What would be a good ‘micro motor’ and controller?

[iconParticipant @icon]

I have a couple of watchmaker’s lathes that share a very traditional sewing machine motor and foot controller – the controller gets rather hot under my stockinged feet after prolonged use. There must be a better ‘pseudo-three phase motor’ solution these days, along the lines of the brushless motors I use in helis and quadcopters?

[John HaineParticipant @johnhaine32865]

Look for Jack sewing machine motors on Amazon etc

[not done it yetParticipant @notdoneityet]

Most brushless motors are multi-phase (rather more than just 3).  Most 3 phase motors are induction motors where variable speed is often controlled via a VFD.

Maybe wear something over your stockinged feet?  The controller is likely operating near its maximum rating.

Could you not use one of those motors from a larger heli or quadcopter?  Maybe use a common driver/drill as a power source?  There are loads of alternatives out there.

 

[Martin of WickParticipant @martinofwick]

You could use a modern electronic (thyristor) foot controller for sewing machines (instead of the old graphite pile types), which at least is unlikely to boil your foot. Or purchase a cheap (£5 to £25) generic ac motor controller from the usual on line markets and wire in

There is no plug and play brushless unit available that I am aware of unless you want to get one of the far east 500w to 1000w servo motor and control packages (circa £100+ and probably too much for a watch lathe). Some are now adapted for lathe use rather than sewing machines. As usual, no backup.

If you scan about on the net,  sometimes you can locate small (but not toy)30 to 60v 100 to 400w brushless motors that run at a reasonable speed, but you are on your own as far as sourcing and rigging up power supply, drivers and controllers. Some claim to not require a hall effect controller, but as usual with Chinacarp, they provide no useful information.

Brushless CNC spindle packages are available, but are likely too high RPM for lathe use.

There are some nice 1/6 Hp 3P induction motors on ebay for £30 delivered at the moment, but you will have to get a a VFD for £40 and wire it up yourself.

[Martin of Wick]

On Martin of Wick Said:

 

There are some nice 1/6 Hp 3P induction motors on ebay for £30 delivered at the moment, but you will have to get a a VFD for £40 and wire it up yourself.

Can you give me any links/search terms for these motors – this sounds like exactly what I need.

[not done it yet]

On not done it yet Said:

Most brushless motors are multi-phase (rather more than just 3).  Most 3 phase motors are induction motors where variable speed is often controlled via a VFD.

Maybe wear something over your stockinged feet?  The controller is likely operating near its maximum rating.

Could you not use one of those motors from a larger heli or quadcopter?  Maybe use a common driver/drill as a power source?  There are loads of alternatives out there.

 

Really? All the Brushless DC motors I’ve seen were 3 phase. That runs from tiny ones for fans (low power) and models (high power) to large industrial ones used including servo systems and even linear versions. The only options over 3 phases are 4 and 5. A 4 phase has all the disadvantages of a 2 pole. A 5 pole does not divide into 360 degrees very well and I can’t see the advantage. Six phase is same as 3 Phase with more poles. Six phase motors do exist but mainly in high power variable speed applications so you can use two sets of inverter output devices (or 2 inverters) to get the power but modern high power semiconductors have reduced the need for that.

Can you give an common example of a small non 3 phase BLDC motor?  I’m aware of 5 phase, as compared to normal 4 phase, stepper motors but that is a different application and rare. Vexta seem to be the biggest maker of 5 phase steppers.

Robert.

[Martin of WickParticipant @martinofwick]

And plenty of brushed motor options running at 24 to 48v  circa 300w and 3000 rpm.  Yer classic AC sewing machine motor is fairly awful – bugger all torque, too high RPM and usually with an energy wasting ‘foot warmer’ (which might be ok in the winter though!)

Almost anything else is better these days but at a price. I was thinking of switching out the original motor on my Singer 201 for a 350W brushed DC cycle motor on 36V with a generic DC motor controller adapted for foot control. What’s not to like, low safe voltage, low controllable quiet speed and bucket loads of torque so you can sew tin cans together!

[Peter Cook 6Participant @petercook6]

I use the same sewing machine motor as you do, but use a cheap thyristor speed control like this with an on/off foot switch.

One switch is wired as on/off, one is wired as foot/continuous and speed is controlled by the knob. Stop/start with the foot switch always returns to the same speed.

[Martin of WickParticipant @martinofwick]

Ikon, this should get you somewhere close

motor =   0.12kW, 1365rpm, 230-400V 3Phase, 50Hz, B3 Foot Mounted, GAMAK Electric Motor | eBay

 

Controller = 750W 220V Variable Frequency Drive Inverter Converter VFD Single To 3 Phase> | eBay

[Ian PParticipant @ianp]

Link below is as close to a £30 ebay motor as I can find

‘Spares no longer available’ is unlikely to bother anyone here!

I’m tempted to get one just I ever want to power a smallish machine.

https://www.ebay.co.uk/itm/325889161484?

Ian P

Oops, I replied earlier but forgot to submit

[Martin of WickParticipant @martinofwick]

If you really really wanago brushless, this would probably have enough grunt for a watch lathe…

Neodymium Magnetic Brushless Motor 1450-4550RPM High-torque Mechanical Power New | eBay

power supply £30+ Hall less controller £15

so loads of stuff out there if you want to get creative.

(Why don’t my links come out as links? I’sure they used to…)

[Andrew EntwistleParticipant @andrewentwistle]

This thread is worth a read.

https://www.model-engineer.co.uk/forums/topic/brushless-dc-motor-for-mini-lathe/

I run a Perris (Cowells predecessor) lathe using the Vevor brushless sewing machine motor I mentioned in that thread. I re-boxed the controller in an aluminium enclosure and used a 10-turn potentiometer for speed control (electrically isolated since the potentiometer ends up at high voltage). The torque is only limited by belt friction at any speed.

Andrew.

[Robert Atkinson 2]

On Robert Atkinson 2 Said:

On not done it yet Said:

Most brushless motors are multi-phase (rather more than just 3).  Most 3 phase motors are induction motors where variable speed is often controlled via a VFD.

Maybe wear something over your stockinged feet?  The controller is likely operating near its maximum rating.

Could you not use one of those motors from a larger heli or quadcopter?  Maybe use a common driver/drill as a power source?  There are loads of alternatives out there.

 

Really? All the Brushless DC motors I’ve seen were 3 phase. That runs from tiny ones for fans (low power) and models (high power) to large industrial ones used including servo systems and even linear versions. The only options over 3 phases are 4 and 5. A 4 phase has all the disadvantages of a 2 pole. A 5 pole does not divide into 360 degrees very well and I can’t see the advantage. Six phase is same as 3 Phase with more poles. Six phase motors do exist but mainly in high power variable speed applications so you can use two sets of inverter output devices (or 2 inverters) to get the power but modern high power semiconductors have reduced the need for that.

Can you give an common example of a small non 3 phase BLDC motor?  I’m aware of 5 phase, as compared to normal 4 phase, stepper motors but that is a different application and rare. Vexta seem to be the biggest maker of 5 phase steppers.

Robert.

Agreed, but 360/5 = 72 degrees – what’s not “very well” about that?

[Martin of WickParticipant @martinofwick]

You can now get those brushless motorising units configured for use as power unit for general rotary equipment, with a generic machine control pendant rather than sewing machine specific. £140 on the bay half that from aliexcess.

550W- 2.2KW Brushless Servo Motor & Controller Driver For Belt Sander CNC Lathe

I would take the power ratings with a pinch of salt, but one would certainly be a contender. I have the sewing machine version, not put into use pending conversion to VR control. Somewhat surprised to learn that it gets mains voltage down to the VR. I thought the hall sensor control side was 0.5 to 5 volt. I did have some notes from my previous fiddlings, but cant find them now.

 

 

[Martin of WickParticipant @martinofwick]

Andrew, can I ask how hot the motor gets when you are working the lathe moderately hard?

[Peter Cook 6Participant @petercook6]

Question, what problem is Icon trying to fix. The heat from the old fashioned resistive controller or a specific need for a more powerful motor?

As I read the OP the issue is the controller not the motor. Sewing machine (universal) motors are easily controlled by modern thyristor units – sold as lighting or fan controllers.

If he is happy with the power of the existing motor, then the simplest solution is a cheap thyristor controller to replace the one he currently has.

[Clive SteerParticipant @clivesteer55943]

Although the Jack Industrial sewing machine motor unit is a ready to go bit of kit it may be too powerful for a small watchmakers lathe. I have fitted one to my Pultra 1770 which is similar in size to the Cowells.

However I have recently been using fairly powerful brushless motors, salvaged from a laser printer, together with a small BLDC motor controller which works from 24v. Rather than using a mains powered supply I have used an 18V power tool Lithium battery which makes a relatively safe and portable setup. I have purchased ,from eBay, an adaptor that is designed to take a power tool battery, in my case a Dewalt, and has a USB connector and is intended for charging ones phone. I make a simple mod to this to bring out the 18V power direct from the battery terminals. I think the total cost of parts was around £30 excluding the Lithium battery. Unfortunately this isn’t a ready to go bit of kit and does need some understanding of electronics and some mechanical parts need making.

A couple of Nidec printer motors I purchased new from China are rated at about 80W and being out runners produce good torque. These have onboard motor controllers but as yet haven’t worked what signals are needed to drive them. To get around this I brought out the motor winding connections and those of the Hall sensors to feed to an external motor controller so I could evaluate the motor which proved its was quite powerful.

CS

[Michael GilliganParticipant @michaelgilligan61133]

A very interesting post, Clive !!

… a few more details of the motors you are using would be much appreciated.

MichaelG.

[John HaineParticipant @johnhaine32865]

I don’t see how the motor power is relevant.  The lathe only consumes the amount of power it needs to run at the set speed and support the cut.  It isn’t as if the motor keeps on consuming 750W while the lathe only needs say 25W and the rest goes into causing a meltdown!  The motor power is the maximum it can deliver running at the specified speed.  Given the convenience of the Jack solution and the fact it has been used by other people in similar applications must make it a good candidate.  Simple thyristor dimmers and the like are best avoided in this day and age.

[Peter Cook 6]

On Peter Cook 6 Said:

Question, what problem is Icon trying to fix. The heat from the old fashioned resistive controller or a specific need for a more powerful motor?

As I read the OP the issue is the controller not the motor. Sewing machine (universal) motors are easily controlled by modern thyristor units – sold as lighting or fan controllers.

If he is happy with the power of the existing motor, then the simplest solution is a cheap thyristor controller to replace the one he currently has.

I find the motor absolutely feeble, and the speed is very hard to keep constant. It’s also rather noisy! I have one of the ‘Jack’ type sewing machine/controller setups on my Singer 20U (sewing) machine, replacing the traditional constant running clutch motors. It’s great, but I was looking for something a bit smaller – I have my watchmakers lathe on a board that I can stow away when it’s not in use. I’d like to keep that convenience and the sewing machine motor is quite large (relative to the lathe!).

[icon]

On icon Said:

[…] but I was looking for something a bit smaller – I have my watchmakers lathe on a board that I can stow away when it’s not in use. I’d like to keep that convenience and the sewing machine motor is quite large (relative to the lathe!).

Exactly the relevant  point ^^^

MichaelG.

[Andrew EntwistleParticipant @andrewentwistle]

Hi Martin,

I have not worked the lathe hard so I don’t know how hot it can get, I’ll do a test with something like 1″ steel and will get back to you, probably the end of the weekend.

Andrew.

[BazyleParticipant @bazyle]

Even a domestic sewing machine motor is large compared to the headstock of a Boley. I think apart from the noise a modern battery drill is about the size/power you need. Maybe asking on the Model Boats forum (see bottom of this forum page) would get advice on a simple package of motor and controller as they will have experts on the small motor field.

[SillyOldDufferModerator @sillyoldduffer]

Whilst brushless are the best of all possible motors, I’d be inclined to go for a brushed e-scooter motor.   120W is a common size, plenty of power and torque for a watchmakers lathe, bigger if needed.   Also required, a power supply and PWM controller.

Duffers patent list of motors for machine tools, worst to best:

• Universal motor, common on old sewing machines and small lathes.  Chief advantage speed control, otherwise poor torque and low power.  (Though speed control is technically easy, it’s done with a rheostat, liable to give the operator a hot foot!)
• Single-phase motors.  Chief advantage they work off ordinary AC mains.   Otherwise no speed control, low starting torque, unwelcome vibration and relatively poor reliability.   But being able to deliver conveniently up to several HP covers up a multitude of sins.
• DC Brushed.   Low vibration, speed control, high starting torque, and good power.   Disadvantages, brushes reduce efficiency and reliability.  Bit of a pain even though brushes are consumables.  DC supply required.
• Three-phase AC.  Highly Reliable and efficient with good power and torque plus low vibration.  Significantly enhanced by powering them with a VFD, which provides speed control and other goodies such as soft start.
• DC Brushless.  More like a 3-phase motor than brushed DC.  Markedly more efficient than 3-phase, plus somewhat better power and torque characteristics.  Good speed control.  Main disadvantage is a special controller is required, but these aren’t expensive or rocket science.   Closest yet I think to the ideal machine tool motor.

In practice, Universal and Single-phase motors work ‘well enough’ for many purposes.   But no-one who has had reason to upgrade to one of the better types has ever complained.

Dave

[Peter Cook 6Participant @petercook6]

I have installed this motor with this controller on my filing machine. I use a 24v power brick to supply it. Its a 100W brushed DC motor 100mm long and 68mm diameter. It works very well. Quiet, lots of speed control plenty of torque to drive the filing machine. It was simple to install and although the controller has a push on/push off switch in the knob I included switches on/off and foot/continuous to make it a bit more ergonomic.

 

 

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