DIY CNC in Home

The birth of the idea

In our new age of the digital revolution can be often heard that work automation leads to the emergence of many new creative professions. Robots and smart machines help to realize a lot of interesting creative and technological ideas.

3D-printing became ingrained in our everyday lives, mastering of processing equipment becomes easier. But different working operations require the whole machine tool fleet, even if it’s a small workshop. One machine just cannot do. Thus was born the idea of a multi-DIY-machine that can replace several machines.

I will try to describe the concept of this machine which can be put on each work table. The multi-functional food processors can be considered as a direct analogy. All elements are based on the one “mother unit" (box), to which is possible to add and configure various modules. The main idea is the maximum ease of installation and selection of modules. Therefore there is no need in any special skills, everything is intuitive clear and accessible.

Here is the schematically description of the configuration options:

- Three-axis CNC “mother unit"

- Adding the milling spindle we get the CNC milling machine

- Setting the laser head we get the CNC engraver/cutter

- Adding the swiveling axis we get the four-axis CNC milling machine

- Adding the vise we get the milling machine for working with metal and hard plastic

The development began at the 2013. Then I already had some limited experience in construction of coordinate systems, and it was decided to start with a “parent equipment” of the milling machine.

For the selection of the components some requirements are to consider:

- ease of connection;

- compactness;

- ergonomics;

- easy installation for the next serial production.

The first difficulty was associated with the ability to easily connect, as all open systems and controlling systems of coordinate machines, which are known to me, are based on the LPT interface. This greatly limited the range of the used computers. The solution was found, I decided to use open software project GRBL based on Arduino. As drivers I used A4988 chips of the company Allegro.

I hastily selected and put together electronics, because at that time I was completely sure that I was late and needed to do everything quickly (how much I was wrong). I got two boards on the well-known components. Now drivers operate in step mode 1/8, soviet stepper motors work perfectly DSHI200-1-1.

3D-printers developed actively and the appearance of the machine was copied from them, which determined the layout of axes and the overall characteristics of the machine.

The housing became supporting, the X-axis was fixed and the work table (the Y-axis) moved under it. The Z-axis was combined in a single unit with the carriage of the X-axis. The linear bearings were pressed right into the housing, which greatly saved the cost of the components, but at the same time is does not give a loss in stiffness.

The axes move on the cylindrical guides about 12 mm in diameter with the help of the trapezoidal screw.

When I finished with the electronics, form factor and axes configuration, it was necessary to determine the material from which it was possible to create the machine.

I needed some slab material, which I could simply process, buy cheap and then make easily the machine.

The choice fell on Plexiglas 10 mm thick for the main structure and 5 mm for overlaps.

This material is strong and sufficiently elastic, it is easy to mill or cut with the laser and then glue together and paint it.

After collecting all my thoughts I started drawing the model and preparing components for production. As a result I got a modular construct adapted for fast assembly and adjustment. All units were designed so as to be maximally “box-shaped”. This simplifies the control of the geometry of the machine and increases the strength of the modules.

Speaking of overlaps, which were cut from the 5 mm thick Plexiglas, they perform not only a decorative function, but also fix the guides inside the housing. This also saves money on parts.

So, after the preparation of the project, the simulation is complete, the purchase of components and preparing files for production took a half years. I ordered milling parts made of plexiglass. Get about 1.5 square meters. meters thick Plexiglas of 10 mm and 5 mm., a total of 27 items.

I decided to glue with dichloroethane because for Plexiglas better than dichloroethane can be ONLY “dichloromethane” – as this chlorine derivatives is more fluid and less toxic than dichloroethane.

“The Glue” is usually made from the same material, which you are going to glue (made from its shavings) – 3-5% by weight and spread “the glue” as thin as possible.

The photo presents the test assembly. If you will matt the Plexiglas, the appearance of the machine will be more complete, but still the machine was painted with the matt white paint.

All wiring is hidden within the housing. The electronics is placed under the bottom of the machine (there is no Power Supply on the photo yet), all connectors are on the rear panel.

Dimensions of the machine: 365×430×420. Working field: 200×200×80. As the spindle I decided to use an inexpensive Chinese engraver with a capacity of 125 watts, which is enough to machine the plywood, plastic, engraving PCB.

Now we can say that only the first phase of the project is finished – creating of a working prototype of the “mother unit”. Further much the concerning of the replaceable module assembly is to be done: swiveling axis, the installation of electronics and laser engraving, the purchase and testing of the printing head for 3D-printing.

An important stage is the development of the software. If I want to present the DIY-machine “for everyone”, so I have to create an user-friendly software.

We hardly can say that the bunch of CAD+CAM+G-code sender is simple, because each of these software products requires a thorough study and pretty specialized skills and knowledge.

In the future it would be desirable to develop, assemble a team, because it is difficult to cover the entire spectrum of work all by myself.

A draft of the next integration of the machine is under the preparing, which will be more compact, more expensive, adapted for the processing of jewelry master models and non-ferrous metals.

The next step is to create a 4th axis. But this, I'll explain later.

Thanks to all!