Centering a Round Work Piece in a Four Jaw Chuck

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Harold_V
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Re: Centering a Round Work Piece in a Four Jaw Chuck

Post by Harold_V »

SteveHGraham wrote:I get the impression that Richard is like Harold. Maybe a tier or two above the video guys,
Richard_W wrote:I don't consider myself to be above Harold. I have him on a higher plain.
Thanks, Richard, but I don't agree. I see both of us on a common plane, but with different backgrounds. There's not a doubt in my mind that I would learn a great deal from you, just as I suspect you might learn a few things from me.

The field of machining is so large that it's not common to find a machinist that has experienced everything, and those who claim they have are most likely to not be highly skilled in any of them. It takes years of daily "practice" to become proficient on machines---that meaning you can be handed a print, pointed to a machine, and turned loose, being expected to produce any number of parts in a timely fashion, per print, without supervision.
As for the video's that were posted... I don't think you really want to know what I think of the ones I looked at. I will give the guys who made them credit for trying to show the correct way, but they left out more than they showed you. This thread is proof of that.
I agree.
Years ago I used to subscribe to Live Steam Magazine. What turned me off, more than anything, was the endless string of "how to" articles that were published by those with no real machine shop experience, providing guidelines for the project. I understand they are well meaning--but that doesn't change the fact that their instructions often were not good. Practice does not make perfect---but perfect practice does. If one seeks instruction, it should come from one with knowledge, so bad habits are not created (or poor practices incorporated in a process).

Harold
Wise people talk because they have something to say. Fools talk because they have to say something.
martyn
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Re: Centering a Round Work Piece in a Four Jaw Chuck

Post by martyn »

Bill

Like you, I have had great difficulty centring work in a four jaw independent chuck. An hour is really fast!

What I do is measure the diameter of the workpiece with vernier calipers. I then set the jaws as accurately as I possibly can to the circumference of the chuck body i.e. I feel with my finger and look with my eye until all feel flush. I now wind them in, two diametrically opposed at a time and measure the gap (with the calipers) between each diametrically opposed two jaws until all are as exactly, as I can make them, the same distance apart as the diameter of the workpiece.

(How many turns you can take on the key each time depends on the size of the work and the chuck. If it's going to be a small workpiece in a big chuck you can probably advance by two or three complete key turns each time. If it's big work in a little chuck one turn, or even a half, may only be appropriate)

I now insert the workpiece which may need a very light tap with a soft hammer to get it to go in (this is a good sign).

Now take your dial indicator and test the workpiece. If you are lucky and it was a nice round piece of new bar from the
materials' stockist you may find the run-out is small enough to be acceptable. If not use the key on opposing jaws to keep
reducing the run-out by a half, having observed first, of course, on which side the 'wobble is'. You will now only be moving the keys as little as an eighth of a turn at a time. Allow much time for the process, but eventually you should get it sufficiently true to satisfy the job. As you gain confidence you may be able to use two keys on opposite side, one drawing back one pushing but both ever so slightly.

A WORD OF CAUTION If you are using Chinese chucks, and many of us have to on the basis of cost, they are often so inaccurately made as to have much (and what is worse, varied) slop in the adjusters. 'Feel-out' this slop before you
move the jaws i.e. feel for the resistance.

Hope this helps. I've tried other methodology but found the above has a reasonable chance of success.

Martyn
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seal killer
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Re: Centering a Round Work Piece in a Four Jaw Chuck

Post by seal killer »

Richard--

I understand, now. That was a great explanation. Thanks!

--Bill
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Richard_W
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Re: Centering a Round Work Piece in a Four Jaw Chuck

Post by Richard_W »

SteveHGraham wrote:I get the impression that Richard is like Harold. Maybe a tier or two above the video guys,
Richard_W wrote:I don't consider myself to be above Harold. I have him on a higher plain.
Harold_V wrote:Thanks, Richard, but I don't agree. I see both of us on a common plane, but with different backgrounds. There's not a doubt in my mind that I would learn a great deal from you, just as I suspect you might learn a few things from me.
I like the way you worded that. My feelings exactly! Harold you have a knack for putting your thoughts to paper and its as though you were here sitting in the room.
Harold_V wrote:The field of machining is so large that it's not common to find a machinist that has experienced everything, and those who claim they have are most likely to not be highly skilled in any of them. It takes years of daily "practice" to become proficient on machines---that meaning you can be handed a print, pointed to a machine, and turned loose, being expected to produce any number of parts in a timely fashion, per print, without supervision.
Harold I couldn't have said it better. Some of my experience has been here's the print make it. They don't care what machine you use, just get it done. You may use 4 or 5 different machines to get it done and often the shop foreman has no idea what you are doing. I feel you have that back ground as well.
As for the video's that were posted... I don't think you really want to know what I think of the ones I looked at. I will give the guys who made them credit for trying to show the correct way, but they left out more than they showed you. This thread is proof of that.
Harold_V wrote:I agree.
Years ago I used to subscribe to Live Steam Magazine. What turned me off, more than anything, was the endless string of "how to" articles that were published by those with no real machine shop experience, providing guidelines for the project. I understand they are well meaning--but that doesn't change the fact that their instructions often were not good. Practice does not make perfect---but perfect practice does. If one seeks instruction, it should come from one with knowledge, so bad habits are not created (or poor practices incorporated in a process).

Harold
You know Harold I had the same experience with HSM and LS back in the early 1980's. I bought an Issue at Powells books a few years ago and it still turned me off.

Richard W.
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Harold_V
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Re: Centering a Round Work Piece in a Four Jaw Chuck

Post by Harold_V »

Harold_V wrote:Years ago I used to subscribe to Live Steam Magazine. What turned me off, more than anything, was the endless string of "how to" articles that were published by those with no real machine shop experience, providing guidelines for the project. I understand they are well meaning--but that doesn't change the fact that their instructions often were not good. Practice does not make perfect---but perfect practice does. If one seeks instruction, it should come from one with knowledge, so bad habits are not created (or poor practices incorporated in a process).
Richard_W wrote:You know Harold I had the same experience with HSM and LS back in the early 1980's. I bought an Issue at Powells books a few years ago and it still turned me off.

Richard W.
I realize that makes us sound pretty bad, but it's no different from a skilled craftsman or professional in any other craft, trade or profession. To listen to those with little or no experience dispensing advice is often so bad as to be offensive. They don't have it right, but they don't have the necessary background to form an understanding that that is the case.

Frankly, that's one of the reasons I have so much to say on this forum. Well meaning individuals try to help, and almost always do, but there's the odd occasion where something is suggested that you *just know* is not a good idea. I like to point out the pitfalls. Doesn't make a guy very popular, but I figure if I can save one person from one negative experience, it's worth the effort. The hard part is having them understand that you understand the problem, and are speaking from experience. That is often offensive to a guy that generally won't be told, in spite of having desperate need. I've seen that quality in people far more than I care to admit.

I subscribed to Modeltec, as well. Back in the early 90's, they published an article with instructions to weld a small boiler using 6013 rod. Anyone who has done welding on boilers understands that there are no approved procedures for that rod for a steam boiler. I wrote the editor, suggesting that publishing such an article could prove to be the cause of an innocent reader's death. No retraction, no warnings of any kind were forthcoming. I stopped subscribing.

I was not alone in my complaint to the editor. It turns out a second party had submitted pretty much the same complaint. We did not know one another, and, in fact, lived in different states. We are now fast friends, and readers, here, know him as Russ Hanscom. Something good came from that experience.

Harold
Wise people talk because they have something to say. Fools talk because they have to say something.
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SteveHGraham
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Re: Centering a Round Work Piece in a Four Jaw Chuck

Post by SteveHGraham »

Doesn't make a guy very popular
I grant you absolution. We can't handle the truth, but give it to us anyway. It's like free money. If no one else thanks you, I certainly will.
Every hard-fried egg began life sunny-side up.
stevec
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Re: Centering a Round Work Piece in a Four Jaw Chuck

Post by stevec »

SteveHGraham wrote:
Doesn't make a guy very popular
I grant you absolution. We can't handle the truth, but give it to us anyway. It's like free money. If no one else thanks you, I certainly will.
Hey! what do mean
Doesn't make a guy very popular
Who are you quoting? how do you even do that?
Do you expect us to re-read all the preceding drivel (oops! sorry guys!) just to find out who said that?
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SteveHGraham
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Re: Centering a Round Work Piece in a Four Jaw Chuck

Post by SteveHGraham »

Well, I read all the drivel. I figured everybody did.
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stevec
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Re: Centering a Round Work Piece in a Four Jaw Chuck

Post by stevec »

You obviously don't "re-read" it or you would have been able to say who you were quoting.
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SteveHGraham
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Re: Centering a Round Work Piece in a Four Jaw Chuck

Post by SteveHGraham »

Man, I know it's nice to have a couple of beers with lunch, but let's slow down and take another look. It's obvious I was addressing Harold. He's worried about offending us by dropping too much knowledge on us.
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stevec
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Re: Centering a Round Work Piece in a Four Jaw Chuck

Post by stevec »

Thank you.
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Harold_V
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Re: Centering a Round Work Piece in a Four Jaw Chuck

Post by Harold_V »

SteveHGraham wrote:
Doesn't make a guy very popular
I grant you absolution. We can't handle the truth, but give it to us anyway. It's like free money. If no one else thanks you, I certainly will.
I'm more concerned with how I look when I make statements like I did. As if I'm, somehow, better than others. I don't mean it that way, but it's all too easy for others to get that impression.
Truth is, when you work in a trade, as I did, and you have concern for the work you turn out (as I did), you learn how to do things well--or you don't survive (I did). You get to the point where you simply won't do things certain ways, which are often commonly accepted as being normal. For instance, you will NEVER see me center punch a hole location, not unless I'm drilling a hole with a hand drill. I can't think of a better way to get a hole where it's not wanted than that method.

I think the point I'm trying to make is that any person, that has a given trade or skill, has the potential to perform at an elevated level as compared to those who don't share the same experiences. Doesn't make them better or worse than others, but different.

I gladly share my expertise with others, and expect nothing in return. However, there's not shortage of folks who take offense---often induced by ego. After all, they have a machine or two in their garage, and they, too, can make chips. They often fail to recognize (and respect) the fact that the caring, seasoned person may have performed that very duty countless numbers of times, and can do it without fear of error, and with superior precision.

Having a couple machines in one's garage isn't quite the same thing, is it?

Cooks have sharp knives in their kitchen, too, but that hardly qualifies them to do surgery.

I don't mean to come off as being better than others, but you can take this to the bank. A guy that puts his ego in neutral, and has limited experience in machining, can learn a great deal from me---just as he can learn a great deal from others that have worked in the trade. Some folks simply can't put themselves there.

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