Oops it's a left hand thread.

woodchucker

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

GG
 
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
 
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
 
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!
 
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.
 
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