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10" 4 jaw chuck almost 4" center hole looks good to me

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  • lalatheman
    replied
    BC, even That further develops the concept for me,and am grateful. I see in the present line of thinking, the rear extension would have continuous rows of closely spaced tapped holes for each jaw position, running from just behind the chuck body to the faceplate the whole thing is bolted to. Then on the end of the "extension" a mounting ring would be welded, of appropriate diameter to be drilled for mounting it , when the "real" chuck materializes.
    If the outside surface of the extension is turned true, some kind of depth gages could be inserted through unused tapped holes to determine rear of workpiece radial allignment.

    Thanks Dave
    Last edited by lalatheman; 07-23-2018, 08:38 PM.

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  • BCRider
    replied
    Have you done a search for "sanou chuck review" at all? The independent sources indicate that first off the insides are full of crap and it needs a full strip down, cleaning and deburring before use. And one video review showed a smaller four jaw independent chuck with a massive amount of bad jaw alignment. It's a massively long and slow paced video for what it is but it does have good information.

    So be prepared for needing to at least do some jaw edge grinding to true up the hold.

    The "reviews" from a couple of reseller sources for these chucks such as aliexpress did not indicate the same issues as the independent sources. But no surprise there, eh?

    Doing just a basic "sanou chuck" search right on YouTube brought up a bunch of other reviews as well. Flipping rapidly through a few makes it seem like there's good and bad with these chucks. So it's a bit of a gamble.

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  • BCRider
    replied
    David, if you're going to go to the trouble of making the rear extension and fitting it with the four way screws for secondary support why not just make a longer pipe and fit it with front and back screws so you have a 2 station by 4 screw chuck that is self made? It'll solve the issue of how you would fit this 4 jaw to such an extension. And potentially you'd have a "pot chuck" that has the size capacity of the pipe you use rather than being limited to "just" the 3.9 something inches of this four jaw.

    To avoid the long screws sticking out and causing a nasty snagging hazard you could add on stiffener rings near the screw holes as deflectors and have two or three sets of different length screws to minimize the bolt stickout on the outside.

    The only downside with a pot chuck of this sort is that it really can't be used with anything other than both sets of bolts being on the part in question. The bolts would not have the same support as proper jaws. But if you NEED both to support the longer work it would not be a hard thing to build or use.

    It would justify using this large hole chuck on a simple backplate by itself for shorter but still lengthy pieces that require that large a center hole.

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  • lalatheman
    replied
    All the discussion brings up relevant and important points.

    I am leaning toward trying the big hole chuck....as an additional.... four jaw for that lathe ,which is a 16" leblond dual drive , the center hole is 1.6".......Right now I have 3 four jaw chucks that fit that machine........a heavy duty 10" ....an 8 inch.... and a 4" and one 8 jaw I made , , a front and back set of 4 radial bolts , in tapped holes in a very heavy wall tube, allowing dead on center line workpiece adjustment with lathe centerline........and a There is a 6" 4 jaw SELF CENTERING PLUS independent adj on each jaw here too, the yard sale sticker price $8 still on it, havent mounted it to a backing plate yet.

    The current discussion kind of stimulated my mind, and since the immediate reason for buying it is to gain the use of the large center pocket,behind the jaws I think I will space it out about 4 inches off the mounting plate, probably using some 8" pipe i have ,allowing it too hold aprox 9" of stock to the left of the jaw face.
    Need it very often ? no.....need it somtime ? for sure

    And for the times the jaws are not "streight" enough or whatever its called , it will be easy to drill and tap 4 holes in the pipe for a "spyder" or whatever its called , effectively turning it into an 8 jaw chuck

    Dave Lawrence
    Hummmm
    Last edited by lalatheman; 07-23-2018, 10:29 AM.

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  • 754
    replied
    What I do use a lot..
    I have a 6 inch 4 jaw threaded to fit south bend spindle I think.
    I made a straight adaptor about 5 inches long , plus the chuck threads and register and I mounted the 4 jaw on that.
    I have a 16 in lathe with 10 inch 3 jaw.
    My 14 inch 4 jaw weighs about 90 lbs and I have a Camlock spindle.
    So many, many times for small 4 jaw works I clamp the 6inch 4 jaw with the arbor I made into the 3 jaw. great for pieces 4 inches square or less.. saves the cleaning and mounting of the heavy 4 jaw.

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  • 754
    replied
    For a lot of work it does not matter much. (The lathe has been not wired up the last year and a half)
    I think at times I used a 1 1/2 or 2 thou shim under a certain jaw.nand it would bringbitbunder 2 thou.
    The point I am making is it has always been a very good chuck 95 percent of the time, and never was an issue for 90 percent of the work.

    But what I keep reading often on here, is that folks have 3 jaws, that cant easily clamp work at 3 thou TIR or under, and then rely on a 4 jaw for that kind if work.. that us not the case for my lathe..
    And I used it every week for 28 years and the chuck was always very good.
    And it came with the lathe, not like I had to buck up out of my wallet to try to get something better, to improve the situation.
    Not sure if that clears up what I meant.

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  • Mcgyver
    replied
    Originally posted by danlb View Post
    Just to throw my two cents in... A chuck that is .005 out usually just holds the work off center. That can be worked around. Shims can center it. Grinding can help with the bellmouth condition. Soft jaws correct a host of flaw

    If jaws are worn or otherwise damaged/worn, then that's a different story but it can still be worked around.


    Dan
    yeah you could do that stuff, but reality is when you need two surface concentric, really concentric like to .0002" as sometimes happens like the spindle housing I just did, you do things in one setting or you use the four jaw for the second ops. That's why 4 jaw accuracy matters more to me than 3 jaw.
    Last edited by Mcgyver; 07-22-2018, 06:43 PM.

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  • danlb
    replied
    Originally posted by Mcgyver View Post
    If you think its BS, and your chucks are to 2-5 thou out, you never do work that requires better than that?
    Just to throw my two cents in... A chuck that is .005 out usually just holds the work off center. That can be worked around. Shims can center it. Grinding can help with the bellmouth condition. Soft jaws correct a host of flaw

    If jaws are worn or otherwise damaged/worn, then that's a different story but it can still be worked around.


    Dan

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  • J Tiers
    replied
    Originally posted by wierdscience View Post
    Edit: Yes,of course you want to complete the part in one chucking whever possible,3/4/6 jaw or not,that's just common sense.

    Repeatbility-Not necessiarily,on a quality 3-jaw the final step in manufacturing is to chuck a lash ring and then do the final grind on the jaw faces.When that is done,the pinion used to clamp the lash ring is marked.That pinion is known as the master pinion.It is the only one of the three that will produce repeatable runout because of the way a scroll chuck is designed.On a Bison 3-jaw the master pinion is marked usually with a -0- stamped in the chuck body right next to the master pinion.
    On Bison chucks anyway,the jaws and slots are numbered 1-3 and so long as you always keep the jaws in their mating slots and use the master pinion the chuck will repeat.Some people insist on using all three pinions to tighten a chuck,that's fine,whatever storied talisman floats your boat,just so long as the last pinion tightened is the master.
    This holds true throughout the whole use/truing of the jaw faces and or soft jaws.Always use the master pinion when taking out the lash before machining/grinding.
    I do not think any of my chucks have more than one pinion, so no issues finding it..... Using that makes everything better, but it still is not super accurate unless you have set the adjust tru, or are using bored soft jaws. And the scroll can screw things up if it shifts around at all, so scroll center bearing wear is an issue. Have shimmed a couple chucks to fix it, with good results.

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  • Mcgyver
    replied
    Originally posted by 754 View Post
    My Victor 10 inch 3 jaw at 25 years old was pretty good, usually clamp round at 2 to 5 thou runout.
    If there is 5 and you turn and reclamp it usually gets better.
    I did regrind the inside of the jaws at one point, but it's always been a good chuck.
    The 5 inch Pratt on my S Bend is pretty good too.

    Regarding the 3jaw not accurate BS,
    .
    If you think its BS, and your chucks are to 2-5 thou out, you never do work that requires better than that?

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  • Arcane
    replied
    Originally posted by danlb View Post
    Sigh....
    One of you is talking about the EBAY listing (standard scroll) and one is discussing the AJAX TOOL listing, which is a combination of scroll and independent jaws.

    Just hoping to clear it up without hard feelings.

    Dan

    Opps! You're quite right! My apologies to smithdoor.

    Boy, I'm sure glad I didn't say anything even more embarrassing!

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  • danlb
    replied
    Originally posted by Arcane View Post
    The description is quite clear.
    Sigh....
    One of you is talking about the EBAY listing (standard scroll) and one is discussing the AJAX TOOL listing, which is a combination of scroll and independent jaws.

    Just hoping to clear it up without hard feelings.

    Dan

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  • Arcane
    replied
    Originally posted by smithdoor View Post
    The photo said self centering and the looks like too

    Try shars.com they good prices and purchase a 8" a few years ago works great

    Dave

    Sent from my SAMSUNG-SM-J320A using Tapatalk
    The description is quite clear.

    Combine the advantages of a scroll chuck with those of an independent chuck • Each jaw may be adjusted individually with an independent operating screw • After the desired eccentric setting has been made, all jaws can then be opened and closed simultaneously with the use of a scroll and pinion

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  • smithdoor
    replied
    Originally posted by wierdscience View Post
    Read it again,the ebay listing says -Independent-
    The photo said self centering and the looks like too

    Try shars.com they good prices and purchase a 8" a few years ago works great

    Dave

    Sent from my SAMSUNG-SM-J320A using Tapatalk

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  • wierdscience
    replied
    Originally posted by Mcgyver View Post
    . My comments come from my shop paradigm, where the jaws are solid.
    You should indulge yourself in two-piece jaw bliss.Heck I think even 4-jaw chucks should have two piece jaws

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