G0704 type milling machine help - motors

Hi All

I'm hoping someone has had a similar experience and may be able to offer some advice or direction.

In the space of one week both the x-axis power feed motor and spindle motor have failed on my milling machine (G0704 type - 750w motor)...bad luck indeed!

I've already replaced one motor in the power feed unit and bought a second spare at the same time. Tried fitting that one but it's also dead, or I've damaged the unit more that I thought. I've got a source for a replacement so we'll see.

A few days later, the spindle motor went, this is apparently very common for these machines so perhaps I should be grateful it lasted over five years - the smoke being emitted last week was in hindsight more than a clue of things to come!

A quick search of the 'net proved these are a little harder to source and there appears to have been a variety of motors fitted to these machines over the years. I found a couple of sources for a replacement but I also have an eye on the future - what happens when it fails again at any point over the next few years and parts are even harder to come by? The only reason for continuing with the OE option at this point is to get me up and running whilst I research alternatives, which leads me on to the question...

I plan to convert the mill to three phase, powered by an inverter. I've previously done this for my old Myford S7, current Boxford lathe and Boxford pedestal drill. I love the flexibility and control this solution provides; plus the motors are sturdy, easy to source and relatively cheap, as are the inverters.

Has anyone here converted their chinese mill to run on 3-phase? If so, which motor did you use, how big is it and how are you controlling it? This last part is in reference to the OE switches, is it possible to retain the original look? The on-off switch will need replacing for a momentary version (I think) and I'm not sure about the rotary switch? I'm interested in what can be done.

If all else fails I'll just buy a control pendant from ebay and wire that in, but would really like to keep the original switches if possible.

Thanks for reading...

wrinx

I would look for a Grizzly forum, there must be some around. There you will probably find a huge amount of info.

Steve.

The hard part of upgrading the mill to 3-phase would be keeping the original switches, but only because it would involving drawing out a circuit and rewiring the existing controls. Easier to fit a 3-phase motor of about the same size as the dud, with a VFD and pendant to suit.

Not converted a machine myself, but there's nothing special about Chinese kit that would stop you. The VFD controls needed are On/Off, Forward / OFF / Reverse ( possibly doubling as ON/OFF), Emergency Stop / NVR, and a speed control pot, very like the existing setup. The Speed display might be easy or hard depending on how it's implemented. Hard if it's built into the existing motor control board, easy if it's a separate unit that can be left in place. Tachometers are cheap enough, but finding one to fit the gap could be a little tricky.

In principle, fairly straightforward, but with a bunch of finicky details to sort out. If you've already converted two other machines you must know more about the tricky practicalities than me!

Dave

Thanks Dave - thinking about it I've done three! All involved using pendants which make it more or less plug and play but I was hoping to keep the original box this time, however my knowledge of switches and electrickery is a bit shaky.

Best approach may to to find a pendant I can sink into the existing box.

Also need to find a 3-phase motor that'll fit too, space is a bit limited up there.

wrinx

Edited By wrinx on 17/03/2020 19:04:33

There are probably more users familiar with the Warco WM16 which is broadly equivalent to your mill. People have fitted a 3phase motor and VFD but it doesn’t seem to be an oven ready conversion.

Mike

Wrinx

i,m in south sheffield and I have converted my mill (slightly bigger than yours) to 3 phase on both main motor and power feed

let me know if you want to look at it?

ian

Thanks Ian

wrinx

Well well...multiple numpty of the week awards to me!

Presumed the spindle motor had died after witnessing sparks and smoke emissions, and knowing how fragile they are on these machines I jumped to the conclusion it had died. Turns out the motor had burnt through one of the power wires, now repaired and it spins fine under power although I haven't tested it under load yet. There may be a reason it overheated and burnt the wire but a replacement motor is on its way and will go into stock if the original is fine.

The power feed motor was presumed dead because, again, they are a known weak point. Replacement motor also dead which is odd, so put 12v through it and it spins! Looks like the original motor (which is definitely dead) went pop and took out the board No replacement for these board so I need to look for an alternative power source Trying to order another motor for a spare again because they are getting hard to find.

Still looking to fit a 3-phase motor in future!

wrinx

Glad my post helped. Too late to save your money? Distance buying - particularly if not yet dispatched.

Is the feed motor 12v? Is the psu for it ok? There are lots of little low voltage speed controllers on ebay.

I could send it back but I'm happy to put it into stock for when the motor finally goes...or I'll sell it later if I decide to go 3-phase.

wrinx

The power feed motor is 90v - there's a few potential controllers on ebay so I'm sure one will be right for the job

wrinx