Sunday, February 27, 2011

CNC tests: aluminum

Last time I tried how my CNC3040 machine deals with wood and plastic. Now it's time for some metal.

I tested on a piece of scrap aluminum, so unfortunately I have no idea of the alloy. The tool used was a 3mm 4-flute carbide endmill. Cutting depth was 0.4mm. For coolant I used Biltema brand "Multi-Spray".

The lower cut as seen in the picture was made with a feed rate of 50 mm/min and the one above it at 100mm/min. The faster cut looks cleaner.

I still need to do some more testing, but this machine does appear to be capable of light metalwork.

Generating G-Codes

As I said in my previous post, there is a dearth of CAM programs available for Linux, so I mostly have to write my G-Code by hand or combine output from various code generators. To make this task a little easier, I wrote a preprocessor with some code generation features too: JGCGen.

JGCGen is written in Java and uses Apache Velocity as its templating engine. This allows you to easily combine input files, write macros, generate code with loops, etc. Check out JGCGen's readme for a more comprehensive introduction to what it can do.

The g-code for the little name plate on the image to the right is, of course, generated with JGCGen. Yeah, it's not all that pretty and finished, but the code is only 24 lines long!

Addendum to the last post: You can cut plastic with a 2 flute endmill. Just keep the feed rate high enough to keep the chips from melting and clogging up the blades.

Friday, February 18, 2011

CNC tests: Wood and plastic

Today I did some tests on my CNCDIY 3040 router/mill to see how different speeds and feed rates affect the cut on various materials.
The materials tested were wood (oak), acrylic and polycarbonate.

I used a simple test pattern (G-code available here) with motions in different directions to help detect backlash and inaccuracies.

Saturday, February 12, 2011

Hobby CNC

For quite some time now, I had been wishing for a CNC router. On almost every project I did, whether that be woodworking or electronics, there was usually some part that made me think "if I had a CNC router, this would be easy;" but I couldn't justify spending thousands of euros on something (no matter how cool) I'd only be using for hobby work.
Recently, I found a manufacturer, CNCDIY, that makes affordable desktop CNC routers. They have (at the time of this writing) two very cheap models, the 2520 and the 3040, both under $1000. I decided to buy the 3040 as it has a slightly larger working area and has ball screws instead of trapezoids. According to the manufacturer, the 3040 can mill soft materials like wood, plastic and even aluminum. I would guess milling aluminum is very slow work on a machine like this compared to a "real" milling machine, but this machine should be just perfect for my needs. (Wood, acrylic, PCBs, possibly thin aluminum parts)