I made my first foray into cutting aluminum. I wanted to make a 2" medallion. The aluminum was a 12"x12"x0.125" 6061 plate.
I did the engraving with a 30 degree 1/8" shank V bit. As you can see, I had to put a riser waste board on so the V bit could reach. This was my first attempt and I was very happy. Then I installed my new 0 flute 1/4" EM to cut out the medallion. I rezeroed Z, loaded the new tool path, pressed play and away it went. This is where the odd behavior occurred. It circled the the medallion a few times and then everything froze up (i.e. UGS and communications to the controller).
I tried running the tool path again after I recovered (had to shut down UGS and bring it back up). The same thing happed. I then tried G-Sender and had the same issue. To make a long story short I was able, after 5 more attempts, starting from scratch, to get the job done.
Here’s what was happening, as near as I can tell. I think that I had created a capacitor with the aluminum acting as a plate and, some how, it was building up a charge. I haven’t had any problems with my Longmill behaving like this for a long time. Some times you stumble across solutions. I was probing with my multimeter from the router body to the aluminum plate to see if voltage was building up on the plate. I know a multimeter is a poor tool for this since it won’t catch any instantaneous voltage peaks but it did show that voltage was building up on the plate. With the meter it peaked at +/-0.25V. The interesting thing is that as long as I connected the router to the plate through the meter the job would run without freezing. Evidently the meter was bleeding off the charge from the aluminum plate limiting to a level that didn’t cause problems. I ended up putting a screw into one of the side holes of the router mount and clamping one meter probe there and wedged the other probe under a far corner of the aluminum plate and was able to complete the 5th medallion.
I’m not sure what the noise path was back into the controller. I do have an earlier LM controller and I know that Sienci has added noise filtering on some of the I/O signals so this may not be a problem on newer controller. So I just mention this here in case other experience similar issues. Tying the aluminum plate to ground should also have resolved this problem.