How close is close enough?

All discussion about lathes including but not limited to: South Bend, Hardinge, Logan, Monarch, Clausing and other HSM lathes, including imports

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LIALLEGHENY
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Location: Bohemia, NY

Re: How close is close enough?

Postby LIALLEGHENY » Mon Jul 03, 2017 4:21 pm

Harold, that's beautiful work!!!

Here's another thought towards striving for perfection... We all know that parts have tolerances +/- .005, .010 or whatever the engineer has spec'd out. Many times the parts are thought of individually when these tolerances are assigned, but consideration is passed over when looked at as an assembly. What happens to your assembly when your parts ( which all fall into tolerance but are at the high limit) are assembled? Your assembly may now have "grown" and no longer fits or functions correctly.

Nyle

jcfx
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Re: How close is close enough?

Postby jcfx » Mon Jul 03, 2017 5:12 pm

Harold V, the focusing device is thing of beauty, is the focusing mechanism rack and pinion, if so did you build that from scratch too ?
I own a few antique brass lenses for view cameras and they fine focus with a rack and pinion, coarse focusing is done thru
moving the camera's standards.

pete
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Re: How close is close enough?

Postby pete » Mon Jul 03, 2017 5:24 pm

At an average .045" wall thickness Harold that's a work holding problem right there without the going out of round issue. I can see where a lot of experience had to be used to get working parts at the end. And a nice pat on the back for the owner to have had your name engraved on it.

Garys analogy about what makes a real craftsman is a great one and something I need to remember. On any job I've worked at the people who really enjoyed what they were doing were almost always the best by a noticable difference.

If your not producing commercial parts where that time is money problem shows up, then sometimes striving for more accuracy than what's really needed can be part of the hobby as well. For myself it's an interesting (but frustrating at times) side hobby like Ron mentions. Trying for that unobtainable perfection sure doesn't do the ego any good either. But continual practicing for when it might or will be needed certainly isn't wasted effort imo. If your always used to .001"- .005" being good enough then trying to machine a light press fit bearing bore to a few 10ths is going to be real tough. A good guess about what depth of cut your machine should take after all that practicing sure helps.

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SteveHGraham
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Re: How close is close enough?

Postby SteveHGraham » Mon Jul 03, 2017 5:35 pm

Harold, Harold, Harold. You can use the phone to take photos. You don't need to have it connected. I think you're determined to deprive us of machining photos.

I know you have an Internet connection. Unless you're logging in using mental telepathy.
Don't trigger me, bro!

hobgobbln
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Re: How close is close enough?

Postby hobgobbln » Mon Jul 03, 2017 11:10 pm

I share a similar thought process with Nyle.

I was making some parts for a company a friend of mine started based around just a simple "can you make me a ____ ?" That turned into me making >10,000 pieces at night and on weekends on my hobby machines. Almost every part I make was built around threads and the devices they were meant to fit had threads that were sometimes WAY outside the tolerance. So I made the conscious choice to make sure my parts were as close to "perfect" as I could. I checked every other part and made sure that not one single part left my shop more than +- .0005 of the theoretical center of the spec and you know what? Not a single part was ever returned because it didn't fit.

I didn't HAVE to keep such close tolerances and I certainly scraped a few parts along the way, but I learned an awful lot and it helped to cement a lot of the ideas and tricks I have learned from all of your posts the last few years. It also gave me the confidence to be able to look at a part and say definitively that I can or cannot make it correctly.

So while I often make things for myself that are "close enough", knowing that I can make things even better when it counts matters.

Griz

Harold_V
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Re: How close is close enough?

Postby Harold_V » Mon Jul 03, 2017 11:43 pm

jcfx wrote:Harold V, the focusing device is thing of beauty, is the focusing mechanism rack and pinion, if so did you build that from scratch too ?

No. It was purchased, I think, from PIC Design. Not sure, though, as this was back in '86, as I recall. Might have come from Browning. Aside from fasteners, I did machine the rest, though.

The buyer wanted to buy an 8" Clark telescope, owned by a local fellow, but it was not for sale. He offered to lend me the focusing device so it could be copied, however. The buyer wanted a larger lens, so I made that change, and I also made the adjusting knobs slightly larger, and farther spread, so fingers didn't get wedged between the knobs and body.

Here's a picture of the two devices:

Telescope2-resized.jpg


H
Wise people talk because they have something to say. Fools talk because they have to say something.

Harold_V
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Re: How close is close enough?

Postby Harold_V » Mon Jul 03, 2017 11:55 pm

SteveHGraham wrote:Harold, Harold, Harold. You can use the phone to take photos. You don't need to have it connected.

Seems like I can do that with my Sony, which I already own. What am I missing?

I think you're determined to deprive us of machining photos.

What a lovely thought!
In truth, I figure little of what I do is of interest. For example, I built all of the light switches for our lighting system in our house. Started with the board from the original maker, which was highly altered. I then built a second board, on which I could mount switches and wiring, and moved the existing LED to the face plate, which I also made and engraved. I even made the push buttons and did the anodizing and dying of the face plate. The switches bear nothing in common with those provided by the builder, which had a reputation for being troublesome (Mylar switch plates, printed circuits on the back side). A huge project, taking a lot of time, but, who cares? Not very exciting.

If you'd like to see some pics of the switch assemblies, I can provide them. Just figured no one would care.

I know you have an Internet connection. Unless you're logging in using mental telepathy.

Well, yeah, I do, if that's what you'd like to call it. I have a DSL connection that is reputed to be up to 5mbps. I'm lucky if it hits 1.5 mbps, and often find it running well under 1mbps. That's the price I have to pay for living in a remote area. But we're almost free of traffic. Nearest stop light, which is a flashing 4 way stop, is twelve miles distant. I like that!

H
Wise people talk because they have something to say. Fools talk because they have to say something.

Harold_V
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Re: How close is close enough?

Postby Harold_V » Tue Jul 04, 2017 12:19 am

pete wrote:At an average .045" wall thickness Harold that's a work holding problem right there without the going out of round issue.

Indeed! You have to be creative. The part was driven by light pressure, held with a live center pressing a center plate. The plate fit the existing bore.

I learned, right off, that the part would not be stable until it was fully machined, and being a rolled and welded tube, that was a bit of a chore. Multiple passes of light depth were taken, with coolant running continually, to keep the part cool. The first time I got it right, it went out of round in polishing, so I reverted to flood polishing. A real mess, but highly effective. I'm proud to say the tube turned out beautifully.

I can see where a lot of experience had to be used to get working parts at the end.

I learned, long ago, that you must have a big box of tricks from which to pick, and having extensive experience in difficult work is a definite asset. When I ran my commercial shop, I was well known for tackling difficult work, which I attribute to the good work ethic instilled in me by my savior, Jay Dobson. A finer man I've never known.

Garys analogy about what makes a real craftsman is a great one and something I need to remember. On any job I've worked at the people who really enjoyed what they were doing were almost always the best by a noticable difference.

Absolutely! You can generally tell when a guy has "the gift". He works differently from others, and takes great pride in what he does. I worked with one such individual- a guy from South America. He was heads and shoulders better than all other lathe men I've ever known. If you messed with his machine (like changing the compound from 30° to 29°), you heard from him, and it wasn't polite.

You can often tell who has made parts simply by looking at them. When they are nice and uniform, good finishes, consistent sizing, you know they've come from one who is concerned about details and takes great pride in what they do. However, in today's CNC world, unfortunately, that is no longer the case. The dolt who has little interest in quality can turn out work equal to that of the guy who cares, because the machine doesn't know the difference between one who does, and one who doesn't. Both of them push the same button.

If your not producing commercial parts where that time is money problem shows up, then sometimes striving for more accuracy than what's really needed can be part of the hobby as well.

I've had that discussion with several people over the years. I truly believe that if one trains to work precisely, it takes VERY little more time to do so once the skill is developed. Payback comes from being able to deal with tight tolerance work with ease, to say nothing of being able to handle parts for second or third operations without concern. In today's society, where the bottom line is all important, that philosophy is no longer valued, however. The last job I held, I was told by one of the owners that he'd rather see me crash through a job, quality be damned, so that if they couldn't sell the parts, there'd be enough time left to make them again. I do not share that philosophy, and would be ashamed to have anyone think I did.

For myself it's an interesting (but frustrating at times) side hobby like Ron mentions. Trying for that unobtainable perfection sure doesn't do the ego any good either.

Probably not, especially in the learning curve, but that's exactly what I went through in my training. I got so demoralized that I couldn't do anything right, but, slowly, ever so slowly, things got better. They will for you, too, although keep in mind, I did this 8 hours daily, 40 hours/week.

But continual practicing for when it might or will be needed certainly isn't wasted effort imo. If your always used to .001"- .005" being good enough then trying to machine a light press fit bearing bore to a few 10ths is going to be real tough. A good guess about what depth of cut your machine should take after all that practicing sure helps.

I've tried to install that in those who read my ravings. Some get the idea that they'll never be called upon to do any close work, yet fitting a bearing is quite demanding. A snug slip fit is just as demanding of skill as a press fit, and you don't achieve that level of proficiency unless you practice. You can't learn these things by reading a book---they have to come from your hands and mind. Just like playing a musical instrument. Practice, practice, practice. And eventually things make sense.

H
Wise people talk because they have something to say. Fools talk because they have to say something.

Mr Ron
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Re: How close is close enough?

Postby Mr Ron » Tue Jul 04, 2017 12:22 pm

SteveHGraham wrote:Harold, you're always on me about soft jaws. Here is a product YOU need to start using: a digital camera. If you're too cheap to get a new smartphone and a smartphone account, you can pick up a used smartphone for nearly nothing, use it as a camera, and upload the photos to your computer using USB.

http://www.ebay.com/itm/Samsung-Galaxy- ... SwAPVZJ658

I have this feeling you're using a 1997 Nokia.


Calling someone "too cheap" shows a lack of respect for someone with a whole lot more intelligence than you have.
Mr.Ron from South Mississippi

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SteveHGraham
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Re: How close is close enough?

Postby SteveHGraham » Tue Jul 04, 2017 12:24 pm

Always showing the love. Thanks for shining the light of your warmth on my Independence Day.
Don't trigger me, bro!

Harold_V
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Re: How close is close enough?

Postby Harold_V » Tue Jul 04, 2017 3:37 pm

SteveHGraham wrote:Always showing the love. Thanks for shining the light of your warmth on my Independence Day.

Chuckle! And I feel the love, Steve! :P

Steve and I are friends, and I understand his razzing. Don't let him fool you.
In regards to intelligence------I envy his years of education. This high schooled boy doesn't hold a candle to his years of formal education. But then, his years of education don't hold a candle to my years of shop experience. In the end, it's all good. We need one another.

H
Wise people talk because they have something to say. Fools talk because they have to say something.

earlgo
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Re: How close is close enough?

Postby earlgo » Tue Jul 04, 2017 7:07 pm

After 47 years as a mechanical design engineer, I have seen more than a few drawings that had insane tolerances. Some of them were on surfaces and edges that were waving in the breeze. Some of them were to locate holes from a bend line, and some were from the boiler plate on the title block with no regard for what they actually described. When I was instructing my interns, my rule of thumb was that the price doubled for every place behind the decimal point. It seemed to stick. In my world, close enough was what worked at the most economical price.
Now, it is whatever I feel like at the time.

HaroldV wrote:I have a DSL connection that is reputed to be up to 5mbps. I'm lucky if it hits 1.5 mbps, and often find it running well under 1mbps.

Sorry this is off topic, but is relevant to the tangent. We are hardly in a remote area and still have a DSL. We were recently upgraded to 10MBPS. The installer proved it my running the Windstream speed test, but he did it on the download only. After he left I used the same Windstream software and ran the upload speed test and it rated 1.5 to 2 MBPS.
On a recent trip to visit my son in the remote area of Redmond, WA, I asked him this very question and he said that the providers do this on purpose to prevent ordinary users from installing and running a server from their home. Those who do require a special permission/approval etc.

--earlgo


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