• Still working after about two years

    Jerry Biehler • 2 days ago • 0 comments

    Been using this thing for about 2 years ago and it works well. I dont have to worry at all about leveling the material before cutting as long as it is in the travel range of the setup. Makes cutting metal so much easier. 

  • Control enclosure

    Jerry Biehler • 2 days ago • 0 comments

    Need to label the buttons. Buttons for home/reset, up, down, fast/slow, and follow mode.

  • Assembley

    Jerry Biehler • 2 days ago • 0 comments

    Starting to get this thing put together on the laser itself. Using the large cutting head I am limiting my height quite a bit which should be fine for most things. I do have a shorter head I can also use. Ended up resin printing a lot of the parts. Its takes several iterations to get everything right. Have one piece printing now because it was just a but too flexible. I also need to install some counterbalance springs on the spoon.

  • PCBs arrived

    Jerry Biehler • 2 days ago • 0 comments

    PCBs for the focuser arrived. It's mostly just breakout for the Teensy, power supply, and TTL-RS232 conversion. Ordered them this weekend from JLCPCB and they arrived today. My DigiKey order is going to take longer than the PCBs.

  • Proof of concept working

    Jerry Biehler • 2 days ago • 0 comments

    One thing that has annoyed me about the laser cutter is keeping it in focus so I am working on an auto focus similar to what I worked on that was on a Mitsubishi laser cutter. Most commercial laser cutters use a capacitive distance sensing system that measures the capacitance between the work and the cutting tip. This works great for metal, for non-metallic, not so much. On the Mitsubishi laser I worked on they had a "spoon" that went around the tip. The spoon rides on the surface of the work and feeds back into a transducer of some sort, I am guessing a LVDT.

    So thats what I am replicating. I had a Keyence GT2 linear displacement sensor with RS232 interface and a copley servo drive. I found a neat little maxon brushless servo motor on ebay that has a tiny ball screw built in. The motor drives a wide linear rail and has a couple limit switches for end stops. Im using a teensy 3.5 to handle reading the position of the sensor at about 200 times a second and then converting that to a frequency to drive the step input of the drive. If the number is negative it moves on one direction, positive the other. There is a settable deadzone in the middle. The sensor allows you to set the zero at any point in its travel. The teensy also handles the serial communications to the servo drive to home it as well and watch for faults. There are buttons for home, jog up, jog down, jog speed toggle, and track.

    Spent a few hours last night debugging it and tried it for real and it works. I just clamped the sensor read head to the block where the cutting head would be and use a steel block as what would be the work surface. I still may need to do some tweaking to some parameters but it works pretty well.