Taig lathe DC motor

I enjoy seeing the projects other members have completed, and am in awe of the standard of engineering on show. As a contribution, and in thanks to those who have helped me up the learning curve I offer phase 1 of my first real project.

I have converted my Taig lathe from a basic synchronous motor to an Arduino controlled DC setup. Speeds now available range from <100rpm to 10,000 rpm ( spindle limits).

The new motor is a 200V DC 200W 4000rpm ex vibration plate spare from E-bay which came with a a driver unit (the black box) which accepted a PWM input.

Implementation has involved learning turning, milling, Arduino programming, 3D design, 3D printing, and resurrection of my 50 year old electronics expertise.

Phase 2 is to build a new baseboard to bury the wiring, Phase 3 is a leadscrew and thread follower system for screw cutting.

More images are in the Album.

Edited By Peter Cook 6 on 02/02/2021 23:36:30

Looking good Peter,

I would be interest in seeing an article on the hardware and software, etc that you used.

PauL

Well-said, Paul

+1 from me

... but it does prompt an interesting question regarding the publication of articles in the magazines :

Do we have similar ‘Code of Conduct ‘ constraints to those of the forum ?

If so ... publishing a detailed “bill of materials” may prove unacceptable.

MichaelG.

Edited By Michael Gilligan on 03/02/2021 08:28:02

Nice! But to be pedantic the original motor was almost certainly a single phase induction motor, not synchronous.

How are you finding the motor? Does it perform well? Good torque? I ask because I have just bought a similar one for a cowells lathe.

I believe I have the same motor on my Cowells drill now - giving variable speed on it's three pulley settings. It's a 200W, 200v DC brushed motor. It seems to have enough power but I only use it for small work - having a larger 12-speed Warco for any heavier drilling.

The motor is held in a 3D printed 'saddle' designed using Open SCAD and 3D printed on my Sovol S01. I thought about replacing the existing control board with one of my Micromite speed controllers - very easy to do as it's just PWM (a few lines in MMB) but decided to retain the existing controller - at least for now.

I 3D printed a box for the controller but used Solid Edge 2020 to design it - partly to practice my emerging skills in 3D CAD but also because this was very much a one-off, custom design. I was quite pleased with the result and the new set-up works well with the existing IR remote. I've still got a few things to do before it's finished but getting there - albeit slowly.

Regards,

IanT

Edited By IanT on 03/02/2021 12:03:15

Here is another view of the Drill/DC motor set-up. I'm afraid I cannot see how to rotate this image - it was the right way up when imported...

Regards,

IanT

BTW - if anyone has the same DC controller board (as can be seen above) that originally came with this DC motor - I'd be quite happy to share the STL file for the printed box to mount it in (or the Solid Edge .par file if preferred).

I'm sure it's not perfect (e.g. could be improved) and takes about 11 hours to print but I was quite pleased with it.

Regards,

IanT

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.

Nice work, I'd be interested in doing something similar at some point.

Rob.

Hello Peter,

Yes, I realised that the board could be replaced with any PWM signal source but decided that I'd try the existing set-up first and avoid adding any further to my TUIT list. The existing board let's me set speed incrementally or just use the three pre-sets (slow, mid and fast) which is what I tend to do - but in theory I have a 9-speed drill now.

Regards,

IanT

Good to hear about the motor.

Since you mentioned making a new base board you might be interested in this I made using aluminium extrusion:

**LINK**