Six months ago I posted
about fixing up and finishing some Gigaminx parts that were printed with a messed up 3D printer. I have finally used them to build a puzzle, and thought I would share some new ideas I tried.
I started from a single set of masters, and damaged ones at that. With a lot of work, I fixed them up, but I still only had one of each piece.
On a Gigaminx you need 60 copies each of three parts of the smaller, 30 edges 20 corners and 12 centers. Far to many to cast one at a time. Most people print multiple of the smaller parts and make molds containing many. A good setup is:
Four copies of the small parts (15 casts), two of the edges/corners (15 and 10 casts required) and one of the centers. So 15 casts later you should have a Gigaminx.
Starting from a single piece each, I didn't want a ton of wasted silicone rubber and a bunch of mold halves to flip over and confuse, so I decided to try pouring a single mold from the same piece, but multiple times.
I started by making three molds: The three small pieces in a row, the edge and corner together, and the center alone.
Next I wanted to make molds of the small pieces and centers next to and attached to the one I just poured. Here is how I did it:
1.) Take the bottom half of the mold and build a low box twice its size, so you have room right next to it.
2.) Spray your mold release at this point, you won't be able to later.
3.) Pile up a bunch of stuff to hold the mold top at a level where the edges just touch, but it won't let silicone drip through. I used cut up old business cards and Elemental Fluorine pieces
4.) Build the box up higher and pour a second top half of the mold, right next to the first. Since you don't have mold release on the second half, the new rubber will bond to it.
5.) Wait for it to cure, and you have a solid double top
6.) Flip over. You now have a solid double base, and a single top. Remove the top (and the pieces) and spray mold release again.
7.) Replace the pieces (careful not to touch the rubber sprayed with mold release) and pour again to make the second half of the top.
8.) Now you have a single block mold of twice the masters you actually have.
For the three-small-piece mold I took slightly different steps as I didn't want to end up with a double mold and no easy way to make a third and fourth. So after pouring the double top, I poured a single top again, and used that as the basis for another doubled mold.
In the end, I had exactly the molds I wanted but only did the clay work once on a single set of masters:
What to do now? If only I had... this...:
Next it was time to cast:
The pieces came out pretty well:
One note: When you make your alignment pegs, make them asymmetric so it is really obvious when you have them backwards. I didn't, and a few times I mashed down on the mold and thought I had waited too long on the first half. It happens instead I had the mold top backwards, so I was mashing together a mis-fit. The parts came out half center edge, half center corner. Frankenpiece!:
With *many* hours of cleanup the puzzle started to come together. This is what I had when I went to my first day of IPP:
You can see that as much time as I spent on the masters, I could have spent more. Next time...
By California Cube Evening I was about 2/3 done.
Random picture: My messy, messy desk:
I finished a day later, and it looked nice:
One and a half hours of stickering later it looked better, but you can see those in the New Puzzles thread here
In the end the puzzle moves OK, but I didn't round the edges nearly enough, so it catches far too much. Fixable, but it would take a lot of work. My instinct is to round the masters and pour molds again, and cast again, but that is a lot of work. Maybe later.
Moral of the story?
1.) With a bit of time you can build multi-piece molds from single masters. This may make PolyJet a reasonable option where with multiple masters it may have been too expensive. It also means you can spend that much more time on the single master getting it perfect as you don't have to replicate the finishing so many times.
2.) Only clay once. Use half of your mold repeatedly as the new clay base to pour other second halves. If half of your mold tears, don't start from scratch, just pour another second half.
3.) Yes, I could have just junked those pieces and paid a bit more for multiple copies of masters. But I was in a unique situation, with a set of pieces that fell into my hands. I wanted to do what I could with them.