Chinese Mini-Lathes/Mills – DC Motor Controllers

[Andre ROUSSEAUParticipant @andrerousseau66124]

Experienced a complete failure of the DC motor-controller of your Chinese-made mini-lathe/mill? …..what to do? NO problem! Get a hold of “SILICON CHIP” magazine, July & August 2024 issues wherein you will find a construction article for a 100% compatible motor controller, indeed, it was designed specifically for this type of motor.

[Michael GilliganParticipant @michaelgilligan61133]

Very useful reference, Andre !

… I am also very impressed by the Search facility on the magazine’s page

https://www.siliconchip.com.au/Articles/ContentsSearch

MichaelG.

[John HaineParticipant @johnhaine32865]

Doesn’t seem to a schematic so hard to assess whether it would be any more robust.  Better I think to buy a KBE unit, the one on my little mill seems to be bulletproof (so far!…)

[Stuart Smith 5Participant @stuartsmith5]

The circuit diagram is on pages 48 and 49 of the July edition. It isn’t a simple circuit!

[John HaineParticipant @johnhaine32865]

Doesn’t seem possible without paying?

[EmgeeParticipant @emgee]

Link below to part 1 of the article.

https://www.siliconchip.com.au/Issue/2024/July/180-230V+DC+Motor+Speed+Controller

 

Emgee

 

[John HaineParticipant @johnhaine32865]

Thanks, but that goes to the first two pages but it does not seem possible to see subsequent ones – you just get a “preview” message and an invitation to purchase the issue or subscribe?

[Michael GilliganParticipant @michaelgilligan61133]

Seems reasonable, John … it’s presumably an active publisher running a business.

MichaelG.

[John HaineParticipant @johnhaine32865]

Absolutely agreed Michael. Just makes it hard to judge whether this might be better than the originals.  Lower risk would be a proper industrial controller and they aren’t that expensive.

[Robert Atkinson 2Participant @robertatkinson2]

Having looked at the snippet of available information the controller looks unusual. Quite complex with both current and back-EMF feedback. Looking at the image of the PCB I’m a little concerned that it needs 6 multi-turn pre-set potentiometer adjustments….

Robert.

[Andre ROUSSEAUParticipant @andrerousseau66124]

It actually IS a simple circuit. You’ve lost sight of the objective: maintaining accurate speed control UNDER LOAD. If you want complicated then search out those that incorporate micro-controllers. The article fully explains the circuit operation. Piece of cake!

[Robert Atkinson 2Participant @robertatkinson2]

But accurate speed control is not required by a lathe…
Can anyone who has read the full article tell me what the 5 multiturn pots are for and how thay are adjusted?
The fact that they have used a circuit that “provides the same pulsating DC voltage…” makes me wonder. That means the motor will have at least some 100Hz torque ripple. Any DC motor will be quieter and smoother on DC or high frequency PWM DC than unsmothed rectified AC.

Robert.

[Stuart Smith 5Participant @stuartsmith5]

Robert

I have access to the article but have only skimmed through it. It does look like the output is not true dc but a pulse width modulated version of the full wave rectified mains (ie does not have smoothing capacitors). The setting up of the various pots is detailed in the article. It uses an IBGT for the output.

Stuart

[Andre ROUSSEAUParticipant @andrerousseau66124]

“…accurate sped control not required for a lathe…?? Nonsense! See what happens if your spindle speed drops in the middle of parting-off a high-alloy steel component….. or the surface finish of a large diameter workpiece during a facing cut of an alloy steel. After all, the designers of the original motor controller included closed-loop control for this same purpose – guess they didn’t know much about lathes then!

[Robert Atkinson 2Participant @robertatkinson2]

Being pedantic perhaps but I still maintain ACCURATE speed control is not required. What is required is CONSISTENT speed under varying load. A vairiation of +- 10 or even 20% will not make any sigificant difference on a lathe This can easilly be done with a brushed DC motor with load compensation. Speed drop under load is more likely to be due to a lack of motor power.
I’d also question your “100% compatible” comment. This design is not specific to mini lathes and is not a “plug and play” replacement for a mini-lathe PCB. It is an electronics project.

Robert.

[Andre ROUSSEAUParticipant @andrerousseau66124]

Hi Robert, not quite sure why you’re putting the capitalised emphasis on ‘accurate’ and ‘consistent’; you appear not to have read my prior post in which I clearly and un-ambiguously stated, ..”maintaining accurate speed control UNDER LOAD” (Yes, capitalised!). The standard Chinese lathe motor is not spectacularly powerful but rather than this being the cause it is more appropriate that it’s a case of an operator pushing the task beyond the capability of the machine. Usually, the machine gets blamed instead of the guy in the mirror. Furthermore, I don’t recall saying anywhere or making a single reference to this circuit being a “plug-and-play” replacement for a mini-lathe PCB. By return reply, could you please provide me the screenshot where you can demonstrate I made such a claim, I would be most interested to see it. You also appear not to have ACTUALLY read the whole article: I have. You may be assured that the circuit is entirely based on the original lathe DC motor controller as used on Chinese small machine tools, i.e. it IS 100% compatible with the range of brushed DC motors used in these machine tools. Furthermore, the designer of the controller, John Clarke is one of the most qualified and experienced electronics designers out there and has multiple motor-controllers and power control designs to his credit, far too many to count.

[Andre ROUSSEAU]

On Andre ROUSSEAU Said:

… Furthermore, I don’t recall saying anywhere or making a single reference to this circuit being a “plug-and-play” replacement for a mini-lathe PCB. By return reply, could you please provide me the screenshot where you can demonstrate I made such a claim, I would be most interested to see it. …

Well, Andre your opening post says, my bold: “Experienced a complete failure of the DC motor-controller of your Chinese-made mini-lathe/mill? …..what to do? NO problem! Get a hold of “SILICON CHIP” magazine, July & August 2024 issues wherein you will find a construction article for a 100% compatible motor controller, indeed, it was designed specifically for this type of motor.”

With respect, though this doesn’t actually use the words ‘plug and play’, I read it that way.  It’s a hazard of the internet: quite a few of my posts are misunderstood!

Where I agree with Robert is that the article describes an electronics project, not an easy way of replacing a burnt out board.   The big problem with it as a practical answer is cost.  An amateur will probably have to buy all the components retail and that makes a DIY build very expensive compared with buying a mass-production controller.   Especially if he has to have the PCB made, and doesn’t have the electronics wherewithal needed to assemble, test and debug it.

I was interested to read the article and resulting comments, but no way would I make one – even though I could.

Dave

Dave

 

[Robert Atkinson 2Participant @robertatkinson2]

Hi Andre,

You said “Experienced a complete failure of the DC motor-controller of your Chinese-made mini-lathe/mill? and “a 100% compatible motor controller”. To me this imples that it is 100% compatible with a mini-lathe i.e just fit it in place of the original PCB. From the freely available part of the article this is clearly not the case. Even motor reversing is “optional”. It does not mention lathes just treadmill motors. It’s a general purpose design that requires some skill to assemble and adjust. The earlier article specfically states that it is not for the inexperienced:

The designer appears to be a “staff” author with the magazine and it’s predecessor for 40 years. He has a Bachelor of Engineering degree. I can’t see how this makes him “one of the most qualified and experienced electronics designers out there”. He does seem to have designed a lot of motor speed controllers. About 15 including revisions and updates. So have I but most of mine where part of commercial projects so had to work reliably and meet safety and EMC requirements. I’m not saying his arn’t reliable or safe but it isvery different writing a article to producing a product.

Robert.

[Andre ROUSSEAUParticipant @andrerousseau66124]

I think you ned to grow up a bit mate. First-off, you might try putting your glasses on: My initial post CLEARLY stated 100% compatibilty with the electric motor. Where EXACTLY did I make a single reference to being compatible with the machine tool’s control box?? Furthermore you seem incapable of getting your facts straight; the article DOES clearly and unambiguously state that it is for use with machine tool motors. Let me give you some fatherly advice sonny, when you place statements in quotation marks you are putting words in my mouth in order to make a back-handedly grasping attempt to win a pedantic argument. Pathetic, and utterly childish. The only thing you accomplish by using such a cowardly low-ball tactic is to start a real argument so you’ll just have to suck up the confrontation that results. I suspect I have a few more grey hairs on my head than yours so you might want to show a bit of damn respect as well.

As for your for your ignorant and dismissive comments regarding John Clarke’s design ability you don’t appear to understand that SILICON CHIP sells construction kits for all these designs and they do so globally, probably in far greater numbers than the controllers you claim to design so you may be assured they are of more than a professional commercial standard.

The thing that makes your overall commentary and attitude so offensive is that you clearly aren’t even interested in using this controller so instead of pouring your toxic graffiti over someone’s post who I might add was only attempting to be of assistance to those in need of help you should just ‘click-off’ and find some other post to put people off. Sadly, in this case the people you put off are those who might find such a project to be of value in extending their complement of workshop skills.

[Joseph Noci 1Participant @josephnoci1]

Folk who know me know I don’t post much these days – I do peruse the site actively though..

There is NO place on this forum for Andre and his vitriolic tantrums and downright insulting childishness.

Ban him!

Joe

[Andre ROUSSEAUParticipant @andrerousseau66124]

I don’t do tantrums pal, I just say it like it is because I have something called PRINCIPLES. Do you seriously think I’m just going to haplessly stand by and allow someone to besmirch my integrity by placing words in my mouth that I did not say?? No way am I going to lay down on the ground while someone wipes his feet on me. If you can’t stand the heat then get out of the kitchen. If offends your delicate sensitivities so much then maybe you should just move on to another post with calming pastel shades.

[Joseph Noci 1Participant @josephnoci1]

Meds not working anymore Andre?

Code Of Conduct
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Please refrain from:

Swearing. It can be offensive and it can also mean that some members can’t use the site from work. If you really must use swear words please use asterisks.

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[Joseph Noci 1]

On Joseph Noci 1 Said:

Meds not working anymore Andre?

Code Of Conduct
We’re a friendly community and we welcome new members and have a laugh at the same time as having lively debates. The forum is a resource for all members and to keep it a useful and friendly place forum users have suggested some guidelines:

Please refrain from:

Swearing. It can be offensive and it can also mean that some members can’t use the site from work. If you really must use swear words please use asterisks.

Being abusive or making personal attacks. If you wouldn’t say something to someone’s face then it doesn’t belong on the forum.

Thanks Joe for the reminder (thumbs up)

This thread is becoming very vitriolic and personal. I have not seen anything quite like this on this forom for a while.

Can I remind us “practical people” on here, that there is more than one solution to an engineering problem?

[noel shelleyParticipant @noelshelley55608]

Gentlemen Please, enough ! That we all have our own opinions is fine but there is no need to allow things to get out of hand as this post has. Agree to differ and let the matter rest. Noel.

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