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  1. #1
    Join Date
    Mar 2020
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    Default Mini lathe motor upgrade

    Hello. I am new on this forum and I have mini lathe at home for my own personal needs. Yesterday the 450w DC motor on my lathe died after pushing it a little bit too hard and today I have sent the motor to get it repaired but I am planning to upgrade the motor in the future to a more powerful one. I have found on Ali Express the same type of motors but in 600w,750w and 1100w versions so I was wondering if I can connect any of them to my SCR340 control board without upgrading it. Any help would be greatly appreciated

  2. #2
    Join Date
    Jan 2007
    Location
    Katoomba NSW
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    164

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    It may be able to handle up to 750W but not the 1100W. From what I can find online, after a very quick search, the SCR340 is rated at 1000W input. You would need pretty good heat dissipation (big heatsinks) but 750W would be the upper limit I think. You would also need to check the rated voltage of the new motor to make sure it is within the range supplied by the controller. I think they are 0-180V but not 100% certain of that. It may be on the controller name plate.
    Built: a Bench,a Desk,an Archery Display,

    Those were the droids I was looking for.

  3. #3
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    Mar 2020
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    Croatia
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    I did google it too but couldn't find any decent info about control board or if more powerful motors use the same board but if they can handle 750w motor that would be a massive upgrade. Even if they can run 600w motor would be a decent upgrade over stock one. Heat sink is not a problem because i can make one easy and maybe even put a small fan to cool the control board

  4. #4
    Join Date
    Sep 2012
    Location
    North Yorkshire UK
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    3,359

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    Hi Hepohep,

    The limiting factor with motor speed controllers is the current handling capacity of the Triac/Thyristors and rectifiers feeding the motor. If you can get to read the part number of those devices then you could look up the data sheets on them and determine the power that they can handle.

    Most are quite well capable of handling a bigger motor, many are not !

    The usual issue with these motors is the brush holders and poor electrical contacts. I've repaired the motor on my mill four or five times now. What happens is the spade connectors inside connecting the wiring to the brush holders overheats and makes the conductivity worse, which creates more heat until the brush holder fails. The original brushes are also poor, the pigtails in them rapidly becoming open circuit where they fit into the brush, again causing overheating and brush spring failure. This is because when the pigtail fails the spring has to carry the current that the pigtail is designed to !

    HTH.
    Best Regards:
    Baron J.

  5. #5
    Join Date
    May 2011
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    Murray Bridge S Aust.
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    67
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    4,439

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    Hi and WELCOME to a TOP FORUM.
    I'd be a bit wary about fitting a more powerful motor, some lathes are fitted with plastic gears, I've replaced the gears several times in the one I had!!! I was GLAD to give it back when my brother asked for it.
    Kryn
    To grow old is mandatory, growing up is optional.

  6. #6
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    Mar 2020
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    Croatia
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    Quote Originally Posted by BaronJ View Post

    The usual issue with these motors is the brush holders and poor electrical contacts. I've repaired the motor on my mill four or five times now. What happens is the spade connectors inside connecting the wiring to the brush holders overheats and makes the conductivity worse, which creates more heat until the brush holder fails. The original brushes are also poor, the pigtails in them rapidly becoming open circuit where they fit into the brush, again causing overheating and brush spring failure. This is because when the pigtail fails the spring has to carry the current that the pigtail is designed to !

    HTH.
    What kind of motor do you have in your mill? You can put some better spade connectors and better quality brushes in your motor if thet helps. Maybe you could upgrade your motor to a brushless one with matching controller. I thought about that too for my mini lathe but the easiest thing to do would be just bolt on more powerful motor if the control board can handle it

  7. #7
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    Mar 2020
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    Croatia
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    Quote Originally Posted by KBs PensNmore View Post
    Hi and WELCOME to a TOP FORUM.
    I'd be a bit wary about fitting a more powerful motor, some lathes are fitted with plastic gears, I've replaced the gears several times in the one I had!!! I was GLAD to give it back when my brother asked for it.
    Kryn
    Thank you very much.
    My mini lathe has metal gears and it is supposed to be decent quality one. Until now I was very happy with mine and I didn't have any problems or complaints except weak motor. This is chinese made lathe and it is sold under many different brand names and some of them use 600w or even 750w motors but I don't know if they all use the same controller. If they do I could just swap the motor for a more powerful one

  8. #8
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  9. #9
    Join Date
    Sep 2012
    Location
    North Yorkshire UK
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    Hi Hepohep,

    Quote Originally Posted by Hepohep View Post
    What kind of motor do you have in your mill? You can put some better spade connectors and better quality brushes in your motor if that helps. Maybe you could upgrade your motor to a brushless one with matching controller. I thought about that too for my mini lathe but the easiest thing to do would be just bolt on more powerful motor if the control board can handle it
    Basically the same as yours. The mill motor is a 750W DC motor. Upgrading to a brushless would be great if the dealers weren’t stiffing you on price, and of course if it fits.

    I now make my own brushes and springs. So I can basically replace them as needed. I do check them every 100 hours or so. Usually it is the springs that fail due to heating, particularly if I'm pushing it a bit.

    There is a conversion kicking about for an induction motor and a belt drive, however I had an issue with the plastic gears in the early days. Again the dealer wanted a small fortune for a pennyworth of plastic. I found that I could replace the gears with steel ones for slightly less money and a few hours of lathe work.

    Now the only real issue is that the poor quality of the motor causes periodic problems.
    Best Regards:
    Baron J.

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