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Author Topic: Mould of the day  (Read 416 times)

martin goddard

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Mould of the day
« on: September 19, 2020, 06:02:23 PM »
Today is 19th September.
Up in the workshop fitting some new racks and shelving. Space is getting a bit tight.
Had my first  big session on Mike's new NICEM machine.
A luxurious Italian piece of machinery from Milano ,with elegant lines and a really nice slide action.

The reason I was on the big boy's machine was the 9"master mould i was working on. It is very rare for me to use a 9". Usually 6" is ideal.
PZ3 E hull tracks and turret. Should be out in 2 weeks once rear plate done.
Western railway bogie update.

martin :)

Now back to mexrev

Stewart 46A

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Re: Mould of the day
« Reply #1 on: September 19, 2020, 06:31:13 PM »
Thanks fo4 the update Martin, thought you were taking it easy in the garden

Stewart

Colonel Kilgore

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Re: Mould of the day
« Reply #2 on: September 19, 2020, 06:49:28 PM »
I got lost on 9" vs. 6".

Is it the size of the Panzer III bits that necessitates the bigger mould?

Simon

martin goddard

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Re: Mould of the day
« Reply #3 on: September 19, 2020, 07:47:15 PM »
Yes. 6" is fine for figures.
Larger objects need a  9"mould (diameter).

This is because a larger piece often needs channels for "breathing" that figures do not need.

If you put larger items in a small 6" mould  the inner and outer edge are further apart in terms of spin speed.
i.e with a radius of 4.5 inches the inner edge might be at 2.5 inch and the outer at 3.5 inch. An inner/outer multiple  of  1.4.
With a radius of 3 inches the inner edge might be at 1 inch and the outer at 2.5 inch. An inner/outer  multiple of 2.5.

The greater variation in spin speed can cause fill problems. ie the speed is fine for the outer edge but not for the inner. Ideally it would be the same speed for inner and outer. Possible if larger parts were moulded vertically, but  a mould would not allow that in terms of flexibility.

Fascinating? :-\


martin :)

Leslie BT

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Re: Mould of the day
« Reply #4 on: September 19, 2020, 08:15:34 PM »
Great description Martin.

Good job putting all that maths training into producing an understandable answer.

Smoking gun

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Re: Mould of the day
« Reply #5 on: September 19, 2020, 08:36:47 PM »
Hi Martin,
Do you have to "balance" the mould like a car wheel to control vibration?

I remember having to balance centrifuges, by loading up diametrically opposite positions, to stop vibration and prevent accidents.

Best wishes,
Martin Buck

Stewart 46A

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Re: Mould of the day
« Reply #6 on: September 19, 2020, 08:41:23 PM »
Technical stuff is fascinating, a lot goes on to get from the sculpting table to our eagley waiting hands.

Stewart

Grey Heron

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Re: Mould of the day
« Reply #7 on: September 19, 2020, 09:32:19 PM »
Good news Martin. Had a quick look on line for the said casting machine. They certainly are getting more technical from the days of old. Thanks for the update.

Cheers,
Helen

martin goddard

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Re: Mould of the day
« Reply #8 on: September 19, 2020, 09:38:17 PM »
Yes, moulds should be balanced.
The way I usually do is to have similar sized objects in the mould.
Thus, a mould would be all cavalry or all foot.
The problem is that if i have a larger object it must await other larger objects.
This might mean that a mounted figure will not be put in a mould of foot people. The spare space might be taken with a spare dolly or some such.
Added to this conundrum temperature will be different for big and small pieces. Another reason why they cannot mix. Very small pieces such as heads and weapons have their own thing too.



martin :)

Colonel Kilgore

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Re: Mould of the day
« Reply #9 on: September 19, 2020, 09:54:16 PM »
Thanks Martin - that's answered my questions!

Simon

Matías

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Re: Mould of the day
« Reply #10 on: September 20, 2020, 01:37:17 AM »
Really interesting Martin. Thanks.

martin goddard

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Re: Mould of the day
« Reply #11 on: September 20, 2020, 07:05:43 AM »
Glad and surprised members find it interesting.


martin :)

Smiley Miley 66

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Re: Mould of the day
« Reply #12 on: September 20, 2020, 07:09:25 AM »
It goes to show what work goes into our eventual models and projects beforehand.
Miles

Colonel Kilgore

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Re: Mould of the day
« Reply #13 on: September 20, 2020, 08:17:00 AM »
Glad and surprised members find it interesting.


martin :)

I'd have thought by now you would know your audience, Martin   ;)

I for one am very much enjoying this insight into the alchemy of figure production.

Simon



Nick

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Re: Mould of the day
« Reply #14 on: September 20, 2020, 11:30:29 AM »
Yes, I like reading about the mysteries of figure production too.

Nick