Ceramic 3D printing: DIY clay feeding system, printhead and firmware. Part 1.
DIY clay feeding system for 3D printer.
Existing clay feeding systems for 3D printers have their own advantages and disadvantages. Due to a number of circumstances, I had the opportunity to build from scratch almost all existing Open Source solutions for 3D printing with clay, as well as carefully study commercial systems in this area.
During the assembly and operation of various options, I identified both the strengths and weaknesses of the various solutions and came to some conclusions regarding clay supply systems, which I share below:
- system should be as easy to maintain as possible (assembly, disassembly, cleaning, repair), without threaded connections in parts that must be dismantled during maintenance
- walls of the clay tank must be smooth
- tank material must be wear-resistant
- tank materials and connections must not oxidize in a humid environment
- the system must be easily repeatable and parts must be available without pre-ordering or manufacturing
- hose for supplying clay must be with an inner diameter of 10 mm and not create additional friction
- cost of the system should not exceed $150
- tightness of the system must be ensured without the use of an excessive number of gaskets and rings
- it must be possible to increase the volume of the tank without the need to replace most of the parts
Next, I will talk about how to assemble a system based on these conclusions, which can be connected to almost any FDM printer with minor modifications. I note right away that we are talking about a pneumatic-based system, where air under pressure pushes the clay mass. I have assembled and worked with solutions based on stepper motors with gearboxes, and I can say that the advantages that they provide (and in fact there are two of them: the ability to work with thicker masses and synchronization of feed with the printhead stepper motor) do not compensate for their shortcomings in in the form of excessive bulkiness, complexity in assembly and debugging, speed of refilling and cleaning. In any case, both systems have the right to exist, just in my case, preference was given to the option with pneumatics.
As a basis for the system, I will use a stainless steel column named Tsarga (I don’t know how the name of this part is correctly translated from Russian into other languages, but I will be grateful if someone tells me) with the clamp connections. Such Tsarga's are used in the field of home brewing and are widely available for purchase, at least in countries where the amateur preparation of strong drinks is not exotic. The Tsarga diameter can be any: 2 or 3 inches is quite suitable for 3D printing tasks.
Why Tsarga? Simply because stainless steel has high wear resistance, does not create unnecessary friction and does not oxidize in a humid environment. Among other things, Tsarga perfectly holds high pressure and is easy and convenient to disassemble and clean.
In addition to "hooch" components, you will need plumbing connections that are present in any hardware stores, as well as a pair of pneumatic fittings and a silicone thread sealant. Naturally, it is assumed that you already have a compressor (any one with a maximum pressure of 8-10 bar).
Полный список покупок:
- 2" Tsarga, 30-50 cm, 1 pcs.
- 2" Tsarga's clamp, 2 pcs.
- silicone gasket for 2" clamp, 2 pcs.
- 2" clamp adapter to 3/4 thread (1/2 adapter would be ideal (which would eliminate the need for an additional coupling from the next paragraph), but such adapters are very rare on sale), 2 pcs.
- adapter 3/4 to 1/2, internal thread, 2 pcs.
- adapter 1/4 to 1/2, external thread, 1 pc.
- angled push-in pneumatic fitting Camozzi, external thread 1/2, 12 mm, 1 pc.
- pneumatic fitting with 1/4 female thread, 10 mm (Camozzi or Festo), 1 pc.
- pneumatic fitting with 1/4 external thread, 10 mm (Camozzi or Festo), 1 pc.
- adapter connection Rapid to external thread 1/4, 1 pc.
- gel thread sealant Santekhmaster blue, or equivalent, 1 pc.
- PFTE pneumatic tube with an inner diameter of 10 mm and an outer diameter of 12 mm, length ~50 cm, 1 pc.
- polyurethane pneumatic tube with outer diameter 10 mm, length ~50 cm, 1 pc.
- filter lubricator with pressure regulator, internal thread 1/4, 1 pc.
It remains only to put it all together. First you need to connect the fittings and clamp adapters. The input group connection looks like this:
A 3/4 to 1/2 coupling is attached to the thread of the clamp adapter, then a 1/4 to 1/2 coupling is attached to this coupling, to which a 1/4 push-in fitting is attached (10mm, internal thread). Before connection, a gel sealant is applied to each thread. After connection, the group is guaranteed to be ready for use in a day, after the sealant has completely hardened.
Next, I collect the output group:
A 3/4 to 1/2 coupling is attached to the thread of the clamp adapter, then a 1/2 angled push-in fitting (12 mm) is attached to this coupling. As in the previous step, gel sealant is applied to each thread. It is convenient to tighten all threaded connections with an adjustable plumbing wrench, without undue effort.
After the input and output groups are ready, you can begin to assemble the filter with a pressure regulator. A Rapid adapter (quick fitting used in most household compressors and hoses) is attached to the inlet thread of the filter using a gel seal, a pneumatic fitting with a 1/4 male thread (10 mm, outer thread) is attached to the outlet thread.
Push-in connections are used in this system for convenience and to increase the speed of assembly and disassembly of the system for cleaning. Of course, there are similar solutions for clamps and hose fittings, but in my opinion, the push-in connection is much easier to work with and more reliable than other options.
Regarding the length of the PFTE and polyurethane tubes: it should be selected according to the features of the installation in each individual case. Polyurethane tubing must be designed for use in pneumatic systems and withstand pressures up to 10 bar; garden, domestic and food tubing is not suitable for this. I recommend Camozzi, Festo and others from the pneumatics section of the shop. The same applies to the PTFE tube. And two more important things to keep in mind about the PTFE tube: The PTFE tube should be kept as short as possible and I don't recommend replacing it with a tube made of a different material, as this can significantly increase friction and degrade the quality of clay flow to the printhead. Moreover, it will not be so easy to find a 12 mm pneumatic tube with a wall thickness of 1 mm.
Then you can completely assemble the system and connect it to the compressor. Step by step it looks like this:
1. The hose coming from the compressor, with a quick-release Rapid connection, is connected to the inlet of the filter with a pressure regulator
2. A polyurethane tube with a diameter of 10 mm is attached to the filter outlet. This is how it looks when assembled:
3. The input and output groups are connected with a clamp through silicone gaskets to the Tsarga:
3. The clamp screws are tightened until the clamps are tightly compressed around the Tsarga and the clamp adapter.
4. The PFTE tube is connected to the push-in fitting of the output group. Clay will flow through this tube to the printhead.
The assembled system should look something like this (the photo shows the first assembly of this structure, where PTFE tape is used instead of a gel seal, which I do not recommend):
For my printer, I also provided fasteners for the Tsarga on an aluminum structural profile 20x20.
To clean the output group and Tsarga after printing, I recommend using brushes of different sizes. If clay remains inside the PFTE tube, then it can be blown through with a compressor after the Tsarga tank is completely empty. As an alternative, the following purge design can be assembled from additional fittings:
This completes the assembly of the clay supply system. The next part will show you how to assemble the screw head and mount it on the printer.