munter Posted July 23, 2012 Report Share Posted July 23, 2012 I've been casting some small bits lately....failure rate is quite high but I'm still pleased. Quote John Warren Slotcars are my preferred reality Link to comment Share on other sites More sharing options...
Mobbzee Posted July 23, 2012 Report Share Posted July 23, 2012 looking pretty good munter i'm sure the failure rate will drop the more you do Quote http://www.auslot.com/forums/index.php?/topic/12014-mt-panorama-track/ ...My Track Link to comment Share on other sites More sharing options...
manimmal Posted July 23, 2012 Report Share Posted July 23, 2012 Awesome space robot 2nd from the right on the top row On a serious note, that's got to save some searching and some coin, was it difficult and smelly? Quote My mum says I'm an excellent driver Link to comment Share on other sites More sharing options...
Stubbo Posted July 23, 2012 Report Share Posted July 23, 2012 Are you using a pressure pot or chamber? They look nice and crisp. Quote Alan Stubbings Link to comment Share on other sites More sharing options...
munter Posted July 23, 2012 Author Report Share Posted July 23, 2012 Still learning a few basic rules....no pressure pot. Quote John Warren Slotcars are my preferred reality Link to comment Share on other sites More sharing options...
dangermouse Posted July 23, 2012 Report Share Posted July 23, 2012 (edited) Me to John, maybe we should share some tips and castings. I am impressed by your wire wheels. Aside from silicone moulds I have played around with some small castings using plasticene for a mould. I want to try some of this next to make some impression moulds http://www.barnes.co...0pk-p-3003.html video here http://www.youtube.com/watch?v=PsJZQdciTWk&feature=player_embedded#! Here are some of my projects cheers David Edited July 23, 2012 by dangermouse Quote Link to comment Share on other sites More sharing options...
Ember Posted July 23, 2012 Report Share Posted July 23, 2012 John, I'm very much looking forward to the time when you feel confident enough to cast that Revellogram (?) 300SL of yours. I was really surprised at the detail picked up in those Scaley 300SLR shells. I was dumbstruck to see the impression of the 722 tampo. Just seems a matter of getting the bubbles out. But that's bound to be over simplifying things. Embs Quote Computers. They'll never catch on. Tiny Tyers Targa - The build saga continues - Aging wood - A recipe for staining wood - Don't take a fence - Step by step paling fence - An old shed for my new cars - Wooden garage under construction Link to comment Share on other sites More sharing options...
kalbfellp Posted July 23, 2012 Report Share Posted July 23, 2012 John try using a syringe to fill the moulds, one about 10cc should be big enough, just put it in some water after and you can use it again. This should reduce the failure as you have no pressure pot. Quote Phil https://www.hobartminiaturecarclub.com/ Email Link to comment Share on other sites More sharing options...
munter Posted July 23, 2012 Author Report Share Posted July 23, 2012 Thanks for the tip Phil. I will definitely try that. mmm getting the bubbles out can be done by standing on my head and if I hold my tongue in a certain position then..... I think I have that nailed as well but as I said some basic lessons have to be learned first. As Van Gogh or some one said a while back.." I am always doing what I cannot do yet in order to learn how to do it." Quote John Warren Slotcars are my preferred reality Link to comment Share on other sites More sharing options...
dangermouse Posted July 23, 2012 Report Share Posted July 23, 2012 Pressure pots hmm I need to learn some more about them, any info or links to share Phil cheers David Quote Link to comment Share on other sites More sharing options...
grt Posted July 24, 2012 Report Share Posted July 24, 2012 Hi John, I use Barnes 5ml syringes for the small casts, they are plenty big enough. I find the biggest trick tio getting bubble free casts is to get your bleed holes in the right place. I use a small hole punch, and position them at the highest point(s) of the mould, or in corners where air can get trapped. It does mean you have excess resin strings to cut off, but the trick to that is to mould the part upside down, so all the excess resin from bleed holes and the like is on the "back" of the cast. And, of course, even if you still end up with bubbles (as you invariably do every now and then, no matter how good your moulds and injection skills are, you can always fill the bubbles in with excess resin when you cast your next batch up.You just need to open up the bubble (on a hidden side if you can), and drip the resin in slowly to fill in the hole. Its fun though isn't it? Creating your own parts, restoring old wrecks to their former glory, spending time in the "man-cave". (We need a "Tim the Toolman" smiley here - ugh, ugh,. ugh) Quote Graeme ~~~~~~ (Life is like a sewer....................What you get out of it depends on what you put into it!) https://gtoutweb.com/index.htm Link to comment Share on other sites More sharing options...
grt Posted July 24, 2012 Report Share Posted July 24, 2012 John, One other thing I just remembered. Barnes sell a product thats perfect for maikng permanent impression moulds. I've used clay and plasticene before for making temporary one off moulds, but you destroy the mould when you pull the cast out, and invariably, I have found I nearly always need to make another one. I think its called Sil-Pression? I'll dig out the stuff later this week and get the correct name. Quote Graeme ~~~~~~ (Life is like a sewer....................What you get out of it depends on what you put into it!) https://gtoutweb.com/index.htm Link to comment Share on other sites More sharing options...
Garry J Posted July 24, 2012 Report Share Posted July 24, 2012 (edited) For anything that has a flat side (wheel inserts, etc) I use an open, one piece mould and pour the resin from one side until the mould is full. I use a toothpick to pick out any air bubbles, if needed, and get very few failures. For anything requiring a 2 piece mould I use pieces of plasticene to form filler and evacuation tubes. Complicated items can require several evacuation tubes to eliminate air pockets. I have a vacuum pump and made a small chamber with some 150mm PVC pipe and a couple of flanges with 12mm polycarbonate end plates and rubber seals. I only use the vacuum to make the moulds, it's amazing how much air is in what appears to be bubble free liquid silicon. Edited July 24, 2012 by Garry J Quote Cheers, Garry J Old age and treachery will overcome youth and skill Link to comment Share on other sites More sharing options...
Ember Posted July 24, 2012 Report Share Posted July 24, 2012 So it's vacuum to remove bubbles from the silicon for moulding? And positive pressure to remove bubbles from the resin casting? Would be interested to try one day. Only casting I've done has been in glass, bronze or silver. But there's just way too many things on the 'want to try' list. Quote Computers. They'll never catch on. Tiny Tyers Targa - The build saga continues - Aging wood - A recipe for staining wood - Don't take a fence - Step by step paling fence - An old shed for my new cars - Wooden garage under construction Link to comment Share on other sites More sharing options...
FLY in the wall Posted July 24, 2012 Report Share Posted July 24, 2012 BTW. I am sure you all know but just in case that an old fridge compressor will pull a vacuum. They are cheap if you can find one. As casting is not a continuous service application they will work fine. Quote Outside the box looking in. ------------------------------------ You don't own stuff: Stuff owns you! ------------------------------------ Having a cold drink on hot day with a few friends is nice, but having a hot friend on a cold night after a few drinks - PRICELESS. Link to comment Share on other sites More sharing options...
Garry J Posted July 24, 2012 Report Share Posted July 24, 2012 Plenty of examples of home made vacuum pump setups on the net. Here are a couple - http://www.dream-models.com/eco/vacuumpump.html http://www.seabreeze.com.au/Articles/Windsurfing/How-to-build-your-own-vacuum-pump-for-under-50_1293413.aspx Quote Cheers, Garry J Old age and treachery will overcome youth and skill Link to comment Share on other sites More sharing options...
munter Posted July 24, 2012 Author Report Share Posted July 24, 2012 (edited) It is fun grt....no air bubbles in this....I expect the trimmed weight to be about 22 or 23 grams..... interior tray to come. There are a few bogeys here and there but nothing an average modeller couldn't deal to. Edited July 24, 2012 by munter Quote John Warren Slotcars are my preferred reality Link to comment Share on other sites More sharing options...
Ember Posted July 24, 2012 Report Share Posted July 24, 2012 Now that's looking good! Who is a smarty pants then? Quote Computers. They'll never catch on. Tiny Tyers Targa - The build saga continues - Aging wood - A recipe for staining wood - Don't take a fence - Step by step paling fence - An old shed for my new cars - Wooden garage under construction Link to comment Share on other sites More sharing options...
Rob Posted July 24, 2012 Report Share Posted July 24, 2012 The other thing that can influence how the resin flows is the actual viscosity it self, you could try heating it prior to mixing to help flow. We use to run our resins at approximately 40 deg c which allowed for prep, mix and pour time. One side note heating the resin will reduce the pot life of the resin. Quote Regards Rob Link to comment Share on other sites More sharing options...
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