The pencil clamp
When you have finished the batch, line them up and pick out any rejects. If you need small sets, sort them into groups that match best. Here are a few spindles I made using these methods. They are part of a batch of 200. After sawing the blanks to size and turning the first three, the only measurements necessary were to mark the positions of the beads and to size the tenons. Because these spindles are small, I used multiples and fractions of the tool width to position the beads.
Until recently I operated a website at www.turnedwoodenbowls.com. Because of technical problems with it, I set up my new website here. I think it already looks and works better for visitors than my old one, which I have now closed. It’s easier to manage too, though I still have a lot of work to do on it. I haven’t yet republished all of my old posts, and I still have to transfer some images.
I have migrated my list of subscribers. So if you are one of them, you will be notified when I add new posts, and I thank you for your interest.
I’ve published a couple of new posts here so far, on sharpening and on dust extraction. More will follow, so if you haven’t yet subscribed, please do.
Most of the wooden bowls and other things on my product pages here are new. In due course I shall list stock from my old site here. If you are looking for a specific item, just let me know.
This post is for people with little experience of working in metal. Tapping a thread is a useful workshop skill. It’s easy to cut threads in steel with a tap. You can use a drill and tap to fit a cutting bit to a tool shaft, assemble steel parts, or to make up frames for tool stands etc.
Drill the hole for the thread using a tapping drill. This is just a normal twist bit the correct size for the particular thread. When drilling holes in steel, you need a bench drill with the speed set slow. This makes a hole that is square to the surface of the metal. When drilling metal like this it is essential to use a vice or clamp. The drill can catch when it cuts through, spinning the metal round and doing your hand no good at all.
The size tolerance is small, and accuracy is important. If the hole is bigger than recommended, the thread will be weaker, though the tapping will be easier. If it is too small, you will find the tap makes the hole bigger without getting a grip in the metal and cutting a thread.
The correct size of hole depends on factors including thread form and thread size. There are a lot of thread forms, such as Whitworth, BSF and BA, for which drill size tables are available online. I include here tables for the smaller metric threads and Whitworth threads that are commonly used in older machinery.
Taps come in all sizes and threads. You can identify the right tap to match an existing male thread such as a bolt by placing them side by side with the thread peaks lined up. Hold them up to the light, and you can see any mismatch further along the tap. If the diameter matches too, you probably have the right one.
Each thread type and size has three corresponding taps, though you don’t need all three for through holes. They differ only at the point. The first cut tap has a long taper to help start the thread, the second cut has less taper and the bottoming tap has none, because it works when the other taps have already made the start.
As well as the taps, you need a tap wrench.
When tapping a thread, it’s necessary to align the tap accurately with the hole so that they are coaxial. A crooked tap will not produce a good thread. In shallow holes it is less critical, but the deeper you go the more severe any misalignment becomes, and the tap will break. The first couple of threads set the alignment. Don’t try to pull the tap straight once the thread has gripped the tap, it’s too late then. You can sometimes correct it by drilling the hole bigger at its opening and re-starting the thread further in.
A good way to start the tap squarely is to grip it in the chuck of the bench drill used to make the hole. That keeps it on track, but you have to turn it by hand, using the drill lever to keep gentle pressure on the tap so it enters the hole and starts self-feeding. Once the first cut tap is securely held by the thread it has cut, you can switch to the tap wrench. Just wind the tap in as far as it will go, taking care not to bend it. Small taps break easily. Then, if it is a blind hole, change to the second cut, which will go further in, then to the bottoming tap, which will complete the thread to the bottom of the hole. Before bottoming, clear out the swarf.
Another method for aligning the tap is to drill a clearance hole in a bit of scrap metal or wood and clamp it above the hole for the tap. The tap will slide through the clearance hole, which will hold it square. The clearance hole must of course be drilled square.
Lubricate the tap to give a better finish to the thread. There are special compounds, but oil will do. The swarf cut by the tap has to be broken up as you go. To do this, advance a little then turn backwards a bit, going two steps forward and one back. If you don’t, the tap can get locked.
Blunt taps are hard to turn and may seize. You can sharpen them with a narrow, round-edge grinding wheel, but it is easier to replace them. Watch for this if buying second-hand taps, they were probably disposed of because they are blunt.
Tap Metric drill Imperial drill
3 mm × 0.5 2.5 mm –
4 mm × 0.7 3.3 mm –
5 mm × 0.8 4.2 mm –
6 mm × 1.0 5.0 mm –
7 mm × 1.0 6.0 mm 15/64
8 mm × 1.25 6.8 mm 17/64
8 mm × 1.0 7.0 mm –
10 mm × 1.5 8.5 mm –
10 mm × 1.25 8.8 mm 11/32
10 mm × 1.0 9.0 mm –
12 mm × 1.75 10.3 mm –
12 mm × 1.5 10.5 mm 27/64
14 mm × 2.0 12.0 mm –
14 mm × 1.5 12.5 mm 1/2
16 mm × 2.0 14.0 mm 35/64
16 mm × 1.5 14.5 mm –
Size (in) Tapping drill size
1/16 Number Drill 56 (1.2 mm)
3/32 Number Drill 49 (1.85 mm)
1/8 Number Drill 39 (2.55 mm)
5/32 Number Drill 30 (3.2 mm)
3/16 Number Drill 26 (3.7 mm)
7/32 Number Drill 16 (4.5 mm)
1/4 Number Drill 9 (5.1 mm)
5/16 Letter Drill F (6.5 mm)
3/8 5/16 in (7.94 mm)
7/16 Letter Drill U (9.3 mm)
1/2 Letter Drill Z (10.5 mm)
9/16 12.1 mm (0.4764 in)
5/8 13.5 mm (0.5315 in)
Turning metal on a wood lathe is possible, even though the wood lathe is not designed for it. Lathes are designed specifically for either woodturning or engineering purposes, rarely both. The tool holder of a heavily-built engineering lathe clamps the cutting tool firmly and moves mechanically. But if you don’t have an engineering lathe and aren’t too ambitious, you can turn small items in brass, aluminium or even steel freehand quite successfully on a wood lathe. I turned the aluminium finial shown above on my Graduate Shortbed lathe, mainly using a small gouge, cutting as if the metal were wood. I threaded the finial onto a bit of 12 mm studding held in a chuck. Even with tailstock support, that was not rigid enough, so I had to sand it to an acceptable finish. It is about 5 inches tall.
There are problems to overcome. Holding the tool in your hand so that it cuts steel is difficult. The hardness of the metal resists the cut, and the cut is very liable to ‘chatter’. This is vibration that leaves a rough or ridged surface on the work. Working freehand, accuracy is harder to achieve. Some wood lathes have a proper slide rest as an accessory, but without that accuracy comes from the turner’s skill. Making true cylinders or flat surfaces accurate to a thousandth of an inch freehand is not easy. But many items don’t need such precision.
Interrupted cuts, such as turning the corners off square stock, are particularly difficult freehand because it is hard to control the cutting tool. It is risky, too.
Woodturners are familiar with the problem of chatter. When turning metal on a wood lathe it is hard to avoid. To prevent chatter, you need a strongly built lathe, with good bearings. It must hold the workpiece firmly. The workpiece must be stiff, or well supported, so it doesn’t flex. That means minimum projection from the headstock. For example, modifying a drive centre while it is in the spindle taper is easy. A similar job held in a chuck is harder, because the metal can move away from the cutting tool.
Use tailstock support whenever possible. A Jacobs chuck will hold small items. Light cuts using a robust and sharp tool, with minimum projection over the toolrest, should then produce an acceptable result.
You can use a high speed steel woodturning scraper or a graver. A graver, which you can easily make yourself, was traditionally made from square section tool steel with a diagonal flat, leaving a long point at one corner. You could convert a triangular or square file, but a high speed steel tool bit would be better. A round high speed steel bar ground with a pyramid point would work. It would be similar to a woodturning point tool, but with a more obtuse point. Use a graver a bit like a skew chisel. Its edges (not the point) can plane off long, thin curly shavings from steel.
Brass likes tools with zero top rake, so responds well to scrapers. Tools leave a polished surface on brass. Aluminium turns with a graver or even a small short-beveled bowl gouge. Cutting speeds are lower than for wood, but because only small items are possible, the normal low-speed setting on the lathe is probably OK. Some metal alloys are more free-cutting and ‘turnable’ than others. A file will shape the item and remove chatter marks if necessary. Even on a lightweight lathe you can make simple shapes (for example putting a pointed end on a short bit of rod) in steel using a file, an angle grinder or a rotating grinding wheel held in a drill chuck.
Turning metal on a wood lathe is tiring, particularly with steel, because the tool must be held firmly up to the work. It helps to use a pivot pin in the toolrest to lever the tool into the work. This gives more control. If the workpiece is held rigidly, the pivot pin can help prevent chatter too.
Turning metal freehand is hazardous, therefore precautions are necessary. It is essential that the workpiece is secure in the lathe. Chunks of metal flying out of the machine are even more likely to do you harm than are lumps of wood. Eye protection is a must. The swarf is sharp and hot – wood chips hitting your hand are annoying, but metal swarf can cut or burn. Long strands could even catch your fingers and drag them in. Never clear away swarf while the lathe is running.
Turning with a scraper can make chips like little needles. They can get in your skin like splinters. But gloves are risky around moving machinery because they can catch and drag your hand in. Thin ‘rubber’ gloves that can easily tear are safer. A bad dig-in could wrench the cutting tool hard enough to break it and perhaps cause injury. A file thrown back by the chuck jaws can injure you. Tools must always be used with a proper handle to stop the tang impaling your hand.
This post is about dust extractor maintenance. It’s very easy to buy a dust extractor and forget about it. They are simple machines, but problems can grow slowly, so suction declines without you noticing.
Not long ago, I made some wheels out of a commercial cutting board, one of the thick ones used in restaurants or on deli counters. I cut some squares from it with the bandsaw with no problems at all. I put each one in my self-centring engineering chuck and turned it to size and shape. A flat bit in the drill press made the holes in the middle. Back on the lathe mounted on a wooden mandrel to complete the turning. Job done. The plastic material, that I think may be polypropylene, turned very easily with a negative rake scraper, leaving a smooth, shiny surface off the tool. The only problem was the shavings. Long ribbons of plastic wound round the chuck, the mandrel and everything else, with the loose ends flailing as the lathe went round. So although there was no dust, I put the dust extractor on.
Later, it seemed to me that suction at the extractor inlet was not as good as it once was, so I cleaned the filter cartridge. This was a job I had been meaning to do for some time. There was lots of fine dust in it, blocking the pleated filter. I took it outdoors and used a brush and compressed air to get as much dust as possible out. I put it all back together and switched on. Much better!
But was the suction yet good enough? Perhaps there was a blockage somewhere. My extractor is a cyclone unit, and at the outlet of the fan housing there is a grid to stop people putting their hand in and touching the spinning fan. I dismantled the ducting close to the housing to check it. Sure enough, long ribbons of plastic had passed through the cyclone and blocked the grid. It was surprising that air could get through it at all.
I knew what to look for, because once before when re-configuring the ductwork, I found the remains of a plastic carrier bag blocking the grid. Like the bag, the bird’s nest of ribbon was easy enough to remove. But this time I did my risk assessment and decided that although the grid removed one risk, it created another. The first risk was negligible to anyone with any sense, while the second was significant. So the grid had to go. I removed it, put the ducting back together and switched on. Now the suction is back to what it ought to be.
These are not the only times I’ve come across a problem like this. It’s possible for long splinters or other objects to get stuck at a bend so shavings build up, or for debris to accumulate at a low spot. And filters clog up from time to time. But often the drop in suction goes unnoticed, even if there is a vacuum gauge to check it.
So my recommendation is to make a point of scheduling maintenance, and to check suction at your dust extractor often. Whether you remove the safety grid is up to you. An objective way to measure suction would be useful. I shall have to consider a vacuum gauge.
I’ve now made an adjustable version of the pencil block, with a pivoting arm to hold the pencil. The hole for the pencil has a slot through it and a pinch bolt to lock it.
The Graduate lathe was designed in consultation with Frank Pain, one of the first turners to write for the amateur. He was a professional of very long experience and knew a thing or two about lathes and woodturning.
I bought my Graduate lathe many years ago. At the time it had little competition. It was perhaps the most solidly built machine available for non-industrial use, and the lathe you bought if you wanted the best. It was intended primarily for use in schools, back when schools taught woodwork, although my own first turning experience at school was on a Myford. Ray Key, another well known turner, described the Graduate as being ‘head and shoulders above the rest’.
This lathe comes in a long bed and a short bed format. Mine is a short bed, better for bowls and boxes because it takes a larger diameter and you can stand in front of the work without bending. It can be used for spindle turning, though not very convenient for this, and the maximum workpiece length is short. I have now bought a larger machine, but happily used this lathe for bowls and any larger work. It was a great improvement over the small spindle lathe that I owned at the time.
One problem with the Graduate lathe is that its centre height is low. Most people would want to raise the height. I had a welded triangular platform standing on steel pillars made for mine. This brought the centres up to elbow height, which is the normal standard. It also increased the footprint a little, making it more stable. I have not found it necessary to bolt the machine to the floor.
It came with a 3/4 horsepower motor and 4 pulley speeds with a range from 425 to 2250 rpm. This was not suitable for the large discs that I later began making for globe stands, which needed more power and a lower speed. I therefore upgraded with a bigger motor and a Variturn variable speed drive and had a special large steel faceplate made for these jobs. This goes on the left hand end of the spindle and allowed me to turn discs of over a metre in diameter. I installed the Variturn kit myself. It’s a great addition, quiet and smooth, but the lathe still lacks power for very large work. It copes with large bowls, but I prefer a 2 or 3 HP motor to let me work faster.
Although the Graduate lathe was a great machine in its day, and performed very well for most of my work, it has some weaknesses. The shortbed version seems to have been a design afterthought. For all its good points, its design leads to some problems.
The strange tailstock causes some problems. It is not used on the long bed machine. I didn’t often use the tailstock, so the problems I describe below rarely caused much inconvenience in practice.
The curve of the tailstock casting increases the distance between the centres. It is partly hollow, being open at the back. This causes lack of rigidity, and you can sometimes see it flexing as the work turns. The tailstock position sometimes falls where the two bed slots join at right angles to each other. In this position it is not properly supported. Both the foot of the casting and the locking plate below the bed are too small to bridge the slots at this point – an obvious flaw. You can see this in the photo below. I used an extra-large washer below the bed to help bridge the gap.
The curved casting has its foot closer to the headstock casting than its centre point. This means that when you want the point close to the headstock the locking lever below the bed will not turn. The headstock casting obstructs it. This means that you can’t always give a shallow bowl blank on a faceplate tailstock support. You can’t pin a disc against a faceplate with the tailstock.
The tailstock ram is just a screw (hollow, to take a No. 2 Morse taper) with a cross hole for a tommy bar to advance and retract. I made a winding handle to use instead of a tommy bar. The alignment of the screw on my lathe is not good. The upper part of the tailstock twists in the casting. A pin locks it, and there is enough play to throw the centre slightly out of true.
The toolrest holder casting is also curved and hollow, as shown in the photo. You can mount it in either of the two slots in the bed, with the same problem at the point where the slots meet. I find however that it is normally set in the cross slot clear of the junction. When the tailstock is in place, the feet of the two castings and their locking levers below the bed can sometimes get in each other’s way.
The tool rest holder also lacks rigidity to some extent. The foot of the casting is not directly under the tool rest stem, which allows slight flexing. The holder can slide along the bed slots and swivel, which ought to give free movement of the rest. But as it swivels, there are times when you cannot put the rest in the right position. and the toolrest locking handle, which is another tommy bar, can foul a large workpiece. With the tailstock removed, which is how I usually have it, the toolrest holder has more freedom of movement and there is rarely a problem in practice. The rests themselves are excellent for faceplate work – rigid, and with a good slope and narrow top. They are not so good for spindle work if you like an underhand grip with a finger behind the rest.
The headstock consists of a single iron casting from floor level up. The shell is heavy and robust, with a thin wall. Bolts attach the cantilevered beds to it.
The lathe came with an outboard bowl turning bed on the left of the headstock. But the inner and outer beds are the same height, so there is no more capacity when using the left hand bed on the short bed model. You cannot use the tailstock outboard. The spindle rotation originally was fixed (now reversible with the Variturn), so the threads are different and accessories aren’t interchangeable. Turning on the outboard side is in the reverse direction to the normal anticlockwise. Left-handed turners might like this. It can make some cuts easier, for example when hollowing bowls.
The outboard spindle thread is the opposite hand to the inner side. Because of this, if you reverse the rotation, the chuck is likely to unscrew. But the outboard bed is at least a convenient handle when moving the lathe. It would be useful for large diameter work when attached to the long bed lathe.
With the inboard bed removed, you can turn large pieces inboard. The limiting factor is when the headstock casting gets in the way. It bulges out half way down to accommodate the motor. Without the bed, a free-standing toolrest is essential.
With the left hand bed removed, you can turn even larger pieces outboard. I have used my Graduate lathe to turn built-up oak discs of 60 x 1100 mm. The lack of power was a problem though.
Both beds come off easily by removing the fixing bolts. There are dowels to align the beds accurately when replacing them. One person can do this with the help of a temporary wooden prop to help support the weight during this process. Some people set up a disc sander on the outboard side. The bed is then useful to carry the sanding table.
No lathe is perfect. The Graduate lathe in its short bed version is in some ways a poorly designed and under-powered machine. But because of its mostly great build quality the lathe performs very well and can do excellent work. Any of these bowls could have been made on the Graduate. You may sometimes come up against its eccentricities. But it is usually a delight to use and a Graduate lathe is still a good buy. It’s far superior to most of the cheap lathes on sale now. I used mine for many years and was always able to find a way to overcome its limitations. I have never used the long bed version, which has a more traditional toolrest support and tailstock. It should be excellent for spindle work, though limited for bowl turning.