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

[Martin of WickParticipant @martinofwick]

As sod says,  Scooter /cycle motors come in various powers, are compact and have a manageable RPM. I use one like  below for a jeweller’s style  sensitive drill running off a 6A 24v black brick PSU with a relatively decent quality DC controller (ie not the cheapest £3 ones!) speed controller. It even came with a 3M timing gear so I only had to get one more for the counter spindle.  More powerful ones are available

Plenty of grunt for drilling all materials up to 10mm and compact, round belt slips long before motor stalls out (except at very low speeds).

Thought about replacing the ex washing machine motor that powers my picador mini wood lathe. The only advantage of the faintly comically sized washing machine motor is that it delivers an almost perfect 1000RPM when supplied with 36V so it can power the lathe spindle directly without too large a pulley.

 

[Martin of WickParticipant @martinofwick]

Andrew, PM sent…

[Clive SteerParticipant @clivesteer55943]

The BLDC motor controller type I most often use is eBay number 193 153 079 741 which is rated at 380 W and can also operate over a wide voltage range (12 to 60V).

A smaller less powerful version is eBay number 314 153 079 741 but it is only rated at 40W and limited to no more than 24V.

Both of these types need motors with Hall sensors. There are similar types that don’t need Hall but these won’t work to zero RPM or start against high inertia loads

The out runner BLDC printer motor came from a Chinese supplier called meilianu0 or maybe meilianuO. However the motors I purchased are no longer available.

The same supplier has a lower power version eBay number 226 021 167 408

A more common style BLDC motor is eBay number 285 292 763 888

The Dewalt battery adaptor is eBay number 203 996 988 305

Happy hunting.

CS

[Michael GilliganParticipant @michaelgilligan61133]

Thanks for the info. Clive

MichaelG.

[Andrew EntwistleParticipant @andrewentwistle]

Hi Martin,

after improving the belt tensioning arrangement on the Perris lathe I did a succession of cuts on the OD of some 1.25″ steel round for about 20 minutes. The chuck was running at about 400 rpm and I kept the cuts as deep as possible until the one or more of the belts slipped. Input power to the controller varied between 60 W and 100 W. The motor showed no signs of stalling ever and neither it or the controller showed any signs of warming. The motor was sold as 550 W so I guess even if this rating is questionable it is still conservatively rated for this job.

In the past I used a 90-120W conventional sewing machine motor to drive a Pultra 8mm watchmaker’s lathe which also provided more than enough torque and was only limited by belt slip.

Andrew.

 

 

[Martin of WickParticipant @martinofwick]

Andrew,

Thanks for the info. Useful to know that you can run this class of motor at aprox. 1/10 of its rated speed and get adequate power and torque without the consequent high current draw and heating you get with brushed motors or the total loss of torque with induction motors. The primary concern for me was that as these motors were originally produced for the sewing machine market (i.e. high speed low torque devices), there might be issues when running them in low speed, high torque mode.

Being an oriental product, the 550W rating is probably the absolute maximum at highest speed achievable at the point of failure! Who knows what the continuous power rating is. Thinking positively, these motors were aimed at the industrial sewing machine market to replace the typical clutch motor, commonly a two pole induction in the range of 1/2 to 3/4 hp so the rating may not be that far off (assume 1.25 safety factor!)

I have looked and not been able to find any published characteristics relating to speed, voltage current, torque, efficiency etc, so have not been minded to acquire one yet. Secondly, these units never seem to have an accompanying parameter sheet for the control/driver unit

If I had any access to a lab dyno it would be interesting to get one to fully test, especially now you can get them adapted for devices other than sewing machines.

 

 

 

 

[Author]

Posts