Warco GH 18, bench top gear head mill fetteling

[GazzParticipant @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

[GazzParticipant @gazz]

Just a write up of me messing with my mill.

[GazzParticipant @gazz]

So with that little drama over it was time to lift the mill onto the bench, this wasn't going to be as easy as moving my mini lathe, i have a condition where my immune system attacks things it shouldn't like my joints, so i've basically had arthritic type symptoms since i was 14, and it being middle of winter wasn't helping with that, so i was useless and my only help was my 71 year old father.
Of course it meant mechanical lifting was needed unless i wanted to strip the mill right down and rebuild it on the bench.

I looked into hiring one of these manual pallet stackers (a sort of mini forklift with the forks lifted by a hand cranked winch) thinking that would be the safest way to lift it, push it forwards and deposit it onto the workbench… hopefully gently and the right way up, but local hire places only had the heavier hydraulic models that were too big to fit in my workshop.

So i hired an engine crane, i imagine this is the way most people would do it.

I read that you are supposed to lift the mill with a strap around the head and to extend the head up as far as it'll go to balance it all out, the engine crane i hired didn't have the hook positioned right at the end of the jib, so i had to remove the mills motor to get it to all work out.

With the motor removed I found that having the mill head as low as it would go then balanced it nicely, which turned out to be a good thing.

Firstly the engine crane was low on hydraulic oil and i lifted it to about 2mm above the bench height when it ran out of travel, and it turned out the ceiling of the workshop was too low to allow the mill head to be raised to full height.

Once the mill was on the bench the next job was to cut a hole in the roof above it and build a 200mm high 'chimney' to allow the motor to rise into when i raise the head fully.

Thankfully the 'workshop' is in the style of a wooden shed, 6 meters long by 2.5 wide, and i thought i was being generous when i made the roof 2.4 meters high,
The workshop is insulated with 50mm polystyrene slabs, and i'd 'donated' the offcuts to my dad for his model railway, i spent a few hours gluing his offcuts that were left to get enough insulation for sides of the roof extension.

A few days after the mill arrived i was finally ready to try it out, i'd not ordered a milling vice yet but had ordered one of the '52 piece clamping kits' with the mill, looking on warcos site they listed the 10mm stud sized ones for the WM16 mill, and all other mills used the 12mm studs (except WM 40 that uses 14mm)
BUT they didn't actually list the GH 18's stud size, so i assumed it'd have the same table as the WM 18 and ordered the 12mm version.

You know where this is going, the Gh 18 has 11mm tee slots so needs the 10mm hold down kit (their site now lists this mill as needing the 10mm kit) i had to send the 12mm hold down kit back .. costing me almost £7 in postage and get the smaller kit sent out (which is £9 cheaper, and no refund offered) so i lost £16 there.

Below is a photo of the mill a few weeks later, i'd got my milling vice now, but it's more to show the 'chimney' for the motor to extend into, the angle of the photo makes it seem it wasn't needed, i could have got away with 100mm height extension, but wanted to be sure there'd be more than enough space to draw cooling air into the motor,

The VFD box is mounted on the wall to the left hand side of the column near the top, it's only temporary, it's going to live in a new electrical enclosure soon.

To be continued….

[GazzParticipant @gazz]

Finally after having the mill almost 3 weeks i got to do more than just stick the few tools i had up it's snout and spin them up for a short while then take them back out and twiddle the hand wheels, but during that time i was reminded that my arthritic joints are not getting any better.

The Z column is raised with a crank on the left hand side of the mill, it's about 100mm above the table.. so better than the mills with the crank/wheel positioned right at the top of the column, and it's fairly low geared so not too much effort needed to raise or lower the head, but it means spinning that crank handle a hell of a lot, and my left arm is my weakest one.

I can raise or lower the head about 50mm then need to take a break, so a modification i must do will be to fit a motor in place of the crank.
The other issue is that the control buttons are on a box that's connected to an arm fixed to the side of the head, so the controls move up with the head, hence when the heads just half way up it gets painful for me to be reaching up to operate the controls.

I fitted an emergency stop system to the workshop when i built it, a 50 amp contactor shuts off power to a consumer unit that runs all the sockets in the workshop when any one of 10 e-stop buttons are pressed, so at least i don't need to rely on the out of reach e-stop button on the mill if it decides to try and kill me one day.

I also didn't like that the yellow box that the controls are mounted on is so big, with the single phase motor it would have housed 2 contactors and a timer for the auto reverse tapping function, but with the 3 phase motor all that is done with the VFD, so the box is pretty much empty, i plan to fit a DRO to this mill and the display would sit right where it'd get hit by the stock control box.

So my first real modification was to make a new control system, a new switch box will be mounted just below the chip tray on the left hand edge, it will have 2 more controls that the current button box doesn't have, a speed control potentiometer and a button for a ring light around the spindle.

This is a drawing of the new control panel:

The new control panel will be low voltage, and later on a second one will be mounted on the other side of the mill area with the controls for the axis motors when i add them.

All mains stuff will be housed in a 300x400mm wall mounted electrical box, controls circuits will be 12 and 5 volts and contactors will switch the VFD and 24v 15A psu for the planned axis motors, mcb's will be in there to protect the individual circuits, plus an EMI filter and chokes on the input wiring, as the VFD does make a fair bit of electrical noise that the hall effect speed sensor on the DRO doesn't like… makes it think the spindles doing 300,000 rpm!

the VFD programing/info panel will mount in the door of the electrics box as well as tell tale lights to show the psu status, plus the fault indicator and reset button for the VFD, a 120mm fan and vent will keep the enclosure cool, both will have a filter to keep out dust.

To be continued…..

[not done it yetParticipant @notdoneityet]

Presumably the pallet increased the number of points for some of the turns? Warco certainly need to take note of that!

Their reported mill sizes were also totally inadequate – lucky the VFD box could be relocated without Warco needing to provide a fitter/engineer/technician. They should most certainly have provided a suitable cover and reimbursed at least some of the cost for the poor (or lacking) detail re the clamping kit.

It seems as though you may have been used as an unpaid (and costly to yourself) guinea pig.

I think they have, at last, realised that a three phase motor, with VFD drive, is a definite improvement over the DC disaster systems provided previously. It may have been more expensive (or maybe not?) but, IMO, I think your drive system is far superior to the former.

Of course, your machine might just be one with a dud drive system (on arrival from China), where Warco have installed the modified drive system?

Guessing here, too, that the maximum machine height in the Warco description was incorrect now that an induction motor has been fitted on top? If so, they should possibly be paying for your roof-raising costs?

[CirclipParticipant @circlip]

"

Presumably the pallet increased the number of points for some of the turns? Warco certainly need to take note of that!"

Think I would prefer a 10 point turn with an electric pallet truck than a hernia. Would have loved the inconvenience rather than having to deliver d*mn great B&O television sets ( two man lift ) using handraulics. Given the picture of the assault coarse from the road to the workshop door, the construction of a special size pallet "just in case", how much extra does Joe public want to pay for the privilege??

When the statement on walking a mile in someone elses shoes is quoted, try heavy deliveries.

Regards Ian.

Edited By JasonB on 27/04/2021 10:03:12

[CirclipParticipant @circlip]

Thanks for that Jason, don't know how the old "Underlap" problem occurred, shades of a few years ago. Bit like XP, get the system working properly and then some bright spark decides he knows a better system????

As an addition, spline chunk doesn't work either.

Regards Ian.

[JasonBModerator @jasonb]

There was a table lurking in there, but don't know where it came from.

[GazzParticipant @gazz]

Warning.. the following show contains excessive use of the word "VFD"
Please do not view if you are offended by this term

Apparently the last batch of GH 18 mills (delivered up until about Feb 2021) came with the VFD 3 phase motor drive system, i've heard from at least 2 others who were as surprised as me to find this out… and i imagine there are other owners out there who have no idea and think it's single phase fixed speed and the motor just makes a strange whine compared to others.

Kinda daft how they don't take advantage of one of the main things a VFD provides, the ability to allow the motor speed to be altered on the fly… 3 more wires (2 really as there's an unused grey wire in the loom between VFD and control box.. or use the grey wire as a pull through to get the 3 new wires in) and a potentiometer on the control panel, plus one setting change and it's working.

Or mount the VFD box on the wall and leave the front cover off temporarily and use the knob on the setting panel to adjust the speed like i did for a few weeks.

Warco are out of stock of this machine right now, and they've upped the price by 50 quid, so not sure if that's because the VFD system is standard now, or just a price rise due to covid etc, so anyone thinking of ordering one of these because of the VFD… try and get info out of warco to confirm the next batch of these mills will be the same, or back to the old setup,

The lathes that are available from warco with either the DC motor or 3 phase VFD system command quite a premium for the VFD version. i.e the WM 250 lathe, the VFD version is £370 more than the DC motor version.

The 'manual' that comes with the mill has no mention of the VFD, shows a wiring diagram for the single phase forward and reverse contactors, plus the timer needed to ensure the motor has stopped before trying to reverse it (otherwise a single phase motor will just keep going the same direction)

And the sales page shows a photo of the mill with a single phase motor (large connector box on the side of the motor housing the start capacitor)
When i asked if they had the 3 phase motor specs i got no reply, mentioning it in further emails they'd answer the bit about the clamps etc but ignore the motor/VFD questions.

That's why i traced the wires on my mill and made a Colour Wiring Diagram, as all the info i've gathered so far point to no one at warco knowing much about the VFD drive's (purely my assumption, and i could be wrong)

I know of someone who had a WM 290 lathe, from new it had a problem where it seems the VFD is set up wrong, takes ages to get upto speed and cuts out and back in at certain speed ranges etc,
The engineer sent out spent 4 hours and got nowhere, he was told the motor taking so long to get upto speed must be normal as that is set by the factory!!

ERM… it's a VFD, there are parameters to set all this up and it's obvious one of these parameters has been entered wrong, but if the service engineer doesn't know how to adjust them, what hope do us users of the machines have of getting the info on these systems.

The 'cure' for that WM 290 lathe is to replace the whole lathe and hope the next one has it's VFD set up correctly.

I have now learnt not to place too much trust in the machines listed dimensions, fitting a DRO to it i was glad i didn't blindly order the scales based on the sizes listed on warco's site.
A 400mm scale for the X axis that they recommend would have been smashed first time i moved X along it's full 470mm of travel… so i got a 500mm scale,
Same with the 350mm recommended size for the Z scale, needed a 450mm scale for there,
Y was close, it's got 190mm and they say a 200mm scale will do, but you really should have more than 5mm of space at each end to be safe… hence a 250mm scale was ordered for Y… and as i fitted a 4 axis dro, the 70mm of quill travel turned out to be ~78mm, so a 100mm scale was used there… i'll detail the DRO selection and fitment shortly… i did not buy it from warco….

I have not been totally put off buying from warco, i recently bought a rotary table from them because they had it for the best price, i got it in the 10% off sale over the past weekend… noting that i saved £15, but with the £16 i lost on the hold down clamp thing i'm still worse off lol

[GazzParticipant @gazz]

Re: the pallet thing,

The wooden crate the mill was in was constructed with 3 longitudinal strips of wood on the base, which i thought was to allow a pallet trucks tines to go under,

I was told the crate was sent to the main depot of Palletways, where it spent the weekend and then shipped out to me, so not sure if the pallet was from warco, or added at the shipping depot.

Someone posted a photo of their WM 18 mill being delivered, and it's sat on a pallet that is the exact width of the machines crate, if my mill had the same it'd have gone through my workshop door.

That was a little annoying, but not the end of the world, an hour or 2 with a jack, a prybar and the wheels sorted that out, the crate was wrapped in black plastic, so if it rained it should have been ok stuck outside for a bit.

[SillyOldDufferModerator @sillyoldduffer]

Posted by Gazz on 27/04/2021 16:12:12:

Re: the pallet thing,

The wooden crate the mill was in was constructed with 3 longitudinal strips of wood on the base, which i thought was to allow a pallet trucks tines to go under,

I was told the crate was sent to the main depot of Palletways, where it spent the weekend and then shipped out to me, so not sure if the pallet was from warco, or added at the shipping depot.

Someone posted a photo of their WM 18 mill being delivered, and it's sat on a pallet that is the exact width of the machines crate, if my mill had the same it'd have gone through my workshop door.

That was a little annoying, but not the end of the world, an hour or 2 with a jack, a prybar and the wheels sorted that out, the crate was wrapped in black plastic, so if it rained it should have been ok stuck outside for a bit.

Your suspicions are justified! My mill arrived on two pallets: the close fit small one provided by Warco had been plonked on a big one by the carrier, I suppose to make it fit their pallet trucks. The inner and outer documentation had different headers. Also two different carriers were used: one moved the mill cross-country to their local depot, where it was picked up by a local carrier and brought to me. As carriers might alter the consignment to suit delivery needs, I suggest it's unwise to assume anything about the size or shape of packaging unless specifically agreed beforehand. We've all had giant boxes from Amazon containing items that would fit through a letter box!

Not taking advantage of the VFD's speed control feature may be due to the tapping feature, which is too much for a single-phase motor. Maybe the VFD's main purpose is to do tapping acrobatics. As the mill has geared speed control, it makes sense for the VFD to provide uncomplicated constant speed 3-phase – less to go wrong.

I'm not sure the VFD programmed tapping function would still work properly if the user independently altered motor speed. I suspect tapping would have to be arranged to override any speed set by the user and perhaps that's a little too complicated. Even considered unnecessary given the machine has geared speed control.

Worth trying, but it may not be as easy as adding a pot and tweaking a few parameters.

Dave

[JasonBModerator @jasonb]

Posted by Gazz on 27/04/2021 15:54:53:

The lathes that are available from warco with either the DC motor or 3 phase VFD system command quite a premium for the VFD version. i.e the WM 250 lathe, the VFD version is £370 more than the DC motor version.

About half that cost difference is for the power cross feed, not all for the VFD

[GazzParticipant @gazz]

About half that cost difference is for the power cross feed, not all for the VFD

Doh!! i never spotted that, i thought you needed to be at the WM 280 level to get power cross feed, i was originally going to get a lathe to replace my mini lathe, and wanted power cross feed so was looking at the 280, but it was a bit out of my price range but i was hoping to save up,

So if i'd noticed the 250V had the power cross feed i wanted i'd have likely had that lathe now instead of the mill.

[Tim HammondParticipant @timhammond72264]

Concerning your problems re, raising the head via a handwheel, I have a Warco WM12 mill, the head on this is raised and lowered by a horizontal handwheel atop the column, is very awkward to use, and especially hard work to raise the head. To get round this I use a 13mm socket in a battery drill to drive the securing screw on the handle and it works a treat. Perhaps you could use something similar on a temporary basis prior to installing a permanent drive? Note: I too have arthritic hands & wrists and find handle twirling difficult.

[GazzParticipant @gazz]

i did try to do that with a drill, but i'd have needed to make up an adaptor, as the handle on my mill turns a ~20mm D shaped shaft.

The Z axis lead screw is secured at the top of the column with a nyloc nut, so i could have driven that… and i keep thinking that's where i should put my motor rather than in place of the handle, so if the motor system fails i could just pop the handle back on and wind it by hand until i fix the motor.

I know some mills with this set up… i.e. handle on the lower side of the column) have a power Z axis, and in-place of the nyloc nut at the top of the lead screw is a motor coupler (then a gearbox and a motor)

i'm not sure how that motor coupler is fixed on to the lead screw on those systems, it may just be screwed on and locked with a grub screw?

Or it may be an extended shaft above the nyloc nut that secures the top of the lead screw in it's top bearing that the motor coupler fits onto… unfortunately getting up there each time to have a look and take measurements etc means standing on a ladder and leaning over,

But i gotta do that sometime anyway, as before i get to the motorized axis project, i need to finish off the DRO instal, and that's to fit the spindle speed sensor so it shows the speed on the DRO screen, need to fit some magnets on the top of the spindle drive area, then the sensor that picks them up as they whiz round… i keep thinking it may be better to fit that sensor inside the gear head, but not sure how oil resistant the sensor is if i do that (will only be splashes, wont be immersed in the oil)

Where i really find the handle twirling difficult now is when i've been using the mill then go to use my mini lathe, the carriage hand wheel on the mini lathe is only slightly larger than the quill fine feed wheel on the mill, and the cross slide one is even smaller,

I will get on with writing up the next parts of my 'GH 18 adventure' soon, got the new control system to write up, then ordering and fitting the DRO, then on to how i'm trying to reduce the almost half a mm of quill up n down movement due to the sloppy fit of the rack n pinion that winds the quill up n down… oh yeah, between them last 2 i adjusted the back accordion bellow to allow the vice to just fit under it rather than hit it and reduce Y travel, plus changing the bit of rubber sheet that covers the rear Y ways with an accordion bellows and so on.

[GazzParticipant @gazz]

The tapping function on this mill is silly simple, it's just a micro switch that when hit by the depth stop on the quill signals the VFD to go into reverse… you hopefully having remembered to set that depth stop to somewhere before the end of the blind hole you're tapping

Another microswitch at the top of the depth stop rod signals the VFD to stop after the tap has wound it's self out of the hole and the quill flies up to the top of it's stroke …. You gently guided the quill to the top of it's stroke 😀

For the single phase motor version, how it operates from what i worked out from the wiring diagram in the manual is…

The bottom depth stop microswitch releases the forwards motor contactor and starts a timer, when the timer runs down it triggers the reverse motor contactor, the top depth stop microswitch releases the reverse contactor and you can restart the motor in forwards to tap another hole.

Back to the VFD version:

The common wire to these depth stop microswitches is only 'live' when the mill/tap switch is turned to tap, when the mill/tap switch is set to 'tap' the reverse button is disconnected, so can't be inadvertently pressed.. nor can you 'automatically' tap a reverse thread, only the forwards button works.. that is to be expected…

But the thing that worried me when i first tried it, whilst the quill is at the top of it's stroke the depth stop rod is holding the stop microswitch in.. these switch signals are just pulses, but it's blocking another stop pulse from being seen by the VFD, hence the stop button does nothing until the quill is moved down enough to release the top microswitch.

The e-stop button does work at all times thankfully.
But first time i played with the tap function i was alarmed that it seemed that once started you couldn't stop it with the normal stop button. now i understand how it works i know why, and i have made a mod to my new control panel with an extra switch and a diode so pressing the stop button triggers the e-stop when in tap mode at the top of the quill stroke…

i did this as i'll rarely use the tapping function, and would panic if i start the spindle, change my mind and can't stop it by pressing the normal stop button, having forgotten about having to lower the quill a bit to get the stop button working.

[IRTParticipant @irt]

I have had mine for about 18 months now. I was surprised when it arrived with a box on the back of it containing a VFD.

[not done it yetParticipant @notdoneityet]

Posted by Gazz on 27/04/2021 02:50:16:

 

This pic posted by gazz, earlier, caught my eye. Clearly a lot of things wrong if the label indicates a single phase motor while a 3 phase is fitted. Also the indication of 3HP, but only 900W power is mystifying. Are chinese 3HP motors only delivering 900 Watts?

Can anyone please enlighten me? Is it really a 1.2HP motor with an efficiency of only around 40%? Something seems wrong, to me.

Edited By not done it yet on 30/04/2021 08:17:57

[GazzParticipant @gazz]

i wish i knew the specs of the actual motor fitted, but emailing warco results in no replies,
When i ask the same questions as part of a pre sales email, they answer the questions about the other product i was buying, but ignore anything about the VFD or motor.

I'd like to know what the motor's specs are so if i ever need to replace it i have at least a ballpark idea what to look for.

I was told that there's no easy way to find out the motor's specs by measuring it, i was thinking measure the windings resistances, and the current when it's running… i.e. the current to each winding in turn, noting the voltage the VFD is putting out… BUT i know that will be awkward as a VFD does not put out sine wave AC, but more switched DC pulses in a rough form of a sine wave (hence why older motors don't last long on a VFD)

[SillyOldDufferModerator @sillyoldduffer]

Posted by not done it yet on 30/04/2021 08:17:38:

Posted by Gazz on 27/04/2021 02:50:16:

 

This pic posted by gazz, earlier, caught my eye. Clearly a lot of things wrong if the label indicates a single phase motor while a 3 phase is fitted. Also the indication of 3HP, but only 900W power is mystifying. Are chinese 3HP motors only delivering 900 Watts?

Can anyone please enlighten me? Is it really a 1.2HP motor with an efficiency of only around 40%? Something seems wrong, to me.

Edited By not done it yet on 30/04/2021 08:17:57

'Horse Power' is so grievously misused I suggest banning it entirely, or at least insist no one ever takes HP on trust! Dodgy Horse Power claims go all the way back to James Watt. In this case '3HP' refers to the mounting size, not motor power. 3HP happens to be the maximum nominal power available in that footprint: it doesn't mean that particular motor outputs 3HP. Compare the Citroen 2CV car, 'deux chevaux-vapeur', i.e 'two steam horses' which never had a 2HP engine! Confused, you soon will be!

At 240V the label, which doesn't match the motor, claims 6.6A = 1584W Input, in which case the 900W refers to output at an efficiency of about 57%. Another maker of this motor claims 750W out from 220V at 5.2A in, which is an efficiency of 750/1144W (66%), which is interesting because they headline rate their motor at 0.52kW out at 71%. Power out isn't a solid quantity: it depends…

As the power output and efficiency of an electric motor depends on the load and how hot the windings can get it's possible to justify a whole range of different power figures for the same motor. They are all valid at some point. And then exactly the same motor can be driven to a higher power output when fitted with a cooling fan, whilst exactly the same motor could fail within ratings due to being stuck in a tiny unventilated box by the owner. The whole muddle is a glorious opportunity for misleading sales-speak and honest misunderstandings.

Single-phase motors are particularly confusing because their characteristic RPM, Torque and Power curves are all over the place. However, it's true of all motors that power output depends on how the motor is measured, which is almost never stated on the motor plate. For that reason, plate information is more hint than guarantee.

To actually understand a motor, it's necessary to study a graph of all it's performance curves, using them to balance desired efficiency, input, output, torque, and max winding temperature. Only then can continuous power output be predicted, or the higher power outputs available at lower duty cycles claimed.

What's the power output:

• at 90% RPM
• at start (0 rpm)
• just before stalling
• at maximum efficiency
• continuously with motor naturally cooled
• continuously with motor fitted with an impeller
• continuously with motor force cooled with a separate fan
• at 10% duty cycle
• at 50% duty cycle
• 50% loaded
• 100% loaded
• 200% loaded
• at different voltages: How about running a 220V motor at 300V?
• at different frequencies between 15Hz and 150Hz?
• at absolute maximum? Maximum found by adjusting the load irrespective of temperature, efficiency and signs of distress. (Ignore smoke!)

All different!

Getting motor power right is more critical in an industrial setting where work has to be done within a specific time frame and machines are driven hard round the clock. As a hobbyist I don't fret about it. It's enough to keep an eye on the temperature during unusually hard sessions. I have a WM280 lathe and putting anything like it's full 1500W into a job is uncomfortable. It can do piece work rates in bursts but the machine is far more civilised below 1000W. I've never got the motor hot, and measuring the input shows most jobs consume less than 400W in. About 500W is sufficient for most of my metalwork. My workshop's most powerful motor is in a vacuum cleaner, and I don't care what it is as long as it sucks.

Dave

 

Edited By SillyOldDuffer on 30/04/2021 13:47:51

[GazzParticipant @gazz]

Part 4, "Let There Be Light"…..

One of the first things i needed for the new mill was a decent light shining on the work table, about 6 months ago i made myself a little PCB drill press using a dremel clone mounted in a universal mini drill press frame, and one of those cheap tiny (that look bigger in the sellers photo's) X-Y tables to allow me to drill rows of holes in the pcb's in a nice straight line… i use the Y part of the table to set the line i want to drill along, and slide the pcb along it on the X axis.

But after suffering with trying to position goose neck type work lights and always getting a shadow in the wrong place, i fitted a small 'ring light' to it,

 

So i knew i was going to do the same to my 'big' mill before i even ordered it, i chose a 100mm LED 'angel eye' sold to car owners to 'replicate' that BMW ring of light around the headlights look,
I got mine off ebay, and the 100mm version cost me about £8, and handily this seller sells them singularly:
**LINK**

The 100mm angel eye has an 88mm hole in it, and the GH 18's quill is 85mm at the part that is widest, i just needed something to hold the angel eye to that cast iron ring that clamps around the quill and the depth stop rod fixes to.

So i designed a simple plastic holder that the angel eye will clip into and be secured to that cast iron quill ring, the hardest part was getting the 3 pockets the clips go into in the right places plus a slot for the wire to exit, this is where i learnt to 3D print 0.2mm slices of an item that i want to check for dimensions on the real part it's to fit.

 

About 30 minutes of 3D printing time and i had my ring light mount:

2 holes tapped M3 secure it to the quill's ring piece
i made a version that has 3 tapped holes that come in from the sides so the screws clamp to the actual quill… well the larger piece of the quill that stops the quill retracting up too far, so any slight marks from the screws wont ever interfere with the quill retracting,

And my final version of the vertical screw hole adaptor has just 2 holes in it… i always seem to do this, print out something that works but could be better, then i make the mods to the design to make it better and publish that version, but keep the earlier version in use.

 

Here is what the ring light looks fitted on the milling machine:

The .STL files for this ring light holder are available here:

**LINK**
You'll find a some milling tool holders i made on my ThingiVerse page that may be of use too.

There are the 2 versions of the angel eye holder, and also 2 little holders for the 'jelly bean' buck converter that is in the wires to the light, this is because these are designed to go on a car, so a little regulator ensures that the right voltage is always fed to the led's as in a car the voltage could be anywhere from 9 to 18 volts (modern cars with 'smart' alternators can charge the12 volt battery at 18 volts when it's is low from say a winter start!)

I just used a 12 volt plug in power supply to run this right light until i did the major control panel modifications, the 100mm angel eye pulls 300 mA at 12 volts.

It gives a lovely crisp white light .. when buying an engel eye, pay attention to the led colour, some sellers have those garish blue tinted ones, apparently some car owners like that look! i prefer white to be white, not yellow or blue.

In the photo's it looks like it might be a glare into your eyes when using it, but really 90% of the light is fired downwards onto the table, and i really don't notice any glare from it.

 

I've made a few 3D printable tooling wall mounts others may be interested in… i'm on a budget so most of my stuff is the cheapest version you can buy.

Gazz's ThingiVerse Page

I've made holders for R8 collets (based on an interlocking design for ER32 collet holders i found) MT2 collets. MT2 and 3 dead centers, MT2 live centre, center drills, 

Holders for an an economy parallel set, adjustable parallels, wiggler/edge finder, deburring tool, Soba 75mm boring head and 20mm boring bars, various R8 shanked tools like the drill chuck, fly cutter, those £25 indexable face mills from banggood, a slitting saw arbour (1 inch bore plus blade storage) the index plates and accessories for a HV6 rotary table and so on.
Hopefully someone else may find these of use and print some out to use.

 

To be continued……

Edited By Gazz on 30/04/2021 15:26:54

Edited By Gazz on 30/04/2021 15:31:22

Edited By Gazz on 30/04/2021 15:32:12

[GazzParticipant @gazz]

Part 5 "I want that last 10mm of Y axis travel"

I bought a 100mm vice to use on my mill, just a cheapie of course but not just any cheap vice.. it's a

"Versatile-Milling-Vice-with-swivel-base-and-a-self-aligning-spherical-segment "  

Yeah, i got sucked in with the sales patter on this one, it's a bog standard cheapie chinese swivel vice with a ball bearing in the moving jaw to lead screw connection, complete with a slightly mis-milled hold down slot and painted with a 6 inch brush by a blind man it seems:

But apart from that it seems a good vice and i paid a fair price for it, don't get me wrong, I've spent just over £500 with Arc Euro Trade for bits for this mill and will continue to shop there.
They were very helpful when i forgot part of an online order i made, i couldn't use the phone for speech to phone in the other bits, so they let me do another online order, combined them and took off the postage on both orders i made as in total it went over the £75 for free postage limit.

 

Like most people i guess, the first thing i did was take the swivel part off likely never to be fitted again,

But rather than chuck the swivel base under the bench and forget it even exists, i made a 3D printed wall holder for it, just to remind me i have the swivelling part to use if i ever need to,

3D Printable 100mm Swivel Vice Base Wall Mount

This was one of the harder to design 3D parts, it's not just hollow inside, it follows the bases curves and angles, and has a tee slot protrusion to keep it fairly straight (i always like to get plenty of wiggle room in 3D printed parts, it's not exactly printable at micron accuracy what with shrinkage and layer lines and all that.

 

Continued in next post due to character limit for whole post….

 

Edited By Gazz on 30/04/2021 17:08:37

Edited By Gazz on 30/04/2021 17:10:54

Edited By Gazz on 30/04/2021 17:12:29

Edited By Gazz on 30/04/2021 17:14:14

[GazzParticipant @gazz]

Continued from the post above…

 

So i fit the new vice minus the swivel base to my milling table, and notice that if i wind the Y axis back the top of the vice jaw hits the accordion style dovetail slide protector for the Z axis.

I've been robbed of at least 10mm of travel

The fix is simple tho, when i removed the 2 Allen bolts that hold the angle bracket for the bottom of the accordion way cover, i found a dovetail bent-to-shape piece of flat steel is bolted to the column, which means the base of the cover extends downwards by way more than is needed to keep the ways covered.

So i removed that piece of bent steel and raised the base of the way cover up, the bolt holes are in the middle of the L bracket that secures the base of the cover, and if bolted to the holes that held that piece of bent steel on, the vice top still hits.
But drill 2 new holes in the way cover angle bracket, right at the bottom of it, and this is the result:

There is a downside of course, every action and all that like Newton said.

You lose a little bit of Z travel at the bottom as the accordion way cover can only close up so much (maybe removing a couple of the pleats may help this),

This mill has what i think is a fairly generous Z height on it's column… so much that i had to raise the roof above the mill to accommodate it, so it's usually the other way that people won't give up travel in, i.e. upper Z travel not lower.

I have found i usually have an R8 ER32 collet chuck in my spindle, and even with the slightly reduced bottom Z travel i can make the nose of it hit the table.

So i decided i'd rather have the extra Y travel, after all it's only 190mm to start with, compared to over 400mm for Z (don't believe Warco's measurements, i ordered a 450mm long scale for the DRO to accommodate the real Z travel, not the 350mm they state)

And if i ever do need that little extra to lower the head with say a direct R8 collet mounted bit, it's just 2 Allen bolts to pop out and let the way cover move down, i may make up some thumb wheel bolts to allow me to do this without even getting the Allen keys out.

Since this photo was take i have fitted a DRO to this mill, i fitted the X axis scale to the rear of the table, and guess what… with the cover over the scale it robs me of just as much Y travel that i had gained from the Z axis way cover mod.

..etc.

 

But i can sort that out, the cover for the scale is over double the width of the actual scale, so i plan to cut the top of the cover along it's length to make so it doesn't stick out too far past the actual scale, and gain my Y travel back.

Also you can see how the Y axis way cover bunches up, it's just a flat piece of neoprene.
I changed that for an accordion style way cover just like the Z axis one and no longer have the issue of the flat cover bunching up and pressing against the X axis DRO scale etc.

I'll show that mod shortly, then the control panel mods and DRO instal etc.

To Be Continued…..

Edited By Gazz on 30/04/2021 17:19:11

[GazzParticipant @gazz]

Part 6 "Y axis accordion way cover/ bellows"

The Y axis has a neoprene sheet type cover for the rear of the ways on this mill, pretty standard on these Chinese mills it seems, but i didn't like it and wanted one of the pleated accordion type way covers like the Z axis has.

I could have bought one from china on alliexpress etc, or even had one custom made by a camera bellows maker, but i was ordering some things from arc euro trade and saw they did them, i measured up and of course i'd need the most expensive on they sold, it always seems to be like that.

So i bought This One costing £39

The actual item is a little different from that picture, but it's just an extra chromed strip and angles on the end with the taller fixing piece.

It measures 240mm wide, which is handily a little wider than the width of the bottom part of the dovetail castings on the Y axis, so it will fully cover the oiled sliding parts of this axis, and I knew i'd need to cut the pvc formers to make it fit, but the actual black parts of the bellows are just right for the Y axis of this mill.

I cut the pvc formers straight up and across at the edges of the black part of the bellows, i could have tried cutting the angles so they'd go over the dovetail of the Y axis, but i figured as the pvc formers would be off the end of the dovetails when compressed, they might get snagged and not slide over them when moving the Y axis forwards and rip the bellows apart.
The black part of the bellows in the above picture sit nicely over the dovetails with a couple of MM sideways movement if you push them.

I also reduced the overall length of the bellows, as when compressed they restricted the Y axis moving right back, i found if i cut the bellows at the 1st PVC part, i'd have enough length when fully extended to cover the ways and not be too tight, and the metal cover reinforces the end of the bellows nicely.

Above you can hopefully see where i reduced the overall length, i could have cut them even shorter, but it was best to cut them where the chromed metal strip is, as that's where the PVC former part is in them, and that gives a strong point to fix that end to the table.

For the moving table end i used the holes that were already there for the flat cover.. i used a marker pen to 'blue up' the area around the holes, and pressed the bellows against them and it transferred the holes positions nicely.

At the column end (right in the pic above) you can see that i used a piece of aluminium to make up the difference from the foot of the column and the actual column, i used a piece of the aluminium extrusion i had left over from the DRO instal as the packer, the joint where the column meets it's mounting foot is not cast perfectly flush, so you'd need to mill a relief in the packer piece there.

Yes, i know, i drilled the holes off centre, i had to use a right angle drill adaptor to get in there to drill the holes in the column and didn't realise i had the left hand one lower than the right until i had finished tapping it, i can't see these fixing screws when using the mill, and i totally forgot about them untill i took this photo.

This is the cover from the top fully extended:

And here is the cover fully compressed:

I mentioned in part 5 that the splash guard for the X axis DRO scale might need to be cut in half to give me full Y axis travel towards the column, it turns out i don't need to do that after all, as it was the flat neoprene Y axis cover bunching up against the DRO scale cover that was causing the restriction.

You can see the black pen mark on the base of the mill that i put on when measuring up for the DRO scales, that is the true end of the Y axis travel, so i am short of maybe 2 or 3MM's now due to the bellows, the vice now goes even further back under the X axis bellow, and i can live with out that last couple of mm's of travel i think.

 

To Be Continued….

 

Edited By Gazz on 18/05/2021 16:14:25

[GazzParticipant @gazz]

Part 7 "I don't like the stock controls"

This one is maybe going too far for most owners of this mill, but just in-case someone else dosent like how the stock control box rises with the mill head, here's how i changed that… and typical of me, i couldn't just mount the yellow control box on the mills column where it dosent move, i had to go for a whole new electrical control system including rehousing the VFD.

I have issues with my joints (and i don't mean the type you roll) and can find it painful to be reaching above me too much, on most mills of this type the buttons to operate the motor are on a box mounted (i'll call it the 'button box' from now on) to a swing out arm, which in turn is attached to the head of the mill, thus as you move the head upwards, the button box goes with it.

This mill has ~400mm of vertical travel, so that means that about half of that travel puts the head above my eye line, and i found it very awkward to be operating the switches/buttons then.
i could argue that as the emergency stop button is on that button box i wouldn't be able to hit it if i needed it quick… but i do have a whole workshop E-stop system i fitted that kills power to all sockets that machines can be plugged into, there are 10 of them in total, on the edge of the benches mostly.

I also only stand at the mill if i'm doing a really quick operation, i have a tall bar stool type seat i sit at most of the time. also i wanted to add an extra 2 controls, a speed control for the VFD and an extra button for the ring light.

This is the mill with the stock button box on the head, it's wound nearly to full height (it's at the top of the column, but there's another 30 or so mm it can travel before it hits the physical stop)

I also didn't like the wire routing, mains comes in to the yellow button box, goes through the fuse, main switch then back out to the VFD, the control wires come from the VFD to the button box… but also the 3 phase power to the motor comes into the button box, then immediately goes back out and to the motor, and then a wire comes from the depth stop / tapping function switches and spindle shield stop switch (which was removed the day i got the mill) to the button box.

Reaching for the Z column locks meant having to move the tangle of wire conduits out of the way, i also wanted to have a better housing for the VFD to live in, one with ventilation out the top and not just the bottom, and i plan to motorize the Z and X axis at some point, i wanted room to house the 24 volt psu for that, as well as add a few other control items.

 

I decided to have a large-ish electrical cabinet mounted on the wall, that will house the VFD, motor psu, a small control psu so all controls operate at low voltage, some circuit breakers, contactors, warning / operation lights plus a mains filter, as i found i was getting a lot of interference from the VFD within about a 3 foot radius of the mill when it was in operation, and this played hell with the DRO's spindle speed function… saying it was turning at 300 thousand rpm's when it was really doing only 90,
The electrical cabinet will have a 120mm vent at the top and bottom, and a thermostatic fan in the bottom with filters on both inlet and outlet.

To do this i basically stripped all the wiring out of the mill, i'd already worked out the stock wiring for it, This Thread shows the circuit diagrams i drew up that covers the stock wiring and operation of this mill.

 

I purchased a 300 x 400 x 200mm metal electrical wall mount box from ebay for £29 Ebay Link if i was not housing the 24 volt 15 amp psu in there too, a smaller box would have easily housed just the VFD and control items like the contactors and breakers.

I'd also bought an english text VFD programming keypad with display and extension cable, as the one that came with the VFD was in chinese, and i wanted to have the keypad on the front of the electrical box so i can see the display showing the frequency i have the spindle running at, and any error codes and so on.

For the new button box, i got a plastic enclosure 200 x 120 x 75mm in size, this would allow 8 standard 22mm industrial style buttons to be mounted easily, i plan to get another later on to house the Z and X axis motor controls, and the plan is to mount these button boxes on the front of the workbench just below the mill's chip tray, so they will always be in the same place, and i can build up muscle memory and be able to operate them without flailing about trying to find where the button box is since i moved the head.

The VFD will be switched via a contactor, another contactor for the 24 volt psu for the axis feed motors, a 12 volt psu will be used for those controls so any buttons you touch when normally using the mill are low voltage.
There will be MCB's / fuses for the PSU's and VFD in the new electrical enclosure, a EMI filter plus ferrite rings on the power wires, a 120mm filtered fan, panel indicators for the psu's and VFD's fault indicator / reset function, and the VFD programming / display keypad will be on the front of the enclosure too.

 

I've hit the character limit again, so will continue in the next post…..

Edited By Gazz on 18/05/2021 21:23:33

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