Member postings for Gazz

I'm writing this in the hope some of it may be of use to owners or potential owners of this mill.
It's the rambling story of the things i've discovered about this mill and mods i've done to it, more 'chapters' will be added as i make more changes and discover new things.

I bought my first ever milling machine in February 2021, a Warco GH 18, this mill is a clone of a clone of a clone it seems, other versions include the Precision Mathews PM727M and the Grizzly G0761.

I liked the idea of it being a gear head mill, and it was sold as having a single phase AC induction motor which i preferred that over the DC motor style ... not really liking the one in my mini lathe, it has an auto reverse tapping function (which i still haven't used), things like tapered gibs, R8 spindle, 400mm spindle to table height and so on, (all nice stuff when i've only owned a mini lathe and cheap drill presses before)

The mill arrived about a week after i ordered it, i got the 2nd from last one in stock at the time,
Palletways delivered it, and the bloke used his electric pallet truck to bring it round to my workshop, down a crumbling old drive, through a gate it barely fitted, a few 10 point turns and across York stone flags to get round obstacles,

It failed on the last little bit, I'd got the dimensions of the mill in it's packing crate but didn't account for it being placed on a pallet... the crate would have fitted through the door, the pallet was ~100mm too wide... i'd even built a sloped path up to the door when i built the workshop the year before in anticipation for this day.

So the mill was unceremoniously dropped off half way on and off the sloping path, this actually helped me as i used a pry bar, trolley jack and blocks of wood to raise the crate up and pull the pallet out, then i let it down onto some cheap furniture movers like these:

They claim to be rated for 100 kilo's each, the 'axles' are just small pins!
I expected them to collapse but the mill only weighs 190 kilos, and they held up fine.

Once inside my workshop i unboxed the mill, and noticed it had a metal box bolted to the rear of the column, this was not mentioned in the sales ad and added to the published dimensions of the mill.

This was important as i had just enough depth of my workbench to allow the mill to sit with the rear of the column close the the rear wall and not have the front hang off, this box would have pushed the front of the mill off the bench by 130mm.

So i popped the cover off it to see if i could relocate it, i was not expecting to find a VFD in that box!
The motor's plate/sticker boldly states it's a single phase capacitor start motor.. with a claimed 3HP and ratings for both a start and run capacitor!!
I popped the terminal cover off and this is what greeted me:

Thats a 3 phase delta wired motor there.
I know to most this would make no real difference but i was thrilled with this unexpected 'upgrade'
Sure, the VFD is an XSY brand that can be bought for £50 or less, and the motor... bod knows, i emailed Warco asking if they had the data for the 3 phase motor but got no reply.

But this adds a new dimension to the machine for me, i have the 6 gears to choose speeds from 90 to 1420 rpm, and when in the low speeds i should get plenty of torque with the motor running fast enough to be properly cooled, plus with the VFD i can fine tune the speeds (this feature is hidden as standard, the knob on the VFD programming panel adjusts the speed, this is usually on the back of the mill and boxed in, so it's just set to 50Hz..full motor speed from the factory)

Thankfully the VFD has connections for a remote speed control needing just 3 extra wires and a ~10k potentiometer.

The VFD also gives the bonus of almost instant reversing, being able to adjust how fast the motor starts up, how fast it stops and other features adjustable in the software of it.

There is a hard to decipher and incorrect in places wiring diagram on the side of the mills column, so i decided to work out the wiring myself and went through all the VFD settings noting the ones that were set specifically for this mill,

I posted my wiring diagrams and info about that here:
**LINK**

The VFD box was held on with 4 bolts and had a single cable pipe going to it, so it was very easy to relocate it and allow me to fit the mill on the bench properly.
Relocating the VFD box did leave a 'hole' in the back of the column, usually a metal access plate is bolted here (the 90 degree gears for the column Z axis is accessed through it) so i just made up a cover plate out of 3mm perspex for now (it will likely still be in place in 10 years time of course)

To be continued.....

Edited By Gazz on 27/04/2021 03:04:42

think my measurment is out for the length of the 0-25mm rod,

Should it be 70mm? rod length is lower measuring length plus 45mm, not 20mm. think i was reading the upper range to cock that bit up.

Amazingly i have managed to locate someone who was throwing one of these out as the electronics had died (The one thing opposers of digital mic's always point out, electronics die that's it, game over unless it's the type with the standard micrometer barrel fitted as well as the electronics head, then you have a heavy and clunky mic with parts sticking out that just get in the way now)

The dead mic set i'm getting is missing the 0-25mm rod, but has the other 5, so i'll be chopping one of them down,
Just measured the 2 rods that i can measure with my calipers, and they are:

75-100mm = 120mm
100-125mm = 145mm

So i deduce the 0-25mm rod should be 45mm long in total.

At least that is the one rod i can get a little out and be able to set zero easily without a gauge block (looking for a set of them after i get the 4 jaw chuck for the mini lathe, as i want to make an eccentric bushing thing for my 2 month old (chinese of course) mill to improve the quill rack and pinion mesh and reduce the 0.47mm of up n down play it has)

Thinking i'll cut the rod with the ground end intact, and machine the taper and grove for the 'circlip'. and even better if i can do it with the end that will not be used in the lathes jaws.. tho the rods are hardened stainless steel, i doubt my lathes jaws will mark them.

measured the rods diameter with a micrometer (used calipers before) and they are between 4.489 and 4.493mm

So 4.5mm rod should fit,

I 'think' the grove with the snap ring in it is just to hold the rod up the snout of the tool, if i insert a rod backwards, once i've got the air that gets trapped in there out, it will move out a little... more a chance to drop the rod out when not measuring that owt else, as the rod will be pressed against the inner end when pushing down on something to measure.

The seller has offered to let me return it, but then there's the thing of getting another one for ~70 quid.

An option would be for me to buy a non digital chinese depth mic that uses the same rods, can get a 0-100mm one for £42.50,

Take the 3 smallest rods, then try and sell the non digital mic on as a 75-100mm one only... can you tell i'm on a tight budget here

But not selling the other mic on means i'd have paid £111 for the digital one with all the rods, that's kinda getting to what a new one costs from china, but then the risk of import taxes bumping the price up.

I know people will say 'don't bother with the digital part' but i'm really bad at maths and mix numbers up, so even reading the digital readout i can screw things up,
i've got no hope with reading lines and adding the numbers together... going to be hard enough for me to remember to add on the length of the rod when measuring over 25mm... kinda hoped a digital mic would allow you to input the rod's length to add to the reading.

I bought what i thought was a good priced second hand chinese (IP54 branded... yes that's the name on it!) 0 to 150mm digital depth mic.

Turns out the 0 to 75mm rods are missing,

Before i open a dispute and return it, i'm wondering if anyone knows if i can buy the 3 rods i need on their own,

Or if someone has one of these chinese mics that the main head has died.broken, and has some rods they'd sell me (seems most chinese mics use the same type of rods, but the big branded mics that actuall sell spare rods have different ones)

The rods measure 4.46mm diameter, and the bit that holds them in the mic body is a tiny circlip type thing (the type that's like a piece of wire wrapped around a groove)

I did toy with making some rods up, would need to buy some 4.46mm ground steel rods / drill rods, but it seems i'm looking at gauge pins for that exact diameter, might get the 0-25mm one out of one of them,

Of course they'd never be any where near accurate, no way i could get the ends ground perfectly flat at 90 degrees to the shaft,

oh i love the gear head idea, i get 6 speeds to choose from where i get max torque from the motor that will be running at it's normal 1420 rpm's, so getting max motor cooling too.

And the VFD allows me to fine tune those speeds if needed... watching out for the motor heating up and getting less cooling from the shaft driven fan when i lower the speed of course.

My mini lathe has the DC variable drive and 2 gears, i always seem to run that in low gear at below half speed, the motor gets fairly toasty after a while... must get round to fitting a computer style fan to the end of that motor.

I guess as this is the first mill i've owned and only having heard the bridgeport run at hackspace, i find it quiet, the cutters make the most noise.

I too find the number of cables that come and go from that yellow button box a pain, why they didnt route the power into the VFD box, then the motor power wires straight to the motor from the VFD box i don't know, why loop them into the button box then straight back out again,

Getting to the column locks i have to snake my hands through all the wire hoses.

So i am totally re-doing that, the yellow button box is 95% empty space, when it was single phase motor it would have had 2 x 4 pole contactors and a timer module in there to handle the reversing of a single phase motor when in tapping mode,

I'm putting my VFD in a much larger electrical box on the wall, mains will go into the bottom of it, through a couple of mcb's, to a 12 volt psu for the ring light and control circuits, a contactor that will switch power to the VFD, plus an outlet for the DRO to plug into, and later on a 24 volt psu for axis motors.

Then a multi core cable will come out and go to my new button box, which will be all low voltage inside, the new button box will be mounted under the front of the swarf tray (it hangs off my bench by a couple of inches.. just the swarf tray, the mill is firmly on the bench)

Then the cable from the VFD to the motor will come out the top of the electrics box, loop above the mill and go back down to the motor, the only other cable i'll need from the mill will be the one for the tapping function microswitches, and the power to my ring light that's mounted around the spindle,

i'll also have a switched outlet on the electrics box for my DRO (still in the post) and my DRO head will mount roughly where the yellow button box is on the mill now, only it'll not travel up n down with the head like the button box does now, i really don't like reaching above my head to turn the mill on and off when the heads wound all the way to the top of the column.

Sorry, i don't know how to make pictures thumbnailed on this site,

I sized the pictures to A4 size for printing, but set the DPI to 200, so they can be zoomed in on the computer. but to do that you need the pictures... right click on the pictures and copy or save, then open in your favourite photo viewer?

If you bought a GH18 milling machine from Warco in the past year or so, you may have noticed it has a box on the back of the column that sticks out about 150mm.
And operating the mill you might have noticed an a whine to the motor, and that the spindle reverses within about half a second... far too fast for a single phase capacitor start motor to do so usually.

The whine gives it away to anyone who's used a motor on a Variable Frequency Drive before, and if you can decipher that crude and innacurate wiring diagram on the side of the column, you may have noticed the 3 wires to the motor marked U, V and W coming from the 'Transducer Control'

Inside that box on the back of the column is a 1.5KW VFD, and the motor is 3 phase.

This means that in addition to the 6 fixed speeds of the gear head mill, you can also vary the motors speed.

The VFD is set up from the factory so that rotating the knob on the VFD control panel will lower the motor speed... it's set to 50Hz max stock,
The stop/start and direction buttons on the vfd panel do not do anything because it's set up to operate from the push buttons on the control box (that big yellow box that is 95% empty inside, due to not needing contactors and a timer for the single phase motor control)

So i decided to draw out the circuit diagram as it really is and in colour, as well as draw the physical wire routing between the buttons etc, all wire colours are drawn correct as on my mill, so are the markings on the wire terminals.

I've also written up what happens when the buttons are pressed, mostly to show what happens in the milling and tapping modes, but maybe to help diagnose issues in the future.

Finally i've written down all the VFD settings that are specific to this machine, the settings not mentioned are set as listed in the VFD's manual, which is available here:
**LINK**

I hope some of this may be helpful to someone in years to come when the mill is out of warranty.

tho i do wonder if warco know much about this mills drive system, they can't seem to supply me with the motor's real ratings, the plate claims it's a single phase capacitor start motor, 2 capacitors are listed with values as expected for a start and run cap. and the motor is rated at 3HP and 900 watts!!!

Thankyou, i deffo need the same type of glands then, i was thinking that the domed type with the fingers might not have been used for a reason

it's looking like i will be ordering them from digikey then, they claim 4 days to get them to me from america,

6 of them cost £7.68, then vat and £12 postage, so £23.62!! so now to find other things i can buy off them to get to the free shipping level (i will order more glands than i need)

Bod knows how old this bubble etch tank is, it's an RS components branded unit, stock number 556-806, but the controls are flat on the front side of it and they haven't sold ones like that for many years,
It's only really the very end of the cable gland that gets the ferric chloride in contact with them, i think they cracked from the heat cycling over the years.

But i only paid £25 for it, and the heater works fine, just it was leaking 'slightly' which was the air pipe glands that had cracked.

When not in use It will be living on the floor of my workshop under a bench, i think i will get a plastic container that can contain the amount of ferric chloride it takes (i'm guessing 2 or 3 litres?) and it will sit in that all the time, a sort of bund solution.

All these years i've been etching pcb's in a small tupperware container sat in a larger one of hot water, and manually dunking the pcb in and out of the ferric chloride with tweezers.

It'll be nice to use a bubble etch tank of my own.

Edited By Gazz on 25/02/2021 21:17:07

they list one at M13... didnt know that was a standard size... wonder if they mean M12... thos i think the 1.5 thread pitch of thee make them a bugger to get even more

those are the exact ones

6 of them will cost me £7.68

But it seems digi key are in the US, but they say for £12 they will get them to me in 4 days,

so that's an option if i can't find them available in the uk,

yeah, i found loads of the standard dome type cable glands, but i wonder if there was a reason they used the other type in this application,

The 6mm nylon pipe passes through the whole gland at the base of the tank, so the seal must be perfect.

Oh yeah, they must be plastic / nylon, found some metal ones, but they wouldnt last very long exposed to the tanks contents.

Sorry if this is the wrong forum for this,

I picked up a PCB bubble etch tank cheap because it leaked, the leaks are from cracked cable glands that are used for the air pipes from the air pump to the tank base,

Simple enough to replace i thought, but bloomin eck i'm having a hard time sourcing them in the UK,

They are the type that have a female thread, and a male fitting screws down compressing a rubber donut that seals to the cable... or in this case 6mm pneumatic semi rigid tube.

They have a M12 x 1.5 thread on the end, and i've found them referanced as Mpoz 12-1 glands, by 'Rose Bopla'

This is what they look like, i only need 6 of them:

I've found plenty of the standard cable gland types with a male thread and male domed type nut that goes over the fitting, but i don't think those will work in this application... i.e. sealing in a few litres of ferric chloride in my workshop.

Does anyone know of a source of these in the UK? the M12 x 1.5 threads seems to add complexity to them, found electrical sellers that do the M16 and up sizes, but none this small

Edited By Gazz on 25/02/2021 18:40:08

gotya,
i would say a bare VFD of this type would not have any protection from any kind of water, be it a jet, a sprinkle or mist,

I would say a 2 maybe 3mm screwdriver tip could make contact with the terminals if poked up the holes the wires go up in the bottom (or say 6mm if a wire is not present)

Bbut it is a chinese unit made to the cheapest possible price, so we should really treat any external screws on the unit as pottentially live?

but either way, i now know i would not like any VFD to be mounted bare on a wall near a machine that can throw little chunks of metal about when in use, not to mention the possible use of a mist cooling system, or grinding in the same air space.

I have emailed warco about getting the correct motor plate for this mill, and also to ask to exchange the hold down clamping kit i bought for it, as i bought the M12 version after seeing their list showing most mills including the WM-18 they sell listed as taking that size,

And it turns out this mill has the next size down T-nut slots

i've been trying to find where i read that this VFD might have an IP44 rating, but i can't find it again, so i am likely wrong,

But IP44 is pretty low anyway, basically it might keep big fingers out of the live terminals but that's it,

This VFD does not have a fully enclosed base for a cable gland or anything, the actual screw terminals are shielded with a screw on front cover, but you could poke things up the mains terminals holes in the bottom of the case etc.

Here's the base of the VFD with the terminal cover removed.

i think the VFD in my mill has an ip44 rating,

i was wrong about the green box it's mounted in that bolts to the back of the mill, it is closed at hte back not open, so the only air flow if via the hole in the bottom,

i've mounted the green box on the wall to the side of the mill, and i have the front cover off for now, i think i'll add a hole at the top and fit filters over both the top n bottom hole, and cut a hole in the front panel just so i can see the readout for any error codes etc,

Then i'll run 3 wires from it for a speed control pot, and i'd like to add a spindle speed readout sometime, but not sure where i can get to the spindle to fit either magnets or a toothed disc for an IR speed reader as used on the mini lathe.

And whilst i was cleaning the shipping grease off it tonight i spotted the wiring diagram that is for this mill, it's a great big sticker on the right side of the column, so how i missed that before i don't know,

It even seems to give some of the settings for the VFD.

I have seen a wiring diagram for the GH-18 a while back, and that was definitely the single phase motor version, it used 2 contactors for forwards and reverse and a timer for the auto tapping function (it may have also used the timer when you pressed the opposite direction button as well, but i'm not sure)

I think it was a 4 pole contactor for forwards, another other for reverse with the connections to the start capacitor switched...so it gets the 'push' in the other direction at start up to rotate backwards,
And a timer relay between them,

When the microswitch for the bottom of quill stroke is triggered it cuts power to the forward contactor and triggers the timer, when it finishes counting down it then triggers the reverse contactor,
The timer is needed as a single phase motor needs to be fully stopped before reversing it, if it's still rotating even a tiny bit, it will just carry on in the original direction when power is re-applied....this is due to how single phase induction motors work (i'm no expert here, i know just enough to be dangerous... please correct me if i'm wrong, i'm always learning)

On my GH-18 (and a few others i've heard of who mentioned the VFD with as much surprise as me at finding it and a 3 phase motor on the mill... especially with no mention of it from warco) there's just a through connector block on the inside of the back plate of the yellow control box, that's where the contactors and timer were located on the single phase motor versions.

So now to reverse the motor, a signal is sent to the VFD from either the reverse switch or the tapping bottom out micro switch, and it ramps the frequency down to zero which stops the motor (not sure if it applies motor braking as well, but the motor stops fast) it then swaps 2 of the phases to the motor (virtually i guess, as at least 2 of the phases are made by the VFD) then ramps the motor back up to it's original frequency... in t'other direction, this is accomplished in under a second.

So the motor direction switches on the front of the yellow control box are just switching signal wires to the VFD it seems, and the VFD is doing all the magic like motor braking, almost instant reverse, motor start speed ramp up etc.

Of course, being a cheap chinese VFD, it takes a few seconds to 'boot up'.... or more likely charge the capacitors up when first turned on,

And a good thing is the fan on the VFD only runs when the motor is running, sure a temperature controlled fan would be nice, but it's better than the VFD's that just turn the fan on when power is applied to it, there's space for 2 fans in the bottom of the VFD case, i can't imagine the racket of 2 of them buggers howling away, one is enough.

And no, i still havent cut any metal on it (i don't think i'll actually use it, i'll just keep it as an ornament so it's in perfect condition when i sell it on

I only just got it lifted onto the workbench today (used an engine hoise) and i've just started removing the yellow shipping grease that is slavered all over it, it looks like the measuring tape on the front of the X axis is stained by the stuff, and no amount of acetone is removing it, and i'm worried i'll take the printed markings off the tape soon (and yep, I have removed the film that was covering the tape.. but it did take me a while to notice that)

I'm more curious what the motor is rated at really due to the wrong plate on it, thinking if i needed a replacement in say 10 years time,

I was going to mount the VFD straight on the wall (if i put it back on the rear of the mill column, then i will have to rebuild the workbenches to allow the front of the mill to be supported due to that box pushing the mill forwards so much from the workshop wall, and that would mean the 2 other benches that are part of the U shape would need their cupboards making smaller and so on)

So now i know it's better to have it in an earthed metal box i will likely mount the green warco box it's in on the wall.... on stand offs to allow air to it from the hole in the back,

And i'll fit some filter material around the opening to stop grinding dust getting in,
only talking about angle and bench grinding here, but now i know that a metal dust laden atmosphere and a VFD isnt a good thing, i'll do what i can to stop that happening.
(my tig welder has cooling paths that deliberately ensure no dust gets to the actual components, i don't think a £50 VFD will be built the same)

And i'll take the advise too about the control panel being for set up and testing, it does clip out of the VFD body and an extension cable can be fitted if i wanted, but i think that yes, a remote pot on a small panel near the mill will be better to adjust the speed (maybe that's why there's an unused grey wire between the VFD and control box, a pull through for 3 wires for a speed pot)

I've been thinking of maybe fitting a tach so i can read the actual spindle speed, that'd be more use to me than seeing the frequency the motor's getting,
Seeing the VFD display would only really be useful to see any fault codes,

The VFD plate: