Thanks for the kind comments.

John H – Quite correct it was a 1/4HP induction motor not a synchronous one. My excuse is that it was late when I typed the posting.

Hollowpoint – I have not really used it in anger yet so can't really comment. However tests show good torque down to 400rpm on the motor (more than the induction motor) and adequate down to 200. That gives me 135rpm (400) and <68 (200). I can control the motor down to about 70rpm (26 rpm on the spindle), but there is no useable torque down there. Top speed is limited by the spindle bearings which are rated for 10,000 rpm.

Ian T – that looks exactly like the kit I got (down to the same remote control), however I decided against using the DC control board, display and remote as you did. Investigation of the motor power control (the black box) showed that the input from the control panel to the board was a simple 5v PWM signal and the 5v supply and input stage on the board within the power controller was fully isolated from the power side.

I decided to build an Arduino based controller (another learning curve) which would also measure and display the spindle speed. The display is a standard 4 * 20 character LCD display. Like you I designed (in my case using MOI) and printed a box for the Arduino, the interface circuitry and the display (two more steep learning curves – the box was my first attempt at 3D printing).

The speed measurement is by a Hall sensor (again standard Arduino kit) activated by a couple of small magnets let into the back of the spindle pulley. Another bit of 3D printing holds the sensor in place between the pulley and the back of the headstock. The control knob is a rotary encoder (I decided a simple pot was too coarse for the 0-4000 rpm of the motor). The run/stop switch and control knob are in a separate box so that I can move them about and find the best (most convenient) location before building them into the new baseboard.

In the longer run I plan to add feedback control to the spindle speed using the PID libraries available for the Arduino – but so far attempts to do so have ended in failure – I am going to have to get out my old control theory books to get the parameters right.

If anyone wants any more info, please let me know.

Colin,

Mine did not have holes in the motor tube either. It did however have three holes in the shaft end plate ( and the other end).

Having checked, it weighs about the same as the Sherline motor which people happily mount to the headstock so I decided to do the same. I used a length of 25mm square aluminium bolted to the T slot on the back of the headstock, and fabricated a motor mount plate that pivoted on a length of 10mm silver steel rod, and uses an M5(?) locking handle to secure it.

The motor performed extremely well. Power was more than adequate, and using the standard pulleys I could get from about 100rpm to 10,000 rpm with reasonable torque. However there were a couple of downsides, which are fairly obvious in the top view above. The motor projects quite a long way past the headstock, as as I mainly use collets it interfered with getting the carriage with my DRO(!) close to the collet. Using a chuck instead of collets it was far less of a problem. The other issue was the proximity of the ventilation holes in the end of the motor to flying swarf. I made a solid aluminium cap to cover the end of the motor to cut the risk. Heat was not a problem.

With 20/20 hindsight I would/should have mounted the motor the other way round. For other reasons I wanted to swap the motor for a BLDC one as part of a revamp of the controller, and I did mount that motor the other way round using a similar mount to the back of the headstock which is far better. I think the same sort of mount would be OK for your motor.

The BLDC motor runs at 48V. Under the covers at the back are the driver, a 12v stepdown board to drive a leadscrew motor and the Arduino. Couple more pictures. The first is a better view of the BLDC mount – I also have a belt guard  (swung up out of the way in the picture). The second shows a better view of the lathe with its base and control panel while the third shows the wiring spaghetti under the covers at the back.

good luck. It’s worth the effort.

The BLDC solution is great, the main issue is probably cost. I got my motor for about half what they are currently asking. It only has one quirk. Over a small range of motor rpm (600-750) it has a tendency to suddenly stop of its own accord. I THINK the issue is that at low RPM the back EMF in the windings is low and over current trips the limiter in the control box. One day I will change something, but at present I simply ignore that motor speed range (use a different pulley setting).

I don’t really have an ELS (yet!). There is a small geared brushless (JGB37-3650) motor in the lathe foot ( 60mm square aluminium box section) which with my Arduino code gives me variable speed power feed in both directions which I find handy.

The motor outputs 6 pulses per rev, which with the gear ratio gives me about 400 pulses per mm of carriage motion. So in THEORY I can track the position of the carriage to about .0025mm. So far I have implemented an electronic autostop which will stop the feed at a predetermined point. However the motor has inertia, so depending on load (cut depth) the carriage stops plus or minus .05-.1 mm out, and I loose track of those final 20-40 pulses.

I don’t know if its a “feature” of the motor, a problem with my Arduino code or a quirk of the Arduino pulse counting hardware. Until I find out the problem, my ambition to have a fully functioning  ELS is on the to do list. As all the screwcutting I need can be met with taps and dies, the demand has not risen enough to drag it up the list.

Even further down the list is an idea to replace the brushless motor with a stepper motor and do it properly, but that means re-engineering the leadscrew fitment – so that is even less likely.

Good luck with whatever you choose to do.

You are correct Bernard – it is a lot of (unnecessary) electronics, hardware and 3D printing. I also have a couple of watchmakers lathes. However I enjoy the “making”, love a challenge and get a buzz from succeeding, particularly at something I have never done before. I can’t see me making steam engines or similar, so I make other unnecessary but satisfyingly challenging useful(?) things.

As I said earlier, the screw cutting “issue”  is on the round tuit list because I do use taps and a die holder for threads and so far have not had a need that would escalate the “issue” up the list.