Turning between centers
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    Default Turning between centers

    I have a part that has to be turned between centers to maintain accurecy when taken out and in the machine in the procces.
    The plan is to allign the axel between the centers but i steel haven't figured out how to actually drive the part?

    Any ideas?

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    You need a lathe dog. They can be bought or made.

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    face driver

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    I do all of my own driving, but if it’s an emergency you could call an ambulance.

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    maxresdefault.jpg

    That guy.

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    As stated...Lathe Dog or Face Driver are the most common methods. Sometimes if you're doing a light skim cut, just add a little more tailstock pressure, and then you don't need a driver.

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    Quote Originally Posted by plastikdreams View Post
    You need a lathe dog. They can be bought or made.
    Quote Originally Posted by KristianSilva View Post
    face driver
    Quote Originally Posted by Coadster32 View Post
    As stated...Lathe Dog or Face Driver are the most common methods. Sometimes if you're doing a light skim cut, just add a little more tailstock pressure, and then you don't need a driver.
    Yep. Small diameter and fairly light cuts, tailstock pressure works. Just dont get too aggressive with the pressure, too much on a small dia part can bend it.

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    Face driver if possible. Lathe dogs work well, but if runout is super-critical, the unequal mass of a lathe dog can cause strange things, and this gets worse the higher the rpm.


    If we're talking engine lathe speeds, then you're probably OK with a lathe dog, but if the runout & circularity is that critical, then stay as close to a face-driver setup [read: radially symmetrical, & dynamically balanced] as possible.

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    Pretty vague. A wee bit more detail would aid your cause.

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    Quote Originally Posted by Jashley73 View Post
    Face driver if possible. Lathe dogs work well, but if runout is super-critical, the unequal mass of a lathe dog can cause strange things, and this gets worse the higher the rpm.
    That applies only to the ancient ones, and they happen to be better balanced, dynamically than first appears. Lathes were slower, back in their day. It just wasn't a problem, nor need it be, now.

    In any case, it isn't at all hard to shop fab a VERY well balanced one.

    Two near-as-dammit identical bars, each with a Vee cutout arranged for equal length of bypass, opposite direction. Equal mass fasteners for clamping. That implementation must be easily 200 years old in use. A small "set" of forged loop and bent-tail were just handier.

    You want a Rzeppa joint for TS set-over tapers? Have at it.

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    Quote Originally Posted by thermite View Post
    That applies only to the ancient ones, and they happen to be better balanced, dynamically than first appears. Lathes were slower, back in their day. It just wasn't a problem, nor need it be, now.

    In any case, it isn't at all hard to shop fab a VERY well balanced one.

    Two near-as-dammit identical bars, each with a Vee cutout arranged for equal length of bypass, opposite direction. Equal mass fasteners for clamping. That implementation must be easily 200 years old in use. A small "set" of forged loop and bent-tail were just handier.

    You want a Rzeppa joint for TS set-over tapers? Have at it.
    You can balance a lathe dog I guess, but they still prevent turning the entire OD in one setup.

    Face driver is better in every way. Especially the hydraulic ones that don't care about the precision of the face...

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    Quote Originally Posted by gregormarwick View Post
    You can balance a lathe dog I guess, but they still prevent turning the entire OD in one setup.

    Face driver is better in every way. Especially the hydraulic ones that don't care about the precision of the face...
    Must be a stock item? Show us a link. Locomotive axles to carburretor metering rods, please.

    Otherwise, I'll stick with women for hydraulic "face driving", thanks!

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    Quote Originally Posted by thermite View Post
    Must be a stock item? Show us a link. Locomotive axles to carburretor metering rods, please.

    Otherwise, I'll stick with women for hydraulic "face driving", thanks!


    So, the basic principle is the driving dogs are actually hydraulic pistons which all share a common reservoir, and therefore conform to the profile of the face with equal pressure. I think Sandvik Kosta were the first to make such, but they are commonly available from a number of manufacturers now. They can be had in surprisingly small diameters.


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    Quote Originally Posted by gregormarwick View Post


    So, the basic principle is the driving dogs are actually hydraulic pistons which all share a common reservoir, and therefore conform to the profile of the face with equal pressure. I think Sandvik Kosta were the first to make such, but they are commonly available from a number of manufacturers now. They can be had in surprisingly small diameters.

    Thanks for that, Gregor.

    I'm sure it will benefit "someone". I just don't happen to be he, this incarnation. At least not until I get another two Delta-Wye transformers bought and can get back to serious workholder hoarding again..


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    Quote Originally Posted by gregormarwick View Post


    So, the basic principle is the driving dogs are actually hydraulic pistons which all share a common reservoir, and therefore conform to the profile of the face with equal pressure. I think Sandvik Kosta were the first to make such, but they are commonly available from a number of manufacturers now. They can be had in surprisingly small diameters.


    Very interesting. Have never seen that type before. Thanks

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    Quote Originally Posted by gregormarwick View Post


    So, the basic principle is the driving dogs are actually hydraulic pistons which all share a common reservoir, and therefore conform to the profile of the face with equal pressure. I think Sandvik Kosta were the first to make such, but they are commonly available from a number of manufacturers now. They can be had in surprisingly small diameters.

    Well if that don't beat all!

    That is exactly what I envissioned from your previous description, but I really ??? the small chambers that it would have to be... ???

    The Hydramax vise jaws have much more biggerer piston sizes, but apparently this works, and if so - would be a God-send for castings and such!


    ---------------------

    Think Snow Eh!
    Ox

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    I have seen these, those piston ends are very sharp (think knife blade, crossed with a one way screw head)

    I have seen the results, they leave a nice 6 way pattern
    on the end of the shaft.

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    I wonder if the "blades" or Drive pins (per the model) are a consumable item. I would automatically think and assume; YES, but how easy/cheap/accessible are they to replace?

    R

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    Quote Originally Posted by litlerob1 View Post
    I wonder if the "blades" or Drive pins (per the model) are a consumable item. I would automatically think and assume; YES, but how easy/cheap/accessible are they to replace?

    R
    Yes, I have seen them replaced IIRC the operator was able to replace them.

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    Now do any here actually think that the OP , who is asking about what is likely his first attempt at between center turning, is going to spring for a hydraulic compensated face driver?

    Get real!

    Just getting both a drive plate and a center in the lathe at the same time is going to be an issue.
    Turning at "dog speed" is never going to cause a problem, that is why they invented carbon steel tool bits.

    Jeesh!


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