"Truing" chuck jaws. Your opinions? - Page 3
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  1. #41
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    really? better to get a decent 3 jaw. if you only chuck up something 20 times a day and it takes you 2 min. longer, you save 240 hours p.a. thats more than a month.

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    I had a guy here a few years ago that decided to counterbore the semi-brand new hard jaws 3/16" deep because he was too lazy to use soft jaws.
    Then he proceeded to skin the hard jaws while holding onto a ring because there was .002" runout.
    I almost punched him in the mouth.

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    Quote Originally Posted by JST View Post
    As for the grit in the chuck..... Don't you ever clean out chucks?
    I never mentioned grit, in the chuck or elsewhere.

    - Leigh

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    Quote Originally Posted by dian View Post
    <snip>... if you only chuck up something 20 times a day and it takes you 2 min. longer, you save 240 hours p.a. thats more than a month.
    If p.a. means per annum, that math calculates to chucking work 360 days per year. (240 hours * 60 minutes/hour / 40 min/day = 360 days) I'll pass, thank you.

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    Default Given that much time (a month)

    Quote Originally Posted by jmcvo View Post
    If p.a. means per annum, that math calculates to chucking work 360 days per year. (240 hours * 60 minutes/hour / 40 min/day = 360 days) I'll pass, thank you.
    I bet even I could fit and machine up a set of soft top jaws.

    After that, It's perfect every time ...;-)

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    FYi i tend to be chucking upto and potentially over 200 parts a day way too much at the moment. (things have gone nutty here) If you can do that many dial in's of a 4 jaw, the works yours.

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    It is amazing how many people on this site do NOT/have NOT "run production"! 4 jaw chucks aren't conducive to production. The 4 jaw is the doorstop.

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    Quote Originally Posted by adama View Post
    FYi i tend to be chucking upto and potentially over 200 parts a day way too much at the moment. (things have gone nutty here) If you can do that many dial in's of a 4 jaw, the works yours.
    adama

    Without needing to get into "specifics"< what sort of concentricity requirement does the present volume chucking work require?

    If the expectation is high, Seems like a perfect opportunity for soft jaws fit to purpose. ;-)

    To jdj's point, a four jaw chuck makes a great two jaw chuck when fitted with machinable top jaws. Two jaw chucking IS conducive to production ;-)

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    Youtube videos are not the best source of knowledge.

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    Before spending a lot of time machining jaws to correct bellmouth it's worth testing the chuck for repeatable concentricity. The center of the scroll pilots closely on the inside of the chuck body. If that is worn and the scroll floats radially, the jaws will tighten off-center by anything up to the amount of float. Ordinarily it's the chuck casting itself that's worn and a new scroll and jaws won't fix it.

    On a CNC passing bar stock thru the chuck you pretty much have to bore the soft jaws all the way thru while they're under tension from an external fixture. Lots of ways to do that, but gripping on the angled surfaces will force the jaws sideways if the angles are not perfectly symmetrical about the centerline--which they seldom are. If you don't mind boring jaws every time you change stock diameter, even a chuck with wornout ways can be good enough for 1st op. But if you have to grip a finished diameter and turn concentric and parallel with it, better bite the bullet and get a new chuck. I've bought relatively inexpensive Strong and Samchully as replacements for Kitagawa and I can't tell any difference. Getting people in the habit of greasing the jaws every shift is probably more important than the brand of chuck.

    Course, on an engine lathe a chuck is lucky if it ever sees any lubrication other than splashing cutting oil. Tough to bring yourself to do after you've turned the spindle on and given yourself a nice vertical stripe once or twice. On a CNC you can at least shut the door...

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    Quote Originally Posted by tailstock View Post
    Bottom line, just get a good 4 jaw chuck , learn how to use it, (only takes a couple of min. longer to set up) and use the three jaw for a door stop. They work exceptionally well for that. I take it we are talking manual machines here, if you are talking cnc chucks just replace it. Mind you if the chuck is worn that much on a cnc, what is the rest of the machine up to.
    God gave us 3 jaws to smite those who insist on making everything harder than it needs to be.

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    Quote Originally Posted by adama View Post
    FYi i tend to be chucking upto and potentially over 200 parts a day way too much at the moment. (things have gone nutty here) If you can do that many dial in's of a 4 jaw, the works yours.
    If you want to get real nice without a collet, take a look at the Bison 6 jaw chucks. They are of the adjust true nature, and I put one on my Clausing.
    I chuck a chunk of TGP and 4" off the chuck, the test indicator barely wiggles. Damn near a collet.

    It wasn't cheap, but I have done nothing but kick butt with it.
    One point, 6 jaws = twice the friction. If you are making seriously heavy cuts, you may be best off with 3 jaws, but this 8" 6 jaw... chuck-n-go.
    I really love it.

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    Quote Originally Posted by APD View Post
    ...and then what would you do? Cant regrind the slots, jaw slides, or scroll. So what are you going to do, moglice or turcite the jaws?

    Whatever the source of the error, if you properly load the jaws and grind them using the lathe ways, they will be as accurate as you can get with the jaws you have.
    The idea is to make a used chuck grip better and more consistently. Your other option is a new chuck.
    Well actually, you can take up clearance in the jaw raceways by centerpunching along the outside edge. I've done it and it works.

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    My point exactly. I don't even know how you could "bellmouth" jaws. They are just sloppy jaws. I guess it's my form of "billet". Billet doesn't bother me, but it sure does bother some people.

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    My 200 bits curretly range from about 1/4"-5" dia, though normally its more in the 3/16"-2" range that gets the most. Run out wise, i like to be able to face and chamfer a bar and get a result that shows a nice even chamfer to the eye. I kinda peg that at about 5 thou run out tops. My 3 jaw after grinding the jaws a few years back reliably hits that. More precision is always nice, but it takes time and costs money and truth be told it makes no difference to my customers needs on most parts. A lot of my parts are just a simple turned shoulder and a thread for securing it, zero run out makes little - no diffrence to parts function. Im as a rule not turning sharfts with different diameters to mount bearings and such.

    Collets are something i have contemplated, but out side the mill its not something i already have. 5c collets to cover my needs would add up to a fair bit and haveing never used them im not entirely sold on just how well they grip, chucks are my bread and butter option. Noone seams to have ever made a er32 collet chuck for a lathe thats fast to operate like a chuck or i would give it a shot.

    I do have a new all steel adjust true with 2 part jaws. Also have the new face plate ready and waiting for it. Just currently it seams to be living on the mill table holding stuff upright to cnc hexs or slots on things. Its too the point if things continue to go like they have im going to buy a second one for the lathe so they can share soft jaws :-) The reason it never got to the lathe is that its limited to about 8mm minimum which is no good here, need to go down to 3mm idealy and reliably at that, hence i need to make up some pointy soft jaws for starters. When i looked the std soft jaws would not reach in that far even once i point them on the mill and have just not had time to make longer ones!

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    Quote Originally Posted by jdj View Post
    It is amazing how many people on this site do NOT/have NOT "run production"! 4 jaw chucks aren't conducive to production. The 4 jaw is the doorstop.
    Not a valid comparison. Manually-operated chucks of ANY jaw-count are not for high-volume production.

    Depending on size and SHAPE of the stock, the APPROPRIATE collet system, master chuck with collet 'pads', fixtured 2 or more jaw POWER operated chuck.. and generally not even being run on a manual or 'engine' lathe AT ALL.

    If not CNC, then an automatic, turret/capstan.

    Someone said 200 pieces a DAY? How about several times that to the HOUR?

    We do have tunnel vision some days, Brethren.

    Bill

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    Quote Originally Posted by Forestgnome View Post
    My point exactly. I don't even know how you could "bellmouth" jaws. They are just sloppy jaws. I guess it's my form of "billet". Billet doesn't bother me, but it sure does bother some people.
    How?

    Do a lot of short pieces that don't chuck up on the whole length. Jaws wear, and working a lot of short top-hat looking parts will do that.

    Have some dumb bunny spin the part. Have the dumb bunny mark up the end of the jaws by chucking a hardened screw "to modify the head"....

    Just the pressure of the tools will be most on the jaw tips, and the very slight movements that result will eventually wear the ends more.

    heck, I dunno other than that, but I know it happens, I've seen chucks with tight t-slots and worn jaws, with the wear mostly at the ends. I really don't care much *why* other than holding down the number of "dumb bunny" tricks.

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  25. #58
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    Default Hold on now...

    We won a couple world wars and to a good extent, the parts and pieces were made by hand on such venerable lathes as the Sheldon and they hadn't even dreamed of a power chuck back then.
    My great Aunt was a 105# and they would hold her by her ankles and walk her around the ship while she operated the cutting torch.
    Don't forget how the first bridge was built:
    Caveman saw pussy on other side of river. " Ug"
    Push'um tree over river... walk across... got pussy.
    I bet you would be completely lost on a manual... anything.
    I have an endless string of " Machinist's" applying here...
    "Go cut me a 1" 8 TPI "
    They say... " Where's the button? Where's the box?
    I tell them there are goddamn dials with numbers right before their eyes.. and get the hell out of my shop, Mr. Machinist...lol

    Quote Originally Posted by thermite View Post
    Not a valid comparison. Manually-operated chucks of ANY jaw-count are not for high-volume production.

    Depending on size and SHAPE of the stock, the APPROPRIATE collet system, master chuck with collet 'pads', fixtured 2 or more jaw POWER operated chuck.. and generally not even being run on a manual or 'engine' lathe AT ALL.

    If not CNC, then an automatic, turret/capstan.

    Someone said 200 pieces a DAY? How about several times that to the HOUR?

    We do have tunnel vision some days, Brethren.

    Bill

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    Quote Originally Posted by Forestgnome View Post
    My thought is that a chuck that shows this indication probably has wear on the jaw raceways, and that the jaws are lifting the same way many mill vices lift. I don't see anybody suggesting grinding the jaws of their mill vise to make them parallel under load. If I suspected bellmouthing of the jaws, I would take them out and put them on my granite plate to check if the face is perpendicular to the raceway. It just seems to me that grinding the jaws without really knowing where the problem lies is a bad approach. Kind of like grinding the ways of a lathe to correct for twist when the lathe hasn't been leveled. What's your opinion?
    Our work has chucks like this not only the 3 jaw but the 4 jaw for our Colchester are useless without Coke Can. An apprentice we had took the 4jaw chuck and ground each one at Tafe on the surface grinder didn't fix the problem

    I have been trying to get new chucks for a year and a half but working with boilermakers has its drawbacks

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    Quote Originally Posted by snowshooze View Post
    We won a couple world wars and to a good extent, the parts and pieces were made by hand on such venerable lathes as the Sheldon and they hadn't even dreamed of a power chuck back then.
    "Sheldon" huh. Won the war. By hand. Who'd have thunk it.

    Oh... filing date 1912, granted 1913. Before War One started:

    http://www.google.com/url?sa=t&rct=j...83829542,d.cWc

    You are even more wrong about all the rest.

    Of course.

    It was the cave WOMAN who 'push'um'.

    Doubt that as well? Just go and look up the word origin.

    Or take a 'detour' and find the French word for "push"...


    Meanwhile:
    I bet you would be completely lost on a manual... anything.
    You have noooo idea........


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