I decided to make a CNC laser cutter with some material handling capabilities for my model plane project.
I have some surgical tubing for the water jacket (the CO2 laser tube is water cooled). It seems to brown the water and I don’t like that since it might accumulate some material in the water jacket. I realize I can clean the jacket with hydrochloric acid but I figure it’s a better idea to not have any material going through the system.
Some of my friends are saying it’s silicon surgical tubing or fuel line from a motorcycle shop. I will check that out the next time I’m at the bike shop.
I went with EMC2 which runs under Linux. It is very easy to use. You need to download an ISO file from LinuxCNC.org then burn a CD from the ISO. Boot from the CD and presto! You have a CNC controller running off the CD without affecting the host computer. I elected to install the Ubuntu Linux software with the EMC2 right onto the computer so that I could boot from the hard disk. This allowed me to run updates and such. It upgraded everything to the latest. This is a Ubuntu 8.04 LTS. I think they are working on getting the next one going which is Ubuntu 10.04 LTS. I will upgrade when I become aware that it is ready and it is stable enough.
My lab does not have any network cables running from my server room. So I installed a Wireless Bridge. I made if from an WRT54G v8 (Linksys router) by installing DD-WRT open source software onto it. I then configured it as a wireless bridge and had it join my network which has a higher end router (also running DD-WRT). Now I have 4 eithernet jacks to plug stuff into to have internet access in my lap. I can remotely access the lab computer across the network (this includes remote desktop and ssh).
EMC2 is pretty easy to configure and run. It didn’t take too much fiddling to get it programmed with all the parameters of my gantry system.
CNC Steppers, Controllers and Power
I initially started to build circuits to control stepper motors. I discovered that you can buy components that are not too expensive. I got a xylotec 4-Axis kit. It comes with 4 large steppers with double shafts, the 4 channel controller and a 24V power supply. The EMC2 software had this outfit listed so it was easy to get up and running. All I really had to do was tin all the wire ends and screw all the wires together. Apparently with this outfit, if you wire something wrong it fries. So I was extra careful. I’m very pleased with this system. It is very powerful and is quiet.
I made a gantry out of 1″ aluminum angle. I used the contraptor methodology of drilling holes and using nuts and bolts. I designed my own sliding elements to use ball bearings. I used yoyo bearings. I used XL timing belts and pulleys which don’t seem to have any back lash.
Also, I went through all the belts sizes and prices to find that 88″ belts were relatively inexpensive. I made a spreadsheet to compare every belt size to it’s price so I knew if I should buy belt by the foot or to a specific size. I eventually went with 88″ belts and decided to just pull the slack out. You can see how I did this in the pictures. You can also see the gantry detail and the Y-Axis truck detail. It runs pretty fast and smooth.