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I'm almost done with my table, just waiting on the cable track, and have to find where I want to mount the Candcnc box. Since I'm waiting on UPS, I decided to hook up the electronics and see if I could get a head start. I've got the motors hooked up, motor tuning done in Mach(used the Candcnc recommended settings), and have the gantry moving. I haven't hooked up the DTHC yet, I wanted to get the following problems figured out first.
The first problem is the gantry(both X and Y axis) isn't moving smoothly. It's hard to explain, but it kind of jerky as it moves along. The motors seem to turn smooth when I had them running off the table, and the gantry moves nice and smooth by hand. I think it has something to do with how the motors are mounted. If you grab them, they seem to have a lot of movement in them(actually, the bracket they are mounted to). I'm not sure if that's how they are supposed to be or not, but the only thing holding them still is the spring pressure from the shoulder bolts and the spring holding the gear tight to the rack. The gantry didn't come with any directions, only a couple of prints, so I'm not sure if they are supposed to be this way.
The second problem is with the z axis. If I hold down shift on the keyboard when I hit the page up or down keys(to move it quickly), either the motor will spin a little then start buzzing like it doesn't have enough power, or the Candcnc control box will go into fault and shut the motors off. The red light on the control box blinks three times, then repeats, which I think indicates a high temp fault. It also did this when I was testing the z axis motor on the kitchen table(except for the motor buzzing). It only does this when I hit the shift key, not during a slow jog.
Any help is appreciated.
Well, to begin with, we need a little more information. Is this a Precision Plasma kit? If so, which one? The gantry should travel smoothly, unless there is something flexing or binding. Is there a gear/belt reduction? Is it rack and pinion? What is the pitch of the screw on the z? What C&CNC kit did you get? the 300oz, or 620 oz motors? What is your velocity/acceleration tuning?
Lets work through this one thing at a time, and you'll be up and running in no time.
Thanks for replying so quick. Yes, it's a precision plasma gantry, the standard one, not the hd. I'll get pictures up soon. I'm using the Candcnc bladerunner dragon cut, with 300oz motors. Velocity is 600, acceleration 35, steps per inch 1018.59 on the x and y. The z is velocity 50, acceleration 35, steps per inch 24,000. It is rack and pinion with no belt reduction. Pitch on the z screw is the standard 3/8-12.
The gantry travels real smooth by hand(both x and y), no binding or anything. It only looses it's smoothness when under cnc power, on both x and y axis. I haven't tried running any test programs yet, just used the arrows on the keyboard.
It appears that your motor tuning is correct for the x and y. Hopefully you will find the problem with the jerky movement. Look for anything flexing or binding. Also make double sure that the pinion gears are tight on the motor shafts. I assume you have 2 motors driving the y axis? Make sure they slaved and tuned correctly.
The 3 flash code is a z axis driver fault, which occurs when the motor is overloaded.
(1 flash = x, 2 = y, 3 = z, and so on)
at 24,000 sti, and 50IPM, the stepper would be turning 600rpm, which is correct, but you should try reducing the velocity and accel in increments to see if the problem goes away during rapid movements. It appears that it is stalling the motor for some reason. Is the z-axis tight? is the z screw tight in the nut? The 300's dont have alot of torque, and almost none at high rpm.
It shouldn't have faulted while running the motor by itself, but I also saw this problem with my 5th axis, and have yet to resolve the issue, but Tom is working on it. (hopefully).
Yes, 2 motors driving the y axis. I'm going to do some more testing at various speeds on all the axis's, and see what happens. The pinion being tight on the motor shafts seems to be a bit of an issue, the x axis likes to walk it's way up on the shaft, and I can't get that tiny set screw any tighter. I'm thinking of drilling the pinion and the shaft out and pressing in a roll pin, but I'll probably contact tom and Ron first to see if this would cause any warranty issues.
You can drill a small indentation in the shaft, to seat the setscrew in, and apply some locktight to the shaft/pinion also.
Here's a pic of the table just for kicks.
Let's see if this video works. I don't have a camcorder, this is with my little point and shoot camera. This thing makes a lot of racket with the motors, but if I take them off and move it by hand, it's smooth as glass.
http://imageshack.us/clip/my-videos/703/rbk.mp4/
I played around with the settings a little more. I changed the z axis velocity from 50 to 35, and the Candcnc box stopped going into fault mode. If I slow the speed of the gantry down, it still rattles, just not as much.
Just for kicks, I changed all the settings in Mach3 to precision plasma's recommended settings, which for the x and y axis is a velocity of 1000 and acceleration of 50, and the candcnc box goes right into fault if you hold down the shift key and move the gantry at full speed. The fault led blinks 4 times, pauses, then repeats.
Sounds like a box of rocks rattling around. Something's definitely not right.
Ok I don't know if this will help diagnose the problem any, but I unhooked the x axis motor from the candcnc box so I could move it back and forth to watch the pinion alignment, and with the motor gear still engaged to the rack, it rolls smooth, no rattling or anything. The minute I hook it back up and run it under power, it starts rattling again.
I have a mill that runs on mach 3 and steppers, and I was told not to turn the motor while it is connected to the gecko drive. Something about back feeding voltage or something. That's why I unhooked the motor from the candcnc box before turning it in case anyone was wondering.
Wow, watched the video... and I Lean is right... sounds like a box of rocks! Something definitely is wrong.
Lets hope Ron and Tom chime in on this one.
Just for testing sake, could you remove the spring and fasten the motor to the mount. I'd like to see what it runs like if you manually set the pinion engagement to the rack. Perhaps a test with it slightly loose, and one with it snug. It sounds as though the engagement force may be severe, although I cant see why it would.
Just something to check.
Well after talking to Tom today, I've got some of it figured out. I switched computers to the pc in my house, and 95% of the rattling went away. So obviously, it's a computer problem. I say 95% because I still get a rattle here and there, but this computer that is working better is running windows 7, which is not at all supported. It's acting a little weird, like whenever I mouse over icons and files and what not, I here a little click from the motors. Also, the z axis still stalls if I hold down the shift key and jog it. This might not be an issue once I get the machine running correctly, since the thc is making small movements anyways.
I'm about to go through the xp optimization file from the mach3 website and see if I can't get my xp machine figured out.
p.s.
I should also mention I've only had the xp machine for a couple weeks, it's a $65 plus shipping refurbished Ebay special(Dell Optiplex GX620).
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