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Re: Pissed Off, But

whit3rd wrote in news: snipped-for-privacy@googlegroups.com:

>> > On Friday, July 5, 2019 at 2:28:08 PM UTC-4, >> > snipped-for-privacy@decadence.org wrote: ... > >> > Our lead tech has banned 1/4-20 from the shop floor in favor of >> > 1/4-28. > >> * makes a lot of sense; holds better - so well that one would >> think they would be reliable even in 1/8 steel panel (never tried >> them in that thin of a panel. > > Doesn't make much sense, to me; that's a NF thread (NC is the > 'standard') and can be jammed up by a tiny bit of grit, or minor > thread dent. There's a REASON for coarse threads, and associated > loose tolerances, in a variety of applications (like a clamp, > where tightening the thing by a quarter inch can take five turns > of a quarter-twenty, but seven of a quarter-twentyeight). > > If your shop were dealing with rust and sandblasting, the fine > threads would drive you crazy. >

You are one of the most accurate posters here.

I built hyper-hypothermia machines using stainless construction, but they bought regular zinc plated 1/4-20 x 1/2 screws that had six strikes on the head, but the friggin things twisted off like taffy. NOT grade 8 by any stretch.

My dad worked at Milacron, so I knew what a grade 8 bolt worked like.

These weren't it. The right stuff will SNAP OFF, and after a lot of overtorqueing. These were 'cheap chinese'. They didn't like me much after I told them they were ripped off, and it turned out that it was the VP of the place that made the buy.

I would use fine screws for rack modules and lab gear. Not field gear or say for the bot contest assembly stuff.

Coarse or fine threads... I would rinse clean any dust or grit blast media before putting a threaded screw with a threaded hole if it were at all possible. We used a really good brominated solvent that left zero residue.

I would take the extra moments to make a clean assembly using either pitch.

Reply to
DecadentLinuxUserNumeroUno
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Well I smell lawsuit, and possibly even punitive because in another applica tion those inferior bolts may have caused and insidious problem. If I was y our boss I would have the lawyers on it yesterday.

But then if they are offshore that complicates things to the point of maybe not being worth it.

If you have a sense of civic responsibility, somehow without them sticking it up your ass you should find a way to publicise this so that they don't u se these things in like cars and planes. Well they probably wouldn't anyway but what about ultralights, power saws, go carts, all that ?

Reply to
jurb6006

On Jul 11, 2019, Phil Hobbs wrote (in article):

It was also to accommodate the higher strength of steel. The rule was that NC was for cast iron, while NF was for mild steel.

For the most part, metric screw series split the difference.

Joe Gwinn

Reply to
Joseph Gwinn

This is not a new problem.

Although counterfeit fasteners were first detected in the U.S. in early

1985, it is a ...

Mikek

Reply to
amdx

That makes sense. It costs real money to stock all that inventory.

I can think of many suck projects.

I'll have to check them out. Thanks.

Reply to
krw

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