Member postings for Max Tolerance

As explained above Gauge blocks / slips are used to measure to very precise dimensions. In a full set of imperial there are normally 81 blocks plus two protective slips and in a metric set there are usually 88 blocks + two. I have seen and actually own sets with larger numbers of blocks however with a standard set you can combine blocks together to make any size going up in .0001 imperial or .001 (or finer) in metric up to the capacity of the full set. Normally there are standard sizes 1" 2" etc or 25mm 50 mm then there are increments of smaller amounts .1 .2 etc then even smaller units .01.02 etc. So by using the correct combination any size can be wrung together. When a good undamaged slip is wrung to its neighbour due to the lapped surface finish the slips "stick" together and can only be parted by using a twisting motion NO OIL should be used. Immediately the slips are finished with they must be separated. If left for a long period it will be found that they cannot be parted without considerable damage rendering the blocks useless.

A type of gauge block was first developed by Joseph Whitworth of screw thread fame when he was standardising the inch measurement using them he developed a micrometer measuring to 1 millionth of an inch accuracy. The Government of the day showed no interest in these and they were ignored for years. However on the outbreak of the first world war it quickly became apparent that an easily transported system of gauges were needed in order to produce weapons, shells, bullets etc. in factories all over the country to a standard size so that they fitted together. So the government imported a large number of sets from Johannson in Scandinavia hence the name joey blocks sometimes used by the more mature engineers.

The answer is one word "accuracy" A vernier caliper is just that, a caliper and should not be confused with a Gauge. Many beginners (and unfortunately some who should know better) are confused by the difference and are under the impression that a modern electronic caliper is the last word in accuracy. However they are making some serious errors with this. First off the resolution of a caliper whilst useful for determining the general size of something is nowhere near the standard required for truly accurate sizing. Do not be taken in by the apparent ability of these instruments to read to two or three places of decimals, simply put they don't. There are fundamental design faults involving bending, contact area and pressures that preclude these instruments from "accurate measuring tools". In industry gauges are used. These range from adjustable units e.g. Micrometers which are designed to mitigate the worst of the drawbacks mentioned and can measure to reasonable standards of accuracy if used correctly. Through to go-nogo gauges which are unadjustable being made to exact size and to traceable standards. The way these work is that a part should fit in the Go part but not in the nogo part, if it fits neither then it is too big if it fits both it's too small. The above is a simple example and with modern methods it is possible to use lasers etc. to measure to accuracies undreamed of by Mr Vernier. Who incidentally only invented the scale not the caliper.

Probably been used on a drill grinding machine the Brierly company type. I have two of these chucks both made by Pratt Burnerd one is on my brierly and the other is threaded for the J&S 310 T&C grinder.

Work out the maximum and minimum diameters. Turn a piece of steel between centres with the two diameters at the required distance apart. Put a DTI in the tool post and set your top slide to give the same readings on both diameters.

Just a thought that the aluminium, paper, cast iron (presumably) bed and acidic coolant would make a reasonable battery so the effect could be electrolytic.

Hi Brian,

Only just seen this thread. I have a Smart and Brown lathe and as you state it does have 19 tpi on the gear box. Whether there was ever a metric version I cannot say however with a set of change wheels one of which is a 127 T then metric pitches from 0.2 mm to 5.0mm can be cut. When I bought the lathe many years ago I was fortunate to get an original screw cutting chart that lists the metric pitches and also B.A and diametrical pitches available when you have a full set of change gears. If you want more info let me have an email address and I will send photo's.

The body of the mill is connected to the base by four through bolts accessed by removing the rear belt guard and the ventilation grills in the base. However you will also need to remove the two drive belts (easy job) and of course the knee elevating screw. The nut for the elevating screw is fastened with three cap head bolts easily accessed, but once you remove it there is nothing to stop the whole knee and cross slide assembly from sliding off the bottom of the column when you lift the body from the base. There are some knee locking bolts but I would not rely on these holding since they are only designed to take out the "play" whilst machining. One other thing to be aware of is that these mills are inherently top heavy and if you are moving them by road they need to be very securely roped to stop them falling over. The machine weighs aprox 500 Kg with most of this in the main body and very little in the base, so little will be gained from a weight point of view from splitting the machine although you can reduce the height required which is obviously your question. If I were to move one of these I would leave it in one piece, secure it to a large pallet with ratchet straps and stick it on a pallet carrier with tail lift, it costs a little more but saves a lot of hassle.

Having studied the picture again I may be mistaken with the manufacturer. It is a long time since I saw one but it is more likely to be the Pitter gauge unit. It works exactly like the matrix unit but is not quite so sophisticated. The pulley on the back would have had a cord and weight to keep any backlash out of the measuring micrometer.

It looks like part of a Matrix screw pitch measuring machine made by Coventry gauges, though its not complete. It should be mounted on a massive cast base with centres.The screw was mounted between the centres and the indicator placed into the thread. The reading was adjusted until the scale was set to the zero line. The whole unit (which was mounted on balls running in a parallel "V" was then advanced using the micrometer causing the stylus to ride up the flank of the thread and back down into the next thread until the scale again read zero and the pitch advance noted from the micrometer dial. This was then repeated until all the threads were measured and any deviation from the correct pitch noted. It was probably made in the 50's or 60's

Richard,

The first thing to address is what do you intend to make on your lathe. You have bought a used machine that may have some problems but these may or may not be an issue depending on what you are doing with it. You mention some wear to the bed which can be rectified but more serious is the chatter you are experiencing. This could be caused by using blunt or incorrectly set tools or it may be caused by play in the slides. More worryingly it could be the bearings/mandrel in the headstock that need attention. If you are unable to diagnose and rectify these problems yourself then you will need the services of someone who can, and if that someone is a professional engineer trying to earn a living then it could be quite expensive.

However as stated it does depend on what you want your lathe for. The speeds you are asking for and lever tailstock suggest small drills and tiny components, if this is not the case then 2000 revs whilst desirable is not essential. Like wise a lever feed tailstock is only really needed for very delicate operations.

It may be that a cheaper and better option for you would be to buy a more suitable machine for your needs and now a days the far eastern products can be a better choice, they are moderate in price and accurate enough for most applications.

Finally as the above poster says there is no reason why you cannot bore a cylinder even if it takes a few sessions. As long as you leave the job set without disturbing anything you can just do a single pass then leave it for another day before you do the next one. Even if you have to stop halfway through a pass it would not really matter except on the last one.

There are a lot of people out there who have a very poor understanding of how to treat bearings. Even "skilled" fitters, mechanics etc. often have no real idea of the principles behind the modern ball or roller bearing and even less when it comes to some of the older type technology such as plain or white metal bearings even wood is used in some circumstances. As the works engineer in a large factory I am in charge of the maintenance and installation of a large number of different types and sizes of machines and one of my first tasks with any new maintenance apprentice or employee who we take on is to educate them into the mysteries of bearing removal, fitting, and maintenance.

I have fitted many thousands of bearings over my lifetime of every description (yes even wood ones) and my major findings are this:

Never ever let a hard hammer anywhere near a bearing. This includes using them on assorted drifts, bits of pipe etc.

When ever possible always use either a purpose designed press or some arrangement of screw, spacer, push or pull device to fit bearings.

When removing bearings the above advice is the same unless you are intending to scrap the old bearing.

When fitting medium to large bearings it is a good idea to GENTLY heat the bearing first to fit it to a shaft. Never use naked flame always use either an induction heater or even a hotplate but remember we are talking 100 or so degrees Celsius not cherry red heat!!!

Never fit a bearing to a shaft by pressing on the outer ring or fit into a recess using the inner ring.

As Hopper advised do not over fill a bearing with grease. I always show new starters a brand new bearing to demonstrate this point.

The maximum speed for a bearing is attained when running in oil if this is the design of the machine carefully remove any manufactures grease before fitting using a suitable solvent.

Never ever dry or "clean" a bearing using compressed air !!!!

When fitting new bearings cover the work surfaces with a plastic sheet and do not remove the packaging until ready to fit the bearing . Cleanliness is vital.

If you follow the above instructions then you ought to get a long trouble free life from your bearings. Remember that over 95% of bearing failures can be traced to fitting or contamination problems.

It is the stage from a Vickers projection microscope, used to mount the specimen to be viewed. The microscope was of the inverted type so the object to be viewed was mounted above the objective and the image projected back to the viewing screen or eye piece . The two rows of holes at 90 degrees to each other had fingers attached and if a specimen was marked with a datum edge it could be removed and replaced in exactly the same position in the field of view or moved via the micrometer thimbles and returned to the same place again. Obviously the stage could also be rotated if required.

Well done !! Always glad to hear when someone has succeeded. I was lucky because I got three phase put in for free, all I had to do was dig a trench across my front garden the electric board did the rest all for no charge. (This was in the days before privatisation) I don't think SWMBO would appreciate a bill for £11,000 !!!

Further to the posts above. The outer sheath colour can be almost anything although I agree that in modern practice it is generally reserved for 110v site equipment. However looking at the original photo's and the wiring plate the machine must be of a certain age. The plug on the OP photo looks like a 1950/1960's type of unit which was very common (in a variety of sizes but of the same construction). There should be a metal outer ring which was threaded to allow the plug to be securely screwed to the socket. these sockets still turn up on older machinery especially T&C grinders etc. where an auxiliary motor was sometimes connected. Secondly regarding the colours the grinder is a Swiss machine (which could have been supplied through a London agent) so the colours shown on the plate will reflect Swiss practice. Most of Europe had different colour schemes for their wires. However the cable presently connected is undoubtedly a modern addition of uncertain origin.

What the OP needs to check is whether the machine is still wired for the 415v three phase supply and whether there has been any internal wiring changes since it came out of industry. Some times machines have been modified by amateurs or unscrupulous electricians and if this is the case then it should be examined by an industrial electrician used to three phase. However if the machine has been acquired straight from a factory and was in use prior to this then all should be well. It is probable that the cable shown just goes direct to an isolator on the machine. A photo of the grinder would help here.

Finally please be aware that converters such as yours do not give a true three phase supply such as would be obtained from the electricity company. They do work and will do what you want them to but it is important that they are wired in accordance with the manufacturers instructions.

Assuming that the original wiring has not been altered the grinder will run on a three phase 415v supply which will be supplied by your converter. There is no need to delve into star and delta connections if this is the case. The only time in "our" size motors that we need delta is when we are trying to run from a 240v three phase supply such as is usual from an inverter. If you are using a five pin plug then connect the earth wire to the large pin. Connect the three phase (live) wires to the pins marked L1 L2 L3 in any order. Ignore the N pin, this would only be required if there were single phase circuits on your machine, however with only four cores in the cable then this is obviously not the case here. Start the grinder and observe the rotation. If the machine runs backwards change over ANY TWO of the phase wires and the rotation will then be correct. Make sure the earth bonding is good. On some of the older motors this can be dodgy. Make a good strong connection to any metal part of the motor using a ring connector either crimped or better still soldered to the earth wire. It is also good practice to bond any other electrical boxes that may be on the machine.

John,

I have absolutely no intention of having an argument with you on this forum. The original poster asked if there was anyone else of a similar opinion to him regarding subscriptions. I tendered my own view.

As a long term subscriber to ME (over forty years ) and also having bought and subscribed to MEW since issue one I was under the impression that people may be interested in why I stopped my annual subscription after all this time. I bought the magazine through all the troubled times when editors were changing and even when the magazine failed to be published for a period in the late nineties I kept faith and renewed every year. However because I no longer have an annual subscription I am attacked by you because people shouldn't visit this forum if they don't have an annual subscription. You fail to consider the fact that I may still be buying issues when there is something of interest to me (aproximately every other issue) But no matter you have spoken.

Yes I cancelled my subscription, yes I still visit this public forum and yes given your attitude maybe I have made the correct choice.

I cancelled my subscription to both mags two years ago. I had got to the stage where I wasn't reading any of the articles, generally they were too basic or they were about subjects which I did not care to follow. I think the final nail in the coffin was an article describing how to use a three jaw chuck !!!

One of the problems seems to be that the "older" modelers have either gone to the great workshop in the sky or they no longer need guidance on how to build a loco. This leaves the new starters who unfortunately were not taught engineering at school for all the usual reasons. Or the more general reader who may have taken the magazine for many years and just continues to subscribe. The latter group are getting smaller.

In my experience many new modellers underestimate the amount of knowledge and experience needed to construct a detailed model and lack the patience and tenacity required to spend years on a project. Therefore they think "CNC" that must be easy, just press a few buttons and hey presto!! or "why can I not just buy a kit" like the aircraft people do. One day I would imagine it will be possible to download a "model" from the internet and have a cup of tea whilst the cnc machine center turns out the parts then there will be no demand for the magazine at all.

The point I am trying to make is that the demand for a detailed model magazine is in decline, there is no appetite for old fashioned ways of doing things and even less for old steam engines which disappeared from main line use fifty odd years ago. The modern demand is for a touch screen, instant results,just ask google type of approach which is the way the world has evolved. Thus as the pool of experienced engineers gets smaller so the in depth articles get less, and as many of the old skills have now virtually disapeared there is now no-one left to describe them. I would be very interested to see if it is even possible to commision "expert" articles now.

I have every issue of ME and MEW from issue one to 2011 and some of the earlier issues are a mine of information if you are interested in a world long past. The query slips were introduced in 1905 because the then editor had a free service offering information for readers. However he felt that many of the requests were coming from non-subscribers to the magazine hence the introduction of the slip. No slip no info.

Tony, Many of these books were first published during the early years of the "Model Engineer and electrician" magazine that is to say from 1898 to 1910. They were intended to give instruction to early amateur experimentalists and hobbyist's. Many of the titles cover electrical subjects which were very popular at that time. Lists of available titles were regularly published in the magazine for many years at prices which we would find quaint, sixpence (two and a half pence) being typical !!! Percival Marshall the editor at the time commisioned many of the books himself from experts of the day and even offered prizes of a Guinea (twenty one shillings or one pound five pence) for suggestions for new titles during 1904 and maybe later. The books continued to be published for many years even though some had become outdated. Many of them contained material which had been previously published in "Model Engineer and electrician" and they are a facinating glimse into times gone. Subjects like high voltage machines and "make your own 200 volt D.C. generating plant" would be frowned upon now and things like DIY X-ray machines and experiments with radium would have our modern H&S inspectors in a dead faint !!!!!

I have owned a model "A" for thirty years or more they are an excellent machine and will hold to fine limits if in good condition. The headstock bearings are bronze in a tapered bore with nuts on both sides to adjust the play; assuming the mandrel is not damaged and the bearings worn then they can be adjusted very finely. If need be they can be replaced but you would need a lathe to make them.

There is a norton box for threading giving a large range of imperial threads as well as a full change gear set allowing BA and module threads if metric is required then a 127 gear is added to the change gear train. I have cut thousands of imperial and metric threads on this lathe without problem.

Bracehand used to supply parts for these machines I don't know whether they are still in existence. Parts also come up on auction sites fairly regularly especially the collets though most of them are imperial. One thing that is brilliant on these lathes is the cross slide travel, it goes completely past the centerline and enables some awkward jobs to be completed especially when running the lathe in reverse.

All in all a good buy if in good condition but as noted previously they have been around for a long time and many of them are past their best.

I have a three phase supply direct into my house. It was put in for free by the old Norweb electricity company before the sell off under Maggie. Yes I do have three separate meters and have installed a three phase distribution board along side my single phase household system. The pro's are the ability to run three phase machines directly without having to fit new motors or inverters etc. this is great for grinders and most other machines where speed control is not really an issue. On ex-industrial machines there is always a speed change system either belts or gears or similar which give a useful range, however I still fit inverters (three phase models) to some of my lathes for the better control they give together with soft start and easy reverse etc. also suds pumps and feed motors work as intended.

The main con's with three phase is the problem of finding a supplier who can handle it !!! most companies who supply the home market simply have no provision to handle three meter readings they usually assume one meter to be an off peak one and the other to be a separate granny flat supply or something. This results in some pretty odd situations for e.g. when I got a bill for £73000 for one months bill because they thought my meter had gone completely round the counter and started again; they could not understand it was two separate meter readings.

There is only one supplier I have found who is willing to supply to me without classing me as an industrial user and all the problems that brings such as VAT, accounting, carbon levy or whatever. The other main con is undoubtedly the cost of installation now. I would imagine it is prohibitive.

I would be very reluctant to give up my three phase set up because it is undoubtably better for the type of machinery I have where everything is industrial in origin. Indeed some of my machines would be imposible to run in any other way because it is not possible to convert the specialised motors without huge expence and loss of power. The other great advantage of course is the amount of power I can draw without worrying about tripping the circuit breakers or blowing the mains fuses.