Member postings for John Fielding

OK Full marks to Neil and Roderick Jenkins. I wondered how long it would take for the penny to drop.

It is in fact a one off lathe made by Joseph Clement for Charles Babbage between 1823 and 1824.

Joseph Clement was a highly skilled machinist and now I can see the connection between this lathe and the Holzapffel company, they were almost next door to one another in London.

Charles Babbage, with Joseph Clement doing the machining, tried to make the first British (note others had already succeeded) Difference Engine for computation and printing of mathematical tables for navigational purposes. I wasn't sure it was still in the Science Museum, but Neil has now confirmed that point. His design was a failure and he later tried to make an "Analytical Engine" before giving up on that task and eventually died whilst making his Difference Engine 2. His son carried on but only complete about a quarter of the machine. The lathe passed to his son but I wasn't certain what became of it. I seems he bequeathed it to the Science Museum in his will.

It is an incredible piece of engineering and the parts that were churned out by the hundreds all had to fit to ridiculous tolerances today we would find hard to work to. Incidentally Babbage also had other wide interests. One was the invention of pressure die-casting to make identical components for his Engines. This was in the mid 1800s.

That is a very interesting collection of pictures!

It is definitely a Myford ML7 but the tailstock isn't original. In fact that lathe in the picture is the very first style Myford made. Later numerous refinements and changes occurred leading up the the Super 7 variant introduced later. The first ML7s were produced in the Beeston factory late 1946. I have the ME for 1946 which is the original announcement it would be going into production towards the end of the year and it is exactly the same as the pictures, even down to the odd index dials. Later Myford changed these to the Mazak types most people are used to seeing.

It may be a good investment from a historical point of view, it seems a bit pricey, but Austin 7 cars now also sell for ridiculous prices!

Some of you are getting warmer but nobody so far has hit the nail on the head.

Interesting about Holtzapffel, I had assumed from the name it was a German company but googling it I found it was actually a British company albeit the originators were sort of German as they came from Alsace, that often disputed little area which oscillated between Germany and France.

I will disclose the answer in the next day or so if nobody gets it right. I think you will be surprised with the true story!

Hi Trev67,

In a word NO. But I did have some success using a method devised by Westinghouse in the USA. This method they claim can reclaim most troublesome cells. Note I used the word cells and not battery. This method I have tried and it does to some extent work but there is no guarantee.

What it consists of is a huge power supply that can bang a huge current into the cell for 1s and then it immediately discharges it at the same rate. They call it "Pulse Charging" or "Pulse Reconditioning". Repetitive pulses over a period of a few minutes can make a cell recover to about 70% or more of its original capacity. Note the original capacity is what the cell had before it died. If the cell was a 2Ah cell and when it went belly up it was down to an actual capacity of, say, 1Ah then you might get 700mAh after pulse charging, but it is a moot point.

I messed around with this method for a few months and then lost interest. The Westinghouse papers describing this technique said that the repetitive pulsing and discharging appears to "shake up the chemicals" and bring them back to life. It can work but I didn't think it worth the effort to productionise and market the product. However, some folks do sell such rejuvinators and make some pretty fantastic claims to its efficacy. Somehow I am bit sceptical from my experiments, but I haven't tried one of these modern types.

Hi Neil,

Buy yourself a cordless drill and make an adapter to fit the cross-slide handle

Ketan,

I am surprised you are having difficulty with CI, it is one of the easiest metals to groove and part off.  Maybe the top rake isn't suitable on that carbide insert?

Edited By John Fielding on 14/03/2016 12:19:07

I use counterbores for forming flat seats with a hole in the middle. They are freely available for most sizes of imperial and metric bolts. I gave up on D bits years ago!

Hi Russell,

Actually it doesn't really make any difference what state of charge the NiCads have before being put into storage. Over a long time period they will self discharge down to zero. Lower temperatures slow down the inherent discharge but don't completely stop it.

I went over to Germany and spent a very informative few days talking to the scientists and engineers at Varta. They were the original inventors of the NiCad technology under the original German company name, which I now forget, but they gave me dozens of research papers written over the years. The subject of cell matching was my particular topic but we covered the whole gammut. It seems that cell matching is really a waste of time and effort and my experiments also seemed to point to that particular area, so that is why I convinced the company to send me overseas!

The top scientist, who was one of the original patentee's, was well into his 80s and he told me the original work was done during WW2 for the Nazi war effort for the V2 missile battery pack. He also told me cell matching suffers from aging. If you take say three or four identical cells and they are matched to within 0.001%, which they somehow managed to find by selection from thousands of cells, then over a charge-discharge cycle of ten they tended to drift apart by as much as 10%. Over twenty cycles it was like 20% and so on. After 50 or more cycles they can be as much as 70% variation and that was what he was currently working on to find the reason and a solution. That was in the mid 1980s so things have improved a bit but not by a huge amount. He is obviously now designing batteries in heaven!

NiCads were killed by the environmental lobby and NiMH became the chosen flavour for a while, now it is LIPO and the other variants.

The scientist was also intrigued by my information about zapping cells to bring them back to some sort of life.  After a while he leaned over during our discussion as said "Jah, that is absolutely correct. But you should have asked us, we could have told you that!"

Edited By John Fielding on 14/03/2016 10:53:24

In my view there is no such thing as good and bad lathe, milling machine or whatever. The days when British machine tools and the US machine tools were regarded as the best in the world has long gone. A beginner will get some useful experience and learn a lot even with a clunker umpteenth hand lathe. As the old saying goes "When you are first starting out any old thing will do, but when you decide to take it up seriously - get a good one!"

Well as far as chinese machines its take your pick. Don't be conned into believing all chinese lathes are actually made in China. Some of the best far eastern machine manufacturers are actually in Taiwan, which used to be Formosa in pre WW2 days. The Chinese government have been pressing the Taiwanese for years to come back into the fold but they don't want to! Taiwan was formed after WW2 when the Japanese were booted out and made to cede the territory back to the chinese who elected to go there to escape the oppressive conditions on the mainland. So a thriving industrial empire arose on the island of Formosa and they chose to rename it Taiwan. The mainland chinese were stuck back in the 1800s mindset with a largely agricultural form of existence. The more go ahead members of the chinese politicians did a runner to Formosa and took all the countries gold and other currency and gave the others the middle finger! Look at the stuff coming out of Taiwan in the 1970s and 1980s, companies such as Rong Fu who make some excellent small machine tools, sold by Warco and others are still thriving and mainland China is only now catching up.

I was curious to find out more about Rong Fu so I looked at their website and there was my RF-25 mill and a whole lot of others.  Of course it had been refined a bit from my 1990s machine and had more safety guards and slightly difference twiddly bits but it was still the same basic machine. Then I went onto Google Earth and found their physical address and looked around the Taipei area were they were situated.  In a square kilometre or so I counted nearly 100 machine tool manufacturers making all sorts of lovely machine tools.  That little area just out of the main city is a hive of activity.  I looked at loads of websites and was amazed at the variety of machines on offer.  Interestingly there were several companies making as near as makes no practical difference, the same milling machines, each one had slight detail differences but you could clearly see they all had the same parentage!  Turns out it was a government policy to promote parallel development and assembly to offer maximum employment and nobody has a problem with "copying", it is a cultural thing over in this region!

Edited By John Fielding on 14/03/2016 10:23:11

Martin you might like to reconsider your choice of bearing material!

I have long ago ditched the use of bronze on two counts. The first is the cost, it has gone through the roof recently and when I priced it recently I nearly needed CPR, the cost was astronomical! Today my preference is to use cast iron and Doug Hewson also advocates its use as it has some very good benefits over bronze.

Cast iron contains flakes or nodules of graphite, which is in itself an excellent dry lubricant. It also has a surface when machined which is porous, similar to phosphor bronze, so it has millions of little inclusions that hold oil. Bronze in the harder varieties has a surface which is smooth and doesn't hold oil to any great extent. So if the bearing is starved of oil it tends to pick-up steel splinters and these grind the bearing away. Cast iron is marginally softer and can accommodate tiny metal debris better, like white metal linings do.

But it really comes down to ease of machining and cost in my book. Cast iron of the continuously poured or spun cast and chilled variety after the continuous pouring promotes the maximum growth of the graphite particles and it is a fairly "soft" material to machine. When the bearing is run it has the ability to form a glass hard surface, which still has tiny oil pockets and graphite. Good cast iron is like machining chalk, and a good HSS or carbide tipped tool will make light work of it and the surface finish straight off the machine is more than good enough to use right away without any honing. Honing does give a better initial finish but just running will do the same thing after a while if the fitting is acceptable.

Cast iron is an interesting material from a metalalogy view point. Unlike other metals it has no plastic region when heated or cooled. The difference between the liquid state for pouring and the solid state is only a few degrees, so it "sets" almost instantly. Steel and other materials go through a plastic state as they cool from the liquid state. Hence, they can be forged or squeezed into shape when hot, cast iron doesn't have that capability.

Another good material to use is Vesconite, which is a self lubricating plastic.  Fitted as a sleeve into a steel or cast iron housing it offers some give and it can tolerate minimum oiling and accept a fair bit of debris.  It is extensively used in the mining industry where the underground conditions have high dust in the air and shackle pin bushes on tipper trucks, front end diggers etc use it widely.  Take a look on their website and see the steam locomotive page where it is used to refurbish the valve gear on the South African locos at Reef-Steamers.  I can vouch for its efficacy as I also use it in some jobs. Vesconite is one of the hidden materials but it is made in South Africa and they have a plant in the USA also making it under license and NASA use it as well, so it is well respected!

Edited By John Fielding on 14/03/2016 09:37:34

I am not too familiar with the lathe mentioned but it looks to be a bigger version of the mini-lathes. The limitations will be a) lack of rigidity and twisting of the bed under big cuts, b) insufficient spindle power to drive a tool with big cuts, c) lack of saddle lock is definitely going to be a problem, d) slides are probably not able to resist big cutting forces.

On my Myford Super 7 parting off was still an issue even after tinkering with all the slide and bed adjustment to eliminate slack, until I bit the bullet and invested in the optional rear parting tool post. What a revelation! I had promised myself one day I would get one. On a trip to the UK I finally visited the Beeston factory and exchanged a lot of money for the item. Arriving back home I fitted it and I was gobsmacked how easy it was to part off things I would never have thought possible before. Before 1-inch BMS was about the limit, now 2-inch was a walk in the park. On ali bar 4-inches didn't even raise a sweat. The length of the parting tool blade was the final limitation on the diameter for ali bar. I can just manage 6-inch but the blade sticks out a little more than I like, but the blade doesn't seem to mind.

The secret to parting off are to lock the saddle, make sure all the slides are correctly adjusted and to work as close to the head stock chuck as possible. It goes without saying that the work must be held very tightly in the chuck, so a 4-jaw chuck is much better than a 3-jaw chuck. Keep the feed on as hard as possible without crowding the lathe and use floods of coolant, except cast iron which works best when cut dry. Use low speeds when parting off for maximum torque. On a lathe with a fancy variable speed drive I think you will be limited with the torque but on a geared head or belt driven lathe slow speeds are torque multipliers!

In my appie days I spent 3 months at the English Electric Napier Works on the East Lancashire Road in Liverpool at the government training school and I worked on everything from a little Boxford up to a WW2 Dean Smith and Grace monster with a 8-foot long bed and a 18-inch chuck. That lathe would part off 6-inch diameter steel bar like a hot knife through butter, it was, despite its age and hard life in the munitions factory during the war, a very solid machine with a huge motor and it had self act on the cross-slide to boot. So knock the cross slide drive on and stand well back as the blue ribbons of steel came at you at a furious rate of knots.

Talking about scraping bearing surfaces.

I did do some scraper training as an appie, but not much since then. However, in the 1960s I was invited to see an old Lancashire cotton mill engine in a factory (in Burnley IIRC) that was about to be demolished. I think Fred Dibnah dropped the chimney later, before he was famous.

The engine was installed around the middle of the 1880s and had worked almost continuously until the demise of the cotton industry around the mid 1950s or so. So it was about 70+ years old. The interesting thing was the crosshead slide. This had been made as part of the bed casting and had been "machined" by chipping out with chisels along its length and breadth and then hand filed and finally scraped to flatness. You could still see the tiny scraper impressions made all those years ago. The stroke was about 6 foot and the crosshead was about 12-inches wide. So around 6 or more square feet of cast iron had been hand filed and scraped.

I got hold of an old engineering book and looked up how they did it before the days when milling machines were in common use. Seems the scraping was commonly done by hand by two men who worked together and a gauge plate of flat cast iron about a foot square was coated with soot and oil and then rubbed on the surface to show the high spots and then the fitters went at it with files and scrapers. It must have taken days of work to get it flat over the whole area. Thankfully we today have milling machines and grinders. But you have to take your hat off to those men in bygone days, their work was still evident after millions of sweeps of the crosshead over all those years of running. They don't make them like that any more!

I came across this picture of a rather unique lathe in a book I bought from a secondhand bookshop at the weekend.

I was intrigued by some of the special features it has and I wondered if anybody has seen it before.

Of course the book gave a full description of the lathe and who built it and for who it was made and I thought the brains trust might like to see if they could identify it and what it was intended to be used to make?

A couple of clues: It is British and it was made in the early 1820s.

Let's see what answers we get and then I will give you the full details later!

As the thread seems to have wandered off course into NiCads and other rechargeables I can tell you some interesting facts about these.

Over the years in my professional career I was involved in several deep studies into rechargeable battery packs for the military equipment my company manufactured. The original range of products all used a 15V dry-cell battery made by Eveready. Since this was the "standard" battery pack all man-pack radios were designed around this battery. Two of our competitors also standardised on this battery and it became "the battery of choice". The original radios were "build to print" ones we obtained a licence to manufacture from a European company and they used the same battery. So it made sense to use the same shape and format when a new radio was on the drawing board. The radio could be extended in length very easily but the same bottom die-casting and battery box was used throughout the series.

Later Ni Cads became available and naturally we looked at changing the battery to this type, but still keeping the same battery box mechanics. The box could be made a bit deeper if need be to accommodate various cell configurations.

In selecting the cells we had a limited choice as the sanctions had a severe impact on our source of supply. We had two choices, Tadiran in Israel and Eveready in this country. Of the two Tadiran was streets ahead in the technology.

To decide on the cell which best suited our various products we ran extensive tests over about a 2 year period. From this mass of accumulated data we learnt all the was to know about NiCads, warts and all. One serious problem is that when a NiCad battery pack is discharged below its recommended capacity the battery can suddenly develop a drop in output voltage. This is caused by poor capacity matching between the individual cells. If all the cells had the same capacity then they would all sink in voltage as the battery is discharged. But if one or two cells had a lower capacity they would run out of energy before the others and then they flip in polarity as the discharge current through them continues. So when the pack is recharged the flipped cells stsy flipped and now subtract from the total voltage. Charging a cell with the wrong polarity normally damages the cell beyond repair.

A flipped polarity cell can only be reversed to the correct polarity if you have access to the two terminals on the cell. Simply recharging the whole battery pack does nothing to reverse the cell polarity. I devised a method of reversing the polarity which in 80% or more cases was viable. I called this technique "cell zapping". Basically it uses a huge pulse of current applied for a very short time to blow away the crystaline growth which develops when the NiCad is left in a dischaged state and which also occurs when it is reverse polarised. But for this to work you must be able to connect to the individual cell terminals and preferably with the other cells disconnected. Hence, you have to dismantle the battery pack. In the military radios we didn't have a moulded plastic casing at first. The individual C-size cells fitted into a carrier like a torch or other appliance. So swapping out a dud cells was simple and quick.

I hope this post isn't too long!

Emgee,

Have you actually performed capacity tests on NiCads?

I have done many charge/discharge tests on hundreds of different types to ascertain the actual capacity in various stages of a battery life and it is very clear that 2% per day at elevated temperatures is quite normal for some cells. NiMH are slightly better but not by much. The change to NiMH was more to do with environmental aspects than battery life or capacity.

I developed automatic charge/discharge equipment to do extended life testing for NiCads and other types to assess the best choice for our applications and there is a huge difference between different manufacturers cells and batteries. Some batteries which claim 40Ah for example struggle to make half of the when tested under standard conditions. This is the Peukert Factor coming into the equation!

Hi Steve Vine,

That is a bit like how long is a piece of string, but I will try and give some pointers.

The minimum voltage is highly dependent on the plate technology in use. Modern batteries use silver and other exotic materials to alloy the basic lead and these are claimed to be able to drop to lower minimum cell voltage. For a standard lead-acid cell the figure of 1.75V is considered to be fully discharged, but that is the open circuit voltage. As soon as a load is applied it will drop because of the ESR. The generally accepted min and max voltages for 12V automotive batteries is 10.5 to 15.6V in use. The problem is that if a batteries is unused for a long period the plates start to sulfate and the ESR goes up even more. So a simple answer is - if in doubt put it on charge!

Hi OuBallie,

Sorry my post was long but it is a deep subject and without all the facts people jump to incorrect conclusions.

The old LED on the battery (used to be torch bulbs in olden days) does absolutely nothing, zip, nada, to prolong a battery life. In fact it is about the worst thing you can do.

As I tried to explain, ALL rechargeable batteries no matter what the technology, NiCad, NiMH or SLA suffer from a slow and steady inherent discharge mechanism. The old wives tales that you should only ever store batteries in a fully charged state is total rubbish. A typical NiCad, or similar type, will discharge at about 2 to 3% per day at ambient temperatures of around +20C. One thing we did for the military users here to prolong man-pack radio battery life was to buy old supermarket freezers and store the batteries in them. In the Free State at the main store the warehouse temperature gets to +45C in summer. High temperatures make batteries discharge faster, lowering the battery to about -10C slows down the discharge by a couple of % per day. But it doesn't stop the discharge altogether.

Also this boll*cks about never stand a car battery on a concrete floor is also BS. There is no scientific proof it does anything at all to a battery capacity. I have been around batteries my whole working life and worked on many battery designs and charging systems, so I think I know a little bit about the topic. In 2006 I published a textbook on this topic which is sold worldwide and nobody to date has pointed out any errors in my statements. They are all based on well documented facts.

Sorry for the rant - time to cool down.

OK Kwil,

Maybe not forever, but 24 years is pretty good going I would say. All Inknow is that in 24 years I probably won't be turning metal into swarf anymore!

Car tyre valves (Schrader valves) also work well and cost almost nothing. Grab a handful from your local tyre fitters as they cut them out and toss them in the bin when replacing tyres.

Forgot to mention another pointer.

If you google a US company called Deltran they have some very comprehensive papers and other facts about battery charging. I have used their products and they are, in my opinion, one of the top companies in this market. The engineers there are real experts in their subject.

Another factoid about lead-acid batteries that may interest the readers is the way professional large battery bank chargers are designed. I have been involved in several designs over the years. These batteries are monsters, the smallest bank was 100,000 Ah for a small exchange.

To reach the absolute maximum state of charge requires the final cell voltage to reach about 2.6V. For a 12V battery that is about 15.6V. The charger has several settings, the initial trickle charge to bring the voltage into the range where normal charging can safely take place. This is a current limited supply which raises the battery voltage to around 11V. Thereafter the main charger circuit is enabled and it has the current limited to 1/10 of the battery capacity, so for a 40Ah battery it is programmed to only allow a maximum of 4A to flow. When the battery voltage rises to near the nominal fully charged condition the charger switches to a sort of trickle charge rate of 1/20 of the capacity, so 2A maximum is used for a 40Ah battery. When the battery hits 14.5V the trickle charger voltage is raised to 15.6V and held there for about 30 minutes. This is called the Conditioning Charge Phase. The earlier phases are Trickle, Bulk Charge and Cut-Off Charge.

This last little bit of charge puts the final 5 to 10% capacity into the battery. Then after the timer has elapsed the charger voltage is set to just below the first cut-off voltage at about 13.8V and the trickle current is limited to 1/50 of the capacity.

Charging with this method gets as close to 100% as it is possible to get. So if you examine this method and compare it to the standard alternator system used on cars you can see that you can never get to 100% capacity. The best you can achieve is about 90%, but that is OK for most cars.

In large battery bank installations I have been involved with the design we always had temperature sensor inputs to modify the charging voltages. But these battery banks were designed for a minimum life of 15 years for telephone exchanges where if the mains fails they must continue to run for at least 8 hours. So no expense is spared to maximise the capacity and life of the cells.