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WM18 - Broken it again :(

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Mike Poole19/02/2020 09:52:23
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If you use a variable speed motor to control speed then don’t forget that the power is also reduced. A 1hp motor only produces that power at full speed, at half speed it will reduce the power by half (roughly).There are calculations for material removal rates and the power required. A large drill will need to be run at a suitable slow speed but it still wants power to cut. As Jason says he adjusts his cut and speed to accommodate the reduction in power. Speed reduction by belt drive and gears has the advantage of keeping full power (ignoring losses). Electronic drives do fall short when larger diameters need slow speed but still want full power for a reasonable material removal rate. VFD conversions of conventional lathes have the benefit of retaining the mechanical speed selection so for larger diameters the back gear can be utilised so the speed control can be run at a high speed and thus develop full power to effectively multiply the torque available for cutting. Low speed high power exposes the compromise of electronic speed control.

Mike

not done it yet19/02/2020 12:03:09
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Do the purveyors of these machines point this out to prospective purchasers? NO, THEY DON’T! There is inter-company competition to attract the buyers with as much cheap hype as possible, this being just one facet.

Nobody(?) runs their machine at highest speed, at the chuck, all the time - unless the spindle speed is lacking (mine is only 1750 which is ‘slow’ and plain bearing machines are even slower). Carbide tooling is not best served at low speed, of course.

Not a lot different to band saws, which might appear to have twice the power, but are really no better than the ones which actually provide half the output power.

Little different to the compressors which, to some, appear to be far more efficient (by quoting ‘air displacement instead of the far more useful ‘free air delivery).

Unsuspecting punters are often being hoodwinked into buying machines that are not quite what they think they are.

There is one well recommended seller (by forum members) that does not, at least, over-hype their machine power by over-rating the drives. There are likely quite a few that do.

Years ago, small stationary engines from one manufacturer were rated differently to competitors. They eventually had to reduce their ratings because they got so much flak from dissatisfied owners - that their engines were ‘gutless’ - and their reputation suffered as a result (they reported ‘flash’ output, not a continuous output).

This is likely why ‘old iron’ is often better than buying new. OK if the buyer is aware and able to make fair comparisons. Not so good for the new starters, with no basic knowledge of this advertising hype. Mechanical wear is another problem for the ‘non-mechanicals’, of course.

Just ask any myford owner how many motors the machine has gone through in its lifetime of 50, 60 or 70 years.🙂

I’m still awaiting any reply on whether the figure quoted for this machine is actually to the motor or usable power out - or even power to the lathe, not necessarily to the motor, even. My current lathe has had a motor change (guessing simply from single phase to three phase) and my previous was likely still on its original (the direction change-over switch was a three phase type and certainly more than thirty years old when I bought it) and the instruction manual did warn about reduced motor life if started on a high speed setting, instead of reducing the speed before switching off. My first lathe only had its original motor (although its position was not ideal re magnetic swarf collection🙂.

Old is not always good, but is almost certainly more reliable.😉

Circlip19/02/2020 12:21:58
1045 forum posts

Ah but NDIY, you're not playing fair. Not everyone has the intelligence to select an appropriate cutting speed when using a lathe headstock equipped with GEARS. Much more lucrative to have a ready market with replacement Motors and elecfronic speed controls. Far more exciting to get it wrong and watch the smoke waft about and then try to fault find.

Regards Ian.

JasonB19/02/2020 12:23:53
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Posted by not done it yet on 19/02/2020 12:03:09:

Do the purveyors of these machines point this out to prospective purchasers? NO, THEY DON’T! There is inter-company competition to attract the buyers with as much cheap hype as possible, this being just one facet.

The fact they say "max drilling capacity 16mm" is quite clearly giving the limit of what the machine should be expected to do.

Other suppliers have ratings such as Craft/hobby/trade or model engineer/engineer and a lot state hobby use only or non production runs etc.

Sieg know that some people won't read the instructions so also put the max capacity on the front of the mills head, you can't point it out much more obviously than this. Unfortunately there are still those who know better and that is why we tend to get more posts by people with problems with their machines than by those happy with then and that distorts many peoples views of these machines

drill max.jpg

I would say Warco list Input to the motor not output from what has been said here over the years.

Still like to know what lathe you were using?

And once again I will point out that the WM18 is a mill as you still seem to think it is a lathe.

Edited By JasonB on 19/02/2020 12:30:30

Edited By JasonB on 19/02/2020 13:18:36

Martin Connelly19/02/2020 12:27:26
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I spent 33 years as a manufacturing engineer. I frequently had to tell workers from apprentices up to people close to retirement to use the correct speeds and feeds when drilling. The machinists used the correct values but fitters, pipe fitters and electricians all came out with the same statement. They were told to run big drills slowly so they chose the lowest possible speeds if they were drilling anything over 12mm or 1/2". They also set auto feeds to the lowest value when they should have upped it for large drills. This, they claimed was what the tech college was teaching.

Recommended for a 22mm drill into steel is about 250 rpm and feed is 0.3mm per rev.

If you use CNC you have to put in either these numbers or tell the program you are using what you are doing and it puts in the correct values.

Do not assume these rpm values are for industry only, they are better for the drills and better for the finish of the cut surface. The feed value is important and should be used whatever rpm is used, any lower and the drill rubs, any higher and the drill is being forced into the workpiece too fast. A spray bottle of cutting fluid is all that is needed most of the time but back off and let the drill cool for deep holes as required.

If you don't have a chart for drilling feeds and speeds into various materials then get one and use it or get a phone app if that suits. It's like the regular advice for parting off, don't be tentative, let the tool cut not rub. For electronically controlled motors (other than VFD 3 phase) use the recommended speed to get tbe power out of the motor rather than running too slowly and overheating the motor.

Pet rant.

Martin C

JasonB19/02/2020 12:40:20
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Posted by Martin Connelly on 19/02/2020 12:27:26:

Recommended for a 22mm drill into steel is about 250 rpm and feed is 0.3mm per rev.

Well that would just bring my WM280 to a halt.

All the old charts and working practices need to be used as a guide at best when working with direct or two speed range variable speed DC brushed and brushless motors.

This was one of the reasons Ketan wanted the lathe and mill beginners series written by Neil and myself, apart from a bit of metalwork at school we don't have all the old engineering aprentiships behind up but have used these types of machines to good effect for a number of years. There are obviously people out there completely new to using a modern hobby lathe and going by requests for back issues and even if they will be made into books seem to be addressing questions they want to know. By comparrison I have not seen any such requests for the beginners lathe one running at the same time in ME on an old Myford and once again making tooling my views on which can be read in the latest MEW

Martin Connelly19/02/2020 13:23:36
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That's why these machines have a maximum drilling value below 22mm. Turning the power down is only going to make matters worse.

Martin C

Martin Hamilton 119/02/2020 13:50:13
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As Jason has said some importers use output wattage whilst others state input wattage on the same machines. Take the warco wm180 lathe with brushed motor for example, they claim a 600w brushed motor fitted. Some other different importers of the same machine claim 450w brushed motor fitted with the same motors. One uses input wattage & the other output wattage.

Mike Poole19/02/2020 14:11:49
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Dirty Harry said “a man has got to know his limitations” it applies to his machines as well. smiley

Mike

not done it yet19/02/2020 14:13:17
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Still like to know what lathe you were using?

And once again I will point out that the WM18 is a mill as you still seem to think it is a lathe.

My lathe is a Raglan 5”. Over 50 years old? Probably in as good, or better, nick than most modern offerings. Most definitely better value for money - of that you can be assured.🙂 It will out-last me and likely its next 5 owners,too.

A (vertical) mill is only a ‘back to front’ lathe stood on its end. Makes no odds as to whether one will cut a hole any better than the other. That is simple physics. Or perhaps you can give some reason why a lathe should be able to drill holes better than a mill? Indeed some hold parts on the lathe saddle/cross slide and drill (or mill) with the drill (or cutter) in the lathe chuck. An example of a vertical mill layed on its side, perhaps?

I pointed out that I knew his was a mill or that I drilled on my lathe earlier. Unimportant really, unless you are trying to lay red herrings! Simple reason I gave was that all my larger drills are long and tanged (so not so easy to eject them after use in the mill spindle - head space quickly disappears with extra holders, no direct wedging opportunity to remove a drill and I don’t like thumping my spindle bearings more than necessary 🙂.

Additionally, it is being used in horizontal format at the moment. Mill is the Centec 2B (I wouldn’t even try with the Raglan, of course) and although it has a 1.2HP motor, the vertical head is only driven by a single belt - I may well fit twin sheave pulleys at some stage - not like the twin belt drive to the main gearbox. Gearbox was only initially rated for a one horse power motor, so I endeavour to not overload it.

Hope that satisfies your curiosity. But we are still comparing an 1100W motor with a 746W one. One doesn’t cope and one does (without any problem). Further, we are not told whether a (common sense practical) pilot was drilled, what material was being drilled or even at what speed. So no absolute comparisons but just a fairly clear general one.

buy cheap, buy twice comes to mind. In this case, buying a 16mm machine and using it for a 22mm task comes back to haunt the user.

JasonB19/02/2020 14:51:59
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Thank's that is all I needed to know, you are using a mechanical variable speed machine so motor can be at it's optimum speed for a given spindle speed unlike electronic control.

You did mention that you had a 3-phase motor fitted, If I assume you have that on a VFD then did you have it at 50hz and use the lathes variable speed to get your drilling speed or did you select 1750rpm position on the lathe and drop the spindle speed by use of the VFD?

lathe would generally be more rigid for two similar sizes machines, in mill terms your lathe has a 5" throat which would be a lot more rigid than a comprable mill that may have a 10" throat at least that's what my schoolboy physics would suggest.

Dave Halford19/02/2020 15:34:26
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Posted by Martin Hamilton 1 on 19/02/2020 13:50:13:

As Jason has said some importers use output wattage whilst others state input wattage on the same machines. Take the warco wm180 lathe with brushed motor for example, they claim a 600w brushed motor fitted. Some other different importers of the same machine claim 450w brushed motor fitted with the same motors. One uses input wattage & the other output wattage.

The trouble with this whole thread is some people insist on mixing electrical watts with mechanical watts.

The mill in question may well be 1100W input, now that's makes a it mill with a 1hp motor and a 2 speed gear box that swallows 1kw of lecky which should be capable of driving cutters of shank 1/4 3/8 1/2 5/8 the largest of which strangely matches the max drill size.

Cutting speeds and feeds are dependant on the hp available, but this is never mentioned in the charts which assume big industrial iron. I have a chart that lists 50rpm for a 2" cutter on high carbon steel, we all know that might be the official speed, but not on a 1hp machine.

 

Edited By Dave Halford on 19/02/2020 15:36:14

not done it yet19/02/2020 16:32:22
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C’mon, if the machine flexes - and I would not expect my Centec to flex to any discernible degree - it is a pansy machine. We are down to power from the motor to drill a hole. Simple as that. We have two real options on this thread - poor motor characteristics (or poor machine design in utilising the power available) or operator error. Possibly a combination of the two?

I actually doubt the single V belt to the vertical head on my machine would cope with anywhere near a kW at low speed (even the 1/2HP Raglans were fitted with twin drive belts to the spindle).

Sure, at 30m/minute cutting speed and zero at the centre, the 16mm bit would have 40% increase in rotational speed, but the fact remains that a 60 75 year old design with later power upgrades, to twice the original, cut a 22mm hole with no problem, compared to a modern machine - supposedly with 50% more power - which should have been restricted to a measly 16mm. It’s what you get for cheapness - high running/repair costs.

Defend them as much as you wish. I chose to buy a robustly engineered - mechanically and electrically - machines.

JasonB19/02/2020 17:33:21
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Not defending them just stated that they can't be expected to perform like industrial and have been explaining since why.

Maybe read my first reply again

"If you keep breaking it I would be looking at a new operator rather than motor or at least treat it as a hobby machine and don't expect it to cut like an industrial one"

The OP chose the hobby machine route but seems to treat it like an industrial machine not helped by people on here saying "I can drill 22mm no problem" without stating what they are using.

Yes a hobby machine will flex more than a similar size industrial one and they won't have the same power available at the spindle due to electronic variable speed for a similar size of motor ( a fact you still don't seem to be able to grasp or want to). But with the right technique and treating with respect are capable of producing the same quality of work in the right hands.

Edited By JasonB on 19/02/2020 18:24:26

SillyOldDuffer19/02/2020 18:37:17
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Far Eastern hobby machines are what they are, and no-one claims they are perfect or just as well made as an ex-industrial machine. What NDIY forgets is in the good old days there was no way a hobbyist could have afforded a new Raglan 5" lathe. (Unless exceptionally rich.)

To me it's a straightforward choice between the risk of buying new Far Eastern and the risk of buying second-hand. Unfortunately second-hand machines are also only what they are: just because NDIY has a good Raglan doesn't mean that all 5" Raglans are excellent value for money. Far from it - they're a dying breed - the last Raglan was made over 50 years ago.

NDIY argues the WM18 mill is inferior to the Raglan lathe because the Raglan can drive a bigger drill with a smaller motor. True enough, but so also is the opposite case: the WM18 can spin much faster than a Raglan. The mill can do 2800rpm with the DC motor happily delivering full power at that speed. So the WM18 outperforms the Raglan for small drilling, and it can drive carbide tooling, and - of course - it's a much better mill than any lathe can ever be! As a drill in ordinary sizes, any mill is a better bet than a lathe because lathes have to spin the whole job, which limits the size and shape of the object they can manage. Milling machines can drill holes in much larger objects, anything that can be got on the table. And if a hole larger than max recommended drill size is needed on a mill, it can still be done - drill a hole within the limits of the machine and then bore it to size. It just takes longer to do.

Some confusion on the thread about motor power. Motors should only be compared when the gear ratios are the same. The Raglan does better turning a big slow drill that the WM18 because the Raglan has an effective backgear. On the other hand, the Raglan isn't geared to drive the chuck at high-speed because its bearings can't cope.

Horses for courses! Comparing the Raglan to a WM18 is roughly equivalent to comparing a traction engine with a motor car - as tools they are good at different things!

I don't care what people own, but I put it to anyone concerned to 'prove' that old is best that they are damaging the hobby. How many newcomers are put off by loud claims Far Eastern kit is simply no good? Actually my experience is Chinese machines are affordable, and low-risk bought new because bad examples can be sent back, and they perform reasonably well, warts and all. Consider the alternative: the future of the hobby is grim if only tools made by long bankrupt firms are good enough!

Dave

not done it yet19/02/2020 19:48:22
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Jason,

I am fully aware of the deficiencies of the modern average chinese drive. That is why I chose to go the reliable route. I grasped all that a very long time ago - long before I took up lathe-work as a hobby.

I hope you are not trying to suggest I ‘egged on the OP’ to get him to drill a 22mm hole with a chinese hobby motor - I did not, only demonstrating after his ‘accident’(?) that there ought to be some explanation about how, and only when, that claimed 1100W was available as my meagre 746W motor coped admirably.

A lot of readers will perhaps now take that into account before jumping for the least expensive machine that will supposedly do the job.

You may not be aware, but the Raglan lathes were also supplied to run up to 2500rpm - but without the auto-feed sections active. I could go to the limits of my chucks, I suppose, if I so wished, as the bearings are so much superior to most chinese offerings, it seems. VFDs seem so much more reliable than the DC route. Same with my mills, the top speeds could quite easily be exceeded, but I tend not to, preferring to look after them.

Dave,

I bought my 5” after running a delightful Raglan Little John - that after a thoroughly unenthusiastic time with my fist lathe, a new chinese offering (but it did have an AC motor). Compared to a myford, the LJ was incredibly cheap, yet of vastly superior performance - the latter likely reflecting the cost differential when new. The 5” is a good cut above the LJ, them having made improvements throughout the lathe.

You are totally wrong about the bearings - they are very long lasting and able to cope with very high speeds! (see above). I have never yet used the back gear - the VFD goes low enough for all I have needed. Such basic misunderstandings are likely why the Raglans are not more popular and more expensive.

I’m not going out to drill a 22mm hole with my mill, but I am quite confident that it would cope just as well - given I were to double up on those drive belts. It would certainly not smoke the motor like the OP’s, as I have driven it hard on occasions. Not often because there is no need, no rush - it is a hobby.

As a passing thought - the motor was, apparently, sufficiently powerful to actually drill but gave up because it was not capable of running for long at even an output of only one horsepower, or less. Says volumes, for potential purchasers to take note of.

Goodnight both.👏🏻

Andrew Johnston19/02/2020 20:15:25
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Posted by not done it yet on 19/02/2020 16:32:22:

C’mon, if the machine flexes - ........................ - it is a pansy machine.

Ah well, that's the Bridgeport in the flower bed then. When I stalled it recently playing with a face mill it's knocked the head slightly out of tram. Not surprising it stalled, I was pushing my luck in terms of metal removal, about 2.5 cubic inches per minute. That's pushing it for 1.5hp. But at least I now know where the limits are.

There's no reason why a DC motor drive should be less reliable than a VFD. There's a saying in the world of power electronics that any fool can design a circuit that works, but designing one that doesn't let the magic smoke out under fault conditions takes skill and costs money. smile

Andrew

mgnbuk19/02/2020 20:40:25
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Recommended for a 22mm drill into steel is about 250 rpm and feed is 0.3mm per rev.

22mm = 0.866". 0.3mm is approx 0.012". So volume of metal shifted at 250 rpm is

0.433 x 0.433 x 3.142 x 0.012 x 250 = 1.767 cubic inches per minute ?

At the "rule of thumb" that steel is shifted at 1 cubic inch per hp per minute, that would require a 1 3/4hp motor - a bit more than a WM18 can bring to the party at  250 rpm.

Nigel B

Thanks Dave - obvious error rectified ! blush

Edited By mgnbuk on 19/02/2020 21:08:59

Edited By mgnbuk on 19/02/2020 21:10:41

Dave Halford19/02/2020 20:56:52
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Nope smiley

not done it yet20/02/2020 07:26:23
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Nigel,

No different than your calc but if you use D^2/4 instead of r^2 you don’t have to calculate the radius - after all we, as engineers, generally only measure the diameter.🙂.

They only teach pupils to use Pi r^2 in school because it is easier ? When did a school aged pupil measure a diameter? Only when wrapping thread around a cylinder and calculating the relationship between circumference and the diameter from the circumference. Then they say circumference is 2Pi r, rather than Pi D! Why? Because are is taught as Pi r^2. Beats me why, but that is the way of all school text books!

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