Member postings for Clive Foster

That is a remarkably crude data-plate.

Normally motors capable of being configured in both Star and Delta have 6 terminals in the junction box witha set of links to get the coils in the appropriate order.

In the UK permanently wired motors on things like machine tools, especilly older ones, are commonly wired Star for 420 volts so changing needs digging into the internal wiring. Usually the data plate simply states 420 volts but I have encountered a couple that had details for 230 volt Delta connections on the data the plate as well with a simple punch or similar mark to identify which way the internal connections were set.

The first time I encountered such a motor I was unamused to find hard soldered connections after opening it up instead of the expected set of screw terminals to facilitate re-configration hidden under the junction box. It took a fairly forensic examination of the, somewhat aged, data plate to discover the indicating puch mark.

If you are lucky the reconfiguration connections will be on the back side of the visible board. Not something I've seen but I'm told it has been done.

Clive

Chris

Further to what AlanW has said it doesn't seem unreasonably difficult to come up with a functional equivalent to the spindle on my 15AY which has a similar style of large diameter bearing carrier to Alans modifications.

Mine has an MT 3 taper. The exposed spindle is 1 1/2" diameter and the quill carrying it only 1 5/8" diameter so the main body of the spindle must be rather smaller to allow adequate quill wall thickness. I imagine a inch or so. The bearing carrier is around 3 1/2" in diameter.

If you obtain an MT 2 to parallel sleeve it could be joined to the spindle by a simple tube having the appropriate diameters to accept the sleeve at one end and the spindle at the other. I imagine a couple of inches or so overlap on both would be plenty for high strength loctite bonding. Even without the pin used by Alan. The joining tube will need slots cutting in opposite sides to take the ejector drift.

Obviously you will have to accept some loss of quill travel and clerance between table and spindle to accommodate the bearing mount and MT taper extension. Fitting the bearing on the joining sleeve would be the most rigid arrangement and minimise the reduction in spindle to table clearance. I suspect Pollards used an angular contact ball bearing to take the loads.

In your position I would use it as is and decide what to do later to make it exactly what you want. Start wih a 3 phase motor and VFD.

Clive

Edited By Clive Foster on 16/01/2022 21:22:51

Chris

Professional woodworking shops are hard on their machines.

Pro equipment has, historically, been hefty and strong to put up with it. Just because the material is soft it doesn't mean that a light duty flippity flop machine will be up to producing accurate results.

If you aren't in the trade or don't know someone with a higher end wood products workshop its easy to overlook the standards of accuracy and repeatability needed to ensure things fit together with snug joints without lots of hand fettling. A, now unfortunately deceased, friend who had a small high end wood workshop reckoned he would be generally working to 10 thou or better if he was set up to measure it rather than just making things fit. He built a small traction engine and considered the accuracy needed no more onerous.

Clive

colin

Well done.

I'm sure everyone who has participated in this thread is glad to hear the happy outcome.

Clive

DiogenesII

I think the 12AX was current up until the mid 1960's or so when it was replaced by the Corona 100/A that I had. Which basically gained more boxy styling, a larger spindle and multi-vee belt drive. Lost the screw feed belt adjuster tho' for a simple permanent spring loading system. Push the motor against the spring to shift the belt.

Pretty much the whole Pollard range got re-vamped to more modern styling in the 1960s -1970s but little change in the innards.

I suspect that Chris will find a Corona 100/A manual adequate for general what goes where and how does it go together information subject to a bit of engineering experience to sort out detail differences.

Clive

Chris

Spindle diameter is probably insufficient for MT2 adaption. Minimum diameter for MT2 seems to be around 1 1/8" inches, 1 1/4" sounds safer. Yours is probably about 1".

Picking up on the mention of Corona models by DiogenesII it looks like these, later machines, were fundamentally an update of your drill with muti groove vee belt drive, silly skinny looking thing, and a few, mostly cosmetic changes. The Corona 100A/1 I owned before I getting the 15AY was fitted with an MT1 taper in the spindle.

Generally the Corona versions appear to have been for woodworking use with appropriately higher speeds.

Pollards made a huge variety of machines and there is lots of commonality through the ranges. I suspect the sliding carrier for the quill & spindle assembly is the same as that used for the metal working machines with MT2 and, possibly, MT3 spindles. Easily checked by measuring quill diameter. If so it would be mechanically practical to chop the end of your spindle off and weld on an MT2 carrier.

Something I considered for mine when frustrated by the inability to use larger drills. Plan A being to operate on an MT2 jump up sleeve.

Never summoned up the courage to try! Sleeve is still kicking around here if you fancy a go!

I'd previously asked Pollards, who were still supplying limited spares at the time, if an MT2 spindle could be obtained and fitted. As I recall it they said that although an MT2 spindle could theoretically be fitted the job was impractical because the splines wouldn't match my pulleys.

Clive

Chris

13 AX manual will be of no help to you, that is a direct drive machine with a 4 speed pole changing motor directly above the spindle / quill assembly. See the pictures of the 15 AX in the catalogue on that makes up most of the Pollard section on Tony's Lathes.co site. Tony actually gives that information in the pre-amble but its not obvious unless you have some familiarity with Pollard products.

As you know yours is a more basic belt drive machine. Fortunately very little to go wrong.

I have a 15AY with 6 speed gearbox.

Clive

Me.

Simple answer.

Just buy a VFD from a reputable supplier like Inverter Drive Supermarket and try. You may decide your motor works well enough. Even if you end up changing the pulleys to improve low speed grunt it will still go fast enough.

Boring details.

No need for a two speed motor. A 6 pole single speed motor will work fine with a VFD and give essentially the same power characteristics. Vector drive would be best. You may decide to up the power a little over standard but I can't see the gain being worthwhile. If you need more torque at low speeds consider adjusting pulley sizes a little. Top speed should still be more than enough.

A standard 1,400 rpm motor needs a smaller motor pulley to help compensate for power reduction at lower speeds when driven by the VFD which will be operating in constant torque mode . In general over ± 1/3 rd of motor nameplate speed you will not notice any motor power issues from the VFD. Once you start dropping below 2/3 rds nameplate you may notice if working hard on large jobs. A 6 pole motor pushes the "you may notice" speed down sufficiently that a home shop worker is virtually certain never to be affected. Lots of folk do just fine with a 1400 rpm motor though.

Theoretically an 8 pole motor will be a closer match but again the extra cost isn't worthwhile.

Two speed motors are expensive and don't play well with vector drive VFD boxes. Although a basic voltage / frequency drive can work well enough its impossible to set the internal parameters to match both speeds. So you end up with a compromise that suits neither. In particular you can't get a maximum current setting that suits both speeds so there is a potential safety hazard.

Clive

Edited By Clive Foster on 14/01/2022 13:53:49

In general hydraulics are considered safer because there is no stored energy to drive an explosion. The fluid leak rapidly takes the pressure away once it becomes large enough. Pinhole leaks like the gas line Perko7 alludes to are pretty much just as dangerous.

I wonder what the relative safety of a simple air over oil system is compared to pure pneumatics or pure hydraulics.

My motorcycle lift has an X frame under the platform with a big vertical air over oil ram to do the lifting. The actual ram is hydraulic but its operated via an airline plugged into the top via the usual input and bleed valve controls.

Clive

Martyn

Nice to hear that you got sorted out in the end.

My cheapo works pretty well but clearly isn't up to the standard of the real thing. Realistically its as good as I could expect for the price and does the deed, with care.

Guy Lautard published drawings for a Blake style unit that appear to be well thought ot and should work well.Clockmaker standards needed in some places tho'. Its pretty obvious where slack clearances canr unin you day!

Clive

SillyOldDuffer

Nice diagram and explanation of a proper digital phase converter. Thats the sort of thing Phase Perfect in the USA make. By far the best solution technically but very much not cheap, inevitably so. Guess they'd be starting at £4,000 + for a 10 hp box if they came to the UK.

Robert

No data, no brand name, is indeed a very big red flag when it comes to power electronics. Drives Direct seem to know what they are doing and produce boxes that work, even if there are various technical breaches of regulations involved.

I take your point about VFD boxes not being designed for long cable runs and the potential for radiated interference. Mine sits right next door to about £800 worth of box containing hefty chokes and other smoothing devices which nicely deals with those issues. Probably also provides a bit more back isolation protection for the VFD from any motor and switching issues.

That said I've always been a bit sceptical as to whether significant high frequency transients can routinely survive being hooked up to a running motor with its considerable mass of copper and iron along with all the magnetic effects associated with being, effectively, a rotating transformer.

Sitting directly driving an open line now is .....

Hello I'm your aerial today, what can I radiate for you! ....

Basic checks suggest that my smoothing box deals well with any potential radiation issues.

Steviegtr

Putting a soft start box in line to help reduce current demands when starting up under load is an interesting idea. Not sure if its viable as an economy soft start box is very similar in price to a simple VFD of the same power rating. Individual VFD boxes are likely to work out cheaper overall unless you only have one nasty load. The economy soft start boxes only work on one phase so there is a risk that the phase imbalance will trigger the overload programming.

Bottom line is that the only affordable source for the electronics needed to make the sort of device we are discussing are VFD boxes. Although not specifically designed for the job some such capability is inherent which can be exploited even if its officially mis-use. So it just boils down to finding something that will tolerate this mis-use to do the job we want at a viable price.

My experience is that a sufficiently husky VFD box with appropriate smoothing can work very well and reliably when used as a substitute for line power. It may not be strictly to code but it is safe and non-interfering. The key is sufficiently husky. Trying to pare down to you exact needs "today" is risky. Ultimately we are using a device out of its specification so it pays to be gentle.

Clive

not done it yet

We seem to be getting at cross purposes here.

There is a vast difference between simply starting a naked motor with only a plain shaft to drive and starting one under load.

If you wish to use one of these VFD boxes as a transparent substitute for mains utility three phase it needs to be able to direct online start a motor under the same maximum load as it can manage when fed proper three phase. My experience suggests that the four times derating is prudent to be sure things will always work.

There can be no dispute that under the right conditions a considerably more powerful motor can be handled but defining right conditions given the myriads of potential applications and motor designs is flat out impossible. Possibly the best that could be managed in the real world is for the supplier to define maximum naked shaft motor and maximum fully loaded motor powers. Not going to happen for all sorts of reasons. If its even practical.

My experience with my 10 HP Plug'n Play box is that the 3 hp motors on my Hydrovane 502 compressor and Smart & Brown 1024 lathe are capable of making the box work very hard. Almost certainly pushing it close to the single motor start up limits defined by the overload protection programming.

Under sub-zero conditions the Hydrovane motor does the rurrm-rooom-rummm sound speed hunt as it struggles to pull through the middle of its speed range. Accompanied by nicely flickering shop lights. I know from experience with a similar compressor running with the motor connected in delta off a name brand VFD that the rurrm-rooom-rummm is right on the edge of overload trip for a properly set-up vector drive VFD without torque boost enabled. That one overloaded out maybe one time in three under sub zero conditions. Enabling torque boost was a complete cure. Not such an issue for the bigger Plug'n Play box, which will have considerably more built in overload margin than the matching 3 HP VFD had, but clear indication things are working hard.

If I attempt to start the 1024 with the reeves drive set to maximum direct drive speed contactor chatter due to volt drop in the line feeding the controls accompanied by workshop light flashing is almost certain. My machine has 220 volt contactors running direct off one phase so clearly there is a good deal of voltage drop. Run up is noticeably slower even allowing for the chatter. Something I don't do unless an emergency stop has bollixed plans.

The one time I inadvertently started the 2 hp two speed motor on the P&W lathe with the clutch engaged the box really didn't like it. Realising my mistake immediately I de-clutched about half way through run up and the motor spun up as normal. Two speed motors are notoriously inefficient during start up so its likely that if I'd just left the clutch in the box would have hit its overload limits.

VFD overload protection integrates current, voltage and time to, ideally, protect the box from letting the magic smoke out if a short circuit, or near short circuit, occurs either at start up or when the motor is running. There is no way of knowing what the programming of any specific box is but when using in this manner we have to be sure that the start up surge won't exceed the programmed limits. In the real world 3 times derating seems to be OK with the Teco boxes used by Drives Direct. If, as I suspect, the boxes supplied by JFK are made for lighter duty applications the overload settings will almost certainly be relatively lower so 4 times derate is prudent if you expect to start a motor on full load.

Obviously if you know you aren't going to draw heavy single motor starting loads then a smaller box will do. But folk like us aren't really in a position to know what the real loads will be and how they interact with the programming of the box we have bought. Easy to underspecify. I'm on 3.3 derate and can clearly get quite close to the edge without being silly.

Clive

On my Elliott 10M the feed ratchet increments during the stroke direction change. So going one way it feeds over the end of the cutting stroke and the the other over the beginning. At any sensible feed rate you loose very little of the ram stroke to feed. Perhaps 1/2".

Clive

Neil

Apart from Phase Perfect and similar devices which are built as industrial 3 phase utility replacement devices with corresponding costs, all these boxes are based on VFD internals so stepping up to 60 hz should be no problem. Certainly the (expensive) ones from Drives Direct will do the deed.

Have to accept that 220 to 380 /420 volt boxes inevitably loose voltage and overload current headroom when compared to normal same input and output voltage devices. But the 50 to 60 hz change will have no noticeable effect.

Clive

Edited By Clive Foster on 13/01/2022 13:12:27

not done it yet

If you want to use a VFD type box as a 50 hz utility supply substitute and simply switch the motor on with the VFD already running you do need something like 3 or 4 times oversize to reliably handle the starting currents. Don't forget that a voltage doubling VFD already has significantly reduced voltage headroom and over-current capacity compared to one having the same input and output voltages.

If you were to make an electronic device specifically to run at 50 hz and permit direct on line motor switching at any load the motor can start there are, probably, ways of cutting the effective over rating needed. Even so you will need internal components much huskier than a VFD needs.

But if using a VFD box 4 times is about right if you want to reliably start up under full load. Bottom line is that VFD design is optimised to soft start and ramp up from zero to whatever RPM is set without exceeding its internal current ratings. Hook a VFD onto a stiff load like a compressor and you may well find that there is a minimum acceleration ramp time below which the VFD cannot meet the motor demands when bringing the load up to speed so it either stalls out or settles at half speed. Modern vector drives have torque boost settings to give a bit more oomph in the mid range to avoid half speeding. There are good reasons why torque boost shouldn't be the normal setting.

Direct on line starting is just a more extreme example of this, effectively "zero" ramp time. So you need a unit designed for much higher powers to avoid falling foul of the internal settings. For obvious reasons the VFD box has to operate in Voltage/Frequency mode rather than the much more efficient Vector Drive mode which again doesn't help the overload issues.

My Smart & Brown 1024 VSL lathe has no clutch so the motor always starts under load. With a heavy job in the chuck the big Plug'n Play box is clearly working hard to get the 3 hp motor up and running despite its 10 hp rating. Generally if I have a heavy job mounted I'll start another machine first. Usually the drill. The running 3/4 hp motor provides a useful mechanical energy store to draw on as indicated by a slight slow down of the drill. Lathe start up is perceptibly faster. Not an ideal situation so heavy jobs usually go in the P&W which does have a clutch

Just have to accept that you are using a device that is designed and optimised for a different job so you are not going to get theoretical best performance whatever you do.

Clive

Colin

All VFD drives can act as digital phase converters as described by your link. They just need to have protection circuitry and short term overload capacity sufficient to handle the switch on and off transients and starting surge associated with Direct Online switching of the motor with the VFD already running at 50 Hz.

For practical purposes that means the VFD rating needs to be about 4 times that of the motor being started. So you need to buy a 4 hp VFD to run a 1 hp motor. Which is an expensive way of going about things even here and now when VFD electronics have dropped considerably in real terms. In general accepting a bit of run up time is a trade-off for a much less costly device. For industrial standards of reliability you need something a bit better than the general run of protection components too.

That said the idea works well when properly done and used within its limitations. I have a 10 hp Plug'n Play system from Drives Direct which has worked just fine for me over the last decade and more. Basically a Teco V/F type VFD modified to give 420 V (nominal) output with a neutral and, presumably, other tweaks to make it reliable. I have set of smoothing chokes hung off the back to help make its life easier. Largest motor is 3 hp and I never have more than about 7 hp worth of motors running at once. Actual power drawn will be less than nameplate as the hydrovane compressor is about the only thing that gets near to full power. So its working well within its theoretical limits. But even then its not having a terribly easy life. Drives Direct say it will start a 5 hp motor. Not it my workshop it doesn't.

Not cheap! At todays prices the 8 VFD boxes I'd need to buy would be more than price competitive if I didn't need to change a two speed motor as well. Although my box has done me well I'd not go that way today.

I'm uncertain about the boxes sold by JFK. They look to be lower end off the shelf 220 volt in 380 volt out Chinese VFD boxes. Probably pretty respectable performers at what they are designed to do, most likely speed reduction control on things like air conditioning fans et al. But whether they have active devices, protection circuits and capacitors able to cope reasonably long term with the thumping transient loads associated with direct-on-line starting of machine motors may be open to doubt. Long term, reasonably bullet proof performance is expensive. Even at China Inc prices.

I'd derate by a factor of 5 and always start the motors running light if I were to get one. I'd not risk a two speed motor.

Frankly at todays prices individual machine VFD boxes is the way to go. If you have a two speed motor bite the bullet and switch to a 4 or 6 pole single speed one to help torque hold up at lower speeds.

You will never see name brand makers producing such devices as the market isn't really there. Home Workshop and some smaller light industrial outfits are about the only people having the need to run several smaller motors on the cheap by converting single phase.

Clive

PS John Haine

They are VFDs. Just with a clever marketing makeover to exploit the inherent overload capcity of a big VFD to run smaller motors direct online.

Edited By Clive Foster on 12/01/2022 22:42:19

Edited By Clive Foster on 12/01/2022 22:42:59

Normal practice with power feed shapers is to have a plain section of just under thread root diameter a little longer than the feed nut at each end of the feed screw. So the nut runs off the screw before being driven into the casting as a hard, damaging inducing halt.

Feed is commonly by a simple ratchet system driven off the ram drive mechanism. One or more clickc of the ratchet during the return stroke. Only separate control of feed is by disengaging the ratchet plunger from the ratchet wheel. So generally the feed is going all the time the ram is moving.

Given the slow speed at which shapers run its not too hard to pull the ratchet plunger when the machine is running if you so desire. Normal practice is to simply stop the machine at the end of each pass with the clutch, if it has one, or by stopping the motor.

Some of the big boys are seriosuly more sophisticated. Especially the monster hydraulic Cincinnati and Rockwell beasts.

Clive

Edited By Clive Foster on 12/01/2022 16:41:43

I like that design by David George.

A most excellent re-boot of the classic milling / drilling spindle to bring it into the modern world of QC toolposts rather than the old style bolt to the slide unit. Be really nice to see a write up in MEW.

The article in MEW 208 linked to by Bo'son describes a very impressive tool but it is, I think, fundamentally for the "lathe only" shop needing milling / off axis drilling capabilities. It doesn't really translate to the sort of quick on / quick off device for a hole or three that the OP is looking for.

Having had the occasional need I'd seriously consider making Davids design if it were published with sufficient details to make a fast job. Despite using up the backs of a few envelopes over the years whenever the "that would be handy" need surfaced the effort involved in design, manufacture and component sourcing always seemed disproportionate.

Like everyone else here I'll not live long enough to get into the back half of my want-to-do list so things have to be prioritised.

One tiny gotcha to watch out for is arranging how to get the device in line with the lathe axis before applying the correct offset and starting work. I have a Coventry die-head in a QC tool carrier which has the same need to be accurately centred before starting work.

I turned the end of a blank end morse taper to fit the back end of the sleeve that carries the die head tube. Popping the taper in the tailstock and adjusting the slides so the die-head carrier sleeve can slide over the turned down end gets it true to better than half a thou with no drama.

Clive

I imagine that, as always, there are variations and tolerances involved. I don't recall ever handling anything tight enough to be legitimately called push fit. Mostly variations of slide on with a touch of slackness varying from "does it wobble or not" to "yep its got a bit". But not, I think, ever loose enough to have proper up and down shake on the spindle.

As ever the objective is to hold the wheel firmly without any bending stresses so there is a presumtion in favour of materials having a certain inherent flexibility just in case things are well out or a distracting Gremlin visitation occurs at exactly the wrong time.

I don't doubt that the spherical washer pair will work well, albeit rather expensively.

Objectively I can't see that material matters greatly given appropriate care when tightening up. Alloy worked fine for me the one time I needed such a spacer but choice was mostly down to having a ready made spacer just the right size in the handy bits collection. Salvaged from something no doubt or possibly an overmake.

Clive

Have you tried a plain spacer?

The plastic centring bushes used with modern wheels aren't a tight fit on the grinder spindle so a little rock or wobble is pretty normal when testing with the wheel just sat on the shaft. When the nut tightens up on the clamp washers, via a spacer if need be, things should pull nice and straight.

If the bush were a tight fit on the shaft any any errors would lead to the wheel being stressed as the nuts are tightened. Slight slack lets it find the natural position held between the dished washers.

I used an alloy spacer once in a similar situation. Delrin or nylon might have been a better material due to having a little more compliance.

As ever tighten gently and make sure the wheel is sitting nicely.

Clive