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Post by PitYak Studios on Aug 22, 2005 20:43:45 GMT 12
I know, I've heard that sentiment so many times about other forums. I'm glad I could find the information I did find before I started, but it would have been better if I could have found info on products I would be using. I get in these long discussions about various molding products then chip in "ah yes, but what about..." and noone has any clue sadly.
And that reminds me too, I'm meant to be casting.
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Post by PitYak Studios on Aug 22, 2005 21:09:41 GMT 12
Hey Stu, have you noticed how a large volume of resin goes off quicker than small amount? (I hadn't until it was pointed out, but never mind)
Well, I've just poured one of my right angle sandbags, which is a solid wall with a small base around it, so in the mold looks like a deep trough, with a shallow shelf around the top. The big mass of resin in the sandbags themselves has bloomed, and the stuff around the top hasn't! Freaky!
(There you go, not just tips on products you can find here, but live commentary as they are used!)
And all this talk about modular terrain; I completely forgot about my modular barricades. I've got a set cast up and have never even undercoated them. I think I posted a pic somewhere earlier.
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Post by c0d3monk33 on Aug 23, 2005 8:32:07 GMT 12
I have noticed that the resin tends to start blooming in the centre of a pour and works out to the edges until the whole piece is white. I've also noticed it can take a good 8-12 hours until the resin is completely set hard. Sure you can pop a piece out of a mold in an hour but you can't sand it or cut it reliably until the next day in my experience. I reckon the exposed faces probably set slower because they're exposed to the moisture in the air which slightly retards the reaction there? Maybe? Did you post some photos of your modular stuff? I missed them Phil, post'em again! I'm curious to see how our respective pieces compare  . I assume you're talking about the 15mm pieces you created for a client? I've been casting like crazy and I'm resisting the urge to start putting together a 15mm 1200x600mm trench terrain piece |
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Post by PitYak Studios on Aug 23, 2005 9:12:45 GMT 12
No this was something I did months ago; three corrugated iron / wood barricades, small medium and large, where the small can act as a 90 deg corner piece.
I think I posted pics of the first casts to come out the molds, then completely forgot about them.
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Post by PitYak Studios on Aug 24, 2005 12:08:39 GMT 12
There you go;  |
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Post by c0d3monk33 on Sept 7, 2005 13:59:34 GMT 12
Hey Dustan man! What happened to this project? Any progress on the masters? Molded/cast anything yet or too busy painting Orcs? Just curious |
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Post by PitYak Studios on Sept 7, 2005 15:06:50 GMT 12
.... and painted  |
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Post by dustand on Sept 7, 2005 16:33:15 GMT 12
There has been a lot of conceptualising,
A few changes are that instead of having recesses into which you place a detail plug, the walls will be in 3 sections. Top middle and bottom, Top and bottom will be relatively standard and almost if not identicle, I will create several middle sections, Plain wall, Pipes (4 types) Wire bundles (2 types) andone that will alow me to make custom details which will esentially be textured Corners.
I have gathered enough materials to build my masters, but as of yet Istill got no spare cash for RTV, once I plan to buy some (maybe in a fortnight) I will start building the masters, though I guess that if I build them it will come)
Once it comes time to make the molds do you think you could lend your skills to the project and help us pour them. I hate doing things the first time, I am to paranoid to believe that following the instructions to the letter will work. They always do work but that doesnt stop the paranoia =]
another consideration that i am trying to work into this project is flexability, I would love to be able to cast them up and use it to build 40k and necromunda structures.
I got a lot to finalise before I start building and more concept sketches to draw =\
I have been a little busy to physically do anything but I got to think about something while I am painting and this is usually it.
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Post by c0d3monk33 on Sept 7, 2005 20:13:18 GMT 12
Dustan, imho it's definitely worth taking a LOT of time planning stuff and thinking about what you need before you create the masters. It's also worth taking a LOT of time to create the masters until they're absolutely perfect before trying to mold them.
Regarding molding it's worth keeping in mind the one-sided mold will effectively be upside down when you cast it. By this I mean you create your master based on a flat surface which will become the open face of the mold that you're pouring plaster or resin into.
You also want to watch out for undercuts as Phil has mentioned they trap bubbles and are generally problematic in both mold making AND casting. This could be tricky if you're considering having a lot of pipes/ducting. If so it might be worth sinking the pipes into the wall so they're effectively half-circles in the cross section rather than a pipe (with the related undercuts). Or even better simply leave space for the pipes and add them afterwards to the cast wall pieces rather than trying to get them into the mold itself.
Other tips are to try and make sure the master is well sealed around the edges of base as RTV will tend to run under any gaps. This isn't a biggie but means it can be difficult to peel the mold off afterwards.
I'd love to help that's not a problem. It might be worth creating some smaller pieces to mold first just to get the hang of it ... stuff you can re-use in the larger pieces maybe like control panels, displays etc. Nothing more soul destroying than pouring a large mold only to have the RTV not set properly afterwards (it's only happened to me once thank god. RTV blue catalyst was getting a bit old I think).
The Ultrasil RTV from TopMark is very forgiving in mixing, and you'll get a decent mold you can cast maybe 50-60 times in plaster before any wear starts to effect it badly. Divide that number by two if you're planning to use resin in my experience. Phil may have an opinion about Ultrasil mold life with resin since he does a lot more resin work than myself.
I'm thinking of trying TopMark's 'Wacker' Red RTV product next myself if I can generate enough funds. It's twice as hard as Ultrasil once set so should create longer lasting molds. TopMark only sell it in 1.1kg kits though alas...for around $110.
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Post by PitYak Studios on Sept 8, 2005 8:25:02 GMT 12
watch the hardness thing, it's not that straightforward; sometimes harder also means less flexible, so if your mold really needs to be flexible you might be better off with the softer rubber. You could end up with a mold wich is made from more durable rubber, but that you have to put under greater stress when demolding.
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Post by c0d3monk33 on Sept 8, 2005 9:21:49 GMT 12
Quite true and I had considered that. Those trench pieces are fairly liner though and pretty easy to de-mold without major flexing.
I'm definitely considering the Wacker Red but next time I'm at TopMark I might just ask them it they have a sample mold on hand. That's one of the real advantages to visiting their warehouse...they have cast samples for all the resins and plasters they sell so you can get a 'hands on' feel for the set materials. I don't recall seeing any molds but surely they have some.
I'll see how the Ultrasil molds go for my trench pieces as I'm up to around 20 casts for each mold with no major issues yet.
Anything I discover about their other RTV products I'll post here.
Have you tried the Wacker Red product? Or just used Ultrasil from TopMark? I know you mentioned a 50:1 RTV in the past...was than another TopMark product or not?
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Post by PitYak Studios on Sept 8, 2005 16:45:21 GMT 12
That one wasn't a topmark, i forget who it is but I think it's the same company who do all the fibreglass resins you find in places like mitre 10. I've not tried anything else from topmark, but I will be trying their high temperture rubber if i can find any information on it. (i did try asking them for it, but, you know...)
to be honest I don't have much of an issue with ultrasil, it does it's job and isn't so difficult to use. Could be a bit thinner if anything, to make mixing and pouring easier. and a hell of a lot cheaper, obviously.
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Post by c0d3monk33 on Sept 8, 2005 22:06:36 GMT 12
Yes Ultrasil is all I've used to date and it's certainly a fine product. If you like I can hit TopMark up for some MDS sheets next time I'm around there for specific products. I'll be asking about the Wacker Red. High temp silicone? You're getting into metal casting? Makes sense for your figure work I guess...although you could cast those guys in resin too I suppose. Pouring molten metal around kinda scares me. I'm happy with mildly alkaline plaster and toxic polyurethane resin thanks  . |
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Post by PitYak Studios on Sept 9, 2005 8:10:36 GMT 12
Like I said before, nothing beats pouring molten lead!
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Post by dustand on Sept 9, 2005 12:13:39 GMT 12
I havent poured molten metal since I was just a wee lad making fishing sinkers and plaster molds of things ;D
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. I assume you're talking about the 15mm pieces you created for a client?
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