Warco GH 18 Milling Machine

[IRTParticipant @irt]

On paper it appears that the Warco GH18 could be a good buy.

A reasonable size and no electronic controller to go wrong.

But I can't find and reviews or information from users of this machine anywhere.

Has anyone got one of these? What are their good and bad points?

[IRTParticipant @irt]

Can’t find any reviews

[IRTParticipant @irt]

Not a very popular machine then?

[BazyleParticipant @bazyle]

You might want to check out the equivalents sold by Chester and the USA dealers like Grizzly, HF and PM then search on those. I think the Chester Lux is similar but not sure if it is a gear head.

BTW how long has it been around? That might account for lack of reviews.

Edited By Bazyle on 05/04/2019 19:53:50

[JasonBModerator @jasonb]

Yes as Bazyle says it's quite a new model so not many people with one.

[IRTParticipant @irt]

I didn't realise it was new.

It does look very similar to the Grizzly G0795

[SillyOldDufferModerator @sillyoldduffer]

I have a WM18 and was interested to compare specifications with the GH18. The GH18 is slightly smaller which could be useful if space is short. Apart from the motor controller, WM18 definitely electronic, not sure about the GH18, the other difference is the position of the Z-axis lever, WM18 on the right:

I'm nearly 6' tall and find reaching the handle on the WM18 a bit of a stretch. It might be awkward for shorter persons. The GH18 has the handle much lower on the left, easier to reach but I wonder if the control box might get in the way in some positions?

I think the two machines are of similar capability. I don't worry about electronic vs plain motor control myself, but the position of the handles might help some buyers go for one rather than the other. If non-electronic is a requirement best to ask Warco, what's inside the GH18's electrical control box is a mystery to me!

Dave

[IRTParticipant @irt]

I had the controller go on my wood turning lathe recently.

I could not believe the price of a replacement!

Luckily it was still under warranty, but it has made me cautious of the electronic control of DC motors.

This is what made me notice the GH18 in the first place.

[not done it yetParticipant @notdoneityet]

Not got one, but… looks reasonable as the gears are actually continuously lubricated.

The specs state that the motor is 900W. I suppose we have to guess that the motor is single phase (it does state 6 speeds, I suppose)?

All my machines run on a single phase supply but the motors are all three phase – the VFD does the donkey work! Extra cost for a three phase motor and VFD would be less than £50 at the manufacturing point – and they could have reduced the number of gear changes available in the box, so likely no extra manufacturing expense at all.

I reckon someone is missing a trick somewhere! Or it will be the next “updated” offering when they realise the utility of a VFD?

[SillyOldDufferModerator @sillyoldduffer]

As usual Grizzly provide more information than UK sellers, assuming that the GH18 is much the same as a G0761.

Grizzly's spec says the motor is single-phase and to remove any doubt the parts list identifies Start and Run Capacitors in the motor assembly. (This is my punishment for saying in another thread that single-phase motors aren't used on modern machines! This one does! )

The G0761 Manual also explains the controls. The gear head provides 6 speeds, and the electric controls only do ON/OFF, Forward/Reverse, Mill-Drill / Tapping, and Emergency OFF. There is no electronic speed control.

The GH18 is a good match to Ian's requirement.

My view of motors, in order of desirability:

1. Best. Brushless DC with controller. Pro. Excellent torque and power over a wide speed range. Con. Complex electronics. Cost.
2. Close Second. 3-phase with VFD, Pro. Motor highly reliable. Smooth. Good torque and power over a useful speed range. Con. Complex electronics. Cost.
3. Good Third. DC Motor with controller. Pro. Smooth. Good torque and power. Inexpensive. Con. Brushes wear out, less efficient.
4. Serviceable. Single Phase AC Motor. Pro. works on domestic supply, simple control. Cons. Bumpy, low starting torque, reliability issues due to start/stop overheating and Capacitors, Centrifugal switches and Run Windings. No speed control.

Although single-phase is 'inferior', for most hobby purposes it's 'good enough'. But, now that cost of VFDs has dropped, broken single-phase motors are often replaced with 3-phase/VFD and owners notice the improvement.

Dave

Edited By SillyOldDuffer on 08/04/2019 10:17:47

[not done it yetParticipant @notdoneityet]

“The improvement”. Singular but meant in generality, I know!

”Improvements’ would have better described the enhanced attributes of a VFD. Soft start, braking options, power limiting, continuously variable speed selection, reliability of the motor, smoothness of the motor, etc.

For the minimal extra cost, I am sure most hobbyists would appreciate (not just ‘notice&rsquo the improvements of having the best drive available. The one thing about electronic control boards, supplied by the manufacturer, is that of being mostly tied to an expensive replacement from that supplier on a rather too regular basis. VFDs are now cheap, reliable and can easily be substituted for a superior make, if the cheap supplied one fails.

I think some hobbyists are being short-changed by some manufacturers/suppliers in that older out-dated drive systems are still being foisted on unsuspecting buyers. The likely reason is that these ‘expensive’ control boards are of such low initial cost (and quality) and later replacement costs are ‘extras’ for the suppliers. A bit like BEVs these days – so little servicing is required that dealerships will rather sell an ICE vehicle so as to perpetuate the high servicing requirements during the life of the vehicle.

[JasonBModerator @jasonb]

Dave, you did miss off that the AC motor will probably give the best torque of all as the machine will be driving through a gearbox/belts and always running at it's optimum temp so no overheating at slow speeds.

[Dave HalfordParticipant @davehalford22513]

Posted by JasonB on 08/04/2019 11:23:34:

Dave, you did miss off that the AC motor will probably give the best torque of all as the machine will be driving through a gearbox/belts and always running at it's optimum temp so no overheating at slow speeds.

DOH!

[SillyOldDufferModerator @sillyoldduffer]

Posted by JasonB on 08/04/2019 11:23:34:

Dave, you did miss off that the AC motor will probably give the best torque of all as the machine will be driving through a gearbox/belts and always running at it's optimum temp so no overheating at slow speeds.

Yes, and other things too!

I was trying to keep the summary simple. Motors that keep themselves cool with an impeller are indeed likely to overheat when run slowly, and speed control via gears as on the GH18 fixes that problem, which is a good thing. Another approach, the VFD speed controlled 3-phase motor on my lathe is cooled with a separate motor & fan that runs continually. Although the main motor never gets hot, the fan is hellish noisy. And the cheap computer type fan fitted to the VFD is even louder. Whatever its other virtues my WM280 can't be called 'quiet' and most of the racket is fans!

On the other hand, my WM18 mill has a DC motor, no fans, and a basic 'don't forget to grease me' 2 speed metal gearbox. It's surprisingly quiet and the motor doesn't seem to get hot, perhaps because I rarely cut masses of metal with it in one session.

Noise is rarely mentioned in the specifications when comparing machines and it might be important in a domestic setting. Nothing is ever easy…

Dave

[IRTParticipant @irt]

Thanks for all replies.

I spoke to Warco today. They are out of stock of the GH18 for the next few weeks, but they have one in their showroom that I can see running. This gives me a while to consider my options (and prepare the garage).

So for long term reliability should I look at something with a simple dc motor solution and gears like the GH18, or forget my previous bad luck with the wood turning lathe and go for something with DC brushless motor and complicated electronics? I assume this would include the WM18, and the SX3?

[John HaineParticipant @johnhaine32865]

If you can, step pulleys, 3 phase motor and vfd.

[IRTParticipant @irt]

Hi John, Are you pointing me at the VMC? Too big I am afraid. (No matter how many times I measure the space).

[GazzParticipant @gazz]

I know this is a year old post almost, but i just took delivery of a GH-18 mill.

A box mounted to the rear of the mill column threw me, as it would mean the mill would sit forwards and hang off the front of the bench, so i popped the cover off to see what was in there… to see if i can move it… and this is what greeted me!!!

[GazzParticipant @gazz]

However, the motor plate says it's a single phase motor, wired with 3 phase colours, can you get single phase inverters?? i.e they take in single phase and output single phase… maybe just altering the frequency or something to allow the ramp up speeds and braking etc??

The motor reverses far to fast i think to be a single phase motor where you swap the capacitor terminals to reverse it… where you must ensure the motor is fully stopped before hitting the reverse switch, otherwise it will just carry on in the same direction… but maybe the inverter can sense when the motors stopped and apply the reverse capacitor stuff instantly?

[Ex contributorParticipant @mgnbuk]

Connections at the motor look like a normal delta connected 3 phase motor to me. What you would reasonably expect to see for a motor driven by an inverter on a 240v single phase supply.

I suspect that the "rating plate" is incorrect – I am not aware of any single phase inverters & you would notice a rather bulky capacitor hung on the outside of the motor if it was as described on the plate And 3 HP isn't 900 W either !

Is there any form of wiring diagram in the documentation ? .Assuming the machine came with any documentation, and that any wiring diagram accurately represents the installation on the machine that may clarify the situation. Not much ventilation space around the inverter & I guess that the box has to be removed to gain access to the inverter wiring. It looks to be a preferable arrangment to the propriatary brushless DC drives commonly fitted to these machines, though – no sensors in the motor & any suitably rated inverter could be fitted if the supplied item fails in the future.

Does it work ?

Nigel B.

[GazzParticipant @gazz]

It's got to be a 3 phase motor, no capacitor as you say, and looking at the photo's on warco's site they show a much larger connector box for the motor, which obviousely has the start cap in there,

The mill is still on my workshop floor, but i have ran it and twiddled the VFD knob, and sure enough, the motor slows as the display changes from 50Hz down to zero,

Unfortunately i only got the usual chinglish user manual with the mill, and it shows a 110 / 240 volt wiring diagram (with 4 wires to the motor.. so a single phase set up with the capacitor polarity changed via 2 contactors to change direction) and a 380 volt 3 phase, but with 3 phase coming into the machine from the plug… absolutely no mention of the inverter drive at all,

I've seen photo's of inside the control box the single phase GH-18's, and there's 2 big contactors and a timer module for the auto reverse tapping function mounted on the back plate

None of that is present in my control box, just wires directly to the switches on the front plate, and a single connector block on the back plate.. and lots of empty space inbetween.

I can only imagine the specs changed suddenly, and maybe even warco don't know about it, as they really push the advantages of a VFD setup of the WM-280 lathe over the old DC motor setup versions, and charge more than others do for the VFD versions over the DC motor ones.

That box the inverter is in is open on the back, so the hole is open to the inside of the mills column, i guess it'll suck air up from the base of the mill, then have to expel the hot air the same way.

But i'm going to take the inverter out of that green box and mount it on the wall of my workshop, where i can get at the frequency adjustment knob easily and not have to change any settings to activate an external speed control pot.

[GazzParticipant @gazz]

So now i'm wondering what the motor's rating really is,

Using an online motor power calculator, if it really was a 3HP motor then it would pull 6.59 amps on 240 volts 3 phase,

And those figures match on the plate… 6.6A rating, 3 HP,

but the 900w bit is deffo not going to be right, for a 0.9KW rated motor it'd pull 2.65 amps on 3 phase, 4.59 amps single phase.

And speed… if it's a 4 pole motor it'd run at 1425 rpm, plate says 1420,

I guess when i get it put on my workbench i can do some measurments, i've got a clamp meter.. but what kind of current should i see on one of the phases to the motor? 1/3rd of the total i'm expecting, i.e. 2.2 amps per phase, or does it not work like that with a VFD drive?

[GazzParticipant @gazz]

The VFD plate:

[Dave HalfordParticipant @davehalford22513]

It's not 3 phase, it's a cap run cap start single phase or the cap values wouldn't be on the plate.

I think 3hp is a typo

[MacolmParticipant @macolm]

It is quite possible to design a two phase inverter (VFD) to run a "single phase” induction motor (ie with main and start winding). Indeed, Maplin did sell such a thing briefly some years ago. The phase angle of the second output would simulate the capacitor(s) phase shift, and the effective voltage would probably also need to be reduced.

However, while there might be merit in being able to make an already installed motor into variable speed, there would seem to be little merit in this configuration in a new machine since the disadvantages of the single phase motor would remain.

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