CAD drawing for 3D-printing plaster mold natches, spacers, clips and embeds

Plastic natches are cast into plaster molds to provide a durable and good-fitting interlock to ensure pieces line up perfectly. The traditional one familiar to most people is the 3/8" or 9.5 mm size (nipple diameter). Because of issues surrounding their use (not the least of which are price or even finding a supplier), we designed our own. Ours have several advantages:
-There is never an issue with supply, we make them.
-13.5mm holes in the case molds are all that is needed to adapt to these.
-3D printing case and block molds means we have to pour plaster and rubber into shells with planar mating surfaces downward, they must sit flat on the table. Clips with a very thin flange solve this, they hold the embeds inside in place.
-Casting an embed into a mold is more flexible since we can glue (or friction fit) a natch or a spacer inside.
-Since there are no natches protruding on the flat mating surfaces these can be sanded for better flatness and optimal fit.
Our drawing (right) shows the measurements we use. 3D printing is precise enough that the inside dimension of the embed is the same as the outside of the natch shoulder, yet the natch slides in perfectly (the same good fit happens with the clip and embed and the natch nipple and spacer).

Purchase this for $5.00 at the Downloads page

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The mold-making technique we have always needed

I wanted an easy way to make molds for slipcasting handles that mate perfectly to any shape mug (or pitcher, teapot, etc). I want to pair cast with thrown or jiggered elements and join them using just slip (even when the clay is stiff). We have developed a flexible CAD design that puts 3D printing of case molds within the reach of almost anyone. It requires so little tooling it can be done in a kitchen using spoon mixing and a paper cup! These PLA shells, for example, print quickly to only 11 grams and they peel away from the plaster with a heat gun to give fine detail and perfect fit. Multiple cycles of redesign and print are practical to achieve just the right shape and fit. Cast handles can be produced in quantity and stored in a damp box, removing one of the biggest hassles in the production of handled ware. The feel of the handle is the first thing customers notice, even a hobbyist can now turn a "wet noodle" handle into something designed and utilitarian. You can get this drawing on the downloads page. Worried about mixing or tuning your own casting slip recipe? See the link at the bottom of the source page for this post.

DIY natches, spacers and embeds in a plaster handle mold

Natches, spacers, embeds in a plaster handle mold

This is our third-generation alternative to the use of traditional mold natches (like the red ones in the photo). Here is what you are seeing:

Right: A 3D-printed case mold for a mug handle. Clips (retainers) have been inserted from the bottom side. An embed has been pushed down over the one in the rear.

Center: The plaster mold created from it. The embed at the rear is ready for inserting a spacer (the nipple of the other half will it into that). A natch has also been inserted into the embed in the front. These fit tight enough in the hole that glue was not needed here.

Left: Spacers have been inserted into both embeds. A standard natch fits into the one in the rear and one of our natches fits into the one in the front.

Soon the CAD drawing for these (natches, spacers, embeds, clips) will be available on digitalfire.com.

Links

Projects	Mold Natches Natches are an interlocking mechanism using in plaster molds for ceramics. They enable quick and accurate registry when assembling multiple pieces of a mold.
Glossary	Casting Slip Casting slips are among the easiest clay bodies to make yourself. The ability to make and tune your own will open many doors in your production process.
Glossary	Mold Natches At digitalfire we are big fans of slip casting and want to help people and companies (even hobbyists) to integrate it into their production.

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