A new Milling Machine

This topic has 4 replies, 5 voices, and was last updated 9 July 2026 at 20:27 by Wade Beatty.

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9 July 2026 at 16:42 #855545
Martin Johnson 1
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@martinjohnson1
Hello,

I have just taken delivery of an Elliott Omnimill 00 3 phase machine. Very pleased with my purchase, but now considering just how to run it off single phase. Details of the beast here: https://www.lathes.co.uk/elliott-omnimil-00/ https://www.lathes.co.uk/elliott-omnimil-00/

Initial thoughts are that a Steinmetz connection will do for the 1/4 HP coolant pump (easy starting and speaking as a pump designer, 1/4 hp is way OTT for suds). A VFD inverter would be a nice luxury on the 1/10 hp table feed but I am thinking that Steinmetz might also suffice here, although the starting load would be a lot less favourable.

I have mixed feelings about the two drives for the horizontal (1.25 HP) and vertical (0.75HP) spindles. If I am interpreting the circuit diagram correctly, the control knobs (off/forward/off/reverse) have an extra way which is used to interlock everything so that only one spindle can run and the “off” setting will drop out the incoming MEM starter, thus killing everything. If that is the case, will one inverter suffice for both? I will try and post the diagram shortly.

I am not too bothered about using variable speed on these drives, so wonder if one (or two) of these will do the trick:

https://www.ebay.co.uk/itm/397704177733?var=0&mkrid=710-53481-19255-0&campid=5338590836&toolid=10044&loc_physical_ms=132913&customid=2be61522fd191ff2ac837f6d40449e5d

https://www.ebay.co.uk/itm/397704177733?var=0&mkrid=710-53481-19255-0&campid=5338590836&toolid=10044&loc_physical_ms=132913&customid=2be61522fd191ff2ac837f6d40449e5d

Presumably they are basically an inverter inside configured to start up as the single phase powers up with suitable ramp up times and delays programmed in?

I am hoping to have room in the machine base to lose a couple of inverters or converters, allowing me to use IP 20 units. Is it possible to configure the average single phase to 3 phase VFD to do the same thing as a conveter? I ask this because the cost of a stop,start, fwd rev & speed control unit looks to be extortionate for what is actually supplied. That would also give me the problem of where to put extra auxilary controls. There is another problem if I go down the cheap chinky (AKA gibberish instructions) route which is finding where to wire such things into the inverter.

Whatever happens, I have four motors that need the star point to be discovered. I have had a look in one main drive and there are only three terminals in the box. Does anybody have advice for finding the star point? At the ends of the stator windings? Tucked between two poles? None of the above? How much insulation and taping am I likely to have to dig out to discover said star point?

The back stop is to single phase the two main drives as I already have a suitable motor for the vertical head but have you seen the price of 1.1kW 4 pole motors????

In due course, there will be a vertical / horizontal Tom Senoir M1 going in the for sale ads, located in DL14 if anybody is interested.

Has anybody adapted the Tom Senoir slotting head to fit an Elliott? It looks like it should be possible with an adapter block. I feel a bit of pattern making coming on………….

Collective thoughts on the way forward will be much appreciated.

Martin
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9 July 2026 at 17:16 #855553
Bazyle
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@bazyle
You obviously noted it is only 240v output. One wonders if it is actually just a Steinmetz packaged with maybe a filter. No warning in the blurb about needing a delta wound motor. Do you have an ‘air switch’ (sic) as recommended?
9 July 2026 at 17:53 #855555
Robert Atkinson 2
Participant
@robertatkinson2
As you say Steinmetz connection will do for the 1/4 HP coolant pump.
~~Need to see the circuit for the table feed. Are you sure it’s a 3 phase motor? Often these use a universal motor to provide variable speed.~~

Edit. I see this mill use change gears for table speed.

I’d be vary wary of the ebay units. Probably an expensive capacitor.

Yes you can run a VFD as a fixed con verter, you can almost certainly use the existing control switches. Only one VFD needed for the two motors as only one is run at a time.
VFD adds motor protection, “soft” start and other benefits in addition to variable speed.

Robert.
9 July 2026 at 19:18 #855562
Clive Foster
Participant
@clivefoster55965
Martin

I fear Robert may be a bit too cynical.

Back in the day I built a number of Steinmetz starter boxes with proper protection and automatic starter capacitor control so I know you can do a proper “expensive capacitor” job. But frankly these days a simple “single speed VFD” innards will be cheaper and simpler than an expensive capacitor box. Besides being much more likely to work well. After tens of Steinmetz boxes I’ve no illusions as to how much of pest they can be if a motor lays back its ears and decides not to play.

I think the drive boxes in your E-Bay links do essentially the same job as the Eaton DE-1 “smart starter” units.

Those DE-1 series are simple VFD power units, with no built in controls or display, configured to work as drop in replacements for old style contactor controls. Basically connect and go for simple soft start single speed operation but with a full voltage/frequency VFD inside so they can also be configured as a full on VFD to run via external controls. Book shows that multi speed forward & reverse set ups are easy. There is a set-up widget, which I have, to do more clever things.

I have set up Eaton DE-1 devices to work the way your E-Bay units are intended to and found they work very well indeed in that simple configuration. Just a short, few seconds, delay as the capacitors charge before the motor starts ramping up.

Actually I have a DE-1 in stock ready to do a job that one of the ones you linked to will do just fine. I’m temped to leave the DE-1 on the shelf and go get one off your link!

Although a Steinmetz connection can work just fine I’d not bother with getting the coolant pump running. In my view flood coolant is too messy in the home shop and we never need to run hard enough to properly exploit it. If you have low-pressure air and some sort of low pressure rated oil container available I think one of the cheap E-Bay mist coolant units could be made to work just fine for your purposes. Not bro professional standards may be but a bit of lubricant and bit of air to blow the chips away serves for mots home shop jobs.

All my machines have coolant pumps. All have Bijur Spraymist units, modified to minimise dispersion, too. The Bijurs get used. I know I haven’t turned flood on this decade. Possibly a time or two last decade!

Clive
9 July 2026 at 20:27 #855566
Wade Beatty
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@wadebeatty78296
I have used this converter that came with my Omnimill, it works just fine. No drop-outs. I replaced the .75hp motor with a 1hp motor on the vertical drive.

Regards

Wade
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