Here is a list of all the postings john fletcher 1 has made in our forums. Click on a thread name to jump to the thread.
|Thread: Colchester Student Mk1 Won't Start|
After all the hassle you have had, wouldn't it be better and easier to get a 3 phase motor and inverter. I think you would get the pair for the price of the converter and have speed control. Several of my friends have bought Huanyang inverters for around £90, not one has ever complained about them being faulty and they got a motor from a club members on the cheap as well. The coolant pump was easy to alter so it runs from a 13 amp socket. John
|Thread: 4x6 bandsaw|
Recently Brian Wood of lathe gear fame and who is often on here, described how to align the wheels using a length of wire or fishing cord. I have one and whilst they are very useful they can be trickie to sort, be very patient. John
|Thread: 1P 240V Lafert Motor In Colchester Student Lathe - Wiring Help|
I'm glad to see you have the motor running after all the searching around. By your circuit diagram that relay is a current operated type as fitted to lots of fridges, has to be one that matches up with motor starting current, not any old one. You can easily wiring a reversing switch it be needed, but do also fit a proper motor starter with No-volt release and use it for starting after selecting DOR. John
|Thread: Air line / compressor fittings|
Many thanks to all who replied. I've decided to discard the old hose and fitting and move on to modern ones PLC or Euro. John
I need a connector for my air line to compressor and so far been unable to view one on the net before purchasing. My description, it needs to have a female 1/4 " BSP thread one end, the other has sort of captive half shell which, when screwed down traps the plastic pipe end flange. These were often fitted to cheap DIY compressors. John
|Thread: What Did You Do Today 2020|
Just been reading SillyOldDuffer and thought this maybe of interest.
Some years ago I used to pass by British Steel Appleby Frodingham plant near Scunthorpe and noticed a new works being built close by, that was before Mrs Thatcher was prime minister. On inquiring, I was told British Steel was building the latest computer controlled steel making plant. Later on certain Mr Macgregor (who later became Lord Macgregor) was instructed by the government of the day to get rid of the now, almost ready for testing, plant. My acquaintance told me China bought the lot, and that a party of Chinese armed with pots of paint itemised everything down to the last washer. I was also told that Chinese ship docked in Immingham and took everything away. How can we compete with worn out equipment, when others have the very latest at knock down prices? Perhaps readers from Scunthorpe might comment on the accuracy of the above.
|Thread: VFD Question|
I nail my colours before the mast and agree with Old mart above.
Hello Gerard from the information you recently posted it would suggest your motor is a two speed one, with POLE changing switching to give the two speeds,and NOT Star/ Delta. John
|Thread: Myford ML7 clutch|
Several years ago in Model Engineering Workshop there was an article on making a clutch for a Myford lathe. My friend an I each made a clutch for our lathes. Later I sold my ML 7 and bought a Super 7 with PCF and G/box. My friends clutch is still going. No motor likes to be switched ON. I have never heard of a Myford motor actually failing for that reason, they do get hot but soon cool down and are OK again, a lot of mythology around motors. It's those Dewhirst switches caused problems, OK for changing DOR when the motor is stationary and when used with a proper DOL starter. John
|Thread: Bottled Gas Suppliers|
Adam gas is available up here in sunny Scarborough and in the York area as well. John
|Thread: Electric motor ratings|
To Maurice Taylor I cannot to send you a PM. However, I'm unable to read off the lower numerals on your scope trace, was the duration of the surge current about 4.5 cycles of AC, then things settled down to normal running current.of 3.9 amps. Also, was you measuring the volts drop across a series resistor to obtain the trace.John
|Thread: Myford Super 7 screw cutting gears (metric)|
Hello steviegtr, I've got Brian wood's excellent book and its all explained in the book, together with good clear photos. The shaft you are referring to has a pair of gears on it, which are keyed together. So you can change the outer gear, but you do have to lower the quadrant as the replacement is larger in diameter. In the book, it shows the shape and gives the dimension of the gear adapter which needs making. Brian also suggests making a little tool which makes adjusting the quadrant an easier task. Then you will need the tables of which there was a lot of discussion about in Model Engineer Workshop, when some errors were discovered, not pointing a finger anywhere,. Anyway, I think the book is worth buying. John Steviegtr
|Thread: Dewhurst reversing switch|
Back again Mani. I see your motor is different to the one my friend has,it had just two capacitators and yours has three. All the marking I mentioned came from my friends motor and was attached to each wire.
Leaving all that to one side and looking at the latest picture from you, I think all you have do is move the copper links from the vertical positions to the horizontal positions. I notice both copper links have proper machined slots in them to facilitate easy repositioning. The electric supply still goes to 1u and 1v as before.John
|Thread: Need help on wiring a three phase motor|
Michael Birds picture is a good clear one, showing what is required to convert from star to delta. N is definitely not the earth connection, that was the star point when it was star connected. The program for the inverter can easily be altered/ adjusted down for lower currents rating of smaller motors. Better to get a larger than needed in the beginning than wish you had latter. Some of my friend have bought Huanyang inverters for under a £100 each and no one has had any problems with them. One is more than five years old and still going strong.John
|Thread: 2nd Hand Hearing Aid Reprogramming?|
Ok Clive, when I was in India and Turkey it was an easy job to get the lenses changed and you got a glass of tea whilst you were waiting. I've seen the round lenses, as the optician was sort of proud to show off the process and his little German made grinder. I like the frames as I can look under the car bonnet and not have the glasses slide off. Incidentally was you REME ? John
Not hearing but vision. My workshop spectacles have wrap around my ears side frames, the type grandad had years ago, the frames themselves are very old. The lenses are bi focal and according to my recement eye test need replacing. Does anyone know of a company who will carryout the change for me. I do know how simple it is to ground lenses on the small grinding machine. Not one local optician will even consider the job. John
|Thread: Dewhurst reversing switch|
Hello Mani, first of all take a photo of the motor terminal block as it is now( in motor working mode). Hopefully you have a multi meter or a plain Ohmmeter, better still can you see making on the wires such as U1 & U2 which are the run winding wires. Also Z2, CA4, CA2, SW and CA1 & CA3. Having now got the picture or sketch of the original terminal layout remove the both links and locate U1 & U2. I think the two blue wires are connected to terminal which is CA1 & CA3. A blue wire to each capacitor. John
U1 to Dewhurst terminal 5,
U2 to Dewhirst terminal 7
Z2 to DH terminal 2
CA1& CA3 to DH terminal 6
. 240 volt supply to 1 & 3. Locating U1 & U2 the run winding is important.
|Thread: Colchester Student Mk1 Won't Start|
Usually there are two banks of capacitors, start and run. All in parallel when starting, then larger set disconnects connects manually or automatically when up to speed. I helped a couple friends in the past and one had a manual rotary selection switch which adjusted the run capacitors in or out. When the motor hummed along that was the correct number of caps. If it sounded right it was right.The other had a current operated relay, which disconnected all of the start capacitor when the motor was up to speed, no adjustment, all or non, type of thing. When a pilot motor was fitted things really improved. Coolant pump was wire to Delta and fitted with I think, a 4 micro farad capacitor and ran from a 13 amp socket. John
|Thread: Omron Varispeed V7 - external potentiometer HELP|
Back again, I forgot to mention my inverter is a Omron Sysdrive 3g3ev and the potentiometer is 2K linear. I've had the inverter on my drilling for more than 10 years and almost any very small single pole change over switch with centre OFF will be OK. John
I haven't noticed any one mentioning that the potentiometer should be a linear type.
Peter once you have got the drill working you may consider the following idea. If you wire in a reversing switch it is very handy. I drill 3mm hole, then adjust the speed to very slow, stop the machine. Next put 4 BA tap in the chuck, turn on the drilling machine again and very carefully pull down the quill so that the tap starts to make a thread. Just before the tap bottoms flick the reversing switch. Takes a bit of concentration, but works OK for me and I haven't broken a tap whilst doing it. Same with 6 BA. John
|Thread: Fixing the AVO|
You will find a lot of information regarding AVO meters on Vintage Radio, it is free to join, and there are many pages of AVO info. I haven't heard of anyone carrying out movement coil rewinds before. Good for you and its now working. John
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