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Author Topic: What is easy to cast  (Read 606 times)

martin goddard

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What is easy to cast
« on: December 14, 2020, 06:38:27 PM »
Here is one of my occasional articles giving an insight into what goes on in the PP mould room.

I make no claim to being more knowledgable than others; the intention here is to inform.

Peter Pig figures are cast in various low melt metals.

The metal obeys the laws of centrifugal or spinning force (please don't bother nit picking about centripetal force, just stop reading now).
i.e when the mould spins the metal will go outwards.

Getting the force in the right direction
If a figure points directly outwards in the mould it will fill really easily.
If a figure points in several directions often one direction will fill really well at the expense of the others.
In general terms it means it is easier to cast a rod than a star.
This also applies in 3D.
A figure that is flat will cast better than one which goes in and out of the mould.

Creating the best flow
It is often more important to get the air out of the mould than it is the get the metal in.
Similar to when a full bottle is tipped upside down and the air "glugs" out.

Higher temperature will make the metal flow better but can cause crystallisation type effects (pitting, crumbling etc).

Evenness of temperature
The trick is to get the temperature the same throughout the casting as it fills.
The best way of doing this is to have cavities at the points where the metal is most "grouped".
An example of this is the way PP prone figures have the underneath hollowed out so that the torso is similar in bulk/thickness to the legs etc. One dopey manufacturer (now gone) stated that this proved that PP was stealing metal from it's customers.

Thin bits
Thin bits includes bayonets and swords.
These need to be at the furthest point so that they get maximum force. Trouble is that the metal is often cooler when it gets there.

Flash
Gamers often confuse flash with mould entries.
Flash is where the mould leaks and the figure gets a halo.
Mould entries are the little nubs on the base where the metal has entered.
Flash is a mistake and should be minimal.
Mould entries are compulsory.

A comparison might be broken egg and an egg in a box. Broken eggs are a real pain and still useable if they just have a crack, but any worse and they are of  much less  use.
A box is a method of carrying the eggs. Customers might complain that their eggs came in boxes, but brighter folk would discount the complaint I suspect.

martin :)

Spartacus

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Re: What is easy to cast
« Reply #1 on: December 14, 2020, 07:32:26 PM »
Thanks Martin. I will go to bed tonight chewing all that over.

Terry

Colonel Kilgore

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Re: What is easy to cast
« Reply #2 on: December 14, 2020, 08:43:39 PM »
There's a lot to this casting business, isn't there? And there was me thinking that Mr Pig was just a pretty face... :)

Thanks for posting this all Martin. Having only ever done Prince August "pour in the lead, give it a few taps and hope for the best" casting (albeit we did drill a few holes to help the metal flow to extremities), I find this kind of insight fascinating.

Simon

martin goddard

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Re: What is easy to cast
« Reply #3 on: December 14, 2020, 08:53:34 PM »
Glad it is of interest chaps

martin :)

pbeccas (Paul)

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Re: What is easy to cast
« Reply #4 on: December 14, 2020, 11:31:07 PM »
I find the figure making process from concept, to sculpting, to casting fascinating.  Apart from sculpting, mould making interests me the most.  Itís a great skill to know how to get the figure position right so the metal flows correctly. 

Smiley Miley 66

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Re: What is easy to cast
« Reply #5 on: December 15, 2020, 03:42:38 AM »
That is another little snippet of an insight to how before we receive our well packed parcels, what goes into making our desired figures, tanks and assortment of bits. I think I will stick to the modelling and painting bit, leave the rest to the boys and gals at PP HQ.
Miles

Spartacus

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Re: What is easy to cast
« Reply #6 on: December 15, 2020, 12:07:02 PM »
Now fully restored after a nights kip.
I did attempt some figures about 40 years ago. I think I bought my rubber from Alec Tiranti ltd????
Just made the mould in 2 halves in some small plastic boxes which I remember was fairly easy, I used I think melted vaseline to prevent the upper half of the mould from sticking to the lower one. Also had a couple of pieces of dowel pushed into the lower to give a locating key to the upper.
I had some hardboard pieces and a metal clamp to hold the mouldhalves together Prince August??, Then got pouring. I had to make a few air release holes in the mould which I did with a scalpel. This all seemed to work fine but took ages.
I did this in the kitchen and put the molten metal filled saucepan in the sink to cool down whilst doing this I knocked the rubber tap swivel (remember them) and water flowed into the saucepan. This was my first attempt at decorating the ceiling with silver stalegtites, needless to say I got banned from making any more.

Terry

Sean Clark

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Re: What is easy to cast
« Reply #7 on: December 16, 2020, 12:42:30 AM »
That idea if stealing metal from customers made me laugh.

Truly, in all the years I've been buying Peter Pig figures, the most I've needed to is scrape the underside of the base. Now that's workmanship on behalf of Martin, Nigel and Mike.

martin goddard

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Re: What is easy to cast
« Reply #8 on: December 16, 2020, 02:41:11 PM »
Thank you Sean
I have small lump of metal here for any customer who is upset by the stealing metal incident.


martin :)

Brian Cameron

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Re: What is easy to cast
« Reply #9 on: December 16, 2020, 03:49:18 PM »

Thanks for the informagtive piece Martin.

Some decades ago I cast some figures using the high temp RTV rubber from Tiranti.  Just doing it as per Don Featherstone's various books ie one figure in a mould they came out ok but it took a long time.  Not near as long as making the original figures and they were still pretty crude as I'm certainly not a sculptor.  You certainly needed to carve some thin lines in the face of each mould for the air to exit the mould.

Given some of the rubbish castings I see of 28mm figures the standard of masters seems to be improving but the quality of mould making going down as shown by those bloody 'worms'.  Moulds clearly made by people who fail to understand the points laid out by Martin.

One of the reasons for my change to 15mm for some subjects is the high standard of PP figures - as someone else said, only cleaning up to do is the underside of the base.  And I've yet to encounter (and doubt I will) moulds with extra chunks of metal where pieces have come off the mould after being flogged to death.

Brian

Panzer21

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Re: What is easy to cast
« Reply #10 on: December 16, 2020, 04:27:20 PM »
Many years ago I worked for Wargames Foundry. Bryan Ansell was pursuing other ventures so only had intermittent intervention in the business, it being left to the (ex-GW) management.
I was shocked when I was packing an order and rejected a pack of figures due to several having incompletely moulded bases, to be told "they are OK - the feet are moulded".........
Martin's comment about accusations of "stealing metal from customers" made me think of this...
Neil

martin goddard

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Re: What is easy to cast
« Reply #11 on: December 16, 2020, 08:50:36 PM »
Bet you have some great stories Neil but you had better not put them here on the internet.

martin :)

Back in 1972 and circa, our gaming group in Bournemouth would have regular "days out" to Southampton. The main reason for going was to visit the Minifigs shop/factory in Northam road. I expect John remembers that as he is very old. :)

The 25mm figures were sold individually. The 15mm were in strips. All put in Rowney art boxes or small minifigs coloured boxes. There were always new unreleased items that Neville, Fred or Tony would show us.
A real treat.
Then on to Beatties the model shop (remember them).
After this a walk to Hobby Lobby who had a massive stock of Mini tanks.
Finally a small shop near Edwin Jones Department store that stocked Hinchliffe in little blue boxes.

The choices were all  limited, but the hobby was still  exciting.


martin :)


John Watson

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Re: What is easy to cast
« Reply #12 on: December 17, 2020, 12:36:53 AM »
Thanks Martin. Despite my extreme veneration ( or otherwise an old b****r) in 1972 I was not wargaming. My interests then were beer, football and rock music in no particular order (as they say on Strictly). Added to which I lived in north London then, so nowhere near Southampton. All that aside it sounds like it was a great time then, but of course things move on, and I can only assume that a young Martin G (slim waist and full head of hair etc) was gaining experience for his future forays into wargaming mega stardom. Keep up the good work Martin.
John

Spartacus

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Re: What is easy to cast
« Reply #13 on: December 17, 2020, 07:21:08 AM »
Yes, I remember the Minifigs in small matchbox sized boxes. I had a lot of 15mm ECW in strips.

Terry

Panzer21

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Re: What is easy to cast
« Reply #14 on: December 17, 2020, 06:13:14 PM »
Well Martin, it was a short employment... :)
Some stories I can tell.......the U.S. gentleman who emailed to complain about a Napoleonic French artillery piece; not only were the dolphins and some other parts incorrect, he was incandescent that the wheels were 2mm too small.......
The Frenchman who rang up asking to speak to the Perries personally, as he wanted to know the lace patterns of AWI British infantry......(they were never at the factory....)
Most of the customers were very pleasant, but there were some who were very odd.

Neil