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Motor for Chester Champion Mill

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John Rudd13/09/2017 11:12:49
959 forum posts
54 photos

Basically there are three different species of variable speed drive train for mills/lathes.

The basic pm motor with its troublesome brushes, usually accompanied by a thyristor based speed controller, of Chinese origin or the slightly more reliable KB controller from the States. This drivetrain is probably the cheapest entry level....for smallish mills and lathes, although my lathe had a 1.5kw dc motor fitted!

Then we are on to brushless motors, multiphase with Hall devices for feedback, using a dedicated control board. More expensive than the dc motor, but more powerful for just about the same physical size, can be found on numeroys Sieg machines

Finally, the usual industry standard 3 phase motor with a vfd, using a larger motor, generally found on bigger lathes..

larry Phelan13/09/2017 11:29:00
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395 forum posts
16 photos

Like Duncan,I thought it was a bit odd to hear of an AC induction motor with a controller.

Both my lathe and my mill have simple induction motors [Chinese],as has my bandsaw. Touch wood,none of them have given any trouble [so far !! ] Must be going about 12/14 years now.

Would it be possible to simply change the motor type? Wishful thinking perhaps !.

Nick_G13/09/2017 11:29:42
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1808 forum posts
744 photos
Posted by not done it yet on 13/09/2017 11:12:20:

So the price variation we see as consumers is very often not a distributor being greedy

Sorry, but you clearly missed my point. I did not even suggest that distributors or dealers were being greedy. Even they cannot give a decent warranty period for the motor/control board for fear of excessive claims.

Of course, some dealers are better than others and retain spares at reasonable prices, but it makes no difference to the fact that a too high proportion of these machines were never truly fit for purpose.

.

I didn't miss your point. smiley

The remark you chose to quote was an extension of my personal opinion in addition to my reply to you.. (and as it seems sort of ish backed up by JS in the next post)

Technology moves forward to address issues and problems. Soon brushed DC motors on machine tools will be a distant memory. e.g. In the same way drum brakes are no longer fitted to cars.

Having said all that Jason has had 2 brushed motor machines that have operated flawlessly for quite a number of years now and still to the best of my knowledge still are. (think he replaced brushes on his lathe once) And he probably uses his machines more in a month than most of us do in a whole year. Add to that he builds quite large models so it's not as if he is 'babying' them.

Nick

SillyOldDuffer13/09/2017 11:47:28
2150 forum posts
467 photos
Posted by Mark Lawson 1 on 12/09/2017 22:09:54:

 

...

Ian S C, The motor is a single phase AC induction motor 600W, 240V, 3.6A, 1400rpm, 50Hz E

...

Searching the forum did throw up others who have had a similar problem one two statements seem to make sense; “ these motors fail because of poor quality start capacitors or a dodgy centrifugal switch” “either the start capacitor, centrifugal switch or the fan unit not providing enough cooling”

I really do think the problem is with the Chinese motor ...

Hi Mark,

Looking for anything unusual that might explain your problem, the statement that the mill is fitted with a single phase AC Induction motor is odd. Can you confirm that please? If true, it means the motor and control board on your mill are unusual, which may be a clue. Are you able to post a photograph of the motor? (And if you incorrectly think it's an AC motor, you won't have checked the brushes...)

Secondly, I don't see how a dodgy capacitor and/or centrifugal switch explain your symptoms. Perhaps an expert will comment, but I associate both with failure to start, or in the case of a jammed switch, overheating. That doesn't seem to fit with a motor that starts, initially loses 200rpm, and then runs at a maximum of 10rpm.

It's too early to blame the motor because it's Chinese. Possibly you've been caught by counterfeit motors, or cheap nasty clones, but don't underestimate Chinese industry - they've been able to make decent motors for donkey's years. It would be useful to know what you use the mill for and how much work it does in an average week. (There's a big difference between a couple of hours per week gently milling Aluminium, and 24x7 piecework on Stainless!) Can you think of anything odd about your workshop or household - for instance, do the house lights ever fail.

Don't be too disheartened: the worst that can happen is you replace the motor with a 3-phase type and a VFD. Spending the dosh will be painful, but the improvement acceptable.

Dave

Edited By SillyOldDuffer on 13/09/2017 11:48:02

John Coates13/09/2017 12:16:03
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550 forum posts
27 photos
Posted by John Stevenson on 13/09/2017 11:05:32:
But hey guess what the deep pocketed tight arsed punters reckon its too expensive and so insist on buying the older generation DC package where they have had to cut corners to meet a price.

You bugger! Almost spilled my tea and coughed and spluttered over my keyboard after reading that!

not done it yet13/09/2017 12:24:20
1221 forum posts
9 photos

brushed DC motors on machine tools will be a distant memory.

Not so. There are still many machines on the market, aimed at first time buyers, generally. Often those that are in the market, but unaware of the deficiencies of some machines, particularly the motor/controller combinations.

Nick_G13/09/2017 12:45:06
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1808 forum posts
744 photos
Posted by not done it yet on 13/09/2017 12:24:20:

Not so. There are still many machines on the market,

.

I didn't say there wasn't. I meant their days were numbered.

Unless of course they have a revival like the Bay City Rollers did. surprisefrownlaugh

Nick

not done it yet13/09/2017 14:12:47
1221 forum posts
9 photos

I meant their days were numbered.

You may well have done, but there are lots of them out there, and will be for several years - unless their horrible, not fit for purpose motors/control boards are replaced, before being offered for sale, or these cheap under-designed machines are scrapped.

In the meantime, there will be a lot of unsuspecting buyers (perhaps as JS suggests, or maybe new starters that just don't have the funds for a bright shiny new machine). Ethics, really - whether you support the unsuspecting innocent buyer or the possibly unscrupulous seller pushing off his rubbish machine to an unsuspecting buyer.

I rest my case. It does not, and will not, affect me. I would be very wary of buying second hand chinese and would even avoid new chinese at that end of the market.

But please don't quote me and then include dealers or distributors in your apparent reply to my quoted post. I did not mention them at all.

Michael Gilligan13/09/2017 14:56:50
10196 forum posts
442 photos

'not done it yet'

As a disinterested [not unininterested] observer of this thread ... may I ask a favour ?

When you are quoting others, could you please do so in the conventional manner [i.e. by using the Quote button and thereby including the timestamp etc. of the source posting] instead of just pasting an emboldened phrase taken from some prior post. ... Extracts are fine, but the timestamp identifies the source.

It's a small thing, but it does make it easier to follow the thread.

Thanks

MichaelG.

Nick_G13/09/2017 16:36:11
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1808 forum posts
744 photos
Posted by not done it yet on 13/09/2017 14:12:47:

But please don't quote me and then include dealers or distributors in your apparent reply to my quoted post. I did not mention them at all.

.

I wouldn't know.? - As to date I don't own any far eastern machinery. cheeky laugh

Nick

Graeme W13/09/2017 17:12:35
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931 forum posts
32 photos

For those of you who may be interested, the 'nominal supply voltage in the UK is now harmonised with Europe and is quoted as 230V +10% -6% which means the voltage you measure in your property on a single phase supply can be anywhere between 216v and 253v and still be within permissible limits. My supply normally sits around 242V but I have seen it drop to 235 at peak load times, we are however quite close to the sub station so variation is usually small.

SillyOldDuffer13/09/2017 17:35:28
2150 forum posts
467 photos
Posted by John Stevenson on 13/09/2017 11:05:32:

Posted by not done it yet on 13/09/2017 08:07:52:

...

...

But hey guess what the deep pocketed tight arsed punters reckon

...

Deeply offended by that I am. To be clear I 'm not only tight arsed and deep pocketed, I have short arms as well. When first married my wife and I shared something truly beautiful. But then she spent it.

Dave

David Standing 113/09/2017 19:11:09
679 forum posts
38 photos
Posted by Nick_G on 13/09/2017 16:36:11:
Posted by not done it yet on 13/09/2017 14:12:47:

But please don't quote me and then include dealers or distributors in your apparent reply to my quoted post. I did not mention them at all.

.

I wouldn't know.? - As to date I don't own any far eastern machinery. cheeky laugh

Nick

Stop that right now wink 2

Neil Wyatt13/09/2017 20:07:48
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Moderator
11624 forum posts
531 photos
63 articles
Posted by duncan webster on 13/09/2017 00:30:40:

this problem comes up time and again on the forum, burned out motors and control boards.

Come on Neil, time for an article in MEW on how to replace the horrible DC motor on your Chinese mill or lathe with a three phase squirrel cage VFD drive motor

Keep up at the back Duncan! This has been on the website for three years:

3-phase-conversion-and-other-alternative-methods-of-powering-a-mini-lathe/18752

I'd stress that I blew my motor by trying to take extended cuts at 6 11/2" diameter in cast iron at 60rpm. No one told me that could overheat a mini-lathe...

The board blew in response to a long thread of swarf snaking into the control box, a bit of an unlikely event, but mine was a 1998 machine and 'modern' ones have a rubber gasket blocking the hole.

Personally I don't think the brushed DC motors with the second generation boards have anything wrong with them IF you understand that they must not be allowed to overheat.

The new brushless motors are more pricey, but better as they have more intelligent controllers and really can't be sdescribed as 'horrible' in any way.

Neil

Mark Lawson 113/09/2017 22:07:21
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18 forum posts
5 photos
Posted by John Stevenson on 13/09/2017 11:05:32:
Posted by not done it yet on 13/09/2017 08:07:52:

But hey guess what the deep pocketed tight arsed punters reckon its too expensive and so insist on buying the older generation DC package where they have had to cut corners to meet a price.

 

 

Brushless motors were not an option at the time I bought my mill regardless of how deep my pockets, I don’t have to justify anything to you least of all what I spend.

 

Hi Silly old duffer, my mill is used a few times per month; it’s used mainly for alloy and occasionally a bit of brass I build 1/6 scale RC tanks mainly from kit and either modify parts or scratch build them, I never mill steel or stainless the largest tool I use is a 13mm end mill but mainly 6,8 and 10mm with a .5mm cut.

If I’m going to be spending £300 on replacement motor and board then I’m going to be buying brushless as opposed to these motors.

 

 

Edited By Mark Lawson 1 on 13/09/2017 22:09:26

Mark Lawson 113/09/2017 22:18:11
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18 forum posts
5 photos

dscf0001.jpgdscf0019.jpgdscf8779.jpgdscf8780.jpgPictures of the original motor the latest is the same type

This is what I’m working on at the moment

dscf8781.jpg

Ian S C14/09/2017 10:27:58
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6457 forum posts
216 photos

That is a DC motor with brushes. At 5200 rpm its no induction motor on 50 HZ.

A web site that I had a look at said that Chester removed the Chinese control board , and replaced them with boards made in USA.

Tony Durkin, Sales engineer at Chester Machine Tools has a forum on line where you can ask questions, and forward ideas.

Ian S C

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