"Any Centricast tutorials on mould making?" Topic

My centricast machine works great,but I think I must be doing something wrong on my mould discs,does anyone know about some tutorials on centrifugal mould making for these machines???
Many thanks for any good tips!!!
Gui

Hi, perhaps some of the members could give you some tips if you shared the problem?

The silicone discs(molds)are always pressed too hard so the figures get squashed a bit…do you think I could use the brown rings used for the silicone casting,as some sort of piece that ensures the molds are not too firmly pressed?
Also the metal is poured down the central hole but out it comes again!!!
This is really a mystery as each figure has 2 big channels on each foot(I dont use bases),would the mold need some ventilation?sometimes I see figures with small strips coming out of their helmets and guns…
Bare in mind I am in Portugal where this is not a major hobby and I have inquired many factories with results.
Some of my sculpts went well I have them on my blog,perhaps I should place a picture of the mold so someone can see.
Again many thanks
Gui

One obvious one is don't tighten the nuts too much! Likewise, you must be pouring the metal in too quickly, and/or too much metal, as well as spinning it too quickly.

I would suggest trying less pressure and spin at a lower setting. Every mould is different, and I find that the larger castings need a slower spin speed than smaller ones. For the 20-25mm figures I cast I generally have it set at about 3 for horses and around 5 for foot.

I generally get my moulds professionally made now – Centricast moulds tend to be soft and making them is messy. However, when I made my own moulds I did find that if you warmed the rubber a bit before mixing it was a lot more fluid. Let it settle for a minute or two to let most of the trapped air escape. Likewise, you need to keep spinning the mould for quite a long time at as high a speed as you can get away with. Keep stopping it and topping up with 'fresh' rubber as you go – it is quite surprising how much air is trapped in the rubber.

Many thanks for your advice!
I agree centricast moulds do feel somewhat soft,I have no difficulties with the silicone process,it sets nicely and almost free of air bubbles.
It is the actual casting that is going wrong,and as you have said the pouring might be going on tho quick.
Spinning also might be going to fast usually I try it on 5-6,as slower speeds bring the metal upwards and out…
What is also strange is that half the mould get filled(3 soldiers),and the other half…void!

My soldiers are usually 36mm,as to metal temperature it comes out of the melting pot at 500º,is that adequate?
It is funny I have a similar approach to this hobby as yours somehow,I used to teach,in a Portuguese Architecture University(for the last 15 years)and as it is obvious,being so far south in Europe,producing wargaming/modelling figures is a matter ensuring some kind of wargaming action out here!!!
I have a line of 100 plus WW2 soldiers of many nations,and hope to have more(all of them).
So far only 1/48,varying figure heights from 30 to 40mm.
Also 1/100 and /50 for Architecture models.
I guess I have tons of fun sculpting and then a really disappointing hard time trying to reach mass production…
You did say you sometimes resort to outsourcing for professional moulds,I am considering that solution,would you also have some pointers on good casting services?
Many thanks Garrison Miniatures
in case you would like to see some of my «greens»:
wargames48.blogspot.com

Put your metal in too quickly then, if the mould is poorly vented, you may not be allowing the air to 'escape'. The metal can't get into the mould because of back pressure from trapped air. Anther cause of this could be using metal at too low a temperature. Is it cooling and getting too viscous to fill your mould?

Trapped air must be one of the problems,I will open small channels on soldiers helmets and guns.
I have seen one mould where an outer circular channel topped the soldiers heads and had a tiny hole to the out side,might try that too.
As to the metal,yes,I think it is going in colder than it should,the melting pot reads 500º,but it does look viscous and brittle,a dusty texture unlike my 1st ones that went well.

I am forbidding myself to use lead so the alloy might be another thing…By the way we are having a «big» event on the 1st and 2nd of May on the Portuguese Military Academy,would you like to come over?this year we are expecting a very good attendance.

Thanks for the invite, but the 1st of May is booked for my 58th birthday!

HAHAHA,I will be sending you a happy birthday then!
This afternoon was very sunny out here by the sea!wife and children went to the beach…I stayed casting for hours till now!opened vents and bigger channels and it worked,still results are not quite there yet…
Metal is still riddled with porosity…wish lead was a possibility…copper and tin are not working properly.
Maybe I will get some antimony int the mixture.
But in order to have things ready by the 1st of May I will have to hire last minute casting services.

If you don't already – one I tend to assume people do – dust your mould lightly with talc. Should help with porosity problems.

It is not the talc…Maybe it is the melting pot maybe 500º are not enough to melt the copper and tin to an adequate temperature…how many degrees do people use generally?

Check out tiranti.com for information about suggested pouring temperatures of the metals they sell. Usually 50-60 degrees C above the melting point. However, casting is an art – actual best temperature will depend on the size and complexity of your casting and other factors such as what the cat had for breakfast that morning. People badly underestimate the ability of a cheesed-off cat to cause things to go wrong.

I had a good look on the web found some examples for big plate casts:they use an inner ring that helps distributing metal around did you know?
I am about to try that,I must ask how many 28mm guys you fit in a tiranti big ring mold?
And how the heck you manage to place the big rings on the tri-arm of the centricast???I take ages to place them it is an ordeal!!!
About the cat it is exactly what happens…

Here is my email wargames48@sapo.pt
If you could be so kind as to refer some of information on casting services and or who would sell lead free white metal,it would be really important at this stage with the event coming up time is running out fast!!!

For metal, I use MCP of Wellingborough. They operate world wide, are cheaper than Tiranti and would probably be willing to both supply you and offer advice.

For figures in a Tiranti 9" mould you are probably talking about a dozen or so 28mm figures – depends on the pose. I myself have 2 Tiranti Centricasts and have never had a problem with them. Main problem with them is that they won't take a 12" mould, but then a new 12" machine costs at 4 times as much as a Tiranti. The inner ring comes under the 'art' side – sometimes you use the flat face, sometimes the recessed face. Having the recessed face facing in reduces pressure and may help metal flow; downside is that it increases the risk of heavy flash.

As for casting services, Pete Brown at Castcom will not only cast your figures, he will pack them as well: themouldmaker.com .

Realistically, that's about as much info as I have that I can offer. Best wishes on the event.

I really appreciate your information,your help has given some hope to my adventure,might even turn it possible!
Very generous of you helping out!
Hope you can come over for an event soon!
Again thanks a lot
Gui

Always glad to be of service.

Great luck having your opinion on these matters,I guess many of us do experiment with metals like medieval alchimists!
I have made a new mold with inner ring it is my last hope of producing my stuff at home.
Bottom line I have talked with many manufacturers and I am positive lots of them do use lead in the mixture of their white metal alloys,lead flows easy even in badly made molds.
Lead is however toxic,and so forbidden in the EEC,I am experimenting with pure tin and copper but results are still lacking.
Antimony is also a suggestion from TMP manufacturers but some say it is also really really dangerous and should be mixed in powder form so it melts properly with the tin.
In 1 week if everything fails I will be contacting casting services.

Er….lead is not forbidden in the EEC, I use it in my mix, so do many other manufacturers…..in fact, look at the descriptions of uses for various mixes that include lead on the Tiranti site..

link

Great news then!!!!!!!!
However they state: (…)Special note: Any hazard to health is only likely to occur from lead-rich alloys(…).
People did tell me it was forbidden,in the past I have used it and I know most manufacturers still do,but it scare the living c. out of me so I was leaning towards anything but lead.
Tiranti also has many lead free alloys,I will be trying to reproduce something here as it would be trying to have alloys shipped to Portugal all the time!
The main problem till now has been porosity,but I think I must try lower temperatures!And here I thought I was not using high temperatures enough(500ºtop capacity of the melting pot!).
What should I use half?250ºwould reduce porosity?
They say MP=180ºC and SOT=240º to 280º for lead free alloys what does MP and SOT mean???
Thank you!
Gui

MP = melting point, SOT = operating temperature, the temperature at which you would expect to heat the metal to. Again, mainly determined by trial and error as to which temperature you use.

Tiranti is expensive, try one like MCP – most alloys are part of standard mixes anyway.

The lead issue mostly comes from a new American law that bans the use of lead in toys. Wargames figures may be toys, may be models – as far as I know it hasn't been fully tested yet, but I consider myself covered by a simple statement on my site of:

'NOTE THAT FIGURES ARE NOT TOYS. THEY CONTAIN LEAD. NOT SUITABLE FOR CHILDREN UNDER 14.

WASH HANDS AFTER HANDLING AND DO NOT CHEW ON OR EAT THE FIGURES!'

Thank you,this week I will have a go at lower temps.rather than giving it full capacity heat 500º,dont know why I thought meat would preform better at a higher temperature,but then again this is all new to me.
As to the use of lead someone from the USA told me he thought it was an EEC ban on it,I really have heard antimony is also problematic maybe not as much though.
The other day I was having lunch with my accountant and explained metal is a must because of the feel and quality.
Other materials are just not noble,an analogy was made using the plastic fork and knife of fast food chains and metal ones in normal restaurants.
Metal is here to stay although these day some of the big ones in the business are presenting plastic figures,I have used some plastic figures,it does not do it for me.
the tendency might change but not for some time.

Unbelievable!!! Now that I had finally got it right one thing happens to make it all bad again:
All the figures come out perfect,except for a small hole either on the back or at the front!
The mold has many vents this is really unexpected!!!!

OMG!!!!!!!!!!now the centricast has just stoped working all the sudden!!!
As you did say be careful with this machines,I really have but it just gone silent really strange!
And I just do not have time to send it back to the UK now I am considering having an electrician look at it…