Thanks for these thoughts. I have no problem with single phase switch units and am also OK with 3 phase on paper (though no direct experience)
- and I have a friend who is an ex-RN electrical engineering officer if I need any assistance. For me it's the time - pricing up the RS stuff with all the bits and bobs needed, plus VAT, and the difference starts to look fairly modest even before you reckon all the extra work involved. I'm sure if I was prepared to wait and spend time it could be done for half the cost, but there are other things I'd rather do.
And I do know what you mean about the instructions - I have a
3-phase/inverter on my T&C grinder, bought second-hand with no instructions, and I have no idea how to change anything. Fortunately it is not the sort of machine where I need to, so I have just let well alone.
The jury is still out on what happened - I hope to dismantle the motor assembly this weekend, tedious job as the lathe is hard against a wall and too heavy to move easily - but I'm pretty sure the motor is not burned out. It is locked solid, won't turn even a tiny fraction of a degree (and yes, the clutch etc. is all disengaged). I am wondering if something has got into the casing, or the centrifugal switch has fallen apart or something.
No need for a 'trade account' with RS, I've been buying from them for many years without any kind of trade account (maybe I ought to open one !!). Brad.
Yep - anyone can buy from RS; the difference is that if you have a trade account, the postage is free (as long as you order via the web). Used to be a guaranteed next day delivery too...not quite that good nowadays but never taken more than 2 working days.
Replied to this post as in many ways the comments are different to mine.
I installed a 750watt inverter and 3 phase motor on my Denford Viceroy. I have been involved in machine control systems for many years so have a bit of an idea what I am doing.
1 I used the existing start stop panel to control a single phase contactor. This means I have an Estop button that will kill ALL services to the lathe. Ok I know its just plugged into the wall socket but an Estop button makes sense. Also the belt change door is fitted with a switch, which I have wired into the Estop circuit.
2 I wired a remote control box for the inverter which sits on the headstock.
3 This box facia incorporates 16mm control buttons, a three postion switch and a Potentiometer knob. The VFD is wired "Three wire control". The Three position switch is wired to give me -
Centre Position. System runs forward maintained with a press of Start, Stops with a press of Stop.
Left Postion Motor runs in Reverse whilst Start is pressed. Right Motor runs Forward whilst Start is pressed.
The Viceroy has a screw on Chuck so a continuous Reverse capability was in my mind not a good option. Reverse to date has primarily been used when threading to return the tool to start. The momentary forward run gives a capability and is again useful when threading. It is faster to release the button than press stop when approaching the shoulder.
I was thinking of using a 10 turn pot for speed control but in the end used a standard 270degree. Glad I did. The capability of increasing or decreasing the speed quickly has been invaluable. "5" on the pot is 50 Hz.
The above switch setup involves no programming of the VFD just switch control logic.
4 The VFD was programmed for a relatively slow acceleration and deceleration. Accel to assist the jog function above. Decel to ensure that a big chuck would not unscrew when stopping. IMHO NO braking function should be used with a screw on chuck.
5 I would personally not use the keypad for continuous operation. It is nice to see the display for faults, frequency or current draw but in the end I tucked it all into the machine. Did initial tests out in the open to get a feel of things but then mounted inside.
6 Motor is a 750watt Marelli
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Good price and delivery at the time of buying. No problems so far VFD is an Allen Bradley. I bought a pair new a few years ago for £50 each. The units have been instock for a few years so I "Reformed" the capacitors before using for real. Not sure if needed but I know that many Electronic units have popped their caps after standing around for a long while.
7 Still to cut a hole in the back of the Lathe Stand and fit a fan (on the bench ready) but that's project 397
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