Making silicon mold / casts of Sega SC-3000 Cart Case

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Making silicon mold / casts of Sega SC-3000 Cart Case

Postby honestbob on Fri Aug 10, 2012 10:42 am

Hi All

Just thought everyone might be interested in this little side project. Earlier this year I released a multicart for the Sega SC-3000. And recently I've been been working with a couple of people on releasing some new titles for the Sega SC-3000 / SG-1000 (hopefully we'll have something ready later this year - can't say too much about that yet, sorry).

So in the meantime I've been looking at ways to get new cartridge cases for the games as it is a pain having to cannibalize an old games cart to house the new PCBs.

Injection molding costs around $2500 USD to get a mold made, then about $4000 USD for a run of 2000 cases. That ain't gonna happen :)

The cheapest option is probably to find a sympathetic trader in Japan to ship out a pile of cheap games that noone wants and cannibalize the cases. But that's no fun. And it still might work out to $10 or so per case.

3D printing is a *very* cool technology. You can do amazing things with it and there are now home 3D printers available for $500 to $1000 USD. But unfortunately commercial 3D printing is too expensive (approximate cost per case $65USD to $100 USD). The home 3D printers are cheap to run (approximately $5USD in plastic materials per case), but they are slow in high detail mode and the quality and consistency are a bit hit and miss.

Check out the http://www.solidoodle.com Solidoodle 2 and the http://makibox.com Makibox to see how open source designs and crowd funding are being used by small entrepreneurs to bring affordable 3D Printing to the masses. I know there are lots of RepRap projects around, but these are two cool examples of trying to make 3D printing much cheaper and easier. And if you need a 3D model prototyped in NZ, give Protobuild http://www.protobuild.co.nz a try. They were very helpful with my silly questions about whether 3D printing would work for this project or not.

So, I decided to give moldmaking a go. I went over to Topmark Products http://topmark.co.nz in Ellerslie last week and picked up a pile of stuff. They provide a lot of product to the film industry including the Hobbit and Spartacus. But they are also used to helping out hobbyists and artists and sculptors, so they cater to a wide range of people. They were very helpful and gave me some good suggestions - many thanks to Gabrielle and Alastair for their assistance.

I'm making good progress. It isn't difficult as such, but it does require practice. And it definitely pays off to think carefully about your mold design before you start as the Pinkysil silicon is relatively expensive. The total cost isn't too bad, although I've spent about $250 on getting set up (cost per casting will be approx $4-$6 of resin).

I started off with a test mold of a small thin walled pot to practice how to make a squash or plug mold and make my mistakes on a smaller scale. Plug molds are good for casting thin walled objects like the cart case. The mold was fairly easy to make. I only had a couple of stuff ups there like leaving out the air vents (I had to cut those in later with a scalpel). It took me half a dozen goes before I made a decent cast though. But it was well worthwhile.

As of now, I'm halfway through my making the real mold of the top half of the cart case. My impressions at this stage are that resin casting is a hard way to make any volume of these things. But I'll hold my final opinion until I've finished the first real mold and made a few casts. The EasyCast resin I'm currently using sets in about 30 mins and it tints up quite nicely. I'm not sure if it will be rigid enough though until I've made my first real casting.

I'm making YouTube vids as I go in case anyone else is keen to try this in future.

Part I - Overview, the tools I'll be using, the test mold and test casts, and the setup for the first real mold
http://www.youtube.com/watch?v=TJD4ZeVzn3s

Part II - Mixing the Pinkysil and pouring the mold
http://www.youtube.com/watch?v=Q_jy6Rr9jHU

Part III - first half of mold has set
http://www.youtube.com/watch?v=MgSXVr9K0us

Part IV - first half of mold greased up with vaseline and the box mold reformed ready for pouring second half of mold
http://www.youtube.com/watch?v=_ad_pwYg2dQ


Cheers
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Re: Making silicon mold / casts of Sega SC-3000 Cart Case

Postby tezza on Fri Aug 10, 2012 1:07 pm

I have never used a Sega SC-3000 or have much interest in them, but I have to say what you are doing here is very cool.
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Re: Making silicon mold / casts of Sega SC-3000 Cart Case

Postby honestbob on Sat Aug 11, 2012 9:34 pm

Thanks Tezza :) I'm glad you like the projects. Each to their own with choice of vintage computers. The Sega SC-3000 is special to me since that was my first computer. I'm the same in reverse - I'm always interested to see what neat vintage projects people have going on even if the choice of computer itself doesn't do much for me.

I completed the mold and cast my first cart case top half this morning. It came out very well. I will need a few more practice attempts and minor tweaks to the mold before I get the casting spot on, but the good news is that EasyCast seems to be an excellent choice. I was worried it might not be rigid enough for a cart case. But it feels good in the hand now that I've actually made one.

I'm looking forward to doing the next cast and using the tinting pigment again for a nice black case. But I need to ask my children where my long thin pointed tweezers have gone. I think one of them may have taken a shine to the tweezers this morning as I couldn't find them tonight :)

The test runs I did making a mold and casts of a little metal pot were invaluable as I should be able to use this mold with a couple of tweaks instead of throwing it away. And considering there is about $85 NZD of Pinkysil in this mold, I don't want to waste it if I don't have to.

Lots more YouTube vids below documenting the main parts of the process. Jump straight to #11 if you want to see the finished piece with the flashing trimmed off sitting on top of a real bottom half of an original SC-3000 cart case.

Cheers

Part 5 - the sprue hole setup using nails, kebab sticks, and klassic klay
http://www.youtube.com/watch?v=8FYTPsQZzUg

Part 6 - the second half of mold has been poured and set. Remove nails and start to unbox mold
http://www.youtube.com/watch?v=E3V_4j-ur_I

Part 7 - seperating the mold halves. The moment of truth. Worst case is silicon has slipped into ungreased parts of the bottom half of mold thereby sticking them together. But it seperates easily. Phew.
http://www.youtube.com/watch?v=BNsirfyjpxY

Part 8 - Mixing and pouring the first cast. Coat the top half of plug lightly and fill the bottom half of plug about 1/3 full and gently sit the top half of plug mold into the bottom half.
http://www.youtube.com/watch?v=R3kTH9LhCh0

Part 9 - First cast has set. Open the mold and see how it looks. It looks good. You can see the flashing and the air holes in the expected locations. I need to cut the last little bit of the sprue holes through with a scalpel. But I'll do that on the second pass. I wanted to see how bad the air holes were without any extra venting.
http://www.youtube.com/watch?v=GImouQzyNVw

Part 10 - First cast removed from mold. You get a good look at the flashing and the detail on the other side. Looks good.
http://www.youtube.com/watch?v=jPhpZcyaTVk

Part 11 - finished piece with the flashing trimmed off sitting on top of a real bottom half of an original SC-3000 cart case.
http://www.youtube.com/watch?v=v7v9_U0u-_4
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Re: Making silicon mold / casts of Sega SC-3000 Cart Case

Postby honestbob on Fri Dec 07, 2012 9:58 pm

Hi All

Just an update for you on the Sega SC-3000 Cartridge Case project. To cut a long story short I can now make some very nice Sega SC-3000 Cartridge Cases in blue or black complete with a nice 3D printed SC-3000 Survivors logo on the rear of the cases.

You can read the full story at http://sc3000-multicart.com/sc3000-cart-case.htm

Image

Rear of case showing 3D Printed SC-3000 Survivors logo.

Image
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Re: Making silicon mold / casts of Sega SC-3000 Cart Case

Postby Gibsaw on Sat Dec 08, 2012 9:47 am

That's really well done. Excellent work.
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Re: Making silicon mold / casts of Sega SC-3000 Cart Case

Postby Carcenomy on Mon Dec 10, 2012 7:29 pm

Sheeeeeeeeeeeit! Those look awesome, nice work!
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