10-32 versus M5???

[Parlo]

I’ve found that there is a greater selection of metric washer OD’s (both larger & smaller than inch/Imperial/English); I regularly use 5mm washers on 10-32 fasteners.

I guess that the metric system had the advantage of hindsight when simplifying and rectifying the huge number of "measurement units " that evolved through the old imperial system.

 

[Provincial]

A 5/16-24 thread has an o.d. of .3125" and a pitch of .0416" and an M8-1.00mm has an o.d. of .3150" and a pitch of .0394"

I bought a Kobelco SK400 excavator at a discounted price because it had a bad hydraulic oil leak. I traced it down to a joint in the return lines that had a clamp similar to a turbo clamp. They look like this:

Both of the 8MM nuts were tight, but the one on the leaking end was a plain nut and the other was an elastic stop nut. If I backed off the nut, it spun off easily, and came up tight after contacting the clamp, but not didn't squeeze down the rubber seal. I tried another 8MM nut, with the same results. It dawned on me that a 5/16' nut was very close, and when I tried one, it pulled down the clamp and stopped the leak! It turned out the the fittings were made by Aeroquip in the USA, and used SAE hardware. Obviously, someone had that joint apart in the past, dropped the original nut, and since the machine was made in Japan, used a metric nut to replace it. The difference in the thread lead caused it to jam in just the right spot to be misleading.

The fix cost me about $0.35, but it took me two full days to remove enough parts to get to the problem area, using a crane for many of the items. The discount because of the oil leak was about $10,000.00, so I didn't feel to bad about the time spent.

 

[Provincial]

I guess that the metric system had the advantage of hindsight when simplifying and rectifying the huge number of "measurement units " that evolved through the old imperial system.

Maybe, but then they muddied it up with DIN, JIS, and other specialty standards. Every engineer thinks he should change something that is standard, because he needs something "special."

 

[Parlo]

Maybe, but then they muddied it up with DIN, JIS, and other specialty standards. Every engineer thinks he should change something that is standard, because he needs something "special."

The funamental units remain constant over these other standards. I would guess that most decent engineers were taught to design around standard parts.

 

[ChazzC]

The funamental units remain constant over these other standards. I would guess that most decent engineers were taught to design around standard parts.

I’m a Chemical Engineer and none of my educational training included anything about the details of design other than calculating pressures and using the proper materials. Hardware selection and similar specifications are learned on the job from those who learned the same way, and in most cases based on company guidelines/specifications. Remember the 80’s when you needed two sets of tools to work on a car that was “made” in the U.S.?

 

[Flyinfool]

SOme time engineers are required to make things non standard. I have had to invent new non standard threads or electrical connectors, for machine parts so that the end user would be forced to buy replacement parts from the same company because they would never find such a thing in a store.

I have a 2011 and a 2021 Chevy that still needs 2 sets of tools to work on them.

 

[brino]

The fix cost me about $0.35, but it took me two full days to remove enough parts to get to the problem area, using a crane for many of the items. The discount because of the oil leak was about $10,000.00, so I didn't feel to bad about the time spent.

Okay I believe this is well justified........





I realize that there was some work involved, but what a discount!!!!

Brian