Myford Motor Options

[Hugh Currin]

AS:

I like the "just to the left of the chuck". I recently put a VFD on my lathe and put it on top of the head stock. (If you follow this example, the hat is optional. :-)

I didn't enclose the VFD, as per recommendations, because it was expensive and I don't think it will see chips in this position. It may depend on the installation though. I integrated the VFD control with the existing lathe switches so there's no need to push any buttons on the VFD itself, at least during normal operation. But, if I needed to use the embedded VFD keypad I'd likely mount it in the same place.

Sorry to hear no motor for the weekend. Seems stuff is getting harder to obtain. I had a small lathe shipped today which has been on order since May 26.

I'll make a final decision when I actually see it all in the flesh, but I'm thinking that I won't fit the inverter/controller unit in the traditional place on the stand below the gearbox. I think it would be prone to getting oil and swarf all over it, and I'd probably end up putting chuck keys on it. Behind my lather is a set of dexion shelving with wooden shelves - I use the upper shelves for lathe tools, chucks, centres, collets etc. My current plan is to mount the control unit flat, screwed to the underside of a shelf. That puts all the controls at eye level, just to the left of the chuck. That feels like a better idea (I can always move it of it isn't).

AS

[Allen Smithee]

Just got an email advising that my 3-phase kit will be arriving on Monday. Better late than never (but only slightly).

AS

[Allen Smithee]

It duly arrived at sparrows-fart o'clock this morning. Initial impression is that it is extremely well packaged, with a large carton containing two smaller cartons (one for the motor and the other for the pre-wired integrated inverter/controller unit) surrounded with several cubic feet of shredded tabloids - the most constructive thing ever achieved by a week's worth of Daily Fail.

There's a comprehensive manual describing the complex installation process:

1. Bolt motor to lathe
1a. Attach inverter/controller to something (optional, but very tasty)
2. Plug in.
3. Make swarf.

I will need to make sure I thoroughly understand these complicated steps before starting...

Photos will follow.

AS

[Daggers]

Hi All
I hope you have no objections to a followup post to my post at the start of this thread.
I have just completed the first phase of my budget S7 motor conversion and am running now on the vfd’s control panel. Phase 2, remote pendant control in work.
The only problem I have encountered, so far is the difference in motor shaft diameters. 5/8”(15.87mm) original to 19mm new metric motor. I wanted to keep the original myford twin step pulley so I contacted Myford and was quoted £50($66) for a new pulley of the correct bore, alternative solution needed.
So I found an old 2”” pulley and bored the hole to 19mm, before the conversion, then when the conversion was complete fitted this pulley so I could bore the old twin step pulley to 19mm. Deepened the pulley keyway, fitted to motor with a new key.
Myford running super smooth and very quiet.
Stay safe

[Allen Smithee]

Well it's fitted, and what should have been a simple job taking 25 minutes actually took over 2 hours and wrecked my back. Nothing to do with the kit, and everything to do with those incompetent numpties at Myford!

For some inexplicable reason the Super7's motor is hung underneath the mounting plate rather than sitting on top of it. I tried bolting the mounting plate to the motor and then holding it in place while I refitted the plate's hinge pin, but it's impossible to get it into the right place. So I refitted the mounting plate to the lathe and spent an hour trying to hold seven and a half tons of motor up against the underside while I tried to pass bolts through in in-accessible places and thread washer/spring-washer/nut onto the other side. I eventually had the motor bolted loosly on, but I don't think my left arm will recover for another week or so! It then took 15 mins to nudge the motor into alignment and then tighten down the bolts (two of which were only just reachable and had to be tightened one flat at a time). If anyone else is doing this I would recommend making it a two-person job and then it would be much easier.

I fitted my brand-new cast-iron motor pulley, but even that needed both the start of the bore and the edges of the keyway slot dressing with a stone to remove burrs before it would go on. Took some time to carefully line up the pulleys and then fitted the belt, tensioned it and nipped up the clamp on the motor plate to hold it (Newton-Tesla's instructions say to lock it with just a little more than the motor's weight on the belt).

Then it was just a matter of plugging the motor's pre-wired cable into the inverter/controller box, and then plugging the three-pin plug into the wall. I hit the start button and...nothing. Not a peep. But a few second of logical thinking tracked this down to the fact that I'd pushed the emergency stop button when I'd removed the packaging, and to reset this (I eventually remembered) you have ti screw the button clockwise until it clicks. Then it worked perfectly.

Initial impressions - it is indeed extremely smooth, all the way from zilch to 'kin fast. With the original 1425rpm motor the top spindle speed was allegedly 2100rpm (according to the data plate). This is an 1800rpm motor so I guess it's now doing 2650rpm flat out. I bunged a piece of 10mm aluminium bar in the chuck and the surface finish was noticeably better whether hand-fed or power-fed. With an insert tool I tried taking progressively deeper cuts and it can definitely carve far more off in one go without slowing noticeably - so the extra grunt of the new 1bhp motor over the old and knackered half-bhp one is a bonus as well. The controller has start & stop buttons, a big mushroom emeregency stop button (which the instructions warn you not to use more than strictly necessary as it can damage the inverter's FETs), a forward/reverse switch and a speed control knob. If you wind the speed control knob fully "off" a switch clicks to put it into Jog mode, which turns the start button into a momentary-action switch for a very slow rotation speed (60 rpm or so). There is only one jog speed - I believe the actual inverter supports several, but they (newton-tesla) chosen not to implement this in the external switches to keep it simple. I'm not sure what I'd use a "fast jog" for anyway.

I still have to mount the controller/inverter unit somewhere, and then I'll explore the characteristics in more detail. But my overall impression would be 10/10 for Newton-Tesla for making an easy-to-install turn-key system that just does what it says on the tin with no faffing. Myford get a -5/10 for their cretinous motor mount concept, for which I am sure they will receive their just deserts in the 4th circle of hell at some future date.

AS

[Admiral_dk]

I know the feeling and fustration when things that are supposed to be an easy fit is anything but   

But it's great to hear that you got it all working as it should 
I hope that you will get many good hours with your lathe from now on.

Per

[Mcgyver]

Well done!   You overcame the designer's deep loathing for the customer and want of sadistic revenge and got to the happy place of finishing the job with everything working!

[Niels Abildgaard]

A twenty year old 918 lathe followed me home and got a tombstone to sleep on and a chinese industrial sewing machine motor (100£) as playmate.
I have put VFD on four lathes and time was ripe for something else.
Such motors can be had for silly money with 1500 W and 7Nm torque

https://www.alibaba.com/product-detail/1000w-1500w-Servo-Motor-with-Needle_1600096905094.html?spm=a2700.7724857.normalList.214.591356ecMWLjvi

A very early test is shown here:

https://www.youtube.com/watch?v=wRPKN4mkfbU&list=UUl1kMtx8XGqBr2dNLXEGBPw

[Niels Abildgaard]

A point of reflection - the motor I removed is the size and weight of a small house and is good for half a horsepower at 1,425rpm. The motor I'm replacing it with is a similar size and weight, and is good for a whole horsepower at 1,425rpm. In one of my RC aeroplanes I have a motor which is 50mm diameter, 55mm long and weighs under 350grams which I regularly use at 1.7horsepower at 9,200rpm. So why do I not simply get another one of those with a 6:1 reduction drive for a fraction of the size and (with speed control) half the price? It would probably need a flywheel to cope with the initial tool-contact loads, but what am I missing?

AS

For information only.
My 918 is not far from a Myford sizewise and came with a 560W singlephase motor/capacitor.
I have put a 600W sewing machine BLDC servomotor in the same place so that I can reuse the Gates 710mm belt.
The new motor is smaller and less noissy.I have tried to stall it at low speed and it can be done with a lot of force
of course but the power supply stop feeding and You have to zero speed handle before it starts again.
Having paid 90 € for motor and supply, I feel time for VFD threephase AC are running out

https://www.model-engineer.co.uk/sites/7/images/member_albums/162324/876555.jpg