mark 1 1/2 student with an inverter

[Paul Davies 16Participant @pauldavies16]

i have recently bought a student mark 1 1/2 (the crossover from mark 1 to mark 2).

can it be wired with an inverter to the main junction box of the lathe so that the original stop start works and i can use the original gears?

i know that i will have to wire the motor in delta configuration

[Paul Davies 16Participant @pauldavies16]

[Ian ParkinParticipant @ianparkin39383]

Short answer NO

You need to wire directly to the motor from the VFD

then use the switches to control the VFD

Exactly the machine i have with VFD but i have a clutch too

Ian

[clogsParticipant @clogs]

Paul, I have the mk2….I'm lucky enough to have full 3phase at home, I found the original switch gear a pain (mine was in-line with the chuck in the bottom left cabinet…(all original)….

also I might say bxxxxy dangerous….u loose sight of the chuck when bending down…..

The on/off switch is now housed on a bracket mounted on the top cover. U can now turn the machine OFF safely even if a bomb goes off….the original contactor burnt out and I thought it was a good idea to change everything….

Incidentally I still use the original suds pump switch mounted on the old switch cover….don't use it an awful lot anyway……most tools are carbide tipped…..

Mine never had a clutch but a chuck brake instead, (it was either or not both when ordering a new lathe I'm told)

I, got the simple but brilliant idea for the clutch from ''silly old duffer',(on this forum), he's made the conversion as well …..

• I will happily forward photos should u wish and am sure Mr S.O.Duffer will do the same…
• Found the clutch so handy when stop start function is needed….measuring…
• good luck

[not done it yetParticipant @notdoneityet]

Posted by Paul Davies 16 on 05/06/2019 15:23:08:

i have recently bought a student mark 1 1/2 (the crossover from mark 1 to mark 2).

can it be wired with an inverter to the main junction box of the lathe so that the original stop start works and i can use the original gears?

i know that i will have to wire the motor in delta configuration

Only if you install a very much over-sized VFD – in which case you would lose the programmable features of that option, I think. Prescribed for running multiple motors from the one VFD, I believe.

[Brian OldfordParticipant @brianoldford70365]

Why on earth would you want not to take advantage of the infinitely variable speed that a VFD provides when wired in the usual manner?

[Nick HulmeParticipant @nickhulme30114]

A friend and I re-wired his Harrison M300 for a VFD, we used all the standard switches re-wired to handle 24V control signals for the VFD so it now works exactly as it did with a 3-phase supply but with the addition of a speed control potentiometer.

[not done it yetParticipant @notdoneityet]

Posted by Brian Oldford on 05/06/2019 19:06:44:

Why on earth would you want not to take advantage of the infinitely variable speed that a VFD provides when wired in the usual manner?

Only for running multiple drives from the one unit. Presumably, the frequency could be varied still but if more than one drive was connected, they would both/all be driven at the same speed. I only mentioned it because they are available as ‘plug ‘n’ play for some installations. They have to be grossly oversized, so a rather costly option and only mentioned for completeness of an answer to the OP. You also lose the soft start and other. I suppose it is an option for replacing a static or rotary converter.

Just looked at ‘drivesdirect’ and they only offer 415 volt out for their plug & play items. They would allow the motor to remain star connected and there would not need to be any changes to the current switchgear. Very expensive and I doubt I would consider any such option, but there you go – they are out there.

[not done it yetParticipant @notdoneityet]

Posted by Brian Oldford on 05/06/2019 19:06:44:

Why on earth would you want not to take advantage of the infinitely variable speed that a VFD provides when wired in the usual manner?

Only for running multiple drives from the one unit. Presumably, the frequency could be varied still but if more than one drive was connected, they would both/all be driven at the same speed. I only mentioned it because they are available as ‘plug ‘n’ play for some installations. They have to be grossly oversized, so a rather costly option and only mentioned for completeness of an answer to the OP. You also lose the soft start and other. I suppose it is an option for replacing a static or rotary converter.

Just looked at ‘drivesdirect’ and they only offer 415 volt out for their plug & play items. They would allow the motor to remain star connected and there would not need to be any changes to the current switchgear. Very expensive and I doubt I would consider any such option, but there you go – they are out there.

[Paul Davies 16Participant @pauldavies16]

right i have got my head around wiring in an inverter to power the motor and i can also wire in a pendant to stop start and reverse the motor. how would i go about wiring in new switches for the start stop on the lathe itself and a forward reverse switch. it appears that all i need to do is replace the original switchgear with modern low voltage stuff to run through the inverter but being a clanky and not a sparky i'm unsure where to start. can anyone help?

[Ian ParkinParticipant @ianparkin39383]

So mount your inverter VFD and wire in the 3 wires out to your motor after charging the motor terminals to delta from star…

its best to supply the power to the vfd via an isolater

you can use your original handle switch and the reverse switch easily it don’t make any difference low or high voltage

your start switch just wants a normally open pair

your reverse wants a common to a NC one way and to a NO for reverse so whichever way your reverse switch is it sends a supply to the vfd to start in the relevant direction

You do need to be able to use a meter on continuity to work out the switches

you may also have a switch to the key on the cupboard and one on the gear guard

 

POST pictures of what you have if you are unsure

Edited By Ian Parkin on 11/06/2019 12:56:55

Edited By Ian Parkin on 11/06/2019 13:24:42

[john fletcher 1Participant @johnfletcher1]

On some three phase motors it is a simple job to reconnect the motor in DELTA from Star. Often it a matter of moving the brass links in the terminal box. Has your motor terminal box got four terminals, and has one of the four got three wires attached to it then it can easily be altered. Its not altogether daunting to take the motor apart to locate the STAR point, just take your time and be careful. There was some good picture on here some time ago showing how some one did it. The original controls can be used but on low voltage derived from the inverter, but not in the same manner as it was originally.John

[Paul Davies 16Participant @pauldavies16]

thanks for the pointers. if i get stuck i will post what the problems are with pictures as suggested.

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