Naerok mill - cutting out

[biker_smith]

Hi all,
I've had my Naerok mill about a year now and have been using it for light work, mainly ali.
Since I have had it I have had the same issue - in that it cuts out while taking a cut. I then have to wait about a minute and the then it seems to reset inself and then starts up again.
It seems to get worse the more I use it.
It always restarts OK, but then will cut out again soon.
Any ideas on what may be the cause please?
Thanks - Paul.

 

[Housey210]

thermal overload on the dol starter. Pointless really just replacing overload as you do not know the condition of the coil contactors. Motor rating determins over when sourcing new dol.

 

[biker_smith]

OK thanks Housey - where is the dol starter and how do I fix it?
Regards - Paul.

 

[Spectric]

If the overload is tripping you should check the motor current and not assume the thermal overload is at fault, it may just be doing what is was designed to do.

 

[Housey210]

Direct On Line (DOL) is the on off switchgear., green and red button. Unplug and check the rating level is set to motor rating. example-
https://www.electronicshub.org/dol-starter/. ignore text, just picky.

send a picky with cover off.

nice bit of kit Naerok, (korean backward) 1980's? single phase?

 

[Housey210]

may be worth checking tightness of all terminal screws. Cheapest option at first, starter, as motor for that just might not be off the shelf and spare starter may be handy for something else. Does the motor get hot or smell? Does the rotation slow? Can you lube up the bearings?

 

[johnnyb]

I had this on a mortiser and the trip current could be altered. changed it to be the same as the motor voila!

 

[Housey210]

what's with the tape around the switch gear?

 

[biker_smith]

Couple of photos of the switch gear below. I thought at first the cover was the issue as it was not very secure, hence the tape (great fix ;-)

Thanks - Paul.

 

[Housey210]

is there a rating plate on the motor?

 

[Jonm]

it may just be doing what is was designed to do.

OT but I was reading some customer reviews of carbon monoxide alarms. One review stated that the alarm sounded as soon as it was switched on so they assumed it was faulty and sent it back for a replacement, fortunately not for a refund. Replacement did the same and then the penny dropped. The fault was with the appliance.

 

[Spectric]

Over many years working in various industries it is not uncommon for people to blame instrumentation, an alarm goes off and something makes them question the validity of the alarm rather than just applying the correct procedure this alarm should have. This becomes even worse when there is a history of false alarms because then they can get to the point of just resetting the alarm if the system allows, a good example here was a catchment tank level sensor that had been prone to nuisance tripping, it was common knowledge and had been investigated on several previous occasions without finding a cause so the team would ignore it. Some months had passed and then another alarm was initiated, on looking into this they soon realised the catchment tank of toxic liquid had been overflowing and that was what had caused the other alarm to trigger, it was a major incident, cost a lot of money to cleanup and company reputation was damaged. Another one from just weeks ago when I was in my local garage with car problems, there was a very new motor there which the owner had ignored a warning light and just carried on until the car stopped, basically overheated and cooked the motor so as it was not worth repair even considering the age of the car.

 

[Housey210]

looks like a bit of damage to motor fan housing. I would remove the belt cover and motor drive belt to check free play of motor or noise from fan hitting that cover. Single cap or twin, could be a failing run capacitor. I guess original motor? Does the motor get hot?

 

[biker_smith]

Hi Housey,
Thanks for your tips.
I removed the belt and the motor turns easy by hand with no issue from the below fan. I powered it up without the belt and again no issues.
Checking the motor I can't see any spec plate, even one that may have been painted over.
I did a small job today and no heat or smells from the motor - in fact it did not power off today, but I only used it for a few minutes.
Regards - Paul.

 

[guineafowl21]

Does the mill spindle turn freely on its own?

Your overload is set to 6 amps, which should be more than enough for (what I’m guessing is) a 1 hp motor. There’s either a fault with the motor, or the overload.

Check the capacitor, underneath the cylindrical cover on the motor, for any obvious damage. Beyond that, you really need a multimeter to measure the capacitor, and the current drawn under normal use to see if it’s normal, hence overload at fault, or excessive, hence motor at fault.

Another option would be a plug-in power meter, such as:
https://www.amazon.co.uk/FLOUREON-Monitor-230V-250V-Consumption-Calculator/dp/B01DSQ30FO
Which would be handy for other things too.

 

[Housey210]

know any sparkies! Ring /loop tester on individual supply cable to find current draw. My money still on the dol. from what i can see i found this on net-
https://www.camsco.com.tw/magnetic-contactors/type-c-contactors-thermal-overload-relay.html#group-1
Any motor rewind businesses near you? I've taken one in before and they have tested on bed at no cost. Personally I would swap out the dol

 

[Housey210]

I take it there are screws holding the press buttons in place and not just the tape!

 

[andy48]

I've got the same mill. A while ago it started cutting out, but would work if you held the start button in. No smell of burning. Unplugged it and used very fine sand paper to clean the contacts in the starter switch. Plugged it back in - no more problems. Worth a go!

 

[biker_smith]

Thanks all for your tips - I'll have a play later today.
Regards - Paul.

 

[Ttrees]

Here's another thing worth looking at regarding the switch, should it not always stop the machine,
a panel inside might be upside down,
(timestamped for convenience)