Adventures in Casting

[M-bot]

PART 7: IN WHICH I DOUBLE THE MOULDS AND TRIPLE THE SCREW UPS

With my first success with Pinkysil, I decided to try to make a 2 piece mould. I continued with Scoop's target master - this time the gun handle that sits between the robot legs and the dual gun barrel pieces. I used the same method as before, using the Plastimake to make a just-big-enough container to encapsulate the pieces. I used modelling clay (apparently you need one without sulphur - no idea why - any chemists out there that can shed light?) and half-embedded the pieces in the clay at a point where I wouldn't mind having a seam line in the finished piece. I added a small section of tube that will act as a vent to pour the resin into.




Then I mixed the Pinkysil and (like has been suggested by SMHFConvoy and Gamblor) I cut up bits of previously used Pinkysil to pad out the volume (and hopefully use less of the stuff in the process). Then poured it into the Plastimake basket.



For reasons surpassing understanding, I didn't take pics of the next bit. Probably for the best. When the Pinkysil hardened, I removed it, the pieces and the clay from the Plastimake. I then removed the clay from the piece and the Pinkysil and (keeping the piece still insitu in the Pinkysil), made a new container for that (turned over so the Pinkysil is on the bottom) and poured a new batch of Pinksil.

You can see where this is going, right?

Now, a smarter individual than me would have realised that if the leftover Pinkysil I used to pad out the volume in the mould sticks in the wet Pinkysil, then the 2 parts of this mould would indeed also stick together. But I am not a smart individual and so this was only clear to me in retrospect, when I had to cut it open to retrieve the pieces. I did try to use the weird-ass mould I had just created but it was not successful. No pics in order to spare me the indignity. There was swearing.

I called my mate who told me to use a mixture of Vaseline and hot water over the first part of the mould in a thin layer to prevent the two halves from sticking together. He apologised to me for neglecting to mention it when we last spoke. I told him about my Plastimake basket idea (cos I am a super genius or something) and he told me that people often use Lego. Well duh. Our friendship will endure this.







Poured the resin with the two halves of the mould together, firmly tapped at it to try and get rid of air bubbles (as much as possible anyway), and...


Huzzah! I am invincible!

I'll add another (final) post to this little manifesto soon, to tie up some loose ends. I am actively working on a project (remember the Kickback arms/abdomen from part 6?), so you'll see some more results there.

[Thurmus]

I am loving this series. Great work mate.

[gamblor916]

I'm also following on with great interest. Just make sure that you clean the vaseline off the parts thoroughly or else paint won't stick to it.
Also depending on the part sometimes you can get away with making a 1 pour mould and make slight cuts to the silicone to remove the part.

[UltraMarginal]

Loving the journey! Someone else on here did some moulding last year with the pinkysil. They too used a lego mould casing, there might be some further ideas in their thread. I recall it was mostly head moulds and there was issues with air bubbles.

I wish I had the time to dabble in this stuff.

[M-bot]

I am loving this series. Great work mate.

I'm also following on with great interest. Just make sure that you clean the vaseline off the parts thoroughly or else paint won't stick to it.
Also depending on the part sometimes you can get away with making a 1 pour mould and make slight cuts to the silicone to remove the part.

Loving the journey! Someone else on here did some moulding last year with the pinkysil. They too used a lego mould casing, there might be some further ideas in their thread. I recall it was mostly head moulds and there was issues with air bubbles.

I wish I had the time to dabble in this stuff.

Many thanks gents! I'm loving the journey too.

I must have missed the thread you are referring to UM. Air bubbles are an issue. I am going to post up some failed results in the next instalment where I didn't mix the resin well enough, which was a result of not wanting to aerate the mixture too much, in order to lower the chance of bubbles. Of course, like a fair chunk of this thread, the failure is spectacular!

[M-bot]

PART 8: IN WHICH I TIE UP A FEW LOOSE ENDS, HAVE ONE MORE SUCCESS AND ONE MORE FAILURE

I think this post will pretty much conclude this series. Happy to keep commenting, of course, and if anything dramatic happens down the track, I'll add a bit, but for now, my self-inflicted crash course in casting is coming to an end. From here on, I'm using the skills I'm learning to actually make working customs (of which the red Rumble gun is an example).

First up is an addition to the Plastimake (thermoplastic), even though I did discover that its applications are limited (I did use some to fix my clothes airer at home though - winning!). Even though I'm using an unofficial/no-name version of the Plastimake product, I went on the Plastimake website and ordered some colouring pellets. A 4 pack of yellow, red, blue and black set me back about $15 from memory.

It works by dropping a few pellets (which are about 1-2mm square each) per tablespoon or so of Plastimake pellets and mixing it through while it is soft. Even though the bags are pretty small, it will clearly go a very long way. I started mixing the straight colours and then tried mixing colours together. The results were pretty good, with the exception of the purple and brown, which just look ugly. You can lighten colours by adding extra regular (white) Plastimake to a pre-coloured piece of Plastimake.


This might come in handy if I want to make pegs and such of a particular colour that I don't want to paint lest I get paint wear.

Back to the failed 2 piece mould from the last instalment, the handle section of Scoops Targetmaster. As I had to pour resin into the two halves of the stuck together mould and then jam it together quickly, I was kind of expecting a mess, but it came out close to perfect.


There was a small flaw on the other side (not photographed), but easily fixed.

Another product at Barnes was a pigment for the resin. Like the Plastimake colour pellets, a very little goes a very long way, so even though the small jar was $10 or so, as long as it doesn't dry out, it will probably last me until the grave.

I used the same mould as the pic above, but just focusing on the handle/peg. Came out stellar, the details are translated perfectly.


Since abject failure has been a running theme of this thread (it's like watching Bathurst - barely anyone would be interested if it wasn't for the promise of the odd wreck during the race), I wanted to post up an example of an epic fail of a Pinkysil/Easycast resin attempt. It was meant to be the rear legs and alligator head from a TR Skullsmasher that I was doing as a mock up for another custom, that I will be creating a WIP thread for shortly.

Here's the Pinkysil moulds:


The problem (I think!) was that I failed to mix the resin adequately, or not an exact enough ratio of the 2 parts. The legs disintegrated into a sticky mess, The head came out mostly formed, but the end of the snout was soft and bendy and sticky to the tough. It never hardened. Not good for anything but scrap. Same goes for the moulds, as they still have some of the sticky stuff in them and I don't know how a new batch of resin will react to the material already stuck in the bottom of the mould, and I don't want to waste more resin trying to find out.


If you've been a follower of this thread and have made it through to the end, thanks for sticking around for the fun! I have to say, it's been a blast. If you have a thought to try it out yourself, I say go for it. If my attempts have shown anything at all, its that failure is OK, and that without it, you'll never get to the good stuff. The journey is worth it.

[CBratron]

I've never cast before but have you played around with vents in the mold to deal with voids and air bubbles? I imagine it'd be a pain to clean them out if you're reusing the mold but you'd have less work to do on the molded piece.