micro mill electricals problems, help please!!

[pmdevlin]

Hi all, I will set the scene! I'm pretty new at model engineering, and need some desperate help. I don't even know if I am posting the correct place, mods please move if applicable.

I was today using my micro mill, low rpm, milling some plastic sheet, so no problems here. I bought this off a friend, a very talented engineer, and a regular on this forum, he passed away last year, so my predicament is that I cannot go back to him to talk about the mill he knew inside out. It had been modified to suit his disabilities, it is belt drive, and the control panel was moved away from the machine so he could reach it. I believe its a seig machine, they are the instructions he gave me with it, although it has no markings on it. All I can say is he only used good stuff!

So after a bit of use, the fuse in the control panel blew, I changed it, it blew again. I have inspected the motor, taken it apart, all is good, no binding, brushes good, no signs of excessive heat,. all windings seem to be ok. The connecting block between the control panel and machine is good. Reassembled, fuse blew again.

So, with control panel disconnected from the motor, I can turn on, and turn up potentiometer, nothing is amiss. When connected to the motor, the motor immediately spins up with the potentiometer in the off position, and the fuse blows. I assume with potentiometer in off position, motor should not spin up?

I have inspected inside the control unit, all appears to be fine, and no smell of electrical death! I am now at a complete loss as I have absolutely no knowledge of how the control panel works, what to test, how to test, and what to do now please help! I am thinking the control panel is faulty, as its been modified the manufacturer will be no help, can anybody suggest a repairer or is the mill now finished!, 
Many thanks

Paul

[lordedmond]

I am assuming you are in the UK

Get a 100watt lamp old fashioned type a lamp holder and wire these up instead of the motor ,leave the motor disconnected , now if the fuse blows  it's the controller if not it's likely the motor

Note you can get the bits from arcurtrade or amadeal but if the motor is duff and you put a new controller in it most like will go kaput

It may be simpler if you are not sure to replace both at the same time

Stuart

Edited to include more info as requested below

[Pete W.]

SNIP

Note you can get the bits from arc ... SNIP

Stuart

Hi there, Stuart,

You know what you mean by 'arc' and I think I know what you mean but does Paul?  I suggest you elaborate.

Hi there, Paul,

Your photos are reader-unfriendly - much too large.  I suggest you go to the 'Gallery' section and read about re-sizing photos. 

[velocette]

hi Paul
Check your PM  and posting on HMEM  Eric

[pmdevlin]

will do Eric, yeah just clicked on the photos and they are massive, sorry. I am familiar with arc euro trade thanks for the pointer, I cant replace both components, way too expensive, too expensive even for one of them, hence needing a "fix"

I will do lamp test, and suggested motor test by pm,  and report back
Thanks

Paul

[matnewsholme]

What type of fuse are you fitting?. It may need an anti surge one. You can usually tell by looking at original and seeing if it's a empty glass tube or if it's filled with white powder. If the latter its anti surge.

Matt

[pmdevlin]

its the glass tube, I assume its the correct one as its been fine for over a year. Instructions say its an X1 Super micro mill

[steampunkpete]

When connected to the motor, the motor immediately spins up with the potentiometer in the off position

Strongly suggests that the controller has failed. If the motor is spinning up, chances are that the motor is OK.

Can anybody tell me if it is an AC or DC motor and what the voltage range is? Is it on a plate on the motor casing?

[drmico60]

The X1 mill is powered by a 150 Watt dc motor. This motor has a voltage rating of 180 V. It has an DC electronic controller with feedback via a current sense resistor to help maintain a constant speed characteristic with varying load.
Mike

[steampunkpete]

Would this controller from ebay do the job? The output would need to be routed through a reversing switch.

http://www.ebay.co.uk/itm/Rotary-Knob-Adjustable-Motor-Speed-Controller-AC-220V-Input-DC-180V-Output-/290933673054?pt=UK_BOI_Industrial_Automation_Control_ET&hash=item43bcff8c5e

[drmico60]

Would this controller from ebay do the job? The output would need to be routed through a reversing switch.

http://www.ebay.co.uk/itm/Rotary-Knob-Adjustable-Motor-Speed-Controller-AC-220V-Input-DC-180V-Output-/290933673054?pt=UK_BOI_Industrial_Automation_Control_ET&hash=item43bcff8c5e

I think this would work although the description does not give any indication of the current or power rating. However, this type of controller is usually designed to cope with several amps so I think it would be worth the risk.

I doubt that the controller has ant provision for feedback to maintain constant speed regardless of the load but this may not be so important.

Mike

[pmdevlin]

I really appreciate the help all, its very encouraging.

Following some suggestions (I posted on hmem then realised this was the UK site) I connected a 240v test light to the controller. Turned it on, holding my breath! the test light lit (60w bulb, very bright) I turned on the potentiometer, and the bulb light remained constant throughout the range. I was pleased thinking this means the most expensive item is ok, but is it? Should the bulb have lit with potentiometer turned off (meaning nil rpm for motor) or am I being stupid.

I then connected the motor to a 12v dc feed (don't know if its a dc or ac motor). The motor did not work, however I could feel "resistance" when turning the shaft by hand, which went if the motor was disconnected from the 12v feed. No hot wires suggesting a short. I stripped the motor again and inspected under an LED magnifying glass, I cant see anything wrong with windings etc.

Don't know if I have achieved anything doing these tests, any thoughts?? Thanks for the ebay link, I can breathe more easily now there is a potential fix at budget money :
Again, many thanks, keep the suggestions rolling in, I need a cheap fix!

Paul

[rleete]

I replied on the other forum, but I can repost here as well.  All my problems with my micro mill were solved by replacing the speed control pot.

[pmdevlin]

many thanks, sorry we are diving between the two forums.

By speed control pot, is it this (depending on which board I have)

http://www.arceurotrade.co.uk/Catalogue/Machine-Spares/Super-X1-Spares scrolling down to the SX1-124 Potentiometer.

The control unit from ebay suggested previously, I have no real need for reverse, not use it in 18 months, so I would assume its an easy wiring up job? It has been suggested that 12v on the motor would not be sufficient to spin it up, and the fact the bulb was illuminated with pot turned off suggests its the control unit, as it should have gone brighter turning up the potentiometer?
So I was thinking, if the pot is faulty, should the motor not just run at a constant speed, or not at all? back to the beginning, it runs for a second or two then pops the fuse.
Whilst on the subject of fuses, I anticipate I will be blowing many more before its fixed, and only have 1 left, can I use something like this

http://www.ebay.co.uk/itm/ABB-S201-1-POLE-MCB-CIRCUIT-BREAKERS-2-4-6-10-16-20-25-32-40-AMP-/321302757144?pt=UK_BOI_CircuitBreakers_RL&var=&hash=item4acf22ff18

Thanks

Paul


I need to find someone with electronics experience!

[pmdevlin]

well I have found a local electronics engineer, and have dropped off the motor and control unit for testing. I'm back in work tomorrow so this threads might go a bit quiet for a bit

Paul

[rleete]

I believe that is the correct one.  I bought mine from Little Machine Shop, and they knew which one to send.  It has been a while, so I'm just going from memory.

[JohnHaine]

Other people have used this item number from eBay to replace the speed controller with success

181473818094

[pmdevlin]

well I'm in  a mess now, don't know what to do. The motor has been tested and reported to be burnt out. I took the motor apart before giving in to be tested, and could not see any evidence of this. The guy has connected up to 110v ac to test it, on the basis that the motor has a big spec sticker on it, and it does actually say 240v ac, however, on the arc euro site, the replacement motor says its a dc??????

He says the motor ran for a very short period, then gave up, and a possible short was causing the fuses to blow and the motor to spin up without potentiometer input. I'm confused? I thought it was a DC motor, so why on the big sticker on the can it does clearly say its AC?

So no further on really, except now I need a motor, and might still need a control board, anybody got any recommendations for a direct fit motor other than a massively expensive £88 from arc euro, and that might not even be the fix!

[John Rudd]

Firstly, sounds like the controller board is u/s, with the pot in the off position there should be no power to the motor light bulb whatever....the fact that the lamp lit as soon as power was applied suggests the mosfet on the board has died....A fairly easy fix IMHO....



Secondly, the motor is definitely DC if it has brushes and magnets.....no field coils...would confirm this.

If connecting the motor to an ac source then damage to the motor will occur, the alternating field setup in the armature would cause it not to rotate......


Where abouts are you?
Any where near Hull?

[lordedmond]

The guy you took that motor to test did not know his stuff and he should foot the bill because he has burt out the motor not you

Let me explain ,
I am a time served Sparks and have done some time in armature and stator winding when I gave up work I was an electrical engineer to PhD level
Ok back to your motor a universal motor has a series field coil not a perm magnet one, when the AC volts reverses as it does 50 time a sec the field does along with the armature and every thing is in step so it's ok as it is on DC .
Now with a perm mag field it cannot reverse but the armature field will hence it no go and it will release the magic smoke alas it will not be able to be refilled.

I would bite the built and get a new motor and controller from one of the dealers then you will know it will work. But please do not let that guy anywhere near it

Stuart

[John Rudd]

The guy you took that motor to test did not know his stuff and he should foot the bill because he has burt out the motor not you


I would bite the built and get a new motor and controller from one of the dealers then you will know it will work. But please do not let that guy anywhere near it

Stuart

Lol @Stuart.....

I agree, it's gonna cost you....dearly...sadly.

[BaronJ]

The guy you took that motor to test did not know his stuff and he should foot the bill because he has burt out the motor not you

I would bite the built and get a new motor and controller from one of the dealers then you will know it will work. But please do not let that guy anywhere near it

Stuart

I 100% agree !  Permag motors are DC devices.

Someone, I think it was John suggested that the power FET in the controller had gone (short circuit), replacing it would be an easy and cheap fix.

[John Rudd]

Ok.....

I'll stick my neck out here and offer to repair the controller...

I have the technical know how and the means to test...( trumpet fanfare .... )

Paul if you want to take me up on my offer send me a pm please...

[pmdevlin]

Thanks John, (and others!) Ill take you up on it please, I am Wirral, I will PM you, and will naturally pay for services, successful or not!

I have challenged the guy but he keeps coming back with the fact it has a big spec sticker on the motor, and it says "AC". I too also think he has fried the motor, inadvertently, but as he is the "expert" should he have known this? .

So, just to get it straight in my head, I will be picking up the controller and motor tomorrow. I understand the inside of a DC motor, or at least what it looks like. Would an AC motor be visually different externally? If so, Ill push for him to foot the bill, but I doubt I will be successful if it looks the same externally. (back to the flippin AC sticker on the can!)I would have thought in my simple way, he could have plugged the controller in to power,, turned on the pot, and measured what was going on at the output lead that was for the motor. I was very specific with my description as to what had happened, then surely he would have seen the output was DC, not AC?, and would have been able to assess if the board or pot was faulty.

Unfortunately he would not touch the board as he wanted a circuit diagram, so I have gone backwards really, to the tune of £88 motor, surely there are cheaper alternatives out there?

Paul

PS sorry for duplication on hmem I originally started over there and as there have been responses for courtesy Ill keep posting

[John Rudd]

Paul,
Pm sent....