Shaper 3 phase or Single

[John OlsenParticipant @johnolsen79199]

My 18" Alba has a 460Volt three phase motor with a buried star point. One interesting experiment that I have tried is running it from a VFD which of course only provides it with 240 Volts. ( When running at 50Hz.) This means that the motor is running at half its rated Voltage. It actually runs fine like that, although I didn't try any really heavy cuts. But a heavy cut on a machine like that is about quarter of an inch…It behaved well with cuts of about an 1/8 or so, which is plenty to take off unless you are in a real hurry. So…if you have a machine where the motor is not easily restrapped, it could be worth a try. The other way I have run that machine is from single phase, stepped up with an autotransformer made from two isolating transformers, and applied to two of the connections. Starting in the correct direction is ensured by a boot to the pulley at the right moment. With that setup you don't get full power either, but it is plenty for the above mentioned 1/4 inch cut, on steel or cast iron. It also means that you have a 460Volt supply in the workshop, so don't mess around with this idea unless you know what you are doing.

John

[john fletcher 1Participant @johnfletcher1]

I'm glad you got your shaper up and running, I wish I had the spacer for one. Very useful machines and you can make your own cutters.OK also about the drilling machine idea.The inverter for my milling machine is mounted on the workshop wall, so I made a control box which easily fits on the machine.The box has For, Rev, speed control and digital read out (from an article in MEW) I now drill a hole, switch off, remove drill, insert taper tap and with very slow speed insert tap for a few revs and finish off in the vice. I regularly tap 2,4and 6 BA never broken a tap. All the threads are square,which is some thing I couldn't do in the past.Ted

[colin hawesParticipant @colinhawes85982]

Several years ago I converted my 3 phase Elliot 10M to single phase using a single capacitor in the way shown in the late Jim Cox's excellent book. I had to separate the 3 coil ends at the star point to bring all the coil connections to the terminal box. Sometimes the motor is undecided about which direction to start (something I will get around to improving one day) so I give the clutch pulley a gentle nudge. As the clutch is then used to start and stop the machine I don't have a problem with this unless it safety demands that it is wise to switch off. Much of the time the motor starts easily without any "encouragement" from me. The motor doesn't overheat and will run happily all day with enough power for my needs. Colin

[GoCreateParticipant @gocreate]

Hi

I took my Elliott 10M motor to an electric motor rewind company and they re-configured it to run in 240v single phase. It's been running many years now without any problem, it struggles a little to get to running speed, once up to speed it's fine.

I guess they did similar to that described by Colin Hawes above.

If your not sure about doing the modification your self then this may be a more economical route.

Nigel

[Nigel McBurney 1Participant @nigelmcburney1]

whats wrong with single phase motors,thousands of Myfords have been supplied with single phase motors,, I have an elliiot 14 inch shaper 3 phase running off rotary convertor it runs ok and there is no need for variable speed on a shaper, too much modern technology being applied to sturdy but old design machines.

And I do not see where convertors etc powering three phase motors are smoother than single phase motors, My colchester triumph 7.5HP three phase running off a static convertorwhich affects the spindle and produces slight vibration marks in the work surface, I temporarily tried a single phase 3 hp motor on the lathe and the vibration marks disappeared, a rotary convertor from a different manufacturer would probably improve the situation but at my time in life the expense is not justified,I just live with it , yet my master 2500 running off yet another static converter ( Transwave)gives absolutely no trouble and surface finish is excellent.

[Author]

Posts