how to test a chinese part versus name brand

[Seapig]

I have recently found myself in need of some polyoxymethylene ball bearings. Harkin sells them for about 98 cents per bearing, Lewmar for about 1.25 per bearing. A company in Tennessee sells them for about 15 cents and a Chinese retailer sells them for $3 per thousand.


I would be very surprised if Lewmar or Harkin didn't get their bearings from a Chinese manufacturer but I of course have no proof. For $3 I am thinking of ordering a thousand from China and testing them to see how they compare. If they are crap I can use them as sling shot ammunition.


The question.
How could one go about comparing these items without a bunch of sophisticated equipment?


As always thank you for your thoughts
SP

[tkeithlu]

The Anerican firm places its order with a Chinese manufacturer. The specification is pages (or more) long, and the bearings get tested as meeting the specification. The American company does not want to have to recall every product it sent out because a supplier sent it defective bearings. In other words the American source is your assurance that the quality is OK; where it was manufactured is not important.

Yeah, testing bearings would take a lab full of equipment. In this case, it wuld include chemical analysis.

[Pandor]

Umm…. You do not need to test to any particular specifications. The true test of serviceability is an operational test. Install the bearings and see if the work. Then continue using and see how long they last.

[Seapig]

Originally Posted by Pandor

Umm…. You do not need to test to any particular specifications. The true test of serviceability is an operational test. Install the bearings and see if the work. Then continue using and see how long they last.

Good point, I guess for something as simple as bearings they are unlikely to self destruct immediately and as long as I keep an eye on them I will be able to tell if they are holding out as opposing to wearing out.

[Dave_S]

I try not to buy anything from China. Sadly it's not always possible. It's usually poor quality and I don't like the politics.

The only thing that has lasted that was made in China is covid.

[EngineerRetired]

Originally Posted by Seapig

The question.
How could one go about comparing these items without a bunch of sophisticated equipment?

As always thank you for your thoughts
SP

Very often something as simple as a good weight scale tells the tale. Differences in chemical compounds will almost always show up in its weight.

[Simi 60]

Originally Posted by Dave_S

I try not to buy anything from China. Sadly it's not always possible. It's usually poor quality and I don't like the politics.

The only thing that has lasted that was made in China is covid.

Shakes head

[Capt Clark]

Originally Posted by Dave_S

I try not to buy anything from China. Sadly it's not always possible. It's usually poor quality and I don't like the politics.

The only thing that has lasted that was made in China is covid.

[Simi 60]

Originally Posted by Dave_S

.

The only thing that has lasted that was made in China is covid.

What about the computers, phones and tablets you smash out your anti China rhetoric on?

[goboatingnow]

Originally Posted by Dave_S

I try not to buy anything from China. Sadly it's not always possible. It's usually poor quality and I don't like the politics.



The only thing that has lasted that was made in China is covid.

Their satellites , rockets and warships seem to do a similar job to the west’s. Their gps is quite good and they lead the world in things like 5G backbone and lithium batteries etc.

[thinwater]

Order them (Delrin or acetal) from McMaster Carr or some other respected vendor and they do the QC. Nearly as cheap. About $5 per hundred. I have used them in travelers.

[Seapig]

Thinwater- I never thought of McMaster Carr they didn't come up in the google search. I will remember them for next time. I ended up ordering from BC Precision Bearings in Tennessee. They are a listed dealer for several U.S. and Japanese bearing manufacturers. According to the person I spoke with all Delrin, Acetal and Torlon bearings come from China.



On this general note-- Is there a place in this forum or any other forum for that matter that aggregates suggestions such as that made by Thinwater. He got his bearings from McMaster-Carr they worked well and they are a twentieth the price of the Marine source. One can of course search and read a bunch of posts but it would be nice if there was a "boat hacks" type of list somewhere.

[Nicholson58]

While we are all gathered together perhaps someone knows the answer to this related.

I have Harken Air Blocks with bearings turned to powder. When we left the boat in Antigua for the summer I thought it would be simple to find replacement rollers. Harken apparently has two sizes. I can’t find specifics on their site and they do not respond to inquiries.

There appear to be both rollers and balls. Zoom in. Rollers look OK but the balls are goners.

[Alan Mighty]

Originally Posted by Dave_S

I try not to buy anything from China. Sadly it's not always possible. It's usually poor quality and I don't like the politics.

The only thing that has lasted that was made in China is covid.

Good to see a bloke stand up for principle.

Toss out the tea and ketchup. Give oranges, tangerine/mandarin oranges, and pomelos the heave ho. Send all those weirdo leafy green varieties of the cabbage group straight to the bin.

Toss out the paper, moveable type, and gunpowder.

And be serious: toss out sail battens, lazy jacks, the whole idea of bulkheads and that of sternpost rudders, too. End the junk rig (and all the ideas that came with it, including the afore-said battens and lazy jacks).

Away with those ideas of yin and yang. Don't let silk get near you.

Steer right away from artesian wells. Outlaw wheelbarrows. Spurn the idea of inoculation.

And porcelain! Jeez, some fools call it china or chinaware!

Tinted spectacles? Chinese invention to hide where a judge was looking.

Bureaucracy too - chuck it out along with the notion of exams for entry to the civil service. Norman King Roger of Sicily was the mug who introduced those poisonous ideas from China. Silly blighter commissioned Muslim scholars to write a compendium of all knowledge, unthinkingly opening the way for the idea of experts in government maintaining written files and following rules of procedure. Shocking!

Into the dumper go all the ideas of Confucius and small, ethical government.

Pity our friends in Nippon, Republican Korea, and Viet Nam. They'll have to give up some fraction of their written languages.

The local florist is going to be in trouble - it's going to take a while to sort out the exact origin of those chrysanthemums, peonies, hibiscus rosa-sinensis (jolly name gives itself away!), camellias, plum blossoms, and azaleas.

Same with decorative knots, just not needed.

As for stir frying in a wok! No more. Make it a rule: deep fry is good, boiling or stewing better. None of this piddly splash of oil in a curved pot. Out!

We might need a book burning, but I hear the precedent for that might be Chinese too.

[Seapig]

Before this develops into mud slinging, let us remember that everyone is entitled to an opinion. You may think it is uninformed or if it agrees with you than it is obviously well reasoned but it is only an opinion.


To that end can we please stick to helping each other find working solutions to the very expensive and difficult proposition of owning a boat.


thank you