Any 7x lathe with 5" 4 jaw chuck owners?


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Thread: Any 7x lathe with 5" 4 jaw chuck owners?

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    Default Any 7x lathe with 5" 4 jaw chuck owners?

    I need to turn some 4" stock and currently don't have the means to drill a proper center hole(rebuilding G0704) to enable chucking the 4" stock to turn between centers in my 3" vise. So I decided it's time to upgrade. I want to max out capacity since I have upgraded my cross slide to extend out another 0.75-1" which I may increase later if I can remove a little more material from the carriage and or cross screw nut. I know the 4 jaw chucks have more capacity than the 3 jaw and mini-lathe.com lists that the 4" 4 jaw outside jaws have a max capacity of 5". I have also found some running a 5" 3 jaw chuck and the best information I can find is that the 5" 3 jaw with inside jaws has about 1/4" clearance with the bed which concerns me if you were to use the outside jaws on a 5" 3 jaw much less 5" 4 jaw.

    Pretty confusing to try and type this with all of the 3,4 and 5" chuck size, 3 and 4 jaw plus inside and outside jaws but hopefully clear enough. I'm basically wondering would a 5" 4 jaw limit clearance vs a 4" 4 jaw assuming both were extended out fully utilizing outside jaws?


    I am also including some pictures of my cross slide extension mod. It was done without buying a thing(rare for any upgrade/mod) using a piece of scrap 6061 and some bolts I had laying around from my 3D Printer build a few years ago. I have just enough lead screw to reach the center of a part for facing, boring and drilling plus almost an inch of extra travel which this lathe sorely needs. I know there is an upgrade that includes a new lead screw and carriage top but it's $75 and offers very little.

    Also, don't cringe at my ways I know they look terrible. Probably worse since I started working them and stopped half way through. Still a work in progress.

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    Default Re: Any 7x lathe with 5" 4 jaw chuck owners?

    Looks like the 5" 4 jaw chucks will do every bit of 5". I also 3D printed a 6" faceplate that seems to clear the bed just fine so hopefully the jaws stick out no more than an inch or so. I went ahead and picked up a 5" 4 jaw(independent) for $63 shipped and will make my own backplate from 6061. Littlemachineshop wants $120 + $22 for regular shipping for the 5" 4 jaw chuck and backplate. Sorry but $80 is a bit steep for a backplate when the entire lathe that go for $450 shipped new on ebay.

    For the backplate I will probably print a template for drilling the holes to mount to the stock 3" plate then turn OD, face, bore ID and recess on the lathe itself. Then drill once more for the OD holes/chuck bolts with a template. Hopefully I can get the holes strait enough by hand...

    Attached Thumbnails Attached Thumbnails Any 7x lathe with 5" 4 jaw chuck owners?-5in-4jaw-jpg  


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    Default Re: Any 7x lathe with 5" 4 jaw chuck owners?

    I wouldn't make the chuck adapter / backplate of aluminum, especially if you are using a larger chuck on the machine. Couple of reasons: 1. aluminum is not as stiff as steel and the lathe needs as much rigidity as it can get, so you would need to increase the thickness of the backing plate to compensate, pushing the work further from the supporting bearings and still reducing overall rigidity.
    2. If the aluminum does flex, even a little it will crack eventually, and a spinning over sized chuck is the best way I can think of to get through the thousands of cycles needed to make that happen when you least expect it. This is one of the reasons the highly stressed bits on engines, lathes etc are steel.
    Mike



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    Lightbulb Re: Any 7x lathe with 5" 4 jaw chuck owners?

    Got the chuck in two days from Chino CA to South Florida. Definitely not bad for 10 bucks in shipping. Chuck looks really good considering the price but smells of diesel and is leaking what I guess is HHIP's version of Cosmoline.


    Quote Originally Posted by ninefinger View Post
    I wouldn't make the chuck adapter / backplate of aluminum, especially if you are using a larger chuck on the machine. Couple of reasons: 1. aluminum is not as stiff as steel and the lathe needs as much rigidity as it can get, so you would need to increase the thickness of the backing plate to compensate, pushing the work further from the supporting bearings and still reducing overall rigidity.
    2. If the aluminum does flex, even a little it will crack eventually, and a spinning over sized chuck is the best way I can think of to get through the thousands of cycles needed to make that happen when you least expect it. This is one of the reasons the highly stressed bits on engines, lathes etc are steel.
    Mike
    While I can see where you are coming from and agree to a certain extent about the flex in aluminum I am not too concerned as it will be 1" thick and rarely see more than 500 RPMs. Unlike a lathe in a shop this one will never be used thousands of times, more like 20 over a few years since I really hate using a lathe this small. Hopefully I can get a 9 or 10" in the near future and convert this to CNC.

    Now to make you really cringe. I drew up and 3D printed a 6" faceplate out of PLA(plastic) with 40% infill. I then bolted the faceplate to old backplate, turned the OD down and faced it off. Then proceeded to bolt & true the 5" chuck to within about a thousandths of an inch. Next I used a 10ft piece of string to run it up to 2,900 RPM. Smooth as glass and man does this 5" coast FOREVER. I then decided to mis-align the jaws to produce some vibration and ran it back up to around 2,000 at which point the entire lathe started dancing. Pretty scary over 1,000 RPM but it works just fine.

    If a piece of half hollow plastic works with vibration I would trust my life to that 1" piece of 6061

    Attached Thumbnails Attached Thumbnails Any 7x lathe with 5" 4 jaw chuck owners?-20171102_004829-jpg   Any 7x lathe with 5" 4 jaw chuck owners?-20171102_005014-jpg  


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    Default Re: Any 7x lathe with 5" 4 jaw chuck owners?

    I did the same thing (minus the 3d printed part..)
    I used flat 6061 stock for my faceplate adapter and never even finished truing the outside of it. Turning at 6" diameter, interrupted on these little things goes SLOOW..
    I barely ever touch my lathe though, I did some questionable modifications that made it quite a bit worse than even originally (Crammed a bigger motor in that required cutting out a bit of the frame...)



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Any 7x lathe with 5" 4 jaw chuck owners?

Any 7x lathe with 5" 4 jaw chuck owners?