Hot Tips for Tricky Jobs During Using Lathes-www.sawing-machine007.com

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.

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.

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.

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.

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!

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.

I hate reamers. They always seem to cut over or under the desired size, and very seldom the size 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 about two and a half inches deep with a 5/16""drill. A number 34 Jacobs' chuck mounted on a custom-made arbor, again 5/16" diameter and 2 ½" long, is free to slide in the M.T. 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.

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.

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 is covering, and pushes the others opposite harder into the work, slightly enlarging the tapped hole to the size that you want.

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", which is 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 to 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 and the absolutely minimal overhang from the spindle nose.

There isn’t much between the temperature needed to anneal aluminium and its melting point, which is so low (comparatively), 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.

·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.

Blunt files can often be resharpened 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 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.

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.

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.

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.

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.

·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.

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.

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 power 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..

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.