The Saunders spin casting machine, part 3

Cleaning, repairs and refurbishment

My second Saunders casting machine arrived in a state. To be fair, I knew it would. It was the machine I learned on back when I went up to Gladiator Games with Mike Lewis of Black Hat Miniatures for a crash course in casting and mould making with Bill and Elaine Lucas. Mike and I have known Bill since our early days of roleplaying. Mike was buying Gladiator Games and Coat d’arms paints from Bill and asked if I’d like to come along for the day.

Back then I was still importing everything from Eureka and AB, and being shown the casting process was a revelation. I’d imagined it would be difficult and involve lots of snipping of figures from sprues. Instead, I learned about kiss gates and how they made figures easy to snap off a sprue, how to use packing to bring a thinner mould up to height, and had a stab – literally and painfully when using a Stanley knife – at cutting a mould. Bill showed us his tricks at getting his machine to cast with his moulds and it seemed so easy.

I arrived home fired with enthusiasm to buy a casting machine, and was fortunate enough to find my Mark V Saunders on eBay. No one else bid for it, and it cost just £450. The seller was coming down to Southampton for the cricket and kindly offered to deliver it there free, and Mark Rowsell of Flashing Blade kindly stored it in his garage until I could get friends to pick it up as back in 2007 I couldn’t drive. It fitted in their people carrier with about a centimetre to spare at the top. eBay also provided a second-hand 20kg Tiranti/SEBA melt pot for £100. Nic Robson at Eureka sent me an old mould to use and to prove that I could cast. I just used the machine as it was, melted some scrap Eureka figures (accumulated breakages in transit), and miraculously turned out my first AB French light infantry. It has led to me casting more AB Figures under licence and, of course, Eureka’s 18mm SYW range and my own figures.

The day that machine broke was the day I realized I needed a spare, even if Nelson Engineering of Bembridge did fix the machine in a week. It had been put together without a keyway on the spindle of the main platen, and the belt wheel was held in place simply with a grub screw. A keyway is a groove cut into the shaft of a motor or spindle; there is a corresponding groove (the keyseat) in the belt wheel, with another piece of metal (the key) cut to go into both grooves: this keyed joint prevents the belt wheel from slipping on the shaft. Nelson cut a new keyway, and welded the belt wheel that they’d had to use an engineering solution to remove (they hit it with a hammer). It’s an experience I didn’t want to repeat, so checking the new arrival and discovering it had a keyed joint was a relief. I don’t know whether Saunders machines have never had a keyway or whether my machine was a one-off, but it’s something that any Saunders owner should check.

Saunders casting machine: the keyed joint. The turntable shaft on the right (that rusty bit of brown!) clearly has a keyway – a groove – cut into it. There is a correspondingly rusty key in the groove, mating with the keyseat in the belt wheel, so this assembly will not slip

Mike of Black Hat has gradually been moving over to compressor machines, first an MCP machine that was Calpe’s spare spare (Peter has two of everything as a contingency plan, and at the time had three casting machines) and most recently a secondhand SEBA machine. When Mike said he was selling his Saunders, I immediately said I wanted to buy it. I knew it was in a state, caked with casting metal and the victim of many over-enthusiastic engineering solutions (it had been hit repeatedly with hammer and cold chisel), but it was mechanically and electrically reliable and importantly came with a full set of Saunders weights that would allow me more control over my main machine’s pressure – I was already borrowing one set from Mike anyway.

So the first task was to get rid of all the casting metal that had built up around the pillars and arm adjustment bolts. No matter how careful you are, inevitably metal gets flung around the inside of the machine, either because insufficient pressure has been applied to the mould and it flashes, or because too much metal is poured into the mould and it is flung out of the hole in the top plate. And that’s why you never cast without the protective casing of the machine in place and why you ensure the lid is securely down.

I haven’t got pictures of how to remove metal, but basically it involves knocking off as much excess metal as possible with a heavy hammer and cold chisel – carefully, to avoid damaging any further the platen, pillars or adjustment bolts – and then unscrewing everything, attaching each bit to a wire, and dunking it in a pot of molten scrap metal to take off most of the remaining metal non-destructively. Of course, these parts get very hot, and once out of the metal they need to be left for some time on a fireproof surface – an old silicone mould is fine – until cool enough to handle. There will still be bits of metal in the threads, but these can largely be flicked out with a fine, pointed modelling tool (one of those dental/wax modelling picks sold for sculpting in green stuff) and a fine wire brush.

Another consequence of hitting the machine to remove metal is that the threads of the adjustment bolts and the arm weight shaft may be damaged. They need recutting using an appropriate die from a tap and die set, or a die nut.

Saunders casting machine: the arm weight shaft. You can see a minor dent in the thread just below the halfway point. The shaft is a 5/8 inch BSF (British Standard fine) thread at 14 threads per inch, and the appropriate die nut for repairing the thread is pictured at the bottom.

In essence you lubricate the thread with WD40 or PTFE spray and then just use a spanner to wind the appropriate die nut up the thread and it re-cuts the thread, taking off distorted metal. Alternatively, use a die in its special handle. It’ll still leave a dent, but this won’t impede the movement of a nut or arm weight up and down the shaft. The aim is simply to get everything free-moving again. BTW, wear gloves to avoid getting particles of swarf embedded in your hands.

Saunders casting machine: rethreading the pillar. The pillar requires a 3/4in 10 threads per inch die or die nut to rethread it. I’ve used a UNC (Unified Thread Coarse) die nut; in theory a British Standard Whitworth (BSW) die nut is close enough and should also work. Whitworth threads are cut with a 55 degree angle; UNC with a 60 degree angle. Anyway, the UNC thread certainly allows the pillar to turn freely in the hole in the base plate. I suspect the pillar is a modified valve adjuster from an engine (it has a slotted base that would allow it to be turned with a screwdriver), as the Saunders is clearly made from a number of what would have been widely available parts. But I’ve not been able to identify it

The pillars have two holes through them that allow a tommy bar to be inserted so that they can be turned in a die nut, itself held in a spanner, to restore the thread. The securing nuts for the pillars were badly damaged, and I have replaced them with 3/4in 10tpi UNC stainless steel nuts, which I ordered from eBay. They’re not going to be subject to great pressure, so the stainless nuts should be OK. I don’t intend taking an engineering solution to them.

Saunders casting machine: arm adjustment bolts. The bolts are 5/16in BSF (British Standard fine, 22 threads per inch) and 1 3/4in long. As the original on the left shows, one has been bent too much to allow full travel though the arm, and therefore rather than buy a die nut and recut the thread of these bolts, I simply replaced all of them and the nuts with new

One of the arm adjustment bolts was damaged beyond fixing, so I replaced the lot with new stainless steel ones from eBay. Again, used in compression and not whacked with a hammer, I think they’ll stand up. I will look for a non-stainless alternative. These are 1 3/4in fully threaded bolts – i.e. the threaded length is 1 3/4 inches; the head is extra. It’s the maximum size possible that will keep the head clear of the casting machine lid in normal usage. The bolts and corresponding nuts are 5/16in BSF (22 tpi).

Saunders casting machine: arm bolts. These are 3/8in 16tpi (UNF)  3-inch bolts, with the end 1 inch or so threaded. I have to double-check this. The head of the bolt is on the right; the nut on the left. The bolt screws into both the nut and the left-hand arm of the bracket in the platen

The bolts that provide the pivot point for the weight arm didn’t need replacing. The look to be 3/8in UNF (16 tpi) 3 inch partly threaded bolts, threaded to about 1 inch so the weight arm pivots on a smooth surface. These really are out of harm’s way, which is no doubt why they are OK. I did, however, undo them to take off the arm to rethread the weight shaft, cleaned them up with a fine wire brush and lubricated them with PTFE spray before reassembling. I used a spanner to lightly tighten the nut beyond hand-tight. All the lock nuts on a Saunders need tightening slightly beyond hand-tight because the vibrations of the machine will shake them loose. This is particularly relevant to the lock-nuts for the arm weights in order to stop the weights travelling along the arm when in use and changing the pressure.

I’ve taken the protective casing off the machine. It was held on with only three screws, but it should use more. With only the three, the base flange of the casing lifts from the wooden base, allowing metal particles to get underneath. I took about half a kilo of metal out of the machine. The casing has been damaged on one corner and needs welding, which a local garage has said it can do. I’ll add details of this when it happens.

When the casing comes back, I’ll also sort out the mounting of the new NVR magnetic switch to turn the machine on and off.

The top plate is also “worn” and I’ll be investigating using high-temperature silicone to provide a liner for the top hole to make it easier to remove excess metal that’s escaped from the top of the mould.

Next: New arrival




The Saunders spin casting machine, part 2

Modding the beast

This is the ultra nerdy part about using a Saunders spin casting machine. It will get absolutely the best results and allow easy setting up for different moulds while running a typical cycle of five or more moulds at a time.

The key to getting the most mould-line free castings on a Saunders is where the arm adjustment bolt falls on the top plate. It needs to fall over the centre of the pillar that both separates the two casting machine plates and locks the top plate into position to stop it spinning off when the machine starts up.

What you need is three 15mm turntable spirit levels, typically available from eBay. These are intended to get a turntable and turntable arm set up on a record deck, which will mean nothing to anyone under the age of 30… apart from hipsters with new vinyl record collections. Plus you’ll need some green stuff (epoxy putty) or five-minute epoxy adhesive – green stuff takes longer to set but will allow the spirit levels to be seated better.

First, ensure the casting machine is level. Use a conventional spirit level on the wooden base and if necessary pack under each foot of the machine’s tubular frame until the casting machine is level.

Take off the top platter. For each weight arm and pillar, turn the adjusting bolt in the top of the weight arm and raise the pillar until they touch and by eye align centre to centre. It doesn’t matter about how high the pillar is or how much through the top of the arm the adjusting bolt projects – it simply matters that they align. Link all the arms using rubber bands to pull them together and keep them in place for the next step.

Mix up some epoxy putty and put enough into the base of each spirit level so that any cavity is filled and there is some surplus to provide a bed into which the level can, if necessary, be pushed. Stick one level to the top of each weight arm, being sure to leave enough space between the level and the nut on the adjusting bolt. Carefully press the level into its bed of epoxy putty so that the bubble in the spirit level is centred. Leave to set. (You can use five-minute epoxy adhesive instead, which sets quickly but is fluid and needs continuous adjustment of the level until the epoxy sets firm.)

If you’re thinking why not attach the level to the top of the adjusting bolt, which will be horizontal, it’s because there may not be enough clearance between a level on top of the bolt and the lid of the machine when in use.

After turning the adjusting bolt in the top of the weight arm and raising the pillar so that they meet centre to centre, link all the arms with rubber bands to hold them in place. (The rubber bands have an actual function in this picture!) Stick a turntable spirit level to each arm using epoxy adhesive or putty. The levels will be in a non-stressed position so the epoxy bond should last for years
Press the spirit level into the bed of epoxy putty so that it is level and leave to set. The top of the weight arm slopes slightly and a bed of epoxy putty allows the level to be set as such even though the top of the arm isn’t horizontal. In future that whenever the bubble shows it is level, the adjusting arm will be dead centre over the pillar beneath. And yes, the platen is slightly damaged from having metal repeatedly chipped away from the pillar and mould arm, but not enough to affect the function of the machine
The levels are in place on each arm and being allowed to set. Even with five-minute epoxy, I’d allow 24 hours. Again, the protective casing has been removed for clarity, and the machine should not be operated without the casing in place. BTW, the circle drawn on the bottom plate allows moulds without a moulded locator stud to be roughly centred.

When the epoxy has set, remove the bands and wind the adjusting bolts and pillars to approximately their usual positions.

Place a mould on the bottom plate, and then put the top plate on, locating the tops of the pillars in the appropriate holes to hold it in position. Adjust the pillar height so there is a gap between the shoulder of the pillar and the top plate even when the assembly is compressed slightly.

Adjust the pillar height so that the shoulder of the pillar is clear of the top plate and there is some play if the top plate is pushed downwards. This means that the mould can compress freely when the machine is switched on – the degree to which is compresses is determined by the heaviness of the weight and the distance of the weight along the arm (i.e. the force on the weight arm). Lightly tighten the pillar locking nut to hold the pillar in place. Repeat for the other two pillars. Note that the weight arm also is well clear of the side of the top plate

While holding the weight arm so that the adjusting bolt is lightly in contact with the top plate, turn each adjusting bolt so that the bubble is the spirit level shows that the arm is level.

The arm is held in place (here with a rubber band for the purposes of the picture) and the adjusting bolt turned so that the arm shows as level. The centre of the adjusting bolt will now be over the middle of the pillar that holds the top plate in place. Repeat for the other two weight arms

This adjustment is the key to good castings. It ensures that each weight arm applies the same pressure at the same distance from the edge of the top plate, without tipping the top plate in any one direction. Combined with correctly positioned weights on the weight arm to give enough pressure to seal a mould, this will minimise mould lines.

Update: Using this arm position on the top plate is a starting point. Moulds may benefit from having the arm shown slightly off-level – provided that all arms are the same degree off-level. I get better results on some moulds by having the contact point slightly towards the edge of the top plate, and adjust the bolt so that the bubble in the level is up on the top of the marked circle in the level  – i.e. nearer the bolt (bubble nearer the bolt equals contact point nearer the edge; bubble nearer the edge equals contact point nearer the centre).

Weights can be positioned evenly down the weight arms simply by measuring from a fixed point. When setting up for the first time, I take the weight arm off a machine and measure using a ruler from the pivot point (actually the top of the hole in the weight arm) to the top securing nut of the weight. When in use, I typically use an item of fixed width, such as a metal bracket, to set each weight the same distance along each arm. I then fine-tune the distance by making test castings and increasing or reducing the pressure by moving each weight the same number of turns respectively down or up the arm until the mould stops flashing or starts filling all the cavities. Once I’ve identified the right setting for, say, a 15mm infantry mould, I note which gauge I’ve used and the number of adjusting turns, and then use that setup as the basis for all other 15mm infantry moulds.

Here I’ve set a medium weight at 75mm along the thread simply by measuring with a steel ruler. I’ve shown this on a machine without the casing in place, but it’s more easily done either by taking off the weight arm and measuring or by using a fixed-width piece of metal between the top of the thread and the top of the securing nut. This weight, held by two securing nuts, is about as far along the arm as it can go.

Importantly, this is just a starting point. Individual arm weights may vary very slightly in weight thanks to the accumulation of casting metal from inside the machine (hence it is important to clean them). And the three threads making up the weight arms may vary very slightly in length, adding marginally to the mass and therefore causing a slight difference in pressure on the mould. Even after careful setting up, you may find that one weight may need a quarter or half turn up or down the arm to balance the machine: exactly what adjustment is needed is part of the black art that is spin casting.

The spirit levels allow minor adjustments to account for small differences in mould thickness to be made very quickly. If you make sure a casting session involves only moulds of about the same thickness – there is a natural variation in thickness caused by differences in the original mould blanks and by the volume of the originally moulded figures (big figures displace more rubber!) – then each mould may take only a quarter or half turn of the adjusting bolt to set the machine up optimally.

Also, it is important to bear in mind that moulds may be uneven, sloping to a lesser or great degree, because the vulcanising press is not even. What I do is work out the thickest point of the mould (it is, by and large directly opposite the thinnest point) by running the jaws of adjustable wrench round the outside of the mould until the wrench stops (closing up the wrench if necessary!). I mark the point and then run the wrench round the other way until it stops again, and mark that point. Halfway between those two points is usually the thickest point. I mark that point on the mould with paint or a marker pen. I then always align that point with the same pillar on the mould, so that all moulds always have the thickest point aligned with that pillar, meaning I have the fewest turns to make on the adjusting bolts.

The yellow triangle on the mould marks the thickest point. By always aligning it with the same pillar – here against the pillar I have marked “1” – it ensures the fewest turns have to be made to the adjustment bolts on the weight arms to get them level

Sometimes I just set up the machine perfectly for one mould, securing the adjustment bolts in place by tightening their locking nuts. I then cast only from that mould, leaving slightly longer between spins before opening the mould (i.e. so that the central core is set) compared with operating using a stack of moulds. This keeps the mould hotter, helping the flow of metal – handy for lower density casting metals such as pewter.

I’ll run another blog entry sometime soon on my casting tips, covering metal temperature, mould temperature and talcing.

Next: Cleaning, repairing and refurbishing an old Saunders

The Saunders spin casting machine, part 1

Saunders Mark V spin casting machine

Fighting 15s does all its casting on a casting machine made by N Saunders Metal Products Ltd.  Saunders appears to have gone out of business in about 2002, but its casting machines live on. A number were apparently used by Games Workshop, and have therefore found their way to other toy soldier businesses: machines are also used to cast items such as fishing weights, and they occasionally crop up on eBay. I recently picked up a second machine that needs attention to get it working properly, and stripping it down provided the opportunity to take pictures and show how it works.

The Saunders is a robustly built, bob-weight machine. It is highly adjustable, and with experience and one simple improvement can reliably turn out high quality castings.

Bob-weight casting machines use weights on the end of three arms to apply pressure to a mould. When the machine is switched on, the platen spins, the weight-ends of the arms rise and the short end of the arm is pushed down, applying pressure to the top plate.

A mould clamped by the action of the weight arms. The protective casing of the machine has been removed for clarity. Never operate a spin casting machine without the casing in place and the lid down. The rubber bands are simply holding the arms in place on the platen for the photograph

Pressure on the mould is varied by the following means: speed of rotation, the heaviness of the arm weight, and the distance of the weight along the arm. In addition, the adjustment screw at the top of the arm affects where the force is applied on the top plate: the location of this is critical, and in part 2 I’ll look at the improvement that can be made to get the best results.

Speed control is rudimentary. The Saunders uses an AC motor whose speed cannot be controlled by a variable resistor – those only work on DC motors. Instead, it uses a variable speed pulley – the belt wheel on the motor’s shaft is split and has a spring, which has a dust cover, that applies pressure to keep the two halves of the belt wheel together. The belt face of this split wheel is sloped, and the motor can be moved in its frame to increase or decrease the tension on the drive belt: the more tension, the wider the split belt wheel is forced apart and the smaller the diameter of the drive wheel becomes, and hence the slower the main turntable spins (a smaller drive wheel takes more turns to turn the main belt wheel once).

Saunders casting machine: the drive belt wheel and pressure spring on the shaft of the motor. There should be a dust cap over the spring mechanism

The mechanism to move the motor assembly, however, is basic and difficult to adjust because it is hard to get purchase on the knob used to adjust the distance.

Saunders casting machine: speed adjustment. The motor sits on a frame that can be moved along a screw thread by turning the knob pictured on the right hand side of this photo. An indication of the speed is given by the pointer at the top of the frame
Close-up of the speed indicator, nominally revolutions per minute. This one is set to about 600rpm and indeed spins at that speed; it also spins at 600rpm when set to 700rpm… The dust cap for the spring mechanism on the motor shaft can be seen behind the belt guard, in line with the pointer.

In practice, because of the difficulty of turning the adjustment knob, you learn to work with the speed the machine runs at and change the other variables to cope. It is possible to convert the machine using a DC motor and a variable resistor to provide better speed control, but the cost might not be worth it.

The arm weight and its position on the weight arm, however, give plenty of control. The system may seem arbitrary, but as the pressure applied depends on the principle of levers it’s quite easy to adjust pressure to suit difference moulds. Even on casting machines operated by air pressure and a ram, discovering the initial pressure required to get figures to cast is a matter of guesswork improved by experience.

Saunders casting machine weights (left to right): 985g (2lb 2 3/4 oz), 260g (9 1/4 oz) and 165g (5 3/4 oz). A set is three of each weight (one for each arm); a full set for the machine appears to be three heavy weights, six mid weights and three light weights

My initial machine came with only a set of heavy weights (985g or so); the new machine has a complete set of three heavy weights, six mid weights (260g or so) and three light weights (165g). The arrival of these weights has given me more flexibility. It is possible to have some machined, which I will be looking into: the arm the weights screw onto is a 5/8in BSF thread (British Standard Fine, or 14 threads per inch). The weights may have accumulated metal around the milled edges and it’s important to remove this to get all the same-sized weights to the same weight.

As I said, how much pressure is applied depends on the formula for levers. And here’s the science bit… If you assume that the rotation speed is constant (it cannot be easily changed anyway), then lever formulae decide the force applied to the top plate. In short, a heavy weight at the top of the arm (nearest the pivot) can apply the same pressure as a lighter weight at the bottom of the arm (furthest from the pivot). The relationship is quite simple, involving mass and distance from the pivot point (fulcrum): M1 x a = M2 x b, where M1 is the mass of one weight and a is the distance from the fulcrum, and M2 is the mass of the second weight and b its distance from the fulcrum. Very crudely, without converting into appropriate units,  a 1,000g weight that is 50mm from the fulcrum is equivalent to a 250g weight that is 200mm from the fulcrum.

Where the Saunders limits this is the length of the weight arm, which is around 110mm, so you can’t use a mid-weight at one end of the arm to be the equivalent to the big weight at the top of the arm, because the arm isn’t long enough. With the locking nuts above and below the weight in position, the maximum distance a weight can be positioned along the threaded arm is about 75mm, or about 105mm from the pivot point allowing for the unthreaded elements of the weight and arm assembly. It means the heaviest weight at the top of the arm (it’s about 50mm from the pivot point) is, crudely, 980 x 50 = 49,000 “force units” – the same as two of the 260g mid-weights positioned 94mm or so along the arm. You also have to allow for the weight of the nuts and where the actual centre of mass is for the total weight if you want to be 100 per cent accurate.

Saunders casting machine: combined weights. A 260g weight and a 165g weight together, providing 425g in total – plus the locking nuts. Positioned about 50mm from the pivot point, I find this is ideal for most 15mm infantry moulds. Horses, which have a broad edge towards the outside of the mould, require a 990g weight at about the same distance to seal them effectively. The machine spins at around 600rpm – a higher speed would require less weight. The line marked on the weight and the top nut allow the number of rotations up or down the arm to be counted when adjusting the weight to suit different moulds

In general, once you find out the correct weight and distance along the arm for one mould, that setting will work for most other moulds of the same type. There may be slight differences, and more or less pressure may be applied by turning the weight down or up the arm respectively. Marking each weight with a line allows you to count the turns up or down, so you know how many are required to restore a weight to its initial position. If nothing has cast on a first spin you may be 10 or more turns off: slight flash takes only one or two turns to cure.

If you’re starting with a Saunders for the first time, having the weight as far away from the pivot point as it can go will reduce the likelihood of spraying metal all around the insides and over all the adjustable elements. Getting metal off the parts may lead to the sort of damage my second machine has suffered.

Using lighter weights gives finer control over pressure. That levers formula means that a light weight has to be moved a greater distance to have the same effect of moving a heavy weight a small distance. So one turn of a light weight is equivalent to a fraction of a turn of a big weight.

Finally, it’s important to get the adjustment bolt at the top of each arm set to come down at the same distance in from the edge of the top plate to ensure that pressure is even.  The top platen has three hard metal discs screwed onto it and on which the adjustment bolt lands: the right position is approximately in the centre of each of these discs. The discs are directly above the locking pillars that are screwed into the bottom platen and which have location studs onto which the top platen fits to stop it spinning off when the machine starts up. Basically, to set the adjustment bolts you hold the arm onto the top plate and adjust the bolt so it is central. Doing this ensures that even an uneven mould is evenly clamped by the machine. It’s a bit hit and miss, and the improvement I’ll cover in part 2 deals with how to do this quickly and reliably.

Saunders casting machine: arm adjustment bolts. Each adjustment bolt in the top of the weight arm is set so that when the bolt touches the hard disc set into the top plate, it lands roughly centrally. This places it directly over the centre of the locking pillar located between the bottom and top plates. The rubber bands are just there to hold the arms in position for the picture. Ignore the spirit levels – they are part of the dodge for part 2!

Lastly, a look at some of the basics of the machine. The Saunders should have an industrial machine stop-start switch. However, it’s what is known as a  “dangerous start” switch, because it’s possible to start the machine simply by inserting the plug if the stop-start switch has been left on. However, my Mark V also has a lid-operated safety switch that means it only operates when the lid is down, so replacing the stop-start switch is not a concern.

Saunders Mark V casting machine: on-off switch. This is not an NVR switch, and the machine will therefore start if the On button is left pressed in and the power is switched on…
Saunders Mark V casting machine: lid-operated switch. The lid-mounted bolt (upper left) presses down on a rod in the side of the machine that goes down to a safety interlock switch under the base – and therefore safely away from hot metal. In essence, the lid must be down for the machine to run, and lifting the lid cuts power to the motor

The machine I am stripping and rebuilding, however, has lost its original stop-start switch, and has been fitted with an immersion heater switch. It also does not have a lid safety interlock switch. I will be replacing the main switch with a no voltage release (NVR) switch as a priority, and adding a safety interlock switch to the lid later.

Replacing the switch: although the immersion heater switch will cope with the load, it’s not a safe machine switch. The new NVR magnetic switch will eliminate the possibility of a “dangerous start”

Next: modding the Saunders to make life easier

Update 22 July 2017: Included the term “variable speed pulley” under speed control as that is the technical name for the sprung, split belt wheel.