Help needed with Vevor MX-S716G gremlins

[steve.mcclelland1]

Hi all,
New member here and with limited machining knowledge. Here to pick your brains.
I've just purchased a Vevor MX-S716G mini lathe and upon setup have found some gremlins. So the lathe needs to have forward or reverse selected before the green power on button will work. Once direction is selected and green power button pressed the brushless 800w motor starts immediately, spinning the chuck at 100+ rpm. The variable speed dial will increase rpm but not bring it to a complete stop/zero rpm. I replaced potentiometer and still the same problem. I have checked the circuit board and there are no adjustable trimmers that can control the speed cut off point. Any ideas on what is causing this and how to fix or what to check next? Thanks in advance.

 

[markba633csi]

Steve: I believe you are looking at a designed-in problem/feature
I have not heard of a fix yet for this. Vevor is known for numerous issues.
Others have mentioned this same issue- unfortunately Vevor will not provide electrical diagrams

The NEC chip they use is a microprocessor- all the functions are programmed in firmware- no adjustments
If you can trace out the analog portion of the A/D input you might be able to change components for slower speed
However, the motor may overheat
Without more detailed info it would be risky- personally I would return the machine for a refund
Talk to your credit card company

 

[VicHobbyGuy]

Your Vevor MX-S716G has the motor around the spindle, inside the headstock? That really reduces any options for an improvised repair or re-powering with a new motor and controller. Anyway, those would only be options if you bought the lathe used, or had owned it for a year or two. My advice is the same as @markba633csi's - return the lathe for a refund if possible. BTW, I owned a much simpler Vevor 7x14. Luckily, the brushed motor and controller weren't a problem on that one. It (eventually) worked OK, but I needed the room for other tools, so it went on to a new home.

 

[GrifterGuru]

Much as I hate to say this, the problem you have is that it is a Vevor lathe with a very well known problem.

Start the returns process as there is currently NO KNOWN FIX for this VERY common issue.

Buy any other brand lathe but Vevor. They a VERY low on the totempole of QC and well known for issues. They are also VERY well known for not supplying parts/spares and good luck getting any "extras".

 

[mksj]

Why would you think that a variable speed pot would bring the spindle to 0 RPM, it clearly states "Continuously Variable: Features a spindle that can turn in both forward and reverse directions with 150-2500 RPM continuously variable speed range.". This is a common programmed feature in many variable speed controllers to prevent overheating of the motor at low speed, as well as decreased Hp/Torque beyond the motors operating speed window. Some VFD/controller manufactures go as far to either burn the instruction set into a programmable control chip or lock you out of changing the program parameters with a pass code. My mill only goes from 20-200Hz, when I program VFDs for lathes I usually set the lowest motor speed to 15-20Hz to prevent overheating of the motor. I will agree that the Vevor products are pretty poor, but then they also cost a lot less.

VEVOR Mini Metal Lathe Machine, 7'' x 16'', 800W Precision Benchtop Power Metal Lathe, 150-2500 RPM Continuously Variable Speed, with 3.9'' 3-jaw Metal Chuck Tool Box for Processing Precision Parts | VEVOR US

Discover VEVOR Mini Metal Lathe Machine, 7'' x 16'', 800W Precision Benchtop Power Metal Lathe, 150-2500 RPM Continuously Variable Speed, with 3.9'' 3-jaw Metal Chuck Tool Box for Processing Precision Parts, Protection Devices and Aluminum Alloy Handwheel at lowest price, 2days delivery, 30days...

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[VicHobbyGuy]

@steve.mcclelland1 - You said "So the lathe needs to have forward or reverse selected before the green power on button will work." This seems strange to me. I can't see the 'direction switch' in the Vevor images - Is this the same switch that's common on 7x lathes, with Rev-0-Fwd ? And, if the switch is in the 0 position, and the green power button (under the emergency red button flap) is pushed, the lathe electronics will not power up?
EDIT: I just double checked my lathe with its brushless motor. It's impossible to set it in motion with the power switch. If the speed knob is above the minimum position (zero RPM) on power up, the motor will not run. The speed dial has to be turned down to zero, and then 'up' again. If the direction switch is in Rev or Fwd, the motor will then run. After that, the motor can be started and stopped using just the Fwd-0-Rev switch, but I only do this at low rpms when threading. I got into the habit of always turning the speed knob to zero when using the brushed motor and controller.

 

[RaisedByWolves]

Your Vevor MX-S716G has the motor around the spindle, inside the headstock? That really reduces any options for an improvised repair or re-powering with a new motor and controller. Anyway, those would only be options if you bought the lathe used, or had owned it for a year or two. My advice is the same as @markba633csi's - return the lathe for a refund if possible. BTW, I owned a much simpler Vevor 7x14. Luckily, the brushed motor and controller weren't a problem on that one. It (eventually) worked OK, but I needed the room for other tools, so it went on to a new home.

Much as I hate to say this, the problem you have is that it is a Vevor lathe with a very well known problem.

Start the returns process as there is currently NO KNOWN FIX for this VERY common issue.

Buy any other brand lathe but Vevor. They a VERY low on the totempole of QC and well known for issues. They are also VERY well known for not supplying parts/spares and good luck getting any "extras".

As above.

The spindle being part of the motor on these was hard for me to believe when I first encountered it, horrible design.

 

[matthewsx]

Much as I hate to say this, the problem you have is that it is a Vevor lathe with a very well known problem.

Start the returns process as there is currently NO KNOWN FIX for this VERY common issue.

Buy any other brand lathe but Vevor. They a VERY low on the totempole of QC and well known for issues. They are also VERY well known for not supplying parts/spares and good luck getting any "extras".

Avoid Bolton too.

John

 

[steve.mcclelland1]

Steve: I believe you are looking at a designed-in problem/feature
I have not heard of a fix yet for this. Vevor is known for numerous issues.
Others have mentioned this same issue- unfortunately Vevor will not provide electrical diagrams

The NEC chip they use is a microprocessor- all the functions are programmed in firmware- no adjustments
If you can trace out the analog portion of the A/D input you might be able to change components for slower speed
However, the motor may overheat
Without more detailed info it would be risky- personally I would return the machine for a refund
Talk to your credit card company

Thanks Mark, kind of wishing i'd found this site before i brought it now. Just started the "wtf" dance with Vevor, so i'll wait and see.

 

[steve.mcclelland1]

Why would you think that a variable speed pot would bring the spindle to 0 RPM, it clearly states "Continuously Variable: Features a spindle that can turn in both forward and reverse directions with 150-2500 RPM continuously variable speed range.". This is a common programmed feature in many variable speed controllers to prevent overheating of the motor at low speed, as well as decreased Hp/Torque beyond the motors operating speed window. Some VFD/controller manufactures go as far to either burn the instruction set into a programmable control chip or lock you out of changing the program parameters with a pass code. My mill only goes from 20-200Hz, when I program VFDs for lathes I usually set the lowest motor speed to 15-20Hz to prevent overheating of the motor. I will agree that the Vevor products are pretty poor, but then they also cost a lot less.

VEVOR Mini Metal Lathe Machine, 7'' x 16'', 800W Precision Benchtop Power Metal Lathe, 150-2500 RPM Continuously Variable Speed, with 3.9'' 3-jaw Metal Chuck Tool Box for Processing Precision Parts | VEVOR US

Discover VEVOR Mini Metal Lathe Machine, 7'' x 16'', 800W Precision Benchtop Power Metal Lathe, 150-2500 RPM Continuously Variable Speed, with 3.9'' 3-jaw Metal Chuck Tool Box for Processing Precision Parts, Protection Devices and Aluminum Alloy Handwheel at lowest price, 2days delivery, 30days...

www.vevor.com

Hi mksj, like i said i have limited machining knowledge. I thought that once the lathe was powered on with either forward/reverse selected you would then be able to use the speed dial 0-2500rpm to set desired rpm's.