All 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.

Key phrases linking here: mold natches, natches, natch - Learn more

Details

3D design and 3D printing are enabling a rethink of almost every detail of how molds are made. The way in which natches are incorporated into working molds, what natches need to be and even if they need to be there at all, are all on the table. The precision of 3D-printing can really be leveraged to imagine and create new ways of interlocking multipiece molds.

At its simplest, incorporating natches in mold parts is simply incorporating holes in 3D printed shells to accommodate clips or retainers (and what they connect to, either a natch or an embed). Natches and spacers can then be inserted (and glued) into the embeds after the plaster has set. The biggest benefit of this is being able to sand flat mating surfaces (before gluing in the natches).

More advanced options involve fitting natches to already created working mold parts. This is done by the incorporation of smooth recessed 3D printed platforms to which natch hardware can be positioned and epoxied.

While natches can be purchased, the other hardware needed to embed them necessitates 3D printing anyway. So you might as well print the natches also. Making them all yourself enables not only flexibility in shape and size but also assures that you will never be caught out of stock.

Related Information

Standard 3/8 inch mold natch

Available on the Downloads page

This picture has its own page with more detail, click here to see it.

Once you try these you will never go back to making molds without them. Unfortunately, these are not easy to get in North America. Or even online. But you can 3D print them yourself (we use PLA filament). This design interlocks with standard 3/8" natches used in industry. There are more aspects to printing and using these than meets the eye, here are some aspects to know:

-The base can be widened for sticking on the build plate better. If you need to print large numbers it might be advisable to use a glued plate to make sure they stick well.
-The inner edge is chamfered to ensure better insertion of the nipple.
-Print without infill for better strength.
-These are hollow, no support is needed.
-The bottom can be widened to stick better to the build plate.
-The ribs can be moved.
-A 9.8 mm hole is needed in the mold.

DIY mold making using 3D printing just got easier.

Mold natches, spacers, clips and embeds

Available on the Downloads page

This picture has its own page with more detail, click here to see it.

Plastic natches are cast into plaster molds to provide a durable and good-fitting interlock between pieces. The traditional self-interlocking 3/8" or 9.5 mm (nipple diameter) one has not proven suitable for mold making based on 3D printing. Our solution is a four-part system. To use it, your 3D printed mold shells only need matched 13.5mm holes.
-13.5mm holes in 3D printed case molds are all that is needed to adapt to these.
-3D printing case and block molds necessitates pouring plaster and rubber into shells with planar mating surfaces downward (they must sit flat on the table). The thin flanges on the clips cause minimal issues.
-Casting an embed into a mold enables gluing (or friction fitting) a natch or a spacer inside.
-The use of embeds permits flat mating surfaces - these can be sanded (for better flatness and fit). They also allow replacing natches if they get broken (assuming friction fit).
-A set of four interlocks (4 embeds, 4 clips, 2 spacers, 2 natches) weighs 8.7g.
Our drawing 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 fits. The same good fit happens with the clip and embed and the natch nipple and spacer (although it is necessary to chamfer the bottom corners and bevel the top corners of the spacer for better insert).
Some dimension changes may be needed to fine-tune for printing in your circumstances.

DIY natches, spacers and embeds in a plaster handle mold

This picture has its own page with more detail, click here to see it.

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.

Three-piece vertically printed mold with natches

This picture has its own page with more detail, click here to see it.

These 3D prints slide into slotted side rails for each pouring of plaster. Since the plaster releases easily it is possible to use these multiple times. This method is suitable for prototyping in larger quantities than prints that integrate rails. These are printed on edge so print times are drastically reduced and surface smoothness is much better. This version has a bottom piece eliminating the seam across the base. It also enables putting embossed logos on the base. The holes enable mounting flush embeds - making it possible to sand the mating surfaces flat before gluing in the natches. The three-piece mold produced is shown on the bottom.

Slotted natches make this bottle mold possible

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These enable pulling apart the top halves of our ceramic beer bottle molds while the leather hard bottle is still embedded into the base. Starting upper left and clock wise:
#1 The 3D design for making a rubber case mold.
#2 It has been 3D printed in three parts (which are then glued together).
#3 PMC-746 rubber was poured in and the 3D printed parts were peeled off.
#4 Natch parts have been 3D printed.
#5 The embeds have been rubber cemented onto the rubber mold (to hold them in place during casting).
#6 Plaster was poured in.
#7 The plaster working mold has been extracted from the rubber, the embeds firmly rooted in place.
#8 The slots have been epoxied in place (lined up and positioned accurately so the natches hit the end of the slots just as the halves contact).
Centre: The mold partly assembled.

Why 3D design and printing is a better way to make slip casting molds

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I dread the traditional mold making process, the mess, all the supplies and tools involved. I am a potter, I make functional ceramics. I am not a mold-maker, but 3D design and printing have put it within my reach. This way more fun! There is no stopping this, it’s the future.
-I spend most time on design, pouring the plaster or rubber takes minutes.
-Many fewer tools and supplies are needed, the process is less messy, as easy as downloading a file, printing it and pouring in plaster - this is doable in my kitchen!
-Sanding of flat mating faces is possible (for better seams than I've ever had). This is because natches can be added later (using embeds).
-I can make my own natches and interlock schemes.
-No spare is needed, the 3D-printed pour spouts work better.
-The range of shapes seems limitless. Especially because designs can be split up into pieces, each printed in optimal orientation (and glued together).
-I make molds through multiple design-print iterations. 3D makes do-overs or changes in design as easy as a reprint and plaster pour. So, I can make a mold just to test an idea!

By Tony Hansen Follow me on

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