I am experiencing a new issue with my Lowrider V4. This is my second build and generally things have gone well. However, I started to notice weird misalignments in my cuts. Eventually when I was cutting an arc i noticed that my Y1 stepper just wasn’t moving and caused my piece to be ruined. When I tried to home it Y1 just didn’t move and shook as if it was stuck, but as soon as I have it a nudge it started moving.
Thinking this was a weird fluke I reseated my connections and gave the same cut another go after validating it wasn’t getting stuck and my belts were tensioned.
I started the same cut and the Y1 axis did move but it lost step and over the course of the cut strayed farther and farther from alignment. Once again I tried to home it and it just vibrated without moving. Here are some pictures. They show what the cut did compared to what it should have done. I also took measurements to show how misaligned they were. Once again I tried to home it and Y1 locked up without moving. After giving it a nudge it moved fine. Based on that it would seem the issue is with the stepper itself since it is getting signal from the board and it is attempting to move. However, the stepper doesn’t catch on anything when I move it out of power, and I can jog it back and forth the length of the table without issue when I tried. I am having a hard time determining what is going on. Any help is appreciated
That sounds exactly like a bad wire connection. I know you said you checked your connections, but I would double check them again. The connection at the controller and if its on an extension that connection as well. Look at the DuPont connectors real good and make sure one of the wires didn’t slip back just a little bit.
I will give them a more thorough check. I hadn’t ‘done’ anything with the cnc like touch the wires or crack open the jackpot box so that wasn’t something i was expecting to be an issue. However summer did just hit and its been getting 90+ degrees in the shop. I wonder if that somehow could have let to one of the connections losing integrity
The classic location for this, especially if the problem is on the X axis, is the connection between the motor cable and the extension cable.
Even if the connection looks okay, you may find that the bending and stretching that occurs when the gantry travels along the X axis will put just enough strain on the connector that it causes the motor to stutter and skip in certain locations (ask me how I know…)
The best solution is to bend the cable in an “S” in a way so the connector is inside the S, then tape everything so that the strain on the cable doesn’t pull on the connector itself
I will certainly be taking another look. I didn’t realize a bad connection could cause it just to lock up as well, so i initially didn’t think of doing a second look
Hey guys! I have an update. I double checked my wiring and did not identify an issue. I conducted a few experiments to determine how to replicate and isolate the problem:
I started by homing the Y and jogging it across the length of the table and back. This resulted in a .5 inch deficit for Y2. Looking back at the video there are a few spots where you can see a minor lag on the Y2 side (What is the best way to share videos on here?). I ran the procedure again and the Y2 motor just froze completely.
Next I danced the Y1 and Y2 cables to see if the issue followed… what resulted was the Y2 motor almost instantly locking up when I tried to jog it across the table.
This tells me that the issue is not with the board (I have had some pins die on this board so ESD damage was high on my culprit list) and is either with the wiring or the motor. I did notice that I could move the motor and feel it spin while it was energized, with some resistance. It is like it was partially energized. When I tried to do it again it acted normally. Usually when you try to move the motor when energized the belt just slips and the stepper stays completely locked. This stepper is from an LR3 I built probably 2 years ago at this point. That being said in my 6+ years of 3d printing I have not once had a stepper motor fail on me. Based on the results of my troubleshooting I am led to believe this motor is fluttering out on me… either that or somehow the extender I am using has gone bad. I have my wires neatly protected and organized and am doubtful that the extension went bad.
Well don’t I feel like a silly guy. The little black nuts on the steppers came loose and were colliding with the YZ body. Tightened them up and works like a charm.
I had the braces on mine loosely connected and had collisions as well. The main thing I’ve had issues with since the LR2 are z lifting missed steps due to the weight of my 4’ gantry. Glad you figured it out. Sharp bit and correct feed and speed are the real challenge, but it’s a fun learning experience, which is why we all chose to build this awesome machine!
That’s great news! At some point or another the “silly” things get every one of us. Its great that it ended up being something simple in the end! Glad you were able to find a smoking gun!
It’s half the fun! I also have a 4’ gantry and inherited some of the pain that comes with the reduced rigidity. I have been half tempted to make a second gantry at 2.5 feet and then swap to the 4’ when I need it.
