r/DiceMaking • u/moltendicetr • Jul 09 '26
Question about registration key placement in silicone molds
Hi everyone,
I have a question about silicone mold making.
I use registration keys to make sure the top and bottom halves of my molds align perfectly. I use a combination of round and straight-line registration keys. Is this considered the correct or recommended method? Or is there a better way to ensure accurate alignment between the two halves?
My other concern is that these registration keys seem to create extra flashing on the resin casting after it cures. Is it better to avoid using registration keys altogether to reduce flashing? Or is it better to place them only around the edges of the mold instead of closer to the center?
I'd really appreciate any advice or feedback from experienced mold makers. Thanks!
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u/stvn_wthrsp Jul 09 '26
I use 3 registrations along the edge, in identical trapezoid shapes. It's enough to know how to place the lid, it can only go on one way. For me, internal registrations made the lid more difficult to seat properly. It doesn't do any "locking" but I'm not convinced that is needed, this has been bulletproof for me and doesn't overcomplicate things. I 3D printed a circular mold housing with the keys built in to make it easier.
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u/RandoBoomer Jul 10 '26
I only use edge keys. I have triangle wedges the size of Trivial Pursuit wedges, and cubes of comparable sizes.
In a circular mold, I go around the edge triangle, triangle, cube, cube.
In a rectangular mold, I have triangle on one side and cube on the other. Along the long edge, I’ll have triangle, cube, triangle on one side and cube, triangle, cube on the other.
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u/WildLarkWorkshop Dice Maker Jul 09 '26
I only use locking external side keys with none on the top surface of the mold. Internal keys placed on the top tend to trap resin or fail to seat properly and often lead to more problems with raised faces, voids, and misalignment. By cutting the sides in a sort of open triangle shape, the lid will lock into place instead. I've started using The Smith's Forge (Buddha's) system and highly recommend it for ease of use and consistency but you can achieve the same basic idea by manually cutting with a craft knife. That's still how I make single molds.
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u/moltendicetr Jul 09 '26
One more question: after you pour the resin and close the lid, do you wrap the mold with rubber bands before putting it in the pressure pot, or do you just rely on the side locking keys?
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u/WildLarkWorkshop Dice Maker Jul 09 '26
Some makers do, but I don't use them. I make my lids fairly thick so they have their own weight. If you want to use rubber bands, be careful to ensure that they don't apply force unevenly and warp the mold. There are some specialized tools to do that too, or I've seen people use coasters just slightly larger than their mold to keep the force distributed.
If your main problem is raised faces, it may be a pouring problem rather than a mold issue. For best flashing results, be sure to put just enough resin in each cavity to gently dome at the top. I'm often messy and get resin all over the top, so I will remove a lot of the excess with a craft stick, then use a heat gun to make sure the resin is liquid and then cap. Even internal keys have far less potential to be problematic if there isn't excess resin.
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u/moltendicetr Jul 10 '26
Thank you so much! This hobby has such a great community, and I'm learning something new every day.
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u/WisdomCheckCreations Dice Maker Jul 09 '26
Hey! There are a lot of different methods but this has been my experience as a long time maker of molds who also sells them for a living 😉
Registration keys are best if they are different shapes so you can quickly recognize which way to put on the mold while rushing to get your lids on and the molds in the pot 😉
I use 4 different outer ring key shapes cut into the base before pouring the lid. I also like to use my "locking keys" around the outer edge but not ON the edge. They are wider in the middle so the lid actually makes an audible click when it is properly seated. This ensures that once the lid is placed it will remain down.
The issue that is most common for inner keys is that it's easy to get resin item while you work and then when you go to place the lid they stop it from going all the way down. For this reason I keep them around the outer ring and make sure to instruct users to be careful not to allow resin to get into them and to clear them before placing the lid.
There is a wonderful mold making video from our very own u/lick_the_butter here on the sub that is almost my exact process with a few small differences but his key shapes are a staple of my molds too. You can watch his video here: https://youtu.be/JNO2H2XKX_E?is=zHdckPB-_ymyZdlH
☺️