Problem with Dremel-style rotary tool

[Makatas]

Good afternoon! This is my first post in here and I wish I get some help because I really need it.

I happen to own a rotary tool which is like the Dremel ones, but is not a Dremel. I am satisfied with how it works.
Two months ago I bought a second, because I want to ship it to a friend abroad. So, I got it, I opened the box and tried it, and when I saw that it works flawlessly, I put it back in its little plastic case, supporting it with bubbles etc.
Weeks later, the rotary tool arirved at its destinations, but it is not working properly. What it does:
At speeds 1,2 and 3 it barely turns. At 4,5 and max it turns but will sotp when it meets any kind of resistance. As you understand, it cannot do anything even to the softest things. It really stops and has no torque.
Me and my friend tried to troubleshoot it, she has some technical skills and I aided with mine. She checked the brushes, removed and put back in, then replaced with the back-up ones, it didnt work still. She opeend the case and checked for possible problems with the speed switch or anything, sitll the thing is brand new. It really hasnt worked at all, so I dont know what the problem could be.
Could you please give some suggestions on it?
Thank you all

 

[alexan_e]

Are you and your friend in the same country?
Is the mains voltage same as the specification of the tool?
I suspect that it is a 220v tool and your friend is trying to operate it at 110/120v

Alex

 

[Makatas]

We arent in the same country, but her country also got 230v/50Hz system as my country and she tried it in various sockets just in case her intiial attempt had failed due to electricity socket issues.
There is however an idea I got now form your post, would there be a problem if she used the tool on a socket without ground? Because the plug does have ground and I am sure she used it on socket without ground. Could this cause problems you think?

 

[alexan_e]

Which country is she located in?
The gnd isn't the problem, my dremel doesn't even have one (it has a 2 pin plug), the gnd is just there for safety

Alex

 

[Makatas]

She is in Philippines, I am in Greece.

 

[alexan_e]

according to Mains electricity by country - Wikipedia, the free encyclopedia
Philippines has 220v/60Hz , I don't know the effect of the different frequency on the motor and motor control circuit

 

[Makatas]

Hmm. My bad then. I need to check into it a bit further.
Any other suggestions you might have?

 

[alexan_e]

According to Motors: Changing between a 50 and 60Hz supply. - Electric motors, generators & controls engineering FAQ - Eng-Tips

a 50Hz AC motor working in 60Hz has the following effects

a) It will turn 20% faster.
b) The cooling will increase dramatically.
c) The load's horsepower requirement will increase, possibly dramatically.
d) The V/f will drop which will not cause a current draw increase.

So I guess it shouldn't be a problem unless the electronic speed circuit has a problem with that change and doesn't work properly

---------- Post added at 18:08 ---------- Previous post was at 18:06 ----------

actually c) The load's horsepower requirement will increase, possibly dramatically. may be the problem and the driver circuit cuts the power too far and can't adjust the operation of the motor

 

[Makatas]

I cmae across the same post while googling and was to type those now.
Another search though showed that universla motors shouldnt have problem running on different frequencies. I suspect dremel got universal motor.

 

[Raza]

Hi,
When plugged and tried to run:
1. Does the motor makes an extra vibrating noise?
2. Can she check the motor current on the highest speed, is it according to the specification of the tool?
The only effect on the motor speed with 50Hz -> 60 Hz will be the motor speed will be higher from the specified approximate speed in original.

 

[Makatas]

I wish she could check current, but she cant she does not have a measuring tool. Other than that, the motor does not make vibrating noise that is out of normal.

 

[FvM]

Did you check the type plate of the tool? My tool (from German/Austrian company Proxxon) has e.g 230V 50/60 Hz printed on, I guess, that most electrical hand tools with universal motor and speed control have this specification.

 

[Makatas]

Sadly it only says 230V/50Hz so no clues from the tag.
Do you suspect the brushes, even though the thing is unused?

 

[FvM]

Sadly it only says 230V/50Hz

Still unlikely, that it doesn't work at 60 Hz. If you tell the brand/manufacturer, perhaps some Edaboard user knows about.

 

[Makatas]

It is rather unlikely.
This is one of those tools manufactured in China and the seller just makes huge orders and asks their name tag printed on the tool.
Anyway, just in case, its 135W tool ,6-speed, brand named Skarmax Switzerland and the tool also says DoIt. I havent managed to find anything mroe on all these, but I must say in my latest search in alibaba it seems to resemble this model
40pcs Variable Speed Rotary Tool/135w AC mini grinder/135w multi tool kit products, buy 40pcs Variable Speed Rotary Tool/135w AC mini grinder/135w multi tool kit products from alibaba.com