The following are a few hints and tips culled from one hundred and fifty years of "How to Use a Lathe" books. It's worth remembering that an apprenticeship in turning lasted for seven years - and whilst the rudiments of the craft can indeed be picked up within a few months, experience is all. This is not a comprehensive list of either safety precautions or working practices - further reading is advisable. Try the long-in-print "The Amateur's Lathe" and "The Amateur's Workshop" Or, for a compendium of three books at a discount, these are the ones to buy**************************************************
Machine tools, even small ones, do not take prisoners. Learn from others' past mistakes and Think Safety"George Wilson's" Hints and Tips
Never, ever, leave a chuck key in a chuck. Starting your lathe will fire it across the room and blind or kill somebody - possibly you..
· Machine tools do not take prisoners - they motor on regardless and maim or kill without compunction
· Lathes - and especially some milling machines - can be very top heavy. Take great care when moving them either by road or around the workshop - and don't do it alone. Even "She Who Must Be Obeyed" will keep an eye on you and, unless your life is insured for too generous a figure, she'll phone for the fire brigade and ambulance when you're trapped.
Here is additional; advice about:
- transporting machine tools
- lifting a lathe
- lifting millers, grinders, etc
· Keep a clear, safe and oil-free working area around your machine tools. You must be able to think of better things to do than tripping, slipping and then falling onto a rotating cutter or mechanism.
· Wear snug-fitting, tightly woven clothes. Take off your tie, jewellery (even rings) and remove anything that might get wound into rotating mechanisms.
· Wear eye protection. Once the part has snapped off and embedded itself in your eye it's too late…..
· HAIR - keep it tied up. A female student was killed in the USA in September 2011 when her hair was wound into the chuck on a 6-inch lathe
· Don't play with steel turnings as they snake away from a job - even small ones can grab fingers and clothing and pull your hand (or even you) in.
· If you don't how it works, have you read the instruction book? - for, if all else fails, it does indeed often help to: R.T.F.M.
· Bought a used machine? Before using, check that it's electrically earthed.
Never, ever, leave a chuck key in a chuck.
· Making a bench for your lathe? Avoid wood - it distorts as it dries and changes shape with the weather so twisting the lathe bed . If you can find one, a large old surface plate makes an ideal - if very heavy mount.
· After setting up any turning job, take a moment to pull the job round by hand to check that everything clears.
· Remember, you are using a machine tool - an expensive, precision device. Keep it clean and oiled - and don't abuse it.
· Keep the bed and slideways especially clean. Cast-iron dust can be a real bed killer - if it contains particles of casting sand it becomes a wonderfully effective lapping compound and wears away the accuracy you have paid for.
· Lubricate plain headstock bearings with light oil - little and frequently. Adjustable-drip oil pots (as fitted to Myford ML7 lathes, etc.) may look old-fashioned, but you can see exactly what is happening - and they are completely effective. Buy them from that top-class Company Adams in Coventry
· If your lathe headstock has an oil supply held in reservoirs under the bearings, with wick or other feed - check the level every day.
· Small lathes need all the help they can get. The secret of successful operation is to keep the cutting tools sharp by using a slip stone across its top surface; the sides rarely need attention. Sharp tools are also a lot safer and easier on the machinery; blunt ones tempt you into forcing the lathe and over-straining it
· If you are using a simple tool-holder, with under-tool packing pieces, once you have the tool height set correctly keep the tool and its set of packing pieces together in a tin. This saves a huge amount of time and frustration.
· Nothing transforms a lathe more than a good quality quick-set toolholder with a set of tool-holding stations. If you can afford one, buy it. You won't regret it.
· Keep as much of the tool supported by its clamp or holder as possible. This reduces strain on the lathe and the tendency for the cutting tool to "chatter".
· Check that the top slide is not unnecessarily forward; keep the cutting tool as near to the centre of the compound slide assembly as possible.
· Adjust the top-slide gib strip on the tight side. Unless you are using the slide to take a cut it just provides more unwanted flexibility between the tool and the lathe bed - confirmed by the fact some turners go to the trouble of removing the top slide completely and making a tool post to fit directly on the cross slide - and use that for the majority of their work.
· When taking a cut with one slide, for the best finish, lock the others (top slide, cross slide and carriage. No locks? Consider fitting a simple screw lock to press down on a gib strip near its centre. This tip is especially useful if the feed screws are worn and backlash present.
· On anything other than short, light jobs always use the tailstock centre to support the workpiece end. This both reduces headstock bearings loads and eases those forces that will, in time, make your 3-jaw chuck inaccurate.
· Use a 4-jaw chuck to grip irregular or roughly finished material - using your 3-jaw like a bench vice will ruin it.
· Doing lots of work using a fixed steady? Consider drilling a small oil hole through each jaw in the steady rest - a job that needs doing with some care...
· If you find a 4-jaw independent chuck difficult to set up, persevere - it quickly becomes easier with practise. It helps to use a magnetic base and a good-quality, dial-test indicator.
· Consider investing in a new 3-jaw chuck and using it only for your most precise work. It makes life a lot easier knowing that you have at least one work-holding device that is completely accurate.
· If you have the chance to buy a lever-action tailstock unit for your lathe, take it. The difference in feel over a screw feed is significant - and makes both light and heavy drilling work so much easier.
· If your lathe has a screwed spindle nose ensure that both it, and all items mounted on it, have their threads, register spigots and flanges thoroughly cleaned. Apply a little light oil and fasten using firm hand pressure only; it is not necessary to yank the fittings tight. Taking these precaustions means that, when you come to remove the fitting, it will not be on so tightly that you have to machine it off.
· If your lathe has a screwed spindle nose do you really need your lathe wired for reverse? Accidentally selecting it can cause the chuck or faceplate to unwind from the spindle. (You really only need electrical reverse when screwcutting Metric threads on an Imperial machine, or visa-versa, when it's necessary to leave the leadscrew clasp-nuts engaged).
Never, ever, leave a chuck key in a chuck.
· Before inserting a centre in either the headstock or tailstock, clean out the taper carefully (and the centre, of course) first.
· The headstock centre is soft and the tailstock centre is hard - but there is no harm in using a hard centre in either.
· The soft headstock centre can be trued-up by being turned in position with the top slide; when this has been done make a small corresponding mark on both the center and spindle nose so they can always be put back together in the same position.
· If your machine tools are in a cold building, start them on a slow speed. Let them warm up gradually for fifteen minutes or so - running on no load uses very little energy.
· Do not mesh changewheels tightly; a little clearance between them is necessary. Insert a sheet of newspaper between them and press into mesh - this gives about the right clearance. Lubricate with a dry "open-gear" lubricant, or thick oil. Avoid grease, swarf sticks to it like s**t to a blanket and makes a terrible mess.
· Occasionally dismantle the train of gears to the leadscrew and clean the gear teeth. Accumulated swarf beds into them and may need picking out with a scriber.
· Has the gear on your thread-dial indicator worn out?As a quick, cheap and dirty solution is to replace it with a plastic gear with the same number of teeth. The form of the teeth does not matter, they will distort enough to engage with the leadscrew and need only minimal engagement to turn the shaft.
· Putting a cork into the open end of the headstock spindle stops bits dropping down onto the changewheels and jamming them up.
· Instead of a cork, extend the spindle with a length of plastic pipe so that it protrudes outside the gear-guard case. Because so many different diameters of PVC pipe are available you are bound to find one a snug fit over the spindle end - or even one where the inside diameter is slightly smaller than the major diameter of the threads (if any) on the spindle end and so will "self-thread" on.
· Experiment with the tightness of the changewheel-bracket (banjo) mounting nuts; just "nipping them up" may hold the bracket securely enough for most work but in the event of a bad "dig in" might allow the bracket to overcome the clamping friction and be forced out of mesh - so saving further damage. This might also rescue the gearbox if any of its bearings seize. (If, on a gearbox-equipped lathe, the banjo is being thrown out of mesh do not ignore this warning - check the state of the gearbox bearings, they may be about to seize).
Never, ever, leave a chuck key in a chuck.
· On small lathes parting-off operations are likely to cause the greatest trouble. Using a rear-mounted toolpost, in conjunction with an inverted tool, is the best solution.
· Contemplating a difficult job using expensive materials? A twin-start, internal, left-hand, square-section thread through a 6" block of bronze for example? Enjoy a practice session first on a piece of aluminium.
· 3-jaw chucks often have one keyhole stamped with a circle or other mark - that's because using it should obtain the best alignment. The holes may not be marked - and even if one is, over time wear may cause another key position to become the most accurate of the three - so it's always worth experimenting with a dial gauge and a test bar to see which gives the best result.
· Heavy-duty drilling with a tailstock chuck? Go round the chuck and use the key in all three positions - it may tighten a little more each time.
· Using a Chinese-made lathe to cut a thread? Check that the dial-tread indicator is keyed to its shaft - and not just held on with a nut and spring washer.
· When truing up a lathe faceplate, place your centres in the headstock and tailstock spindles. Place a metal rod, center-drilled at each end, between the centres and apply pressure with the tailstock wheel, as though you were setting up to turn between centres. Lock up the tailstock. The thrust created will remove any slight endplay in the headstock bearing that, if left, would result in a "wavy" surface finish. This idea also works when facing off work bolted to the faceplate - if physically possible to set up.
· Machining titanium or magnesium? Both can ignite and then burn with great vigour. Use a constant flow of coolant and keep the accumulation of turnings to a minimum. If the material does catch fire don't use water as an extinguisher, it will make matters much worse. Get a large bucket and fill it with dry sand. Cover it and keep it by the lathe. The sand will smother the flames very effectively - or buy one of the special fire retardants used in industry.
· Tired of spending ages trying to reset your tailstock after setting it over for a taper? Leave the tailstock in line and make the center move instead. Buy a cheap boring head with a fitting that can take, or adapt to, the tailstock taper. Fit a parallel centre where the boring bar would normally go and, with the holder set to traverse horizontally, you can now "dial-in" the offset you need. These items were once available commercially.
· Trying to adjust plain headstock bearings? Slacken the drive belt completely first - it can make an enormous difference.
· Need to do very accurate - or very small diameter - woodturning? Use a metal lathe with an appropriately high top speed; the compound slide rest, and the availability of taper turning and milling attachments, etc., is almost certain to make the job easier.
· Need an accurate test bar at zero cost? Find a redundant dot-matrix printer or scanner. The steel bar the guides the print/scan head is made from hardened steel and accurate to 0.0001" in 12 inches.
· Machining a taper with the top slide? Dismantle the slide, clean it carefully (use a scriber to get compacted swarf out of the dovetail recesses) and reassemble with care and lots of oil; it will make a great difference to the feel of the slide. For the finest work consider pinning the gib strip (if a push-screw type) to the slide body; this will stop it moving longitudinally on the adjuster screws. Check the condition of the end of the adjuster screws (they should be domed) and the dimples into which they fit. An accurately adjusted, smooth-running slide is essential for successful taper work.
· Machine-tool designers are not super-human. They work within strict price constraints and contemporary safety regulations. Are the electrical stop buttons within reach on your machine? Even some of the most expensive and highly-specified lathes from as late as the 1970s have electrical controls positioned so that, as the operator is being wound into the mechanism, only the wild kicking of their right foot would stand any chance of switching it off. If this is the case, consider the wisdom of having the switches moved to where they can be instantly reached - or, probably better, have additional ones wired in by an expert.
· Using a toolpost grinder? Cover the bedways and other exposed machined surfaced to protect them. Don't use cloth - it's too easily caught up in rotating parts and when removed will, if used for other jobs (as is almost certain) transfer its trapped grit to unwanted locations. Instead use several layers of stout paper, held in place with masking tape. Throw the paper away after use.
· Adjusting taper-roller Spindle bearings and following the maker's instructions? Although the handbook may well tell you the correct mechanical process, it often leaves out the important fact that the spindle should be at operating temperature. Run the lathe for one hour at ¾ of top speed before making the adjustment.
· Need to fit a new chuck to a backplate. Read and absorb the special instructions here
Never, ever, leave a chuck key in a chuck.
· Selecting a changewheel to set up a screwcutting drive? Look carefully; the number cast-in may be a part number, not a tooth count - that is usually stamped in (on the other side, of course…)
HOT TIPS for TRICKY JOBS
· Drilling into a material that causes the point to wander? Use a lathe tool to steady things up. With the drill in contact with the rotating work, very lightly touch the drill near its point with a lathe tool held in the toolpost - but only supply just enough pressure as it need to stop the wobble. Aim to keep the cutting tool against the portion of the drill's edge that is parallel. Move the cutting tool along with the drill bit as you advance it into the work until the drill has fully entered, then retract the tool. This operation takes practice - but is well worthwhile.
· When purchasing drill bits, especially small ones, lay the bit on a flat surface, press your finger across the middle and roll back and forth to see if it wobbles. Many drills are not straight, even good-quality brand ones (and especially cheap imports).
· If a drill, especially a large one, leaves "scratches" in a hole, it's usually because it isn't straight.
· Need to grind a very small drill ? This can be done by hand - but takes practice and requires the ability to accurately observe what the drill tip looks like. Instead of using a horizontal abrasive surface, hold a very fine India stone vertically in one hand and, with the drill tilted at the correct, stroke the stone up and down. By using 4X reading glasses (or a head-mounted magnifier) even a No. 80 drill can be restored. Find some old drills to practise on.
· Need to restore a badly treated really large drill ? Put the drill in a chuck and grind the tip with a tool-post grinder while it revolves backwards. When both lips have been cleaned up, hand grind the relief a little at a time until you are very close. Finish by stoning. If correctly done the drill should throw equal-sized chips on each side.
· Need to drill a really hard material - a file or even high-speed, all-hard (not just the teeth) power hacksaw blades ? Use ordinary cheap carbide masonry drills and run them as fast as the average drill press will go. The effect is to "heat" the metal on contact and so soften it. Do not be too aggressive; the heat may loosen the brazing that holds the tip in place. Drilling thin sections, like hacksaw blades, will result in a need to re-sharpen the drill after each operation.
· Surprisingly, it's possible to deflect a machine tool by leaning on it. Experts disagree about the likely effect, but to test your own lathe (or miller) put a Dial Test Indicator against some convenient part - and start leaning to watch the result (with the machine switches off, of course…).
· When holding material in a smooth-jawed machine vice, slips of paper in the jaws will do wonders preventing work, especially slippery metal like brass, from moving.
· To drill sheet metal (especially brass), or Plexiglass sheet, the bit should be ground vertical on its cutting edges - this helps prevent grabbing when it breaks through. At one time straight-flute drills for brass used to be made.
· When using ordinary layout dye to stop the surface tearing when scribed first clean the bare surface with lacquer thinner (though results may depend upon the particular brand of dye).
· A lubricant for machining aluminium? - One of those forgotten gems, or so it would seem, is paraffin (in the USA called kerosene, or coal oil ) the most effective solution to a built-up on tool tip that I have found for this material. For those who have invested in carbide tooling, are you aware that tips are made especially for aluminium? I have used these at work, dry, and have taken .200" deep cuts (whilst roughing out) with no evidence of a built-up tip, and the swarf chipped up beautifully.
· Finishing aluminium - Where I work, we make a lot of aluminium components for racing-car teams and the hot tip for getting a really good finish on turned parts is to use a bit of "Scotchbrite". To you and I this is the green 'scouring pad' used to clean pans in the kitchen but, when applied to a part that already meets surface finish requirements (normally in the order of 16um) it produces a uniform tone over the whole piece.
· Countersinking - There are not many things that look worse than an oversized countersink, though I suspect that a wobbly chamfer must be a very close second! So, in order to prevent this from occurring, I select a drill of the same diameter as the screw head in question, grind this to 90 degrees and thus avoid the problem. If the drill chatters, this can be resolved by a couple of strokes, literally, with a fine oilstone over the drill lips; this removes the 'dead sharp' cutting edge. Now, the only thing that can go wrong is to countersink too deeply - and even this doesn't look anywhere near as bad.
· A good tip for brass - to keep brass components looking polished keep a solution of 'shellac' dissolved in alcohol handy. If applied (before fingerprints) with a clean cloth it will dry within seconds as a clear lacquer. This is really useful for components that have been knurled. If a darker tone is required, add a few drops of "dragon's blood" - a red dye used by gunsmiths.
· Extending milling cutter life - when the corners have disappeared from that new endmill or slot drill I grind a chamfer in their place and reserve the cutter purely for surfacing operations. For some reason, they seem to live longer if modified in this way- though I have never modified a new cutter in this fashion for comparison - and I am getting round to finishing that "Quorn" - honestly!
· Bluing salts - there is little else that can impart a really professional look to a job than a carefully blued finish. I have tried a couple of the cold-bluing preparations on the market and, having been less than impressed with the result (never mind their toxicity), I have reverted to hot-bluing salts - which proved hard to find. After looking at the various recipes and concoctions listed in 'Machinery's Handbook' and Angrier's 'Bluing of Firearms', it would appear that 'saltpetre' is the stuff. Even better is the fact that it could probably be obtained from Boots or any good chemist; it gives the true "nitre-blue" finish that I crave but if you try it, please be under no illusion that in use, these molten salts are ten-times HOT and if spilled can burn you very seriously. This is a real leather-gauntlet and goggles' operation.
· On reamers and reaming - I hate reamers. They always seem to cut over or under the desired size, and very seldom the one that I want. Therefore, as a general rule, I will bore everything that I can but, where this isn't possible, I have made a very simple gadget to help. It consists of nothing more than a commercially bought Morse taper blank, drilled 2.5 inches deep into its blank with a 5/16""drill. A number 34 Jacobs' chuck mounted on a custom-made plain round arbor, again 5/16" diameter and 2 ½" long, is free to slide in the Morse taper blank. Guided from the tailstock, and fed in by hand, I have achieved a far greater success rate in my tapping and reaming exploits since its construction. My usual reaming limit, at work, is in the order of four-tenths. This device is sort of the "opposite" of the common tailstock sliding die holder used to cut external threads.
· Chattering reamers - have you ever had a reamer cut a pentagonal hole? The solution is to pack out the flutes with lard next time- this always seems to do the trick for me.
· And while we are in the fridge - did you know that many "Loctite" products have a shelf life of one year? As I don't use an awful lot of the stuff, I keep it in the fridge, and it stays in useable condition for longer. Also, I hate turning copper. The only way is to use high speeds, fine feeds and fine cuts - with the suds applied like holy water. To have a better chance of success, milk is the hot ticket as a cutting lubricant but I must suggest that you either get a separate supply from the domestic source, or avoid being caught with a suds brush hanging out of the bottle.
Also, for details about a special "hooked" shape to the cutting tool check to see if this link still works: http://www.gearloose.com/CU.html
· About little drills - little drills (like number 60 or less) need lubrication, the same as all others, but cutting oil and suds are both a little bit too viscous for these sizes and the speeds at which they are run. Therefore, next time you use a small drill, apply a drop of saliva- it's just right for the job.
· About tapping plastic - a frequently encountered problem is to find that a tapped hole is tight. The solution is to fold a strip of paper over one of the cutting edges of the tap, and to run it through the work a second time. The paper conforms to the cutting edge that it's covering and pushes the other, opposite edges harder into the work so slightly enlarging the hole.
· Concentric cutters - I tend to use a lot of "FC3" throw away cutters at home, but despite having the correct collet chuck and the correct collet-chuck adapter (both "Clarkson"), concentricity still remained a problem. The eventual solution took the form of a "split sleeve", essentially a Morse taper blank, bored to a specific diameter and split along its length. I bought one with a ¼" bore to suit my cutters, and drive it home with a light tap using a hollow brass drift. I can now guarantee dead true running every time. My sleeve was made by the "Cleveland" Drill Company, and. despite the obvious expectation, it has yet to rattle out in use - no doubt due to the small size of the cutters used and the absolutely minimal overhang from the spindle nose.
· Ever needed to anneal aluminium? There isn't much between the temperature needed to anneal it and the melting point which is so low (comparatively) that it doesn't even seem to reach red heat before it becomes molten. The solution is to coat the work with ordinary soap lather. When heated, this blackens at about 400 degrees centigrade, which, fortunately, is just the right temperature.
· Have you ever watched a drill skate around the edge of a centre-punch mark? This can be avoided by grinding the end of the punch like a triangular pyramid. I don't know why this works, but it certainly does! Try it the next time you need to cross-drill some round stock.
· Potatoes may seem unlikely candidates for use in an engineering workshop but from time to time can be found very useful when silver-soldering delicate components, or annealing a specific portion of a strip of spring steel. The technique is simply to insert the portion of the work that you do not wish to get hot into the vegetable then proceed as normal. In this way, I successfully silver soldered the ends of a piano wire ring, about 3/16" diameter attached to my "St. Christopher", with a gas blowlamp, without melting the gold.
· Restoring files - blunt files can often be re-sharpened by allowing them to rust in the garden for a few weeks. Due to the erosion of the teeth, the correct form is, to an extent, restored. Another tip: if you can get to a surface grinder take a couple of thou. off the teeth of a worn-out file, rendering it totally useless for most work; but, as no cutting rake is necessary, when the file is presented to a round workpiece (like a turned artefact) it will cut as well as it did when new. What your neighbours will say about a line of rusty files hanging from the washing line is anybody's guess. Burying them in the ground might be better.
· Saving T-slots - If you are concerned about the prospect of breaking out your T-slots whilst tightening the studs retaining your work (they can bottom-out and lever the casting apart), here's a tip that I use. Simply take a cold chisel (or any other blunt instrument), turn your "tee" nut upside down, and wop the last thread over with a hammer. Having done this, the stud cannot pass right through the nut anymore, cannot bottom out in the "tee" slot, and can, therefore, cause no inadvertent damage to the same.
· In praise of the "professional foul" - in industry, when the pressure is on, and minutes matter, some wince-inducing dodges can come into play. Here are two tips that work. Firstly, if a reamer insists on cutting undersize, scrape a piece of H.S.S. (like a lathe tool) against one of the cutting edges. This should be done so as to raise a microscopic burr and thus cause the reamer to cut ever so slightly oversize the next time it is passed through the work.
· The second tip concerns tapped or screw-cut threads. If one is produced oversize (that is, a sloppy fit), the "Geary Patent Thread Rectification Apparatus" is required. Turn a shallow taper on a piece of silver steel, place this in the end of the thread in question, and tap it with a hammer. This will distort the first few turns of the thread, and "tighten" up the fit somewhat. These are both tips that, were you a professional machinist, you should be reluctant to tell the Boss - though, strangely, the Boss has probably used them as well. And no, you shouldn't dream of using them at home.
· As an alternative to the above use a steel ball (bearing) to fix a loose thread. Put the ball on the hole and give it a light whack. This does almost the same thing but does not require you to make anything
· More about reamers - I still hate them, but here is more information - their cutting effect is influenced by the lubricant used. If you want a reamer to cut "tight" use suds, if you want it to cut "loose", use straight cutting oil. Just a simple observation, but it counts.
· Getting swarf out of tapped holes - One way to do this is to purchase a spiral-fluted tap. I don't bother with these and I have reverted to using an old dodge: if the hole to be tapped is filled with tallow, and an ordinary hand tap is used, as the tap progresses down the hole, the tallow is extruded out, carrying the chips with it. When the tap has reached the bottom of the hole in question, the tallow stays with the remaining chips adhering to the flutes of the tap as it is withdrawn, thus eliminating any problem. Incidentally, tallow is the stuff to use when tapping aluminium components that are to be anodised - it doesn't interfere with the anodising process like some commercially-available tapping compounds.
· Busted a tap in a bit of brass? - Here's a great tip - build a plasticene "dam" around the bit of tap to be removed, then mix up a strong solution of 'alum' (available from the local chemist for treatment of bed sores). Pour this into the dam and put the whole lot in the airing cupboard. I don't know if the action is electrolytic, or why it works, but the alum attacks the steel leaving the brass completely unscathed. After a day, a carbon-steel tap will have become loose enough to wiggle out; H.S.S. takes about a week.
· Three methods of tapping straight - You need to be in practice to tap straight; I don't do it often enough to prevent drunken threads, so I use three methods to help me. The first is to get a block of square metal and to drill and ream a hole in it the same size as the shank of the tap; when I place it over the hole to be tapped, the tap passes through it perfectly vertical. The second variation on the idea is to remove the drive belt and quill-retracting spring from my "Westbury" light-drilling machine, allowing me to feed the tap, held in the drill chuck, into the work dead square. The last method is a bit of a last resort, as it still requires a bit of skill. If a piece of borderless mirror is placed on the surface of the workpiece, next to the tap as it is presented to the work, the reflection makes it quite obvious if things are not square. The trouble with this is that unless the mirror is "L" shaped, the check must be done twice, with the mirror in two positions, and I always manage to move the tap whilst performing the second part of the trick! If the mirror is plastic - some CDs have a mirror coating - and a hole drilled though it, you have a perfect 360-degree mirror.
· Cheap parallels - Sooner or later, you've got to have them, almost always in milling work. There is a method of achieving the result without actually stumping up any money, so take heed. The next time that you replace a wheel bearing on your car, please be mindful of the fact that both the inner and outer races have been ground to the same limits of parallelism as the very best engineering parallels - which you, of course, don't want to pay for. Don't expect to find the races from different hubs to be matched to each other though - this is seldom the case.
· A warning to those who restore antique machines. When it's time to get the old paint off, be wary of using paint stripper. I found to my cost that the old-time manufacturers were no so picky about the quality of their castings and had no qualms about applying a filler composed of sulphur, cast-iron siftings and sal-ammoniac to cover up faults in the metal.
· As an interesting aside, the supplier of cast-irons columns for the Victorian Tay Bridge even filled in large holes with sawdust, iron filings and lead - with fatal results; during a violent storm the bridge collapsed as a train was crossing.
· Unfortunately, this early-filler stuff sops up paint stripper like there's no tomorrow, but refuses to part company with the machine, so it cannot be painted, and has to be forcibly removed. You can also come unstuck with paint stripper coming into contact with porous castings, though this is even harder to deal with. I tend to coat everything with car-body filler, rubbing it down so the end result looks smooth as glass and, fortunately, any chemicals remaining in the surface of the metal after thorough washing down are insufficient to seep through it. The same cannot be said for paint alone. The most effective way of removing paint from castings without chemicals is to use an angle grinder fitted with a rotary-wire brush and an operator fitted with eye and breathing protection; be very clear, however, that powered tools must not be wielded near any machined portion of the job.
· Truing up discs held in the chuck - A great trick that I have used is simply to grip the disc lightly in the chuck and to spin it up, at low speed. If a piece of stout card is held over the point of the tool, when it is brought into contact with the work, it cannot cut, but instead can be used to push the disc into the jaws until it runs dead true. The machine can then be stopped, the chuck properly tightened, and the job can continue.
· Adhesives and metal-turning lathes - Woodworkers think nothing of relying on glue to retain a workpiece on a faceplate yet we engineers always seem to fight shy of the idea. I have used the idea successfully on a number of occasions both at home and at work, using various adhesives. For facing back washers and the like, I start by facing a piece of aluminium, held in the chuck, and then stick the workpiece on using either "Loctite" or a mixture of shellac in alcohol, utilising tailstock pressure to hold everything in place until set. Concentricity is usually irrelevant, so setting is very simple and ordinary speeds and feeds can be used. When it's time to remove the workpiece, a sharp tap, or application of heat will break it free. For one job that I am called upon to do at work, I am required to produce P.T.F.E. discs to a tight tolerance. Anyone who has attempted to work with this material will know how hard it is to grip and how easily it "moves" after machining. The only way I have found to successfully execute the job is to stick it to a "faceplate" (my bit of faced aluminium) with double-sided sticky tape; this holds the job securely, yet imposes no stress upon it. Some kinds of double-sided carpet tape can be handy as well. A measure of common sense is required when using adhesives - if you're turning a 3-foot diameter, 600 lb cast-iron manhole cover sticky tape is not the stuff to use - but it can allow otherwise unattainable results on small components..
· Setting accurate angles - The "sine bar" is one of those forgotten tools in the amateur's workshop. It usually brings to mind horrific trig. calculations and visions of slip piles that strike fear in the heart of many enthusiasts. Listen up, people; the sine bar can be made by anyone with a piece of silver steel and a length of gauge-plate in an hour or two and the need for slips bypassed by using an adjustable parallel and micrometer.
After reading about people's struggles regarding the matter of setting their top-slides over to machine a Morse taper it might be worthwhile pointing out that using a sine bar against the side of the top-slide and "clocking" from the tailstock is the easiest, right-first-time method of doing the job. A perennial problem solved.
· Marking out (a tip from "The Lemming") Make up a small bottle of the "coppering solution" described in "Machinery's Handbook" (and other old engineering books) it's merely a strong solution of copper sulphate in distilled water with a little sulphuric acid added - I use a few drops of battery acid - and it works nicely (obviously this process requires extreme care and the use of eye protection and the mixture itself is poisonous). I clean the steel with emery cloth, and wipe the solution on with a Q-Tip cotton swab. It leaves a clean copper plating; one can then scratch in layout lines that contrast as silver against the copper colour. It doesn't seem to rub off as does layout lacquer - and is especially handy for close work when one is filing to lines on very small parts.
· For a series of articles about making interesting, economical and effective lathe accessories, try this link: http://www.kinzers.com/don/MachineTools/lathe_projects/
· For a series of well-written books covering a variety of metal-working topics (and to help support the Machine Tool Archive) see this page.
And, don't forget - never, ever, leave a chuck key in a chuck.