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.

019_saunders_IMG_1277
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.

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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.

021_saunders_IMG_1258
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.

022_saunders_IMG_1262
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).

023_saunders_IMG_1252
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: Casting toy soldiers with a Saunders

 

 

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