LSP_Kevin Posted June 20, 2012 Author Share Posted June 20, 2012 Did you try and use a dusting of talc? Might help the resin get into the tiny thin areas. Just make sure if you do that you blow off almost all of the talc. All it needs is the faintest of coatings( you almost can't see it.) How thin is the resin you are pouring? It should be quite thin. Sometimes with the cold weather it can get a bit stiff and that won't help you at all. I didn't try the talc, as wasn't sure exactly how to go about it (brush it on? pour and blow?), and I didn't want to introduce too many new variables at once. But I'll give it a go on the next round. The kitchen spray that I'm resorting to for the moment as a mould release (for the second pour of the RTV) tends to bead up on the rubber, leaving lumps and impressions that the resin - of course! - captures nicely. So there are a few flaws in the mould, but nothing I can't clean of the resin after the fact. I don't plan to make any new moulds until I can obtain some Vaseline. As for the thickness of the resin, when first mixed it's pretty much like milk, but thickens rapidly while I'm pouring. Because my pour hole is too small, this takes longer than it should, so by the time I've finished pouring (and prodding, and poking, and squeezing), it's getting on more for runny honey. This obviously doesn't help! Let's see how I go in Round 4... Kev Link to comment Share on other sites More sharing options...
radial Posted June 20, 2012 Share Posted June 20, 2012 I to am a novice to resin casting and am enjoying this discussion. I would avoid using talc as my experience was it created voids in the final cast. After many tries with talc I gave up. What worked much better was 91% iso alcohol both to prep the mold and release the part. Have you sprayed your reject parts with primer? May be a bummer because what I thought were perfect parts showed 100s of tiny pinholes that effectively ruined the parts. Btw the alcohol must be completely dry. All moisture of any kind creates voids. Link to comment Share on other sites More sharing options...
LSP_Kevin Posted June 20, 2012 Author Share Posted June 20, 2012 Well folks, Round 4 was interesting. I thought I had it nailed, as I could see resin coming up through both air vents by the time I finished pouring. But upon demoulding, I get this: It looks like the resin has flowed around the air bubble, instead of pushing it out. There's an ultra-thin skin of resin on both sides. As you can see, plenty made it up the air vent itself, so I don't really understand how this has happened. I forgot to try Dan's talc tip, so I'll do that next time, as he's given me the lowdown on how to apply it to the mould. I'd love to hear your collective thoughts on why I ended up with this trapped air pocket. I think I probably need to regroup, process what I've learned and start another new mould using that info. This one's way too leaky anyway! Kev Link to comment Share on other sites More sharing options...
KOTR Posted June 20, 2012 Share Posted June 20, 2012 A little bit of motion might help to get rid of the bubbles. I used to drop the filled mould a couple of times from 1 - 2 cm height to shake such bubbles of. I might add that I usually have the molds in some kind of frame to avoid undesired splitting of the mould halves. Don't ask me how I know... Another dude in here used for the same purpose an oscillating sander, IIRC Link to comment Share on other sites More sharing options...
LSP_Kevin Posted June 20, 2012 Author Share Posted June 20, 2012 Thanks Michael. I did give the mould a series of light squeezes to try to force the resin along the mould, and I thought it had worked pretty well until I demoulded. I suspect the solution requires a re-engineered mould to better accommodate the pouring process. I'll give it one more go using this current mould, using Dan's talc method to see if it improves the flow, but if that fails it's back to the drawing board. Kev Link to comment Share on other sites More sharing options...
LSP_Matt Posted June 23, 2012 Share Posted June 23, 2012 Hey buddy. Not an expert here so just spitballing. Assuming you have working time maybe wiping some uncured resin on either side of the mould halves before you oppose them. Perhaps gently tapping the base of the mould on a bench to encourage air bubbles up and out? I also wonder if you squeeze are you perhaps creating a pumping effect that sucks air in as the mould relaxes? Admire the perseverance. Cheers Matty Link to comment Share on other sites More sharing options...
LSP_Kevin Posted November 26, 2012 Author Share Posted November 26, 2012 Just wanting to bump this one back to the surface, as I'm planning to return to it soon. As it happens, this build/thread has now entered its fourth year! It's really about time I finished it I think... I want to publicly thank Damian (D.B. Andrus) for coming to my rescue with the undercarriage doors; he took pity on me and cast 2 sets of perfect copies of the new-tool parts for me. Many thanks Damian! I'll still have a crack at casting my own parts again at some stage, but will have to wait until the need arises. I'm still waiting on a set of masks from Ian at Ad Astra, who is in turn waiting on the ALPS-printed white decals. I still have plenty of time up my sleeves, so I'm not panicking yet. Kev Link to comment Share on other sites More sharing options...
mywifehatesmodels Posted November 26, 2012 Share Posted November 26, 2012 Good to hear, Kevin! Four years, huh? I won't say anything if you won't! Link to comment Share on other sites More sharing options...
LSP_Kevin Posted November 27, 2012 Author Share Posted November 27, 2012 Good to hear, Kevin! Four years, huh? I won't say anything if you won't! Yeah, don't remind me! This thing had its third birthday on 2 November, and that's just embarrassing for a build that I haven't ever officially given up on! Anyway, I'm hoping to make some progress as soon as my Spitfire crosses the line. Here's a photo of the terrific gear doors that Damian sent me: Now I realise that they're just straight copies of the kit parts, but having tried to do 'just' that myself, I know just how tricky it can be, and I now have an even higher level of respect for quality casting than I did before, no matter what the source. You casting dudes rock! Kev Derek B 1 Link to comment Share on other sites More sharing options...
Daywalker Posted November 28, 2012 Share Posted November 28, 2012 Four years? I thought I was slow! I hope to see more of this one soon Kev, it is an excellent project. Link to comment Share on other sites More sharing options...
LSP_Paul Posted November 28, 2012 Share Posted November 28, 2012 Kev, Some day your FW and my F4U will actually be DONE and then we can start another pair of multi year year projects each! I'm still watching and waiting along with ya man! Git er done! All the best, Paul Link to comment Share on other sites More sharing options...
LSP_Kevin Posted November 28, 2012 Author Share Posted November 28, 2012 Thanks for looking in fellas. I think what I've learned from doing the D-11conversion and the Matchbox Spitfire will stand me in good stead for the rest of this one. Kev, Some day your FW and my F4U will actually be DONE and then we can start another pair of multi year year projects each! Well, the irony in that statement for me Paul is that it's highly likely my next multi-year project will be a Corsair! Kev Link to comment Share on other sites More sharing options...
LSP_Kevin Posted November 7, 2013 Author Share Posted November 7, 2013 Just thought I'd bump this one back to the top for nostalgia's sake, as it's now officially into its 5th year. Yikes! Ironic that I left this one struggling to cast some parts in resin - something I'm still doing with my current model! Anyway, I'd really love to get back to this one, but I really need to make a decent start on my Trumpeter Birdcage Corsair conversion first. Bump over! Kev Link to comment Share on other sites More sharing options...
Out2gtcha Posted November 7, 2013 Share Posted November 7, 2013 Yikes! This ones a blast from the past. Hope to see it out front soon............maybe after the birdcage the hard way Link to comment Share on other sites More sharing options...
Heavens Eagle Posted July 15, 2014 Share Posted July 15, 2014 LOL! I have been seeing Kev making hints on this on some of his other threads. Interesting section on the resin molding of parts. Have been doing a bit of that myself in recent months. As you have some good gear doors now it isn't an issue. What I would have done would have been to mount a number of small gates around 3/4 of the part, then pour a full mold around that with flat sides. Legos on the sides works quite well. Once the mold is fully set I would carve along the gates with a very sharp new blade such that it makes a sawtooth pattern. Only do this where the gates are so that you can split the sides back but they stay attached along one area. The point is that rather than pouring the resin in with a thin sided part, you split the mold open, coat the sides with a thick layer of resin, chase little bubles from crevases quick, then slowly close the mold up chasing bubbles and excess resin as you go. The excess will tend to flow through the gates you added and with the mold fully coated no major air bubbles should stay. Once closed, with flat supports on the flat sides add a little pressure and wiggle to seat everything and drive extra resin from the cut areas of the mold. Then release pressure a little and let it set up. Too much pressure will collapse the sides of the mold in the middle of the part. You only want enough pressure to make the sides engage fully. Link to comment Share on other sites More sharing options...
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