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What kind of plastic to use?

ballen

Active member
One of our shower hoses has an expensive white porcelain handle that keeps breaking when the hose is dropped. The porcelain handle is a tube, about 100mm (4") long and 32mm (1 1/4") diameter, with a through hole about 19mm (3/4") in diameter. I want to turn a new one. What's a good choice of plastic that is:

(1) pearly white
(2) impact resistant
(3) turns well (hss or aluminium inserts) and finishes well (hard shiny surface if possible)
(4) resistant to soap, water, bleach, chlorine
(5) fairly scratch resistant
(6) not real expensive

Is white ABS a good choice? I don't know anything about plastic...
 

car2

New member
White ABS should be fine (in fact most plated stuff on cars and plumbing is typically ABS). ABS is impact-resistant, high-enough temp resistance for hot water, inexpensive, and platable). All that "chrome" plastic on cars (bumpers, hubcaps, trim, etc) is ABS. The "butadyene" phase in the ABS is etched out with chromic-acid, which provides mechanical keying for the subsequent plating (electroless copper, lots of electroplated copper, a little nickel, and a tiny bit of chrome).
 

gustafson

Active member
Not good - IME it yellows with ultra violet etc etc

My choice would be white Polypropylene

On edit, 1 1/4 <> $8 / ft at Mc Master Carr McMaster-Carr

It is inside, so I doubt UV is a problem


I am sure if you soak it in chlorine, it would be a problem, but I doubt a shower head would see any of this type of thing. Even old fashioned abrasive/chlorine cleaners would be momentary contact

This is a handle not a space shuttle support column
 

bhigdog

Active member
One of our shower hoses has an expensive white porcelain handle that keeps breaking when the hose is dropped. The porcelain handle is a tube, about 100mm (4") long and 32mm (1 1/4") diameter, with a through hole about 19mm (3/4") in diameter. I want to turn a new one. What's a good choice of plastic that is:

(1) pearly white
(2) impact resistant
(3) turns well (hss or aluminium inserts) and finishes well (hard shiny surface if possible)
(4) resistant to soap, water, bleach, chlorine
(5) fairly scratch resistant
(6) not real expensive

Is white ABS a good choice? I don't know anything about plastic...

Whatever is on hand, inexpensive, and your wife will put up with. In that order....Bob
 

Joe Gwinn

Active member
I'd use the acetal copolymer from McMaster-Carr, mainly because I've used it in the past.

The Polypropylene will also work I'd venture. Acetal is far stronger, but impact resistance is about the same.

Does it have to be white? Blank could look good as well.
 

BoxcarPete

Active member
It is inside, so I doubt UV is a problem


I am sure if you soak it in chlorine, it would be a problem, but I doubt a shower head would see any of this type of thing. Even old fashioned abrasive/chlorine cleaners would be momentary contact

This is a handle not a space shuttle support column

You might be surprised.

Chlorine with as little as 0.5ppm can cause chemical fatigue in acetal plastic so that the failure stress is below 10 MPa (normally it is 50-70 MPa). See the attached for time and temperature chart. 70°C is a bit hotter than anyone in their right mind would use to shower, but the ppm of chlorine in city water is comparable to the study. 0.76 ppm according to my municipality's water report for 2020.

According to my calculations and a bit of extrapolating from the chart, after around 1000 showers (probably 2-3 years) you could crush the handle in your fist if you had about a 400 lb grip strength. Most people don't, but we're back to square 1 on lacking the toughness required to survive a drop, plus it will look bad after chemically cracking. And that's just from city water, without ever touching it with bleach.
 

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Milland

Active member
White UHMW:

UHMW Polyethylene Rods and Discs

Good fer what ails ya'. Cures gout, dyspepsia, ingrown toenails, spotted liver, and scares away demons and pixies. Hangovers gone in an instant! Now with improved XR-33, the miracle additive of the 1930's.*


*Not all claims verified by the FDA. Use at your own risk. Some fraud and horsefeathers may be included at no extra charge.
 

doug8cat

New member
How about a metal handle with a powder coat finish?
Might be a bit more expensive than just a polymer but you could pick your base metal. I have 0 knowledge of the cost of getting a 1 off powder coat done. It would also give the weighty feel of the original porcelain not cheapo sewer pipe ABS, which personally would bug the ever loving crap out of me every time I would touch it.
Might even consider brass or copper and just let it age, but then I would not have to deal with your wife.:rolleyes5:
 

Milland

Active member
How about a metal handle with a powder coat finish?
Might be a bit more expensive than just a polymer but you could pick your base metal. I have 0 knowledge of the cost of getting a 1 off powder coat done. It would also give the weighty feel of the original porcelain not cheapo sewer pipe ABS, which personally would bug the ever loving crap out of me every time I would touch it.
Might even consider brass or copper and just let it age, but then I would not have to deal with your wife.:rolleyes5:

Thermal transfer with a metal handle would be annoying if it's hand-held during use. Plastic or ceramic would be better in this application.
 

4GSR

Active member
Why not shorten the hose so the handle/head does not hit the ground. Just don't hang yourself with the shorten hose.:stirthepot:
 
Try again. Bleach/chlorine is no bueno.

You might have OK luck if you make sure it is acetal copolymer rather than acetal homopolymer (Delrin is acetal homopolymer).

The few times I machined acetal copolymer it grew and shrank quite a bit with temperature variance and it did not smell too good either.
 








 
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