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  1. #11
    m_c's Avatar
    Lives in East Lothian, United Kingdom. Last Activity: 22 Hours Ago Has been a member for 9-10 years. Has a total post count of 2,126. Received thanks 233 times, giving thanks to others 5 times.
    You've got a major chatter problem.

    I would invest in a bigger boring bar, and cropwell's suggestion of a fixed steady would also help.
    Avoiding the rubbish customer service from AluminiumWarehouse since July '13.

  2. #12
    Quote Originally Posted by m_c View Post
    You've got a major chatter problem.

    I would invest in a bigger boring bar, and cropwell's suggestion of a fixed steady would also help.
    any suggestions for a boring bar. Not sure where i would get a fixed steady for my lathe.

  3. #13
    m_c's Avatar
    Lives in East Lothian, United Kingdom. Last Activity: 22 Hours Ago Has been a member for 9-10 years. Has a total post count of 2,126. Received thanks 233 times, giving thanks to others 5 times.
    Quote Originally Posted by dfox1787 View Post
    any suggestions for a boring bar. Not sure where i would get a fixed steady for my lathe.
    I would go for at least a 16mm bar, or even 25mm, provided it'll fit in your lathe.
    And I prefer ones that take CCxT inserts.
    I wouldn't be too bothered about brand, as there's not much to choose from with cheaper bars.

    It'll also likely be worth making sure all the slides on the lathe are adjusted properly as well, as with that kind of overhang, any play will be magnified.

    Depending on how much you use the lathe, it could be worth fitting a quick change tool post, as they'll also give a far more secure mount for any tools, than the bog standard tool holders. I've personally always used ones from Arc Euro Trade, so I know I can buy extra tool holders.


    Regardless of all that, you'll need to be aware that even with the best setup, you do risk ending up with a tapered bore. A more consistent method for accurate boring on lathes, is to mount the workpiece on the cross slide, then spin a boring bar between centres.
    Avoiding the rubbish customer service from AluminiumWarehouse since July '13.

  4. #14
    If you have a 4 jaw chuck use it! You have a lot of extension from the chuck this will do you no favours at all. A 4 jaw will give you a LOT more rigidity. It's hard for anyone to categorically say what is the problem without being in front of the machine once all the basics have been covered. It may well be you are just reaching the limit of rigidity of the machine with the work length you have. The machine will have a limit like all machines.

    I would do as has been suggested and use a hss boring bar you do not need to buy anything, they are easy to make. You can use a bit of mild steel with a drilled and reamed hole in the end set at 45 deg or 90 deg for a through hole and a grub screw, insert a bit of Hss and grind with a decent amount of top rake as you having problems, i would suggest about 20 deg to start. High rake will help in this situation as it reduces the shear load. This kind of home made bar works very well in difficult situation and works in a contrary fashion to the reasons explained about rigidity. I do not agree a solid carbide boring bar will help on a manual machine. As long as the bar is strong enough to do the job and resist the cutting force and being mild steel this means it has properties to absorb shock because mild steel En3b or even En1a these material are ductile, ductile materials absorb shock and dampen and all you guys know what that means to a machine tool. Harder materials tend to and will resonate more.

    This sounds crazy i know but logic dictates this when you think about it. There is not a comparison using these kind of carbide tools on small machines compared to what carbide is generally designed for which is pressure cutting. This works fantastically on the right machines but not all, and manual not being one of them generally speaking when problems are arising such as you are experiencing now. It's the wrong tool for the job on a baby machine..... as you are probably working out or will soon find out.

    You also need to learn how to grind tools if you own a small lathe and you don't know how. It's a vital skill you can not be without. Plenty of advice is available on that subject.... but its often overly complicated on the internet. A properly ground tool with no honing or stoning will give a very good finish if done correctly.

    Good luck.
    Last edited by spluppit; 14-05-2018 at 03:15 PM.

  5. #15
    As sluppit has recommended make you own boring bar, i would get some square section bar(square section will be clamped to topslide) turn a section slightly longer than the intended bore down to a diameter that will give you a reasonable clearance to clear cuttings then do as instructed regarding the HSS tip. remove the original toolpost and use packing ect to get your tool to centre height and and secure the bar on your topslide with a strongback. 4 jaw is essential, you will have to go softly softly to remove the chatter with light cuts,
    once you have removed them you might be in with half a chance, my lathe is slightly bigger than yours but with that amount of overhang the weakest link will be the topslide, if that doesn't work, you will need to remove the topslide and mount the boring bar direct onto the cross slide.
    Regards
    Mike

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