Another 50Millionths Man?

mturner said:
. I've heard the old South Bend lathes with babbit bearings are very smooth, but some have a lot of wear or clearance.
Michael
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You heard wrong. The SBL's have bronze bearings just exactly like the wheelhead on most precision cylindrical grinders. And the SBL bearings are adjustable for wear. You will not find zero clearance in any spindle bearings.
 
I actually meant sleeve, or plain bearings as opposed to roller bearings. I probably wasn't told babbit. I probably misspoke.

Michael
 
HovisKM said:
After reading this thread for a couple of days, I just had to give a call to some friends at the Joint Special Operations Center, Special Missions Division, Special Weapons. They have an indoor and underground range. I asked a simple question...."Have you ever had a tactical weapon that averaged 1/4" for three or five shot groups for five groups, with factory, specialty shop loaded or goverment ammunition....any caliber...but most interested in .308/7.62 Nato". After he got done laughing.....NO !!! Millions of rounds and thousands of weapons....good enough for me.

Are there flukes...yes...but were talking about a guarantee...not flukes. If this was real...the goverment would probably waterboard him for secrets and disect his brain to figure out how he does it.....I wonder why he just laughed instead.

This kind of reminds me of companies that would send products to soldiers or units for free and then claim in their advertising "Used by the U.S. Military".....painting the roses red....

Hovis
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Well obviously the guy's not high enough up to have used Iron Brigade Armory rifles. The Bro's Chandler can and DO make a 1/4 minute rifle now and then.

For the US Military

al
 
i want to know where they are finding the federal gold medal match that will consistantly hold 1/4" groups!!!!
 
alinwa said:
Well obviously the guy's not high enough up to have used Iron Brigade Armory rifles. The Bro's Chandler can and DO make a 1/4 minute rifle now and then.

For the US Military

al
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A quarter minute rifle isn't a rifle that can shoot one group at that. And believe me....he's high enough up....he runs the department that does the proof testing on Every Single Rifle that goes to the Special Operations Command...It's quite an impressive arms room. One rifle I picked up that is now on display out front, is Gale McMillian's original prototype rifle that he made for the goverment with the original 5R barrel still on it. Close to it is the gold plated AK sniper rifle that Saddam gave to one of his sons. They have litterally thousands of prototype guns that have been tested. The sad thing was....when Clinton was in office, five unissued rare civil war muskets were found and delivered to there....they were ordered (and did) torch them into pieces because the goverment determined that if they were ever to make it into civilian hands, it would reduce the value of those already in collections. It had to do with who made them and their conditon, less than a dozen were known to exist.

Hovis
 
A good post from The Practical Machinest forum.
Hello,
To say that this thread, has been thought provoking, would be an under-statement. Can a person, purchase an indicator, with graduations of .00005"?
Yes. But in all of my 45 years of building precision tooling, the standard rule,
has always been that the measuring instruments, must be able to read to 10%, of the required accuracy. Now, to realize true, verifiable, accuracy, to
+/-.00005", you need another 0, after the decimal point.
I would be willing to state that the spindle bearings, of even a new, CNC turning center, would have more clearance, than that. A part turned, or bored
on most engine lathes, is not truely round, but close enough for the average
requirements.
The return on investment(ROI), has to enter this discussion, at some point.
The old statement, that declares, "We can do anything, the impossible, just takes longer.", might fit this situation. What price for perfection, that does not return a benefit, equal to the required investment?
What Kreiger says, may be different, than what can be proven, in a clean room environment.
Keep thinking,
Bob
 
Most times when I hear of millionths in measuring, I think of either very small parts, or Sunnen, or both! I have one of the cutest toys from them, it's pretty kewl. Called a Sunnen Spinner, and they've not been made for decades. It's a true steel on steel air bearing. It's got a really nice finish, it's really straight, really round, really cylindrical, and it's got a really nice fit! They did not make em out of stainless steel...
 
This goes along the same lines as the post Butch made. When we were asked by Boeing to make a test fixture, it had to be ten times more accurate than the part being tested/measured. Boeing didn't want to look foolish if they rejected a part, only to find out the contractor could prove them wrong with better measuring equipment. We wouldn't have been able to make something that would verify a half thousandth.
 
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