Where to Put the Mold Split? Smush Molds

Where to put the mold split?  That might seem like a weird question...but we are not doing injection molding so it becomes a very pertinent question. 

You actually have to answer a few other questions.  First you need to determine the orientation. Orientation may also determine what type of mold you want to use.  Today we're going to talk SMUSH molds.  We'll talk about Sprue molds later. 

These are all just my opinions based on my results.  You may not need to do some of the things I do based on what you are casting.

One of the benefits of silicone molds is we can put the mold split where ever we want.  Im lazy.  And I want to do as little sanding as possible.  So when I make a SMUSH mold, I like to "Bury" the master so that 1/2 of the mold is more of a lid.  This then puts the mold split on a corner.  So then if there is any sanding its very little and wont affect the detail.

I also don't like to put a mold split on a peg, or a hole or where a size is critical or concentricity needs to be maintained.  I avoid putting mold splits in those areas.

Here's an example of this.  The Sultan mold for the head. 

 Notice how one half of the mold the one on the left is more of a lid.  The other half (on the right) is more of a cup.  Also the head peg is fully contained.  So any sanding is all along the edges of the cast, the peg is fully concentric and true to the master and we can bend the silicone enough to remove the cast without damaging the mold. 

You need to be sure this peg hole gets resin in it and I like to use a pin to smear it around and make sure the sides are at least coated.  Im being picky, but there is a science behind this.  Things like cohesion and adhesion are simple science concepts but they can wreak havoc on your casts.

Here's another example using the Jade head.  It still needs to be washed before I pour the silicone.  I threw it quickly together for this post.

Notice the mold split is in areas easily sanded with the least effect on detail as well as the fact the peg is completed buried in the clay.  Whatever is clay will be replaced by silicone when we make the second half of the mold. 

 

The next thing is you want hard lines and corners.  You don't want to press the master into the clay.  You want the master to be held tightly in the silicone.  If the clay holds the master too tightly you risk pulling the master out of the silicone before you get a chance to make the second half of the mold.  This can sometimes cause problems.  If the master doesn't seat properly you will get an air pocket and a deformed/thicker cast than you want.

 

This next bed took me a few hours to make. 

 Remember years ago I said my pocket knife was my favorite tool?  Well I use my pocketknife to cut hard clean lines around the master.  This makes for clean edges.  Less flashing and most importantly, less sanding.  I used the tip of the knife to pack clay around and into the corners to give me hard lines.  its easier to do now that try and manipulate cured silicone.  Remember...this is the most crucial part of the mold process.  What you do here determines how much or how little work you will be doing later on.  Here is not the place to take shortcuts.  Take your time.  Do a good job and you'll be rewarded and thankful later on.

 

 

Silicone Smush Molds

For garage kit casting I use silicone to make my molds.  This provides some flexibility that we need to make some items as we don't have the same luxury as steel molds with injection molding.

I use smush molds for small HIGH detail parts where a sprue system is impractical.  Another thing, Injection molds are a 50/50 split.  This can be problematic for garage kit casting.  Steel molds don't give.  They have no flashing.  If you have flashing on your cast...your mold gave.  That means your cast is now just a little bit thicker than it should be.  If you are casting 5mm pegs this is now a serious problem as your pin is now bigger than 5mm and most likely out of round.

Silicone provides ways of working around this.  Because silicone does have give...we can make molds using the flexibility of the silicone to help release cast parts.    We can bend the silicone mold to release parts.  Something not possible with steel injection molds.  Hence the 50/50 mold split in injection molding.

Silicone molds are great, fun and easy.  The hardest part, is determining just WHERE to make you mold split and what type of mold to make.

Shapeways Materials Tried

So far, I have tried these materials from Shapeways.  Here's my pov.

Frosted Detail...Nice detail, but the texture is inconsistent.  It varies from smooth to rough.  No consistency.  I wasn't fond of it, so I moved on.

Black Acrylic...segmented.  fuzzy.  Worst one yet for holding tolerances on simple shapes.  Don't like it at all.  Detail success rate depends on which side of the acrylic its one.  One side is worse than the other.

Stainless Steel...if you are dead certain your print is done to your specifications,  I rally like the Stainless Steel.  Finished it has the look of a metal cast product.  It looks porous but Im very happy with it.

Black Acrylite...pending...waiting on product ordered in this material.

Magno's Sold...

Well...I cant lie.  While I don't regret selling them, I cant help but feel a little melancholy.

Outside of a few GEAG's, a few red Falcons and a Awesome Silorg Warrior...Im one pending sale away from having sold  them all.  2 empty shelf cases.  I was so very proud of that collection.  Still am.  Im thankful I was able to find good respectable homes for their care.  A piece of me goes with each one.  Nothing lasts forever in this world.  I don't have any kids and they'll never name a street after me.  But I can pass these along.

Thanks to everyone who took part in my sale or plan to.  And my thanks to everyone who helped me build this awesome collection of Magno's in the first place.

If I had it all to do over again...I would.

Big Man Toys

I just want to give a shout out to my good friend over at Big Man Toys...Lee.

Lee has really taken his craft to new levels.  Self educated with 3D modelling and really pushing himself.  So much so I was more than happy to ask his help when Bry was overloaded with work.

I'm only a craftsman.  Lee is a true artist/sculptor.  And it shows in his modelling.  Lee modelled Jades/Ronins head and did an excellent job.  Im only sorry I wont be adding artwork to the figure so I can give him the credit he deserves.

Lots of VERY COOL goodies over at Bigman Toys, great prices and tons of very down to earth and practical advice.  You'll find the link to his site on the right hand side of this blog under "Homeworlds Hot List".

Well worth the visit.

Mounted Missile Pack

It looks a bit different without the ball adapters.  Looking at it now, I may have to redesign the Centaurus body (if possible) or these wont fit the Centaur form.  But I think they look not too bad.

 

Ready to order...$15.00 each...$7.50 S/H...Tracking +$5.00

Available in Black And White for Sultan and Flight Commander...
Black and Gold (gold is air brushed) for Overlord.

Mini Missile Pack "WITH" Pics

Bry modelled the holder and the nose cones.  I made the masters for the missile bodies.  Bry had modelled the bodies, but Shapeways had issues with it being so small.  We think the missile fins most likely.  As it is, it was just as well as I needed the missile body in 2 parts for easy casting.  More initial work, but less headaches down the road.

The result?

Its the proto.  The 1st one.  Its raw and not finished.  It needs a wash and some clear coat.  The missile cones are tinted red.  NOT painted.

Im liking this a lot!  But to anyone familiar with the Micronauts/Microman/Palisades and related magno figures, It looks a bit odd on the figure without the ball adapters on the end of the missile.  Its a good fit otherwise and sure spices up the figure.  I'll post a pic of it mounted to Sultan later tonight.

Mold: A Definition From A Casting Perspective

What is a mold? 
A mold is a hollow encasement that when filled produces a desired shape.
That's the easy question.

How do I make a mold? 
Believe it or not, there is no wrong answer to that question.  The answer depends on many variables.  You have to consider the part, where to put the mold break line, orientation, sprues if used, are you doing multiple pours, can part be easily removed from the mold, how many are you making and many other possibilities.

I have made a 4 piece mold.  As long as its tight fitting, make 6 or 7 piece molds if need be.  Don't be afraid to get creative.  There is no wrong way to make a mold.  If it works...you did it right regardless of how you did it.

However there are some methods for making basic molds that really an make life simple.

Its time we reviewed and updated Garage Kit Casting.