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Old 11-07-2017, 11:41 PM   #41
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I am so glad you have invested in one of these 4 jaw self centering chucks, especially the soft jaws as well. In fact one set of jaws (if mine are anything to go by) will last you a few good years.

All my self centering 4 jaws (I think 4 or 5 at this time) run to a finer tolerance than my 3 jaws, I don't know why, maybe the extra jaw has something to do with it.

Do learn how to use your soft jaws correctly, they are you stepping stones to greater accuracy with your lathe than almost anything else.

A good strong boring bar, a nice set of smallish files with a small piece of emery and you are in business, and don't forget, you can have numerous recesses across the face of the jaws, starting off small, and going larger the further out you go. Modify smaller ones to take the piece parts you want to hold without having to go to a larger size. Doing it that way, your jaws should last for years, and when they do become a bit scruffy, as long as you haven't gone too deep with the holding recesses, the whole face can be skimmed up to give you a new set of jaws.

BTW, I have found that 3/8" (10mm) to 1/2" (12.5mm) deep is plenty good enough for most precision holding because you have a larger surface contact area inside the jaw nose. Most of the work I do is less than 10mm deep., sometimes only 3 or 4mm, and that would be on say a flywheel of 125mm diameter. Just remember, no real heavy cutting, just precision machining.

Don't think like others do, there was a post by someone on here a few years back stating that soft jaws are there to stop the jaws from damaging the piece part's surface, BUL***T, they are there to give you superior accuracy

Nice one


If you don't try it, you will never know if you can do it!!
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Old 11-08-2017, 08:56 AM   #42
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John, glad you approved my decision. I got your point in an earlier post. I even got one of these Keats angle plates. Looks like something handy to have lying around.
I am indeed hunting for accuracy, so I will explore that soft jaws thing. I will attend the University of YouTube on the subject the next days and see if I can find something. If I don’t get it I hope I can ask you back.


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Old 11-10-2017, 03:02 PM   #43
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As a means of preloading chuck jaws for grinding a toolmaker friend suggested this method. Drill a small hole (3/32) in the tip of each jaw. Insert a dowel into each hole. Chuck a thin walled tube or a snap ring using the pins. Tighten down slightly. That will give enough preload for grinding the jaw.

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