Newton Tesla Electric Drives

As long as you are sufficiently disciplined not to unplug the motor whilst the vfd is live, you could have one vfd and two motors with a 3 phase plug/socket arrangement. Switching to 3 phase transformed my Centec from a noisy vibrating beast to a pussy cat

Edited By duncan webster on 19/01/2018 22:31:57

Don’t think I am well disciplined, possible save my pennies. Think I may change mill and seethe difference, but I also want DRO,

Need to spend time and think what I want for my cash.

But thanks for explaining the benefits

Hi JES

Perhaps this is an intrusion But hopefully it will explain why "Single Phase Motors" run roughly and cause Chatter Marks when Machining. Had this explained to me on another forum

To Quote Ken's Explanation

**LINK**

I hope this will convince more out there that there are better alternatives to "Single Phase Motors"

PS The Extra cooling fan is a great idea

Hi does anyone know if this company is still trading, I have emailed twice, once direct the other through their site, no reply.

I ordered a VFD from them about 3 weeks back and it was delivered promptly.

My lathe, as part of the deal, came with a VFD (Assumed to be NT by the look of the control box ) The motor I selected was 1.5 hp to replace the 2 hp single phase normally supplied.

In over 17 years of use there have been no problems . The VFD just does its job, the motor has never seemed to be short of power. In high temperatures, the cooling fan can be heard running, otherwise unaware of its presence apart from doing what is required.

It has made me IDLE. VERY rarely change the belt from middle gear, and very occasionally use Back Gear (more for my peace of mind, and to give me time to react ) Otherwise just use the control knob, very often used at max speed

There was one problem, the knob began to slip on the speed potentiometer shaft., a new clamp screw cured that

Howard

I have used half a dozen VFDs. 5 current and one previous machine. Current ones are: lathe x1, mill x1, mill x2 (spindle and power feed),and surface grinder x1.

Only one of these 5 drives has been re-motored (unable to start in highest gear when cold) and one has been converted from star to delta.

The surface grinder change (from star to delra) allows me to run different sized wheels at closer to optimum speed (or apparently to change the wheel ‘hardness’ by running at lower speeds). The lathe and one mill already have mechanical variable speed, but are so much easier with the control by a simple potentiometer. The other mill has a 6 speed gearbox.

Some advantages (for me):

Soft start

Variable speed.

‘Jog’ facility.

Simple motor reversal (needed on one mill when changing from horizontal to vertical) easy.

Safe motor reversal (only from reverse to forward on my lathe) without stopping.

Over-current trip.

Ability to expand the operational range of the machines (within safe limits).

Easy remote operation (by pendent control).

More reliable motors (no capacitors, centrifugal switches, overload or NVR switches required).

Easy extra emergency stop wiring with low voltage wiring.

Braking possibilities, where appropriate.

If chatter does occur, an easy (slight) change of speed often reduces/removes the problem.

Fewer belt pulley changes required (not a problem I have anyway).

Probably more reasons, but the above are worth, IMO, a change - even if only carried out at a time of motor failure.

I would look to change any substantial drive if I purchased any more kit (not very likely. The only single phase induction motors I am using are on the compressor, bandsaw and grinders/sanders, I think.

When considering the Newton Tesla package remember it is a one stop shop for a ready to go professionally designed and built unit. The parameters for the VFD will match the motor and good advice available on any deviation. If choosing a set of components sounds cheaper make sure you include cost of a control panel, an enclosure and cables etc. The temptation to screw a cheap VFD to the wall and connect it up with bits of 3core is not acceptable but of course what you do in your own workshop is mostly your business as long as your Setup does not fill the mains and airwaves with radiations that interfere with neighbouring equipment A VFD is one component of a system and should be assembled with the rest of the components required to protect it and make it compliant with electrical regulations for your and others safety.

Mike

I bought a Newton Tesla package two years ago, as i considered it was better to have a package plus customer service from one source rather than buy component parts,Had a problem with some damage to the control box in transit, NT promptly dealt with it. It has run ok ever since . It is a 1.5 hp unit to suit my Elliot omnimill. I have two 3 phase converters for some other machines and I think the vfd produces a better supply current. Plus the advantages of reverse,speed control,small size and the control box could be mounted to a more convenient position,the omnimills switch gear is mounted low down on the base below the swarf tray b--y stupid posn . The Omnimill came with an old corroded single phase motor for the vertical spindle which was on its last legs so I had to look at the options for motor replacement, original 1964 spec was 3 phase 3/4 hp which I considered not powerful enough ,1.5 was more suitable, but the machines bottom belt speed was far too high for tough materials and large diameter cutters.the vfd would overcome this major problem. The other 3 feedmotors a 2hp horizontal drive ,table feed and coolant pump,would have to be fed by the rotary converter. The horizontal spindle also had the speed problem ,lowest speed being too high.So after some deliberation I bought the VFD and its very good,just plug in and go.I have found that i can get a lower horizontal spindle speed by disconecting the motor belt and by swinging the vertical head around in two planes and a long belt I can drive the horizontal spindle via the vfd controlled vertical motor so can a slow drive for 6 inch dia cutters, ithe inconvenience of this long belt drive as I only need the slow speed say twice a year. The vfd was just over £400 but cant complain,the mill was a gift from a neighbour.

One thing I cannot really understand is the comments about noisy single phase motors which are supposed to vibrate which result in poor finishes,and moans about having to change belt pulleys, Back in the 1950s my father bought a combined wood lathe and saw bench I was about 12 at the time,it had a 1/2 hp Brook gryphon motor s/phase and soon learned how to use the lathe though I was banned from using the saw,I thought nothing about changing the 3 speed belt drive and the motor ran smoothly,later on it had to drive my EW lathe ,swapping the motor from from one machine to the other,at the time I could not afford my own motor for the EW. That Brook motor governor controlled starter is still running and powers my power hacksaw without complaint,My S7 has a 3/4 hp English motor supplied with the new lathe in 1974 still runs ok,and never any problem with work surface finish finish and i just change belts /back gear when I need to ,My Fobco new in 1967 has a good English made motor still runs ok.At my first job 3 lathes and two mills had all speeds changed by belt,no one complained about belt changing we just got on with it and they worked and kept on working,I dont remember reading in the ME many years back about any moaning about belt changing or noisy 3 phase motors. As I wrote above the vfd has its place ,can be very useful at some expense ,but is expensive. Though heres a thought how about going back to all belt driven machines via a line shaft and just have one vfd driving the shaft ,I just wait to see if someone asks whats a line shaft?

Perhaps off topic, but regarding single phase noise and problems.

Interesting! But it all depends on the s phase motor. When I got my new s7 in 82 I had to get a motor, and as I had already broken the bank I opted for a cheaper foot mount roped motor. It was TERRIBLE! The chatter and vibration marks made the new machine a real pug. I took it back n got a Brook Crompton redial the mount. Oh what joy! Super smooth, and used until I managed to get a cheap vdf in about 98

I bought NT's CL750 package for my S7 some years ago and in consultation with them also a second motor for my small mill/drill. Changing over from the one to the other takes only seconds. Touch wood, I have never had a problem from inadvertently unplugging the VFD whilst live; a simple precaution would be to attach a warning label to each plug.

Today, I would probably aim for a VFD for each machine and, of course, the choice of supplier is much larger now.

NT's service was good at the time and the few small problems were sorted satisfactorily

Looking for something else that I had seen on the M.E Site, but can't find now, came across references to Newton Tesla upgrade. I had been in touch with the company some time back being concerned that my 1947 ML7 runs on white metal bearings and wondered if they would stand 2000 rpm!. Supplier advised caution working at maximum revs, but it would be nice to have more control over cutting speeds. All the work done on the lathe so far has been done by ear!, If the sound of cutting/turning is nice and silky and the lathe is not labouring, then it's OK. You will now know that I have limited experience in lathe work.

So, gentlemen/ladies, your comments/advice please, bearing! in mind the age of my late and me, a little older. I have read through previous post's but every one seems to refer to an S7?. I would add that nearly all the work done on my lathe is done at the same speed, unless it is very obvious that it is too fast/slow, so the Tesla would be an asset?

Thanks

Mac

I don't think the lathe is an issue provided you don't abuse it by over speeding the bearings. (What happens is the oil pressure rises beyond the point it can be contained inside the bearing, and it releases causing metal to metal contact. The bearing is more likely to wear quickly than fail catastrophically.)

Most of my turning is done at a few standard speeds and, as you say, provided 'the sound of cutting/turning is nice and silky and the lathe is not labouring, then it's OK'.

I find speed control most useful for improving finish. Sometimes quite small changes make an obvious improvement. More noticeable with carbide than HSS I think. It's also useful to be able to crank the lathe up and down over a wide range without having to change belts, as when mixing small and large diameters in the same workflow. So how useful it is depends on what sort of work you do.

I don't recall anyone saying a VFD transformed their Myford into a super-machine, but no-one has ever said it was a waste of time and money either. Useful improvement rather than miracle improvement I feel!

Dave