CNC

This is a new item for my web site. Later I may cover it in more detail. It is one of my hobbies. This is just a quick impression of how one can enjoy a rainy day.
The machine is the work of a couple of years. However the last years, I've not been able to continue on the project as much as I would have liked. Still, I hope to continue in some chunks of time to implement some new features. Currently I need to remove some bug I've introduced the last time I made a lot of enhancements and removed other bugs. I'm not able to support it and there is no manual. I think I need to work on that. This project will never be finished, of course. It is that idea that I like most of it. I always can expand and implement new thoughts. I may have commercial plans in the near future, so I would not share the code, I wrote. (~ 120.000 lines)
It is an joy to see the machine at work!

Pictures:

Some pictures of this CNC hobby so far:

The milling table has a resolution of 2.5 um. Its fastest move will be about 125 mm/sec, but I limit it to a safe and perfect operation. The table has a repeatability of about 0.01 mm.
It is very strong when moving, there is no way you can hold it by hand. One time it broke a drinking glass, which was in the way!

The table can mill lines, circles, ellipses and B-splines. It can correct for the mill diameter (inside contour, on-contour, or outside contour) and all the axes can be scaled, reversed, rotated over all three axes by the indexer. Even the axes can be exchanged, all by software commands. If a front panel has to be milled, or a PCB to be drilled, I don't need to align them at 90 degrees. Just use the CCD camera on one point and the other, then the indexer will rotate its X and Y axes, so that it appears as if the panel was aligned properly. You can move the axes by the knobs. If there is a slight rotation, you will notice the Y-axes turn slightly as well when you move along the X-axes!

This machine knows a lot of tricks. If it can't do something the way I like it, it is a mather of hours (or days) of programming, then it becomes smarter again. That's fun. This way, the programs will never be finished!

The mechanics, electronics, and software is all home brewed and home build. I have used ball bearing spindles that were mounted in a profile. That made the construction somewhat simpler, and it has a dust protection.

The green monitor displays the picture that comes from a CCD camera in an aluminium case,
laying on the table near the lamp. It can be mounted on the place of a spindle.
There is a cross-hair which marks the exact center of a mill.
This way, you can measure as accurate as 0.1 mm!

A milling spindle which can run up to 26.000 RPM, a lot of noise! The spindle power is controlled by the computer.

The camera seen from the front. It has a 43mm mount diameter.

The camera mounted.

A closeup from a picture from the monitor. You can see the cross-hair. For the cross-hair, I designed and build some electronics into the monitor. Like many parts, I got the monitor from scrap.

The computer that drives the milling table, is called an "indexer".
It runs a program, written in C, under DOS, to be real time. Commands can be executed locally or received via the serial port. Via the parallel port, it drives the stepper drivers.

The use of stepper motors has advantages above servo motors:
- cheap
- no controlling in rest (accomdates the use of belts)
- no tuning and parameter adjustment required
- plug&play: very simple in use

This is one of the stepper drivers. It has a driver supply voltage of 50V. (and 5V for the logic) Each of these consist of two motor drivers LMD18245, and a Microchip PIC16C56.
The PIC has a program that takes care for 10x micro stepping. This way, the stepper motors work with a higher resolution (2000 steps per revolution), and operate with almost no vibration. One revolution equals a linear movement of 5 mm. The microchip program is written in ASM. Any amount of micro stepping can be programmed, but I liked the 10x more than 8x or 16x, and find it more fun. The steppers move very quietly and are able to run very fast! Of course the indexer has acceleration and de acceleration parameters.

The rack with the stepper drivers. Note that the Y-axis has 3 motors that work in parallel! This is because the belts, at high movement speeds we need more force. The Y-axes has two active Y-spindles, driven by three motors! Synchronous working is guarantied. There are 3 drivers, for each Y-motor one: one master and two slaves. The slaves do not have the PIC micro controller installed. The driver chips are controlled by the PIC on the master card.

The X-axes motor.

Here you can see one side motor, and a tooth belt, which connect both Y-spindles.

The double-pulley, seen in the middle, fits on the center motor.

At work for the construction of a power pack for the digital camera.

A look at the screen were the parts have been designed.
This computer communicates with the one which controls the milling table.
This program is written in CPP.

Some finished parts, gold plated battery contacts already assembled.

The contacts are connected.

The finished power pack. It can be charged with a custom NiMH charger in about 1 hour.

This is a reconstructed tooth wheel for a clock. The old wheel had been repaired several times, with no luck.
The outer side of the new wheel is 3 mm wide instead of the original 1.6 mm, and the width is fully used. So this is in fact a more solid version than the original one.
It has a module of 0.72. Also I found that the old wheel had lost 0.05 mm of each teeth, the new wheel has it back. Today, the clock is still functioning, using the new wheel, it never broke again!

The yellow shape is a master profile for the tooth wheel. If you modify it, the tooth wheel will have different tooth.

These are trials made out of 3mm thick plastic. They should be produced in 9 mm thick metal being tooth belt wheels. Just to check with the belt if it will fit well. And it does! The openings are milled using B-splines.

A massive silver contact for the digital camera.

Screen shots from the CAD program, which communicates with the indexer. It consist of nearly 100.000 lines of source code.

TTF Fonts can be used for engraving or milling out characters, lines, or complete text creations, including shearing, circular, morphing, etc.

A demo front panel. The parts can be selected from a library and rotated and placed.

A closeup from a front panel. With one mill you can make holes for countersink screws as well.

I got some actuators. It started its life in my brain. A special punch tool, just a fantasy. This tool can engrave art in steel, messing and plastic! It is a very fast engraver. It punches an average of 25 dots per second.

The tool mounted. A CD-box graved with a picture of Tori Amos.

The same picture of Tori Amos, engraved in the back of a mirror! I used a similar technology, but not the engraving tool.

I was wondering how the mirror would like after enhancing it with LED lighting.

The mirror was made using this engraver. Note the adapter ring. It is tight-fitted on this spindle, so it can always stay on it while changing spindle motors. Its spindlespeed goes up to 20,000 RPM.

A prototype of a general purpose fluid pump. It will be controlled by a stepper motor and a high-speed driver. This pump may be a nice solution for giving my plants water automatically. It can also be used to mix oil with pressed cooling air for the mill!

Another general purpose fluid pump with a 72 steps/rev. stepper motor. Extremely fast and precise! It pumps 0.4 ml / revolution of the blue wheel. This equals 173.6 revolutions of the stepper motor or 720*173.6 = 124992 steps. (The stepper driver maintains a 10x micro-stepping mode.)

More plans are already there...

Bright Superflux LEDs for mill-area came from:

www.ledtuning.nl