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Oops it's a left hand thread.

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woodchucker

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#1
My neighbor and I were busy cutting up trees yesterday each on our own properties, today is dump day. Somehow he snapped his chain tensioner adjust screw on the chain saw. So he asked if I would see if I could fix it. There's no way to fix it, so I made a new one. 12-32 with a knurl and 2 bearing surfaces.. I don't have a 12-32 die so I am single pointing it. Damn it's still not fitting. I never checked, it's left hand thread..
 

Ulma Doctor

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#2
i run into LH threads daily, i always have to be mindful of that.
they are easy to spot in relative large diameters, not so easy on small diameters.
if you get to look at how the threads lay, it's usually a dead giveaway.

you can look at it this way,
you'll always now look at whether the threads are right hand or left hand !

believe me i have messed up on simpler things :oops:
 

4GSR

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#3
From a design engineer stand point, I've made my share of screw ups on drawings not specifying LEFT hand when the part got cut with RIGHT hand thread. Ouch! The machine shop doesn't let you forget it, too!
On another note, we had a machine shop make a part for us that has two multi-start threads on it. One is left hand and the other is right hand. They cut them both right hand! Different order, same part, one thread has four starts and the other eight starts, they have come in with both threads cut with four starts. Bam!
 

Olddaddy

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#4
Years ago when I was a young buck I broke two of the five lug nuts off my Dodge Dart......left hand threads on one side of the car, right hand on the other.....dohhhh!!!!
 

wawoodman

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#5
Years ago when I was a young buck I broke two of the five lug nuts off my Dodge Dart......left hand threads on one side of the car, right hand on the other.....dohhhh!!!!
Now that engineer should be taken out back and shot!
 

GarageGuy

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#6
I learned the hard way that the cylinder nut in a milling vise is also a LH thread. :D

GG
 

RJSakowski

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#7
My understanding was that using left-handed lug nuts went back to the horse and buggy days when a single spindle nut held the wheel on the axle. A left handed nut used on the left side of the buggy wouldn't loosen when the wheel turned. This carried through to racing vehicles which used a single nut to secure a wheel to permit faster pit stops. Mopar carried this through to lug nuts. My 1958 Buick also had l.h. lug bolts on the driver's side.

It has since been proven unnecessary provided the lug nuts are tightened properly. I do recall two instances where that failed though. One involved myself where the lug nuts weren't tightened on a trailer and the nuts and wheel came of at 50 mph. The tire past us by and zipped through a farmer's yard with the residents standing in close proximity and on to a marsh beyond. They thought we were trying to kill them and called the law. The second incident involved a car which had just had some tire work. A few minutes later, the woman came storming in mad as a wet hen. She had gotten a few hundred yards down the road and her wheel fell off
 

bfd

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#8
did the same thing on someone elses car broke 2 of 4 studs note to self look for the big "l" stamped on the end of the stud bill
 

RodJShaw

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#9
VW beetles had lug bolts not nuts, made changing wheels a chore as you had to hold the wheel precisely in place so the bolt would go in. The problem is that if not tightened properly they work loose as the LH wheels rotate and very quickly unscrew all the way out. I lost a wheel once through improperly tightened bolts [someone else] and nearly lost one though my own incompetence but fortunately recognized the characteristic 'rumbling' noise of an 'unscrewing' wheel and managed to stop in time. The first event caused a bit of consternation as the wheel careered across two lanes of oncoming traffic, fortunately no-one was hurt and we got the wheel back on by cannibalizing bolts from the other three before the feds arrived! The joys of youth!
 

Wreck™Wreck

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#10
Anyone that works in a machine shop will assume that a thread call out on a drawing unless specified otherwise is RH as 4gsr found out.
 

4GSR

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#11
Anyone that works in a machine shop will assume that a thread call out on a drawing unless specified otherwise is RH as 4gsr found out.
Yeah! Machinists will still ask me if it's right hand to this day if it's not specified on the drawing. And customary, it is considered right hand unless otherwise specified. I always put 'RH' or 'LH' on the thread callout on the drawings I do. That way, it takes the doubt out of the equation.
 

Wreck™Wreck

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#12
Yeah! Machinists will still ask me if it's right hand to this day if it's not specified on the drawing. And customary, it is considered right hand unless otherwise specified. I always put 'RH' or 'LH' on the thread callout on the drawings I do. That way, it takes the doubt out of the equation.
Good on ya, the less ambiguity the better, we do largish jig plate parts for the pharma packaging industry, one customers engineer routinely dimensions parts from all 4 sides of the plate. This may appear to be no problem on paper but when actually programming 70+ holes, slots and pockets at the machine a single o,0 position makes life much simpler.
 

Old junk

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#13
Late night in the shop,cut down tie rod adjusting sleeve,ran tap through one end,flipped it around and was fighting with the hole.in a hurry and tired rh one side lh other dummy.
 

4GSR

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#14
Better yet, try to tap a 3/4-10 hole with a left handed tap. You never though the Bridgeport had so much power either until the magic smoke started to rise from the part! The aggravated part was, I've been pulling 3/4-10 RH taps from that pile for months, too. I kept that tap, too, and still have it today. That was almost 40 years ago, too!
 

savarin

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#15
I must say it warms the cockles of my heart to find I'm not the only one.
I sped a whole day last week making a new fixing bracket to the fan on my powder coating oven to allow a new motor with a longer shaft to be used.
The centre of the fan is a silicone?? tight push fit to the rough shaft. I thought that a thread would be a rough push fit. BUT, it was a l/h thread and just unscrewed. New design on the way now.
 

Bi11Hudson

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#16
Just have to throw in an experience from --way-- back. I had acquired a good bench grinder. Disremember the brand but it did have a "Baldor" motor. The difficult part was the 1/2" shaft. It got thrown out because there was no left hand nut for the left hand side, I guess. This around 1980, when the EPA was taking down foundries left and right.

I turned the city upside down for that 1/2-20 LH nut... to no avail. As it happened, I had both a Dodge Dart and a Plymouth Valiant in my history. The lug nuts were ... 1/2-20. And being Chrysler products, the left side had left hand nuts. A local salvage yard had them by the bucket full, they didn't fit anything newer than ~mid-70s models. I got a handful (doubled) for a dollar. Mostly to pay for them being dug out.

I've used them up making turnbuckles for my tractor. Now I have a tap. But back then, such things were costly.
 

TRX

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#17
one customers engineer routinely dimensions parts from all 4 sides of the plate. This may appear to be no problem on paper but when actually programming 70+ holes, slots and pockets at the machine a single o,0 position makes life much simpler.
Not just that, but you can run into some nasty tolerance stacking problems if you're not careful. Though they usually deal with that by ratcheting down the tolerances.

One all-too-common problem is when people design, say, a chain of holes, each dimensioned from the next. Ten holes +/- .010", the 10th hole can be +/- .100 from the first hole and still be in spec, much to the consternation of the designer...

Unless you have some specific reason not to, it's usually best to dimension everything from a common origin.
 

Linghunt

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#18
Not just that, but you can run into some nasty tolerance stacking problems if you're not careful. Though they usually deal with that by ratcheting down the tolerances.

One all-too-common problem is when people design, say, a chain of holes, each dimensioned from the next. Ten holes +/- .010", the 10th hole can be +/- .100 from the first hole and still be in spec, much to the consternation of the designer...

Unless you have some specific reason not to, it's usually best to dimension everything from a common origin.
That is common actually, you get CAD jockeys with quick trigger finger and had never made a chip in their life. During one small window old company used to send rookie CAD guys down to the "Snake Pit" . They had a tour of duty in all 3 shops ( Elect, Fab , and Machine ) not only did they draw better, but they were also high skilled at sweeping the floor. It built relationships of communication too. Program was dumped by some Dilbert type boss that showed up.
 

whitmore

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#19
My understanding was that using left-handed lug nuts went back to the horse and buggy days when a single spindle nut held the wheel on the axle....
It has since been proven unnecessary provided the lug nuts are tightened properly.
For those situations (like, under the hubcap) where the AXLE has a nut,
there are castellated nuts with cotter pins, and keyed (nonrotating) washers, and a stamped
washer-with-bendtabs gizmo for which I know no name. I'm dubious that there's much advantage
on lug nuts (the wheel can't pivot under 'em to create loosening) though.

A recurrent headache at my PPOE was a slotted bracket secured with a screw
and lockwasher; any movement along the slot was 50% likely to grab the
lockwasher so as to loosen the screw.
 
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