

1) I can machine to size and fit and even include end packing pieces.

2) As the stuff is slightly elastic and deformable it will not transfer
shocks as easily. How true this later part is time will tell.


Many thanks
again

Adrian
Old Jan 23, 2007, 06:11 PM
Tom
Guest
n/a Posts
Re: Engineering plastics: - Delrin??

Adrian Hodgson wrote:

> OK I know my memory is going so I need help here.
>
> Many years ago I bought some red rod! I could have bought green or
> black at the time, but the seller at the jumble said it was ok for what I
> wanted.
>
> I wanted to use the stuff as a bearing surface a bit like an oilite
> bearing. The job was a drop arm or swing arm pivot on a press.
>
> Now I have finally used up all the red stuff I had and could do with some
> more, but what was it really called and is the black stuff better?
>
> If one assumes swing arms in cars etc what are they using now?
>
> Resistant to water, chanes in temperature and good impact resistant
> properties would all be nice to have together with hard wearing of course.
>
> Answers via the news group welcome and this coming Wednesdays lottery
> winning numbers by email.
>
> Many thanks
>
> Adrian
>

If you're talking about suspension in cars, the plastic of choice for
bushings is urethane, comes in a red colour.

Tom

--
Posted via a free Usenet account from http://www.teranews.com

Old Jan 23, 2007, 06:11 PM
Adrian Hodgson
Guest
n/a Posts
Re: Engineering plastics: - Delrin??

On Wed, 24 Jan 2007 12:49:24 +1300, Tom wrote:

> Adrian Hodgson wrote:
>
>> [quoted text muted]
> >

> If you're talking about suspension in cars, the plastic of choice for
> bushings is urethane, comes in a red colour.
>
> Tom


Hi Tom;

Not quite cars but a Gokart and I used up all my red stuff that i thought
was Delrin on the stub axle shaffs and at the bottom of the sterring shaft.

so I started to ask the group what seems to be best now.

The red stuff I have had for some 12 years and could not really remenber
its origin except from an autojumble.

Looking at doing swinging arm suspension at some point so looking what
might be best then and I suppose still be general purpose!

Cheers

Adrian
Old Jan 23, 2007, 08:11 PM
Tom
Guest
n/a Posts
Re: Engineering plastics: - Delrin??

Adrian Hodgson wrote:

> On Wed, 24 Jan 2007 12:49:24 +1300, Tom wrote:
>
>
>>Adrian Hodgson wrote:
>>
>>
>>>[quoted text muted]

>>
>> >

>>If you're talking about suspension in cars, the plastic of choice for
>>bushings is urethane, comes in a red colour.
>>
>>Tom

>
>
> Hi Tom;
>
> Not quite cars but a Gokart and I used up all my red stuff that i thought
> was Delrin on the stub axle shaffs and at the bottom of the sterring shaft.
>
> so I started to ask the group what seems to be best now.
>
> The red stuff I have had for some 12 years and could not really remenber
> its origin except from an autojumble.
>
> Looking at doing swinging arm suspension at some point so looking what
> might be best then and I suppose still be general purpose!
>
> Cheers
>
> Adrian
>
>Hi Adrian

A good all round plastic is Ertalon, comes in various types.
Colour coded.
I've had good success with the various types.
Trouble is today they seem to produce usage specific compounds
at the drop of a hat and if you follow mnfrs guidelines you end
up with shelves of differing grades and type.
Tom

--
Posted via a free Usenet account from http://www.teranews.com

 


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