Member postings for john fletcher 1

Hello Duncan I like your description. It is good practise to exchange any two incoming lines when reversing a three phase motor, and you will be successful every time. Exchanging connections on the motor terminal box you might be lucky on direct on line, but what about star/delta. I once went to a job where the customer has requested to have a motor direction of rotation reversed on a star delta starter/ motor, some one has rearranged the connection in the motor terminal box. The motor started OK on star but what a commotion on delta, it attempted to reverse. It took some time to work out what had happened and to reconnect the incoming lines in the correct manner. Stick with the lines and you always be successful. After a rewind we had a home made rotor mounted in a Perspex tube, the motor was connect up on a low voltage supply and you put the rotor inside the stator and noted which way it rotated, we also had a home made growler for locating stator winding faults. They wouldn't be permitted, now to dangerous. John

When I first posted the story about Peter's motor, never did I ever think I would start such an interest in 3 phase motors. If readers go back to page one they will see that I had already described incorrect motor connections and the result. Anyway I'm sure readers have learn a lot. Not sure of the state of progress regarding Pete's vibrations. Happy Christmas to all. John

As John Haine, above states it's not that simple, I suggest readers read the article highlighted in John's post above.

Now a true story and my experience. Several years ago a friend was given an Italian made circular saw machine which had been used to cut aluminium for secondary double glazing. The motor had literally been ripped out of the housing, a motor with six unmarked wires poking out. My friend asked me to wire it up in Delta and to run the motor via a capacitor set up for a grinder. I traced out the three sets of coils, no problem, but when I attempted to run the motor it got hot very quick and ran very slow with a strange noise. I realised what I had done wrong and knew of the arrangement to which John refers, I had seen it done by pucker winders.I simply rearranged the coils connections until we got it correct, not a long job once you realise what is wrong. This was the first time I had experienced this fault as all other motors had markings on the coil ends. Out of interest I deliberately wired up a motor incorrectly and the fault clue appears to be slow speed, strange noise and motor getting warm if not hot. Better mark the leads out clearly, if possible. John

A friend has a Colchester lathe, fitted with a three phase Delta connected motor powered via an inverter. In former times when the lathe was powered via a converter and the motor connected in Star with a pilot motor running he says he didn't have any vibrations and every thing worked well. Some time later going modern, he bought an inverter for speed control, then he says vibrations started. My friend has dismantled the motor to check the bearings, all OK, he did the same to the head stock( he tells me these are very expensive) all OK. I recall some one HERE in the past suggesting altering the inverter control frequency upwards to reduce the noise of the motor. Your practical suggestions would be much appreciated. John

Yes.I have an industrial quality foot switch controlling my drilling machine, the switch is wired in series with the stop push. My foot has to be pushing down on the foot switch whilst I press the GREEN button. otherwise nothing will happen Take my foot off the foot switch and the motor stops. As the contactor coil current is very small, thin supple armoured cable can be used (Sy), don't want a piece of sheet steel falling and cutting into the cable, I have seen this happen. I have a drill vice and clamps and do use them, especially when drilling sheet steel John

Back to Alan, the Huanyang inverters which several of my friends have is 2.2 KW model, didn't see a part number. I altered the maximum current to what ever size of motor they needed. One has a Harrison I think 130, with a 3HP motor, another a much smaller lathe so lowered the maximum current as per the motor name plate. Once you get the hang of pressing which button and pressing one twice its OK. I've kept a list of notes for future use. If you send me a PM with your email address I'll send you a copy. The first one we bought was £90.40 it came from Leicester and was here in 3 days. One other came from some where in Germany and it was here in less than a week, strange old World. I've had a look inside and they look very good, I have 3 inverters of other makes of so called top quality, all second hand and can't see much difference. John

I have a slightly related question. What is an environmentally friendly and safe way of disposing of exhausted battery acid ( Sulphuric Acid), which has been used for other purposes. John

How many of us ACTUALLY need next day delivery. Some of these delivery persons just might be on zero hour contracts, whilst many of us are enjoying ourselves in our workshops. John

Hello Kenneth, to cut most Metric course threads you will need three extra gears25,33 and 34 these are readily available £9.5 each from Myford here in UK. Also there is a small device which permits the bango to drop further down to fit even more/larger gears to extend the thread cutting range. This home constructed devise was the subject of an article in Model Engineer Workshop some time ago, I have the article. I also have a table showing which gear to fit and which gear box settings you need to cut a particular Metric thread. If send me your email address via a personal message I might be able to help you. John

Dewhurst switches are for reversing once you have stropped the motor, then use your starter to restart the motor again. The contacts are flimsy and are not really adequate for continually starting and stopping the motor especially on an ML 7 without a clutch. I haven't seen the Chinese switches which Andrew refers to but have seen other electrical products and all so far have been good, especially their inverters for around £100. John

If you go to a ship chandler, agricultural part dealer or earth moving equipment dealer I think they will have what you are looking for.I have an equivalent list for oils and here are a few oils suitable for Myford lathe. BP Energol HLP 32, Castrol as Clive says, Gulf Hydrasil 32,Texaco Regal R&O 32, Shell Tellus 32,Mobil DTE Light. I take along a cleaner empty milk container and get a litre for about £2 or a little less. John

Hello Alan, I've 3 friends who have fitted HuanYang inverters and have no complaints what so ever. I programmed the inverts for them and made a simple program list so if you do buy one I could send you a copy. Please don't get the idea I'm an expert, just some one who got there in the end. Generally speaking it is easy to change the motor into Delta. Some one posted an excellent series of pictures on here about changing over from Star to Delta. John

Back to Neil, I do it often but not in broad day light. John

In former times plumbers soldered lead pipe and under ground cable jointers soldered the lead under ground cable outer sheath. To prevent solder going to non intended places they masked off areas using plumbers black as it was known. Recently I've been making a small boiler, I used Copydex and a soft lead pencil to contain/restrict the Silver Solder from going to where I didn't want it to go. I remembered plumber black and wondered if it was still available or how could I make some. John

Dave if you send me a PM with a phone number or email address I might be able to help you. I'm also in North Yorkshire.John

I suggest you get yourself Huanyang inverter 2.2 KW which some of my friends have, for around £100, not one has experienced any trouble or problems. As for a motor running at high speed and not over heating, when you double the speed you square the volume of air the fan is pulling through the windings, but what about the bearings, some cheap motors have phosphor bronze bushes, especially on the non drive end. If the lathe is under powered take many small cuts, its easy to get ambitious taking heavy cuts on a hobby lathe and break some thing There is always tomorrow round the corner. John

Providing the owner doesn't want to run all three motors at the same time and as you say, not interested in using all the feature available, how about one outlet from the inverter and THREE plugs,one for each machine, use any one machine as and when, type of thing. Providing all motors are say 4 pole and 1425 rpm or 2 pole and 2850rpm and set for highest current I can't see any problem.There appears to be a lot of mythology surrounding inverters, perhaps some one who has a lot of industrial experience might like to pass on their thoughts.John

Sounds as if you have a capacitor start and run motor. if so, both capacitors are in circuit when the motor is starting up, two in parallel. Once the motor is up to speed the centrifugal switch opens (it is mounted on the rotor) disconnecting one of the capacitors from the mains. the motor continues to run one capacitor only. The run capacitor is a quality capacitor as it is in constant use and it doesn't matter which way it is connected polarity wise. The actual value can differ manufacture to manufacture. The start capacitor is a special AC electrolytic with a short time rating and it is this one which often fails when the centrifugal switch sticks closed, it is normally a high value 70/ 120 again depending on who made the motor, it doesn't matter which way round the leads go. As the capacitors are working on the mains they too should be tested to comply with the wiring regulations, all electric components and wiring should be tested at twice normal working voltage, so a 500 volt DC insulation tester ie a Megger is suitable.There are also other makes of insulation testers which can be used. A capacitance meter ONLY tells you its capacitance. Should you need further help send me a PM. John

To alter the speed control exchange he TWO wire going to terminals FC & FS leave FR the centre one as it is. Pleased to see you have been helped out, commendable, as it should be.John

I've wired up a few 3 phase motors and Huanyang inverters for my friends, no problems so far and that must 4 years now. I have a Yaskawa, Omron and a very early one supplied by RS about 30 years ago (programmed by dipswitches) mine are all preowned, as the used car salesman says and never had a problem with any of them. Why on earth people continue to knock Chinese products I'll never know, is it our continued EMPIRE prejudice, I ask. Go to Warwick exhibition today and see if you can find a new British made product on sale, it might be badge engineered. The same mentality prevailed in the early 1950's regarding Japanese motor bikes. Possibly some of the more expensive inverters are also out source in PRC or Singapore like the Dyson vacuum cleaners. If you think it will do the job just buy it. John