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Author Topic: My first attempt at making moulds and casting  (Read 2774 times)

Capt Podge

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My first attempt at making moulds and casting
« on: June 15, 2016, 01:06:05 AM »

Having read through a number of build logs, some of which include the making of rubber moulds and casting in resin, I decided to have a go.

One modeller in particular, Radio Joe, has produced some lovely bits and pieces for his warship models.

Inspired by this, I bought the necessary materials from www.easycomposites.co.uk/#!/ (this was way back in March) and finally got around to it.
As the stuff has a shelf life, I thought I had better get cracking...

So, I gathered together a few odd bits to use as practice subjects, made a moulding box from plasticard, mixed the rubber silicon & catalyst, poured as described on their data sheets (available on their website as PDF files) and set aside for 24 hrs.

The only problem I had was that 2 of the items I was taking moulds from came to the surface and needed to be pushed back to the bottom. Fortunately, the mixture remains workable for about 2 hrs.
I think I should have secured the items in some way before pouring in the mixture.

Anyway, the result was ok so I went ahead and mixed the 2-part casting resin, the result of which can be seen in the photo.

I like to think I've done a reasonable job and look forward to creating more in the future.


Regards,

Ray.
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Umi_Ryuzuki

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Re: My first attempt at making moulds and casting
« Reply #1 on: June 15, 2016, 05:22:12 AM »

I always use white glue to cement the masters to the bottom of the mold.
This prevents floating. Also, if you are not using a vacuum chamber to de-air the
rubber or mold, then take some time to brush a layer of rubber on the pieces to
prevent air bubbles from attaching to your pieces. Then slowly fill the mold from
one corner an allow the rubber to flow slowly around and over your pieces.

Be sure to keep the height of your pieces to be molded similar, or you will be using
much more molding material over pieces like the doors than needed while trying to
cover tall pieces like the dice. You can keep the depth over your pieces as low as 3 mm, but
you may find that thin mold may start to curl over time. I typically pour about 6mm of depth
over parts.

One of my latest castings... %)

Capt Podge

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Re: My first attempt at making moulds and casting
« Reply #2 on: June 15, 2016, 02:49:58 PM »

Umi - Thank you very much indeed for your most informative reply. The techniques you have pointed out will be taken onboard and applied to my future efforts. :-))

Your lobster crates look really professionally made - most impressive. O0

Regards,

Ray.
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Martin [Admin]

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Re: My first attempt at making moulds and casting
« Reply #3 on: June 15, 2016, 06:11:05 PM »


Very impressive.  :o

 Where can modellers buy from you Umi?
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Umi_Ryuzuki

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Re: My first attempt at making moulds and casting
« Reply #4 on: June 15, 2016, 06:41:18 PM »


Very impressive.  :o

 Where can modellers buy from you Umi?


Hi Martin,

People can email me to check stock, and I use Paypal to transfer funds.
I don't use a commerce website, and as a side business, I don't keep a large inventory.
 ok2

http://modelsminiatures.com/

 :-)

radiojoe

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Re: My first attempt at making moulds and casting
« Reply #5 on: June 15, 2016, 10:00:45 PM »

Hi Ray you've made a great start there, as you found out I secure the master to the bottom of the mold with Cyrano as I don't use the master on the model I keep them in case I need another mold, it's surprising what you can reproduce with practice. :-))
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Capt Podge

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Re: My first attempt at making moulds and casting
« Reply #6 on: June 17, 2016, 03:05:33 PM »

Thanks Joe.

After re-reading your Brock' build, it seems I failed to register the fact of gluing down the master, which you definitely mentioned earlier. :embarrassed:

...learning all the time. :-)

Regards,

Ray.
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T888

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Re: My first attempt at making moulds and casting
« Reply #7 on: June 17, 2016, 04:09:08 PM »

Ray,
A couple of tips .... when I have a master with fine detail, it's best to paint the master with the RTV ( silicon rubber ) . This stops air bubbles forming around the fine detail.


Also try and keep the masters away from the casting box sides, as the Mould walls will not be strong enough and can distort when the casting resin is poured in to the mould. Also air bubbles can form.
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Capt Podge

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Re: My first attempt at making moulds and casting
« Reply #8 on: June 17, 2016, 04:26:38 PM »

Thanks Dave.

The master door must have "shunted/floated" to the side of the box during the process of pouring the rubber - I will definitely ensure the masters are secured away from the sides in future. O0

Regards,

Ray.

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nemesis

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Re: My first attempt at making moulds and casting
« Reply #9 on: June 18, 2016, 12:05:44 PM »

Ray, Always put, if possible, the mould back into the mould box, that stops distortion. If you have fine detail you should always vacuum the the mix and also vacuum the filled mould, the latter is important.
Nemesis,
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Capt Podge

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Re: My first attempt at making moulds and casting
« Reply #10 on: June 19, 2016, 09:16:05 PM »

Thank you for the info Bill - I'll be sure to add it all into the guide I'm making for future tasks of this nature. :-))

Regards,

Ray.
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