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Resin casting at home in the UK (Is this what I need?)


Foxley

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Hey guys!

I'm totally new to all this resin casting business. I've never done it before and I had no clue where to start at first. I've been researching this for about two weeks now, looking at what I need to get and what I need to do, so hopefully I have some idea of what I want to achieve.

Anyway, basically I want to be able to reproduce and cast miniatures/models and terrain at home, whether they be resin/metal/plastic, without any of the proper equipment companies use to cast their products, meaning it'll be done with LEGO for boxes and some good old elbow grease. Now from my research I need to get some RTV silicone for making a mold, then a resin for the cast and some release agent to get the thing out once done. (Please note: I understand the rules and am not in it to start ripping off peoples work and selling stuff.)

Since I'm in the UK and from other posts I've read on here and Google, TOMPS.com seem to be the best place, so I've limited the products I think I need down to these:

Mold making: http://www.tomps.com/shop/-c-1_7_6.html

Resin casting: http://www.tomps.com/shop/polyurethane-fas...esin-p-129.html (SLOW)

Release: http://www.tomps.com/shop/cilchem-aerosol-release-p-60.html (1711E)

Can anyone who has had experience with this sort of stuff just check over to see if I'm correct in what I need? Have I chosen the wrong products? Am I missing something? I'd hate to order the wrong stuff and be left with a load of bits that I can't use.

Cheers guys!

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I'm also a Tiranti user, have been for over 20 years.

Tiranti has a decent shop and workshop and you can pop in for some helpful advice.

They even do demonstrations on certain days - of course this does depend on where you live, Tiranti's are based at Thatcham, just off the M4.

There site is: http://www.tiranti.co.uk/

Mike

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I get my stuff from Sylmasta. I'm not sure where you live but I go to Scale Model World at Telford every November and I stock up with both RTV rubber and Biresin and it normally costs me £50 for the lot.

I originally used Tiranti but was put off by the high postage charge, hence why I buy it at SMW to avoid that bit. I find that 1Kg of rubber is typically good for about 10 moulds, ie 100g each. The rubber is mixed with catalyst at 5% by weight. The best way I've found for doing this is with some jewellers electronic scales - about £5 on E-Bay. I pour 'enough' rubber into a disposable drinks cup and weigh it. Work out what 5% is and then drop catalyst in until I reach the correct total weight, then give it a good mix with a brush handle and pour it over the master. Leave for 24 hours and job done! Watch out for over large moulds. The more rubber, the harder it is to get a homologous mix with the catalyst!

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  • 2 weeks later...

Thanks for the replies guys, and the links to numerous products. I've been very cautious on what I needed to order, and after seeing some of your recommendations, and not getting a reply from TOMPS customer service team I have taken the plunge with Tiranti.

Here's what I ordered:

T28 Silicone Rubber + T6 Catalyst 1.05kg kit

Axson F31 Polyurethane Resin 1.8kg

Formula 5 Release Agent 400ml Can

Looking forward to it turning up and giving some casting a bash. Always nice to do something new with the hobby! Let's just hope I ordered the right stuff..

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That all seems sensible... next step is to source a pressure pot to expell (crush) all the air bubbles in the resin. That's what I want next, but money is the hold up there :rolleyes:

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That all seems sensible... next step is to source a pressure pot to expell (crush) all the air bubbles in the resin. That's what I want next, but money is the hold up there :rolleyes:

After a pressure pot/vacuum pump at the mo so I can get casting Lightning parts - just shocked at the prices... :(

Not done any 'production quality' casting before - just stuff for own use - but hear tell vacuum to expel air from the rubber when making moulds, and pressure to squeeze the bubbles when casting? Correct?

If I got a resin with longer working time after mixing - would vacuum work better?

Iain

Edited by Iain (32SIG)
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After a pressure pot/vacuum pump at the mo so I can get casting Lightning parts - just shocked at he prices... :(

Not done any 'production quality' casting before - just stuff for own use - but hear tell vacuum to expel air from the rubber when making moulds, and pressure to squeeze the bubbles when casting? Correct?

If I got a resin with longer working time after mixing - would vacuum work better?

Iain

youtube is your friend here ,plenty of demonstrations on how to build your own"homegrown"vacuum chamber. doesnt seem that difficult and with the price of shop bought chambers starting in the range of £1000 ,a lot cheaper

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Hmmm - courtesy of YouTube this is giving me ideas - just need to find a similar food storage jar her in UK - thought this was very neat (perhaps hooking up to one of my compressors rather than a 12v tire pump?):

Iain

Edited by Iain (32SIG)
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I've been making silicon rubber moulds since 1983, mostly for white metal castings. I've never found air bubbles in the rubber to be much of a problem. If you pour the rubber slowly in a thin stream from a height of 75-100mm above the mould box. Also ensure the rubber stream misses the master and flows over it as the height builds up. This way any large bubbles are burst and small bubbles do not cover details of the master.

The other thing is don't make the mould too small. Make it at least 13mm larger than the master all round. This gives space to cut air vents into the cured rubber.

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  • 2 months later...

The consequence of not using the vacuum/pressure equipment is that you will get more bad castings, not that all castings will be failures. I have never used vacuum equipment for mould making and have only had to remake 1 mould because of air bubble(s) on critical detail. I have also made resin casting, although with some failures, although many of these were repairable with filler.

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Hmmm - courtesy of YouTube this is giving me ideas - just need to find a similar food storage jar her in UK - thought this was very neat (perhaps hooking up to one of my compressors rather than a 12v tire pump?):

Iain

Might be to small but, http://www.lakeland.co.uk/15489/Typhoon-Novo-Storage-Jar

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Is there a cheaper version of doing this. Something to dabble in without spending over a £100. Biggest item will be a 1/6 head.

This is a very simple solution that I found works. Of course it may be a case of too much information too :)

I've never really had a problem with bubbles in the mold (follow the earlier advice on how to pour the rubber around your master) but I used to have a problem with bubbles on some of the more intricate detail of parts that I molded (for example, 1/72 F-18 wingfold detail) but found that if I put a thin sheet of wood on four springs (I used the springs from an old pop up game that my kids broke where you had x minutes to put all the pieces in place otherwise it popped up and shot the pieces all over the place).

Then I used duct tape to tape a vibrator :blush: to the undersides of the wood plank ... boy, this posting is opening itself up to so many comments :).

Put your mold on the wood and start the vibrator before you mix the resin (just to save time as you usually only have about 90 seconds to work with the resin before it starts curing) and then mix the resin and pour it into the mold at a fairly slow pace.

Using this and also thinking more carefully about where to place the points through which you pour the resin solved my problems. (Of course I did have some explaining to do to the wife ...

Gary

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  • 2 months later...

all sorts of interesting advice here may follow up on some of them. Otherwise for my Apache cockpit l may end up getting someone to cast it for me. There is a guy locally here but others like me found him to be slow and procrastinates a bit instant of getting it done. Also he likes you to do most of his work for him but still charges the full price which l doubt is the norm. This has put me off getting done by someone else and just relying on myself

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  • 2 months later...

I use a vacuum method for laying up composites for model gliders, including carbon fibre. Sounds expensive until you realise that you can generate a fair vacuum with one of those fishtank air pumps which will set you back about £15. Just connect the vacuum chamber to the suck side rather than the blow. A simple vacuum chamber can be knocked up from a bit of thick wall pvc pipe from the builders merchants with the screw on end caps. Connect a bike pump or tyre compressor to the chamber and you've got a pressure vessel that's good for about 150 psi. Have a look HERE for a sailplanes forum with loads of advice on creating cheap (and in some cases free) vacuum setups, including how to adapt an old fridge motor into a very efficient vacuum pump.

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